Table of Content

15 January 2004, Volume 15 Issue 1

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T-square study on spatial pattern and regeneration of Betula albo-sinensis Burkill population on west slope of Jiuding Mountain

LIU Shoujiang, SU Zhixian

2004, (1):  1-4. 

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The T-square study of Betula albo-sinensis population on the west slope of Jiuding Mountain showed that the population was mainly in random distribution, and in aggregated distribution in a few lines because of the negative human activities and severe destructions. In this region, the old trees of Betula albo-sinensis population were accounted for about 24%, and the younger trees only accounted for 12%. There exited a huge difficulty in the self-regeneration of Betula albo-sinensis population. Therefore, some measures should be taken to protect the population and to speed up its self-regeneration.

Dynamics of Amomum villosum growth and its fruit yield cultivated under tropical forests

ZHENG Zheng, GAN Jianmin, FENG Zhili, MENG Ying

2004, (1):  5-8. 

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Investigations on the dynamics of Amomum villosum growth and its fruit yield cultivated under tropical ravine rainforest and secondary forest at different elevations in Xishuangbanna showed that the yield of A.villosum was influenced by the site age, sun light level of understorey, and water stress in dry season. The fruit yield and mature plant density decreased with increasing age of the A.villosum site. The fruit yield increased with sun light level when the light level in understorey was under 35% of full sun light (P<0.05). The fruit yield at the lower site by stream was significantly higher than that at upper site (P<0.05). The yield difference between ravine rainforest and secondary forest was not significant. Planned cultivation of A.villosum in the secondary forest of the shifting cultivation land by ravine from 800～1000m elevation instead of customary cultivation in the ravine rainforest, could not only resolve the problem of the effect of light deficiency in understorey and water stress in the dry season on A.villosum fruit yield, but also be useful to protect the tropical ravine rain forest.

Variations of photosynthetic parameters in CO₂ acclimation of Citrus grandis leaves

SUN Guchou, ZHAO Ping, ZENG Xiaoping, PENG Shaolin

2004, (1):  9-14. 

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Plastic pots with sand and vermiculite were used to grow Citrus grandis saplings,and 0.05mmol P (normal P level,P) and 0.1 mmol P (higher P level,2P) nutrient solution were supplied every week. The saplings were grown under atmospheric CO₂ (about 39 Pa) and doubled CO₂ partial pressure (81±5Pa) for 45d. The Pn-Pi curve was measured under higher irradiation (1150 μmol·m^-2 ·s^-1) by CI-301PS Photosynthesis System (CID,Inc),and the Pn-PAR curve was measured under higher CO₂ partial pressure (PCO₂ 56 Pa).The results showed that the maximum rate of photosynthesis for 2P plants was 13.3% higher than that of P plants under atmospheric CO₂ partial pressure. Regardless of P and 2P plants,the maximum photosynthetic rate under doubled CO₂ partial pressure was lower than that under atmospheric CO₂ partial pressure,but the photosynthetic rate of 2P plants was higher than that of P plants under doubled CO₂ partial pressure. 2P plants had a higher apparent quantum efficiency and light energy conversion efficiency (P<0.05) than P plants,but no change in Γ^*,Rd and the ratio between carboxylation rate (Vc) and oxygenation rate (Vo) of Rubisco (P>0.05) wwere found. The V_cmax and J_max of 2P plants were 8.3% and 12.5% higher than those of P plants under atmospheric CO₂ partial pressure,respectively,and 2P plants also had higher V_cmax and J_max than P plants under double CO₂ partial pressure. The partitioning coefficient of leaf nitrogen in Rubisco and in thylakoid light-harvesting component was varied in CO₂ acclimation,but it was not in bioenergetics.It may suggest that an increasing phosphorus supply would promote the phosphorus turnover in photosynthetic carbon cycle,and increase the photosynthetic rate under doubled CO₂ partical pressure.Increaing phosphorus supply may be a way to regulate the photosynthetic parameter of plants in CO₂ acclimation.

Dynamics of forest landscape boundary at Changbai Mountain

CHANG Yu, BU Rencang, HU Yuanman, XU Chonggang, WANG Qingli

2004, (1):  15-20. 

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By using Geographic Information System (GIS) abstract and Remote Sensing (RS) abstract technology combined with field investigation and correlation analysis, this study was aimed to explore the dynamics of forest landscape boundary at Changbai Mountain, and to reveal the relationships among landscape fragmentation and changes of landscape boundary indices. The results showed that in the last 20 years or so, tundra decreased by 3694.8 hm², spruce and fir forest reduced by 130482.03 hm², and Korean pine-hardwood and mountain birch forest increased by 41610.4 hm² and 669.78 hm², respectively. The forest landscapes at Changbai Mountain tended to be more fragmented, and the shape of the landscape boundary became more complicated due to timber harvesting, forest cutting for cropping, and other human activities such as tourism. The changes of landscape shape index (LSI) abstract, contrast weighted edge density (CWED) abstract, total weighted edge length (TE-WGT) abstract and weighted landscape shape index (LSI-WGT) abstract could be used as good indicators for the degrees of forest landscape fragmentations, which was approved by correlation analysis among landscape fragmentation and changes of landscape boundary indices. The degree of human activities on landscape could be reflected by landscape shape index.

Patch size distribution pattern and its hierarchical effect of main landscape types in the Wuyishan scenery district

HE Dongjin, HONG Wei, HU Haiqing, WU Chengzhen

2004, (1):  21-25. 

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Based on the principles of landscape ecology and community ecology,the Wuyishan district was classified into 10 landscape types,and the patch size distribution of this district was characterized by six types of probability distribution,including normal,lognormal,Weibull,Gamma,Beta and negative exponential.The results showed that most of patch types could be characterized by lognormal distribution,a few of them could be characterized by Gamma or Weibull distribution.Normal distribution was not suitable to characterize the patch size distribution.For the same type of landscape,its patch size distribution was not the same under three different classifications,which meant that there was a hierarchical effect in the distribution pattern of patch size.Among the three classifications,the distribution characteristics of patch sizes could be better revealed by the second classification(b) abstract For different types of landscape,the distribution of patch sizes were different.None of the six probability distributions could characterize the patch size distribution of all the types of landscape or the whole scenery district.The new patch collective,which was composed of the two landscape types,would keep the pattern if the two different landscape types had the same distribution pattern of patch sizes,otherwise,its distribution would change if the patch sizes distribution of the two landscape types were different.

Effects of vegetation types and landscape features on soil properties at the plateau in the upper reaches of Minjiang River

LIU Shiliang, FU Bojie, MA Keming, LIU Guohua

2004, (1):  26-30. 

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Spatial heterogeneity is one of the important properties of soil. In this paper, the classical statistics method and the principles of geostatistics were used to study the spatial heterogeneity of soil properties on the Tibet plateau in the upper reaches of Minjiang River, and the relationship between vegetation type, landscape position and soil factors. Semivariogram analyses showed that there existed high degrees of spatial heterogeneity in soil moisture and soil nutrients. The test quadrats were assorted into three groups according to the landscape position and vegetation types, and then statistical analyses were made. The taxon results showed that different vegetation types had great effects on soil nutrients, and elevation was also an important factor influencing soil properties. A comprehensive index of soil properties showed that shrubs had the highest soil quality. The same trend of soil nutrients was found in the category of landscape positions. The soil nutrient contents decreased in the order of lower slope>upper slope>middle slope for the lower altitude hill, and lower slope> middle slope> upper slope for the high altitude hill. The results elucidated that the spatial heterogeneity of soil property was the result of the interaction between landscape factors and vegetation types.

Spatial neighboring characteristics among patch types in oasis and its ecological security

JIAO Yuanmei, XIAO Duning

2004, (1):  31-35. 

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In this paper, the spatial neighboring length and number between oasis types and desert or salina-marsh in the Jinta Oasis located in the arid Heihe River Basin of Northwest China were calculated by using ArcView3.0a and buffer zone analysis methods, and the threatening degree of oasis ecological security was discussed. The results indicated that it was different in neighboring length and number between oasis types and desert or salina-marsh, and the influencing area by desert and salina-marsh patches was also different. Grassland and farmland had more neighboring length and numbers with desert or salina-marsh patches, and impacted by desertification seriously. Forest and farmland had more length and numbers adjacent to salina-marsh, and influenced by salinization severely. The assessment of ecological security based on spatial analysis could reveal the threatening degree of oasis by desertification and salinization.

Accuracy evaluation of land vegetative cover index by RS detection

ZHOU Zhongxuan, WU Gang, SHAO Guofan

2004, (1):  36-38. 

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The accuracy of GIS data is important in GIS application. In this paper, a fictitious case and an example were used to discuss the relationship between accuracy of land vegetative cover index and accuracy of image classification, and this relationship was explained by mathematics. The accuracy of land vegetative cover index rested with the accuracy of image classification, but had no direct relations with total classification accuracy. User accuracy and producer accuracy had more direct control on the accuracy of land vegetative cover index than total classification accuracy; and hence, they could not be ignored in the image classification. To improve the accuracy of land vegetative cover index, user accuracy and producer accuracy of the same land type should be consistent to the greatest extent.

Root growth dynamics of Adenophora potaninii populations and its relation with environmental factors in northwest Sichuan Province

ZHANG Wenhui, LIU Xiangjun, LIU Guobin, MA Keming

2004, (1):  39-43. 

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In this paper, the dynamics of the root biomass and form development of Adenophora potaninii populations in different natural habitats in Northwest Sichuan were studied, and the factors influencing the root growth and form development were analyzed. The root biomass accumulation process of the mean individuals of the whole A.potaninii population in its life could be expressed by Logistic equation. From 1～3 years, the root length grew fast, but the root biomass accumulated slowly. From 4 years old, the root system developed in high speed, and the fast growth period of the root system could maintain until 15 year old. The basic patterns of root biomass accumulation process of different A.potaninii populations at different altitudes were similar to that of the whole population. However, the root system accumulation and root development was related closely with habitant conditions, and the root forms of different populations at different altitudes were significantly different (P<0.05) abstract At middle altitude (2800～3300m) abstract, the biomass and form of root system could achieve a higher level, and the good harvest of root biomass could be obtained because of the favorable soil and climate conditions, and the less external disturbance of human beings. Therefore, this area could be an important base for A.potaninii population to grow. Whereas at the lower altitude (2600～2800m) abstract, the biomass accumulation and the form development of root system were confined and maintained at a lower level because of the drought climate and the external disturbance of human beings. At the higher altitude (3300～3500m) abstract area with the harsh habitats, especially with lower temperature and lower pH, the root biomass of the mean individuals was significantly lower, and the individual form of root system was smaller, compared with that at middle altitude area. In order to use natural A.potaninii resource sustainablely, all the area should be planned, and the reasonable rotational prohibition of grazing and digging should be carried out.

Diversity and resistance of rhizobia isolated from Caragana intermedia in Maowusu sandland

GAO Lifeng, DENG Xin, WANG Hongxin, HU Zhiang

2004, (1):  44-48. 

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Fifteen rhizobia strains were isolated from wild shrubby legume Caragana intermedia in Maowusu sandland. A dendrogram was constructed based on esterase profiles, showing a rich diversity of these rhizobia. Many biochemical characteristics were detected, including acid or alkali production, catalase activity, utilization of sole carbon sources, and resistance to salt, acid-alkali and temperature variation. The results indicated that all the rhizobia strains isolated from Caragana intermedia could excrete H⁺ on YMA agar and produce catalase. 73.3% strains could tolerate NaCl stress at 3% concentration, and 80% strains could grow at 50℃.Except the difference in lactose and starch utilization, rhizobia strains had no bias on the rest carbon sources. However, the difference in resistance to stress existed among strains, which might be related to the adaptation of rhizobia to diverse landscapes in Maowusu sandland. It was revealed that rhizobia nodulating Caragana intermedia could be used as a new germplasm to fix nitrogen under severe environment.

Estimation of aboveground biomass of desert plants

ZHAO Chengyi, SONG Yudong, WANG Yuchao, JIANG Pinan

2004, (1):  49-52. 

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Based on the research of plant quadrate in Sangong River Basin in Xinjiang, the fitted equations were given, which could be used to estimate the aboveground biomass of typical desert plant by using the thicket characteristics such as length of crown diameter, width of crown diameter, number of basal branch, length of new branch, basal diameter (D) abstract and plant height (H) abstract as parameters. Using the length of crown diameter and the width of crown diameter as parameters, the fitted equation was set up and tested for estimating the aboveground biomass of Reaumuria soongorica Maxim. It had a relatively high accuracy and a fine linear relationship between the predicted values and measured values. Its coefficient and relative standard deviation was 0.9989 and 4.79%～10.12 %, respectively. The results indicated that the fitted equation was easy and available for estimating the aboveground biomass of Reaumuria soongorica Maxim in large scale. The fitted equations were also set up and tested for estimating the aboveground biomass of Haloxylon ammodendron and Tamarix ramosissima by using the basal diameter and height of plant as the parameters. The coefficients and relative standard deviations of these equations were 0.9902, 0.9875 and 6.87% ～19.22%, 7.49%～18.47%, respectively. Therefore, estimating the biomass of Reaumuria soongorica in large scale through crown characteristics was available, and estimating the biomass of Haloxylon Ammodendron and Tamarix ramosissima through crown characteristics would produce certain error.

A preliminary study on salt contents of soil in root-canopy area of halophytes

XI Jinbiao, ZHANG Fusuo, CHEN Yang, MAO Daru, YIN Chuanhua, TIAN Changyan

2004, (1):  53-58. 

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The results showed that among the 27 sampling sites, the salt content in rhizosphere of herbaceous halophytes increased at 7 sites and decreased at 20 sites. The variation of soil salt content in the RUE micro-area of shrubby halophytes was related to the growth status of the plants. The salt content in rhizosphere decreased a little at the early stage of plant development, but that in RUE micro-area tended to increase and accumulated most quickly at the site of the canopy edge soil.An obvious variation of salt components was found in the RUE micro-area of different types of halophytes. The Na⁺/K⁺ ratio tended to decrease in succulent halophytes and salt secrete halophytes. Among 53 sampling sites, only 14 sampling sites had a higher ratio of Na⁺/K⁺ in rhizosphere soil than in background soil, and only 10 sampling sites had a higher ratio of Na⁺/K⁺ in canopy-under soil than in background soil. However, the Na⁺/K⁺ ratio in the canopy edge soil of Tamarix and Nitraria tended to increase when they grew weakly. By contraries, the Na⁺/K⁺ ratio in the rhizosphere was higher than that in background soil at 3 of 4 sampling sites of Phragmites australia, which indicated that the Na⁺/K⁺ ratio in the rhizosphere of exclude halophytes tended to increase. The variation of SO₄^-2/Cl^- ratio in the RUE micro-area was different in the 3 types of halophytes. For salt secrete halophytes, it decreased obviously in rhizosphere soil, canopy-under soil and canopy-edge soil; for succulent herbaceous halophytes, it tended to increase in rhizosphere soil; and for succulent shrubby halophytes, it tended to decrease in rhizosphere and in canopy-under soil, and tended to increase in canopy-edge soil. The SO₄^-2/Cl^- ratio had no big change for exclude-halophytes. The reduction of the salts in rhizosphere of herbaceous halophytes was mainly because of their plant uptake, and the accumulation of salts in the RUE micro-area of shrubby halophytes was because the salt absorbed from the around soil returned to the RUE micro-area again. Because of the selective uptake by plant, the salt component varied with different types of halophytes. Most halophytes except Phragmites australia take more Na⁺, and hence the Na⁺/K⁺ ratio in the rhizosphere tends to decrease. The SO₄^-2/Cl^- ratio in the RUE micro-area of salt secrete halophytes trended reduce, mainly because this type of halophyte can secrete more Cl^- with its growth.

Population development characteristics of rice crop cultivated on aerobic soil with mulching

SHENG Haijun, SHEN Qirong, FENG Ke

2004, (1):  59-62. 

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Field experiments were carried out to study the population development characteristics of rice crop cultivated both on aerobic and waterlogged soil conditions. The results showed that the whole growth duration of rice growing on aerobic soil was one week longer than that on waterlogged soil. Shorter and narrower leaves and smaller LAI of rice population were found on aerobic soil than on waterlogged soil, which resulted in a decreased photosynthesis, smaller amount and lighter weight of rice grains on aerobic soil, compared with those on waterlogged soil. Among the aerobic treatments, more tillers, lower percentage of filled grains and shorter duration of grain forming were found on soils covered with plastic film than on soils covered with semi-decomposed straw or without mulching. The rice grain yield was decreased in the order of waterlogged soil > aerobic soil covered with plastic film > aerobic soil covered with semi-decomposed straw >aerobic soil without mulching.

Effect of short-term drought on leaf water potential,photosynthesis and dry matter partitioning in paddy rice

HU Jichao, JIANG Dong, CAO Weixing, LUO Weihong

2004, (1):  63-67. 

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Pot experiments were conducted to study the effect of short-term drought at four rice growth stages on leaf water potential, photosynthesis and dry matter partitioning in paddy rice. The leaf water potential of rice plant under water stress was lower than that of CK, and the difference increased after midday.The predawn leaf water potential of rice plant decreased significantly when soil water content or soil water potential went down a threshold value, resulted in an obvious decline in the single leaf net photosynthetic rate. In compared with the well-watered treatment, the net photosynthetic rate under severe water stress decreased by more than 50%. The partitioning indexes of leaf, root and spike decreased, while that of stem and sheath increased after short-term drought.

Impact of localized compaction and ridge fertilization on field nitrate transport and nitrate use efficiency

ZHAO Yunge, SHAO Ming'an, ZHANG Xingchang

2004, (1):  68-72. 

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The primary season of nitrate leaching in the Loess Plateau region is the monsoon,which is caused by heavy rainfall during the growth season of corn (Zea mays L.) abstract Nitrate leaching to groundwater is an increasing concern in agriculture,and is one of the major nitrogen losing ways in dryland farming system.Localized compaction and ridge fertilization is a method for nitrogen fertilizer application,by which,less fertilizer leaching would occur.The NO₃^--N transport in soil profile,corn yields and nitrogen use efficiency under localized compaction and ridge fertilization were investigated through two years field study.The factors that affect NO₃^--N transport under localized compaction and ridge fertilization were studied,combined with simulated experiment. The results showed that NO₃^--N was leached to below 90cm in plat fertilization in the year of about 370mm rainfall,a mean precipitation during the season,while the NO₃^--N leakage of the fertilizer zone was reduced by localized compaction and ridge fertilization,as a result that the NO₃^--N concentration below 60cm was less than 10mg·kg^-1,and NO₃^--N accumulated in 20～40cm with a concentration 80～90 mg·kg^-1. There was no significant difference in yield between application methods with 240.0kgN·hm^-2. However,the absorbed amount of nitrogen was improved significantly by localized compaction and ridge fertilization,and the nitrogen use efficiency was increased by 9%. The bulk density of the barriers had an evident effect on NO₃^--N transport under localized compaction and ridge fertilization,but the effect of ridge slope was insignificant.

Effects of soil available silicon on growth,development and physiological functions of soybean

LI Qingfang, MA Chengcang, LI Hanping, XIAO Yunli, LIU Xueyan

2004, (1):  73-76. 

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Soybean plants were planted in pots to investigate the effects of soil available silicon on their growth, development and physiological functions. When the content of soil available silicon was 55.1～202.8 mg·kg^-1, the protease and lipase activities of germinating seed were increased with increasing soil available silicon content, amylase activity had no obvious change, and the respiration rate of seedlings was accelerated. The bioactivity of seed was increased, but the germination rate had no significant change. The photosynthesis rate, root activity, and nitrate reductase activity of soybean seedlings were enhanced, but the chlorophyll content in leaves had no significant change during seedling growth. The transpiration rate was decreased, while the water utilization efficiency and leaf water content were increased, and the capacity of drought-resistance was promoted. When the available silicon content was >202.8 mg·kg^-1, the abovementioned physiological functions had no significant changes. There was a positively linear relationship between the silicon content in soybean seedlings and the available silicon content in soil (r =0.994) abstract It could be concluded that the silicon absorbed from soil improved the physiological functions of soybean germinating seed and seedlings. As a result, the seed germination and seedlings growth rate were enhanced.

Effects of zinc and boron nutrition on balsam pear (Momordica charantia) yield and quality,and polyamines,hormone,and senescence of its leaves

SHI Mutian, CHENG Rukai

2004, (1):  77-80. 

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Field trial and physiological determination on the effects of zinc and boron nutrition on balsam pear (Momordica charantia) abstract yield and quality and on polyamines, hormone, and senescence of its leaves showed that application of ZnSO₄?7H₂O and Na₂B4_O7?10H₂O on Zn and B deficient soils could increase balsam pear yield and its contents of protein, Vc and 17 sorts of amino acids, especially the contents of essential amino acids for human body, but decrease the NO₃^--N content. The reason was that Zn and B could increase polyamines (PAs) abstract, putrescine (Put) abstract, spermidine (Spd) abstract, spermine (Spm) abstract, indole acetic acid (IAA) abstract, gibberellic acid (GA₃) abstract and ascorbic acid (ASA) abstract contents and superoxide dismutase (SOD) abstract, peroxidase (POD) abstract and catalase(CAT) abstract activities, and reduce malondialdehyde (MDA) abstract, abscisic acid (ABA) abstract contents in leaves, which inhibited membrane lipid peroxidation. The results also showed that there was a significant positive correlation between yields and PAs, Put, Spd, Spm, GA₃, SOD, POD, CAT, but a significant negative correlation with MDA and ABA contents in leaves. There was a significant positive correlation between MDA and ABA, but a significant negative correlation with PAs, Put, Spd, Spm, IAA, GA₃, ASA, SOD, POD, and CAT.

Effects of different application rates of humic acid compound fertilizer on pepper and its mechanism of anti-senility and incremental yield

SUN Zhimei, XUE Shichuan, LIANG Wenju, LIU Yuzhu

2004, (1):  81-84. 

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The effects of different application rates of humic acid compound fertilizer (HA) abstract on the yield and physiological characteristics of pepper (Capsicum frutescens L.) abstract were studied in this paper. The results showed that different application rates of (HA) abstract could affect the physiological activities and yield of pepper. The nitrate reductase activity (NRA) abstract and peroxidase (POD) abstract activity were improved with increasing application rate, but the change rate of NRA was reduced gradually. POD activity in inorganic compound fertilizer treatment was improved significantly when the application rate of fertilizer was higher than 0.3 g穔g^-1,but that in HA treatment changed smoothly. Superoxide dismutase (SOD) abstract activity was improved significantly when the application rate of fertilizer was lower than 0.2 g穔g^-1, and decreased gradually when the application rate was higher than 0.2 g穔g^-1. The change of transpiration rate was consistent with that of SOD activity. The relationship between the application rate of fertilizer and the yield of pepper could be described with quadratic curve regression model. According to the equation, the highest application rate of HA should be 0.27 g穔g^-1, and the highest yield of pepper could reach 165.22g per pot.

Temporal and spatial structure of carabid community in agricultural landscape of Dongbeiwang,Beijing

LIU Yunhui, YU Zhenrong, LIU Yun

2004, (1):  85-90. 

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From May to October 2000, the carabid beetles in the habitats of woodland, field margin and crop field in Dongbeiwang agroecosystem in Beijing were investigated by pitfall traps, and the temporal and spatial structure of carabid community was analyzed. The results indicated that the numbers of both carabid species and individuals were much higher in the field margin and woodland than in the crop field. Both dominant species and rare species tended to live in field margin and/or woodland. Field margins had a positive effect on the diversity and richness of carabid community in their adjacent crop fields. The modest disturbance (plowing in autumn) abstract in the field margin was beneficial for the increase of the individual number of carabid community, and the treatments of irrigation, fertilization and straw return in field had no effects on both the individual and species number of carabid community. Furthermore, the threatening condition to some carabid species was discussed, based on the analysis of the temporal and spatial dynamics of carabid community.

Edge effect on the dynamics of pests and natural enemies in cotton agroecosystems

GE Feng, MEN Xingyuan, SU Jianwei, LIU Xinghui, DING Yanqin

2004, (1):  91-94. 

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Investigation on the population dynamics of pests and natural enemies on the cotton plants in the middle and edge of cotton agroecosystems showed that the population of the 2nd generation of cotton bollworms (Heliocopavar armigia) abstract and seedling aphids (Aphis gossyppi) abstract was respectively 1.94 times and 1.09 times higher, but that of the 3rd generation cotton bollworms and summer aphids population was respectively 62.12% and 97.73% lower in the edge than in the middle of cotton agroecosystem. The population of predacious ladybeetles, predacious bugs, spiders and parasites in the edge of cotton agroecosystem was 73.81%, 35.79%, 52.90% and 39.11% of that in the middle of cotton agroecosystem, respectively. The greater diversity of pest community and the less diversity of natural enemies community were found in the edge than in the middle of cotton agroecosystem. The increase of energy utilization efficiency and gross production in the edge of cotton agroecosystems showed the edge effect of cotton agroecosystems.

Effects of imidacloprid on arthropod community structure in tobacco field

WU Houzhang, CHENG Xianian, WEI Chongsheng, ZOU Yunding

2004, (1):  95-98. 

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The effects of imidacloprid on the structure of arthropod community and its sub-communities were analyzed. The results showed that after applied imidacloprid, the species number of arthropod community and its pest sub-community was influenced, but that of its natural insect enemy and spider sub-community was not influenced obviously. The individuals of arthropod community and its pest sub-community in both treatment plot (Ⅱ) abstract and control plot were decreased after the application of imidacloprid on May 23 to June 13, and the decline degree in treatment plot was larger than that in control plot. The individuals of arthropod community and its pest sub-community at treatment plots had a large decrease, and that in control plot had a large increase after imidacloprid application on June 14. Twice applications with imidacloprid did not reduce the number of the individuals of natural insect enemy and spider sub-community obviously. The individuals of tobacco aphids who were dominant in tobacco field decreased obviously within a period of time after application, and hence, the dominant concentration of arthropod community and its pest sub-community declined, and the diversity and stability increased.

Effects of low and subzero temperature on a Plutella xylostella laboratory population

CHEN Feizhou, LIU Shusheng

2004, (1):  99-102. 

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In this study, the effects of low (< 8 ℃) abstract and subzero temperature on the development, survival and reproduction of Plutella xylostella were examined. The mortality of its egg and pupae at 4℃ and 6℃ increased with time, no egg and pupae could complete their development at these low temperatures, and all died after 55 days and 70 days, respectively. When the pupae were placed at 4℃ and 6℃ for various durations and then moved to 16℃ for development, the fecundity of the resultant adults was reduced, and the longer the duration at 4℃ and 6℃, the further the fecundity was reduced, and the fecundity was reduced to zero when the pupae were retained at these low temperatures for 45 days. The survival of this insect was observed following exposure of various stages of this insect to temperatures below 0℃. The results showed that the mortality of all preimaginal stages increased with decreased temperature and prolonged duration. The ability of cold tolerance of the various stages of this insect was in order of the third instar and pupa > the second and forth instars >the first instar and egg. Temporal exposure to temperatures below 0℃ affected the development of subsequent stages at a favorable temperature. Generally, the developmental time of the subsequent stages increased, and the largest increase of development time was observed with the stage next to the stage treated at low temperatures. Exposure of the pupal stage to low temperature also reduced the fecundity of the resultant female adults, and the reduction was positively correlated to lower temperature and longer exposure.

Experimental population ecology of Carcelia matsukarehae Shima (Diptera:Tachinidae)

ZHOU Changqing, WENG Zhongyan

2004, (1):  103-107. 

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This paper dealt with the developmental zero, effective accumulated temperature, adult longevity, adult fecundity and specific life table parameters of tachinid fly Carcelia matsukarehae at temperature 15℃, 18℃, 22℃, 25℃, 29℃, and 32℃, relative humidity 70%～85%, and photoperiod L:D=12:12. The results showed that the developmental zero and effective accumulated temperature for generation were 5.23℃ and 525.73 day-degree, respectively.The adult longevity was 1.35～8.06 days without supplying nutrient but water, and while fed with 30% honey water, their longevity could prolong to 9.63～36.42 days.The optimum temperature for oviposition was 23.6 ℃, maximum eggs laid by a female were 86.The optimum temperature for population growth was 22～25℃. The specific life table parameters of experimental population under temperature 22℃ and 25℃ were calculated. At 22℃, R₀,T₀,r_c and λ were 24.89, 37.33, 0.086 and 1.089, respectively, and at 25℃, they were 20.01, 32.38, 0.09 and 1.10, respectively. The maximum L_xM_x occurred from the 33rd day to the 38th day after adult emergence at temperature 22℃, and from the 29th day to the 34th day at 25℃.

Relationship between occurrence of Dryocosmus kuriphilus and development of cecidum

DING Yuzhou, BI Shoudong, FANG Guofei, HE Lin

2004, (1):  108-110. 

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Dryocosmus kuriphilus is one of the most important pests on chestnut in China, and cecidum is the jeopardized result of Dryocosmus kuriphilus.Under natural condition, the growth status of different cecidum of Dryocosmus kuriphilus was differed, and the weight of individual cecidum was submitted to normal distribution. The zooecium number was positively related to cecidum quality and volume. For three different varieties of chestnut, their resistance to Dryocosmus kuriphilus were different, and the order was Chushuhong > Mifengqiu > Ershuizao. Torymus sinensis Kamijo was the dominant natural enemy. The cecidum-parasitized ratio was 72.7%, and the zooecium-parasitized ratio was 24.06%.

Techniques of diseases,insect pests and weeds control and their efficacy in bio-rational rice production

LI Baotong, SHI Qinghua, FANG Jiahai, PAN Xiaohua

2004, (1):  111-115. 

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Studies on the efficacy of bio-rational pesticides and agricultural methods against the chief diseases, insect pests and weeds of rice showed that the efficacy of the mixtures of jingangmycin and bacillus-cereus, and jingangmycin and polyoxin against rice sheath blight were 75.16%～94.27% after sprayed once at the tiller and boot end stages of rice, respectively, and better than that of chemical fungicide triadimefon. The efficacy of kasugamycin and blasticidin was 50.54%～72.67% on rice leaf blast and 76.66%～87.42% on rice head blast, and equal to the chemical fungicide tricyclazole after sprayed once at the initial stage of rice leaf blast occurrence and the initial and end stages of earing, respectively. The efficacy of bacillus thuringiensis on Chilo suppressalis and Cnaphalocrocis medinalis was better than that of chemical insecticide bisultap, and the efficacy of saponin-nicotine and matrine was equal to that of chemical insecticide bisultap when the three biorational insecticides were sprayed at 1～2 instar larvae of pests. The efficacy of saponin -nicotine and matrine was above 70%, and lower than that of chemical insecticide imidacloprid 3～30d after sprayed at 1～2 instar larvae of Nilaparvata lugens. The occurrence of weeds could be controlled, and the rice yield could be raised when the suitable non-thorough decomposed organism was applied or weeding was carried after the field had been ploughed twice before rice transplant. The rice yield could be raised by using biorational pesticides and agricultural methods against the chief diseases, insect pests and weeds of rice. The residue of pesticides in rice was lower in the bio-control area than in the chemical control area, according with the demands of health target of green food.

Removal of red tide organisms by organo-modified bentonite

DENG Yuesong, XU Zirong, XIA Meisheng, YE Ying, HU Caihong

2004, (1):  116-118. 

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A series of organo-bentonites were synthesized by exchanging cation surfactants such as cyltrimethylammonium bromide and cetyltrimethylammonium to remove red tide organisms Skeletonema costatum.The results showed that the removal rate of Skeletonema costatum by the bentonites was in the order of cyltrimethylammonium surfactant modified iron pillared bentonite>cetyltrimethylammoium surfactant modified iron pillared bentonite>iron pillared bentonite>cyltrimethylammonium surfactant modified sodium bentonite>cetyltrimethylammoium surfactant modified>sodium bentonite. The removal rate of Skeletonema costatum was related to the length of alkyl chains and the amount of cation surfactants exchanged on bentonites.

Effect of copper pollution on seedling growth and activate oxygen metabolism of Trifolium pratense

CHU Ling, LIU Dengyi, WANG Youbao, LI Ying, LIU Huijun

2004, (1):  119-122. 

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The effect of copper (Cu) abstract pollution on the seedling growth and activate oxygen metabolism of Trifolium pratense was studied by water cultivation experiments.The results showed that under low concentration of Cu (<10mg·L^-1) abstract, the growth of Trifolium pratense seedlings could be improved, their fresh/dry weight and the contents of soluble protein and chlorophylls in leaves increased slightly, the MDA content of leaf cells decreased, the activities of SOD, CAT and POD in the activate oxygen metabolism system slightly increased, and the balance of protective enzyme system was hold. However, with the increase of Cu concentration (10～100mg·L^-1) abstract, there existed an obvious negative effect on the growth of Trifolium pratense seedlings. The seedlings under high concentrations of Cu were shorter and smaller, their fibrous roots were shorter and fewer, and their fresh/dry weight and the contents of soluble protein and chlorophylls in leaves decreased drastically. With the increase of Cu concentration, the membrane penetration, electric conductivity and MDA content of leaf cells increased. Furthermore, the activate oxygen metabolism system was destroyed, the balance of protective enzyme system was broken, the activities of SOD and CAT decreased by 26.67% and 71.31%, respectively, while the POD activity increased by 10.6 times.

Heavy metal concentration in Nanjing urban soils and their affecting factors

LU Ying, GONG Zitong, ZHANG Ganlin, ZHANG Bo

2004, (1):  123-126. 

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The concentration and source of heavy metals in Nanjing urban soils and their relationships with soil properties were studied. The results indicated that the soils in Nanjing urban were not obviously polluted by Fe, Ni, Co and V, but polluted by Mn, Cr, Cu, Zn, and Pb to a certain extent. The heavy metals were irregularly distributed in soil profiles. Fe, Ni, Co, and V were originated from soil materials, but Cu, Zn, Pb, and Cr were anthropogenic input. Probably, Mn had different origins in different soils. There were positive correlations among Fe, Cr, Ni, Co, and V concentration, and among Cu, Zn, Pb, and Cr concentration. The Fe, Co, V, and Ni concentration were positively correlated with soil clay content and CEC, and the Cu, Zn and Pb concentration were negatively correlated with clay content. There were positive correlations between Cu, Zn, Pb and Cr concentration and organic C content, and between Pb concentration and soil pH.

Effect of acid rain,copper,and atrazine on soil hydrolase activity

LIU Guangshen, XU Dongmei, LI Kebin, LIU Weiping

2004, (1):  127-130. 

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The effects of acid rain, Cu²⁺ and atrazine on the activities of soil urease, invertase and acid phosphatase were studied by means of orthogonal test. The results showed that the inhibition rate was H⁺>Cu²⁺, and atrazine had no significant influence on urease and intertase. Interaction analysis revealed that Cu ? atrazine exhibited synergism on soil acid phosphatase activity, Cu譎 had antagonism on soil invertase and urease, but atrazine ? H had no interaction within the investigated concentration range. Among the three enzymes, soil acid phosphatase was the most sensitive one to the contaminations.

Accumulation and distribution of lead in Macrobrachium nipponense

LU Xingjia, XI Yilong, LIU Guiyun

2004, (1):  131-135. 

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The accumulation and distribution of lead granules in the major organs of Macrobrachium nipponense were studied by means of histochemistry, transmission electron microscope (TEM) abstract and atomic absorption spectrophotometer (AAS) abstract analysis. The results showed that many high electronic dense lead granules (EDG) abstract were found primarily in the antennal gland of this species exposed to 0.625 mg稬^-1 Pb²⁺ for 10 days. Under TEM, lead granules were deposited in lysosome, then gradually accumulated in cell apex, and finally individually discharged into gland lumen by apocrine secretion and excreted with urine. There was a small quantity of lead granules in the cells of midgut. Many vacuolus were observed in the cytoplasm of the cells, and the nuclear membranes and cristae in mitochondria were disintegrated partially. The structure of hepatopancreas cells basically remained intact, although there were a few of lead granules in the cells. No lead granule was found in the cells of gills, but a few of lead granules adsorbed on the surface of gill filaments among the gill filaments. The highest concentration (637.6 mg穔g^-1) abstract of lead was found in antennal gland by AAS, suggesting that the antennal gland might play an important role in detoxifying process of lead.

Quantification of non-point sources phosphorus pollution in key protection area of Taihu Lake

GUO Hongyan, WANG Xiaorong, ZHU Jianguo

2004, (1):  136-140. 

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The distribution of various kinds of non-point sources phosphorus pollution in Xueyan Town,Wujin city,Taihu area was researched through field experiments and local investigation during rice growth season. The results showed that of all kinds of phosphorus pollution,about 56.2% (1313 kg P) abstract was from farmland,22.2% (518 kg P) abstract was from town residents,18.9% (442 kg P) abstract was from village residents,and 2.7%(62 kg P) abstractwas from livestock. Besides the strict control of the phosphorus pollution from farmland,attention should also be paid on the control of domestic water pollution from towns and villages.

River continuum characteristics of Xiangxi River

TANG Tao, LI Daofeng, PAN Wenbin, QU Xiaodong, CAI Qinghua

2004, (1):  141-144. 

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The density of epilithic algae and concentration of chlorophyll a, Shannon-Wiener index and primary productivity were chosen to study the river continuum characteristics of Xiangxi River.The results showed that in general,the algal density,chlorophyll a concentration and Shannon-Wiener index tended to be increased with increasing stream order,but this trend was not very evident in the first three orders and even reversed. The primary productivity was also higher in the higher than that in the lower stream orders, and reached the maximum in the fourth order, then decreased slightly.The ratio of gross primary productivity to community respiration was the highest in the first stream orders, which means autochthonous productivity was dominant in the river. The results did not absolutely tally with the RCC forecast, therefore,we can conclude that Xiangxi River had been undergone anthropogenic influence.

Allelopathic effects of secalonic acid F produced by Aspergillus japonicus on Zea mays

ZENG Rensen, LUO Shiming, SHI Yuehong

2004, (1):  145-148. 

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Aspergillus japonicus Saito is a common soil-borne fungus, and exists on the surface of some cereal crop seeds. Secalonic acid F (SAF) abstract is the main allelochemical from the fungus. Bioassays showed that SAF significantly stimulated the seedling growth of corn (Zea mays L.) abstract at a concentration of 0.0375 mmol稬^-1. The root length, root numbers and root oxidation activities increased by 31.7%, 13.2%, and 373%, respectively. Secalonic acid F also increased the nutrient absorption of P, K, Ca, Mg, and S at the same concentration. However, SAF inhibited the seedling growth of corn at concentrations of 0.3 mmol稬^-1 and 0.6 mmol稬^-1. The root length, root dry weight, and shoot length were inhibited by 27.7%, 39.1% and 35.8% by 0.3 mmol稬^-1 of SAF, and root activities were inhibited by 72.1% and 100% by 0.3 mmol稬^-1 and 0.6 mmol稬^-1 of SAF, respectively. The nutrient absorption of N, P, K, Ca, Mg and Fe was reduced when the corn seedlings were treated with 0.3 mmol稬^-1 SAF. Transmission electron microscope observations showed that the corn treated with 0.3 mmol稬^-1 of SAF had a swelling and disorderly arrangement chloroplast, and the stratiform structure of chloroplast became unconspicuous.

Bioactivity of volatile oils from Myoporum bontioides on Plutella xylostella

HE Yanbiao, HE Tingyu, GU Wenxiang, XIAN Jidong, ZHANG Maoxin, FENG Liping

2004, (1):  149-152. 

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This study showed that the volatile oils from Myoporum bontioides had a significant repellent action on Plutella xylostella.When Plutella xylostella adults entered into the 4-arm selective olfactometer,the preferred times and average staying duration,in the order from more to less,were 3,1,4,and 2 arms,which showed a tendency of keeping away from the treatment arms. The males were more sensitive to the volatile oils than the females,when the velocity of flow was 200 ml穖in^-1. On the first day of the 3rd bioassay,the oviposition deterrent rate and IIPC of the volatile oils on Plutella xylostella adults was 94.48% and 0.0552,respectively. A liquid component of the volatile oils from Myoporum bontioides was isolated,purified,and identified as myoporone.

T-square study on spatial pattern and regeneration of Betula albo-sinensis Burkill population on west slope of Jiuding Mountain

LIU Shoujiang, SU Zhixian

2004, (1):  1-4. 

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The T-square study of Betula albo-sinensis population on the west slope of Jiuding Mountain showed that the population was mainly in random distribution, and in aggregated distribution in a few lines because of the negative human activities and severe destructions. In this region, the old trees of Betula albo-sinensis population were accounted for about 24%, and the younger trees only accounted for 12%. There exited a huge difficulty in the self-regeneration of Betula albo-sinensis population. Therefore, some measures should be taken to protect the population and to speed up its self-regeneration.

Dynamics of Amomum villosum growth and its fruit yield cultivated under tropical forests

ZHENG Zheng, GAN Jianmin, FENG Zhili, MENG Ying

2004, (1):  5-8. 

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Investigations on the dynamics of Amomum villosum growth and its fruit yield cultivated under tropical ravine rainforest and secondary forest at different elevations in Xishuangbanna showed that the yield of A.villosum was influenced by the site age, sun light level of understorey, and water stress in dry season. The fruit yield and mature plant density decreased with increasing age of the A.villosum site. The fruit yield increased with sun light level when the light level in understorey was under 35% of full sun light (P<0.05). The fruit yield at the lower site by stream was significantly higher than that at upper site (P<0.05). The yield difference between ravine rainforest and secondary forest was not significant. Planned cultivation of A.villosum in the secondary forest of the shifting cultivation land by ravine from 800～1000m elevation instead of customary cultivation in the ravine rainforest, could not only resolve the problem of the effect of light deficiency in understorey and water stress in the dry season on A.villosum fruit yield, but also be useful to protect the tropical ravine rain forest.

Variations of photosynthetic parameters in CO₂ acclimation of Citrus grandis leaves

SUN Guchou, ZHAO Ping, ZENG Xiaoping, PENG Shaolin

2004, (1):  9-14. 

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Plastic pots with sand and vermiculite were used to grow Citrus grandis saplings,and 0.05mmol P (normal P level,P) and 0.1 mmol P (higher P level,2P) nutrient solution were supplied every week. The saplings were grown under atmospheric CO₂ (about 39 Pa) and doubled CO₂ partial pressure (81±5Pa) for 45d. The Pn-Pi curve was measured under higher irradiation (1150 μmol·m^-2 ·s^-1) by CI-301PS Photosynthesis System (CID,Inc),and the Pn-PAR curve was measured under higher CO₂ partial pressure (PCO₂ 56 Pa).The results showed that the maximum rate of photosynthesis for 2P plants was 13.3% higher than that of P plants under atmospheric CO₂ partial pressure. Regardless of P and 2P plants,the maximum photosynthetic rate under doubled CO₂ partial pressure was lower than that under atmospheric CO₂ partial pressure,but the photosynthetic rate of 2P plants was higher than that of P plants under doubled CO₂ partial pressure. 2P plants had a higher apparent quantum efficiency and light energy conversion efficiency (P<0.05) than P plants,but no change in Γ^*,Rd and the ratio between carboxylation rate (Vc) and oxygenation rate (Vo) of Rubisco (P>0.05) wwere found. The V_cmax and J_max of 2P plants were 8.3% and 12.5% higher than those of P plants under atmospheric CO₂ partial pressure,respectively,and 2P plants also had higher V_cmax and J_max than P plants under double CO₂ partial pressure. The partitioning coefficient of leaf nitrogen in Rubisco and in thylakoid light-harvesting component was varied in CO₂ acclimation,but it was not in bioenergetics.It may suggest that an increasing phosphorus supply would promote the phosphorus turnover in photosynthetic carbon cycle,and increase the photosynthetic rate under doubled CO₂ partical pressure.Increaing phosphorus supply may be a way to regulate the photosynthetic parameter of plants in CO₂ acclimation.

Dynamics of forest landscape boundary at Changbai Mountain

CHANG Yu, BU Rencang, HU Yuanman, XU Chonggang, WANG Qingli

2004, (1):  15-20. 

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By using Geographic Information System (GIS) abstract and Remote Sensing (RS) abstract technology combined with field investigation and correlation analysis, this study was aimed to explore the dynamics of forest landscape boundary at Changbai Mountain, and to reveal the relationships among landscape fragmentation and changes of landscape boundary indices. The results showed that in the last 20 years or so, tundra decreased by 3694.8 hm², spruce and fir forest reduced by 130482.03 hm², and Korean pine-hardwood and mountain birch forest increased by 41610.4 hm² and 669.78 hm², respectively. The forest landscapes at Changbai Mountain tended to be more fragmented, and the shape of the landscape boundary became more complicated due to timber harvesting, forest cutting for cropping, and other human activities such as tourism. The changes of landscape shape index (LSI) abstract, contrast weighted edge density (CWED) abstract, total weighted edge length (TE-WGT) abstract and weighted landscape shape index (LSI-WGT) abstract could be used as good indicators for the degrees of forest landscape fragmentations, which was approved by correlation analysis among landscape fragmentation and changes of landscape boundary indices. The degree of human activities on landscape could be reflected by landscape shape index.

Patch size distribution pattern and its hierarchical effect of main landscape types in the Wuyishan scenery district

HE Dongjin, HONG Wei, HU Haiqing, WU Chengzhen

2004, (1):  21-25. 

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Based on the principles of landscape ecology and community ecology,the Wuyishan district was classified into 10 landscape types,and the patch size distribution of this district was characterized by six types of probability distribution,including normal,lognormal,Weibull,Gamma,Beta and negative exponential.The results showed that most of patch types could be characterized by lognormal distribution,a few of them could be characterized by Gamma or Weibull distribution.Normal distribution was not suitable to characterize the patch size distribution.For the same type of landscape,its patch size distribution was not the same under three different classifications,which meant that there was a hierarchical effect in the distribution pattern of patch size.Among the three classifications,the distribution characteristics of patch sizes could be better revealed by the second classification(b) abstract For different types of landscape,the distribution of patch sizes were different.None of the six probability distributions could characterize the patch size distribution of all the types of landscape or the whole scenery district.The new patch collective,which was composed of the two landscape types,would keep the pattern if the two different landscape types had the same distribution pattern of patch sizes,otherwise,its distribution would change if the patch sizes distribution of the two landscape types were different.

Effects of vegetation types and landscape features on soil properties at the plateau in the upper reaches of Minjiang River

LIU Shiliang, FU Bojie, MA Keming, LIU Guohua

2004, (1):  26-30. 

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Spatial heterogeneity is one of the important properties of soil. In this paper, the classical statistics method and the principles of geostatistics were used to study the spatial heterogeneity of soil properties on the Tibet plateau in the upper reaches of Minjiang River, and the relationship between vegetation type, landscape position and soil factors. Semivariogram analyses showed that there existed high degrees of spatial heterogeneity in soil moisture and soil nutrients. The test quadrats were assorted into three groups according to the landscape position and vegetation types, and then statistical analyses were made. The taxon results showed that different vegetation types had great effects on soil nutrients, and elevation was also an important factor influencing soil properties. A comprehensive index of soil properties showed that shrubs had the highest soil quality. The same trend of soil nutrients was found in the category of landscape positions. The soil nutrient contents decreased in the order of lower slope>upper slope>middle slope for the lower altitude hill, and lower slope> middle slope> upper slope for the high altitude hill. The results elucidated that the spatial heterogeneity of soil property was the result of the interaction between landscape factors and vegetation types.

Spatial neighboring characteristics among patch types in oasis and its ecological security

JIAO Yuanmei, XIAO Duning

2004, (1):  31-35. 

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In this paper, the spatial neighboring length and number between oasis types and desert or salina-marsh in the Jinta Oasis located in the arid Heihe River Basin of Northwest China were calculated by using ArcView3.0a and buffer zone analysis methods, and the threatening degree of oasis ecological security was discussed. The results indicated that it was different in neighboring length and number between oasis types and desert or salina-marsh, and the influencing area by desert and salina-marsh patches was also different. Grassland and farmland had more neighboring length and numbers with desert or salina-marsh patches, and impacted by desertification seriously. Forest and farmland had more length and numbers adjacent to salina-marsh, and influenced by salinization severely. The assessment of ecological security based on spatial analysis could reveal the threatening degree of oasis by desertification and salinization.

Accuracy evaluation of land vegetative cover index by RS detection

ZHOU Zhongxuan, WU Gang, SHAO Guofan

2004, (1):  36-38. 

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The accuracy of GIS data is important in GIS application. In this paper, a fictitious case and an example were used to discuss the relationship between accuracy of land vegetative cover index and accuracy of image classification, and this relationship was explained by mathematics. The accuracy of land vegetative cover index rested with the accuracy of image classification, but had no direct relations with total classification accuracy. User accuracy and producer accuracy had more direct control on the accuracy of land vegetative cover index than total classification accuracy; and hence, they could not be ignored in the image classification. To improve the accuracy of land vegetative cover index, user accuracy and producer accuracy of the same land type should be consistent to the greatest extent.

Root growth dynamics of Adenophora potaninii populations and its relation with environmental factors in northwest Sichuan Province

ZHANG Wenhui, LIU Xiangjun, LIU Guobin, MA Keming

2004, (1):  39-43. 

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In this paper, the dynamics of the root biomass and form development of Adenophora potaninii populations in different natural habitats in Northwest Sichuan were studied, and the factors influencing the root growth and form development were analyzed. The root biomass accumulation process of the mean individuals of the whole A.potaninii population in its life could be expressed by Logistic equation. From 1～3 years, the root length grew fast, but the root biomass accumulated slowly. From 4 years old, the root system developed in high speed, and the fast growth period of the root system could maintain until 15 year old. The basic patterns of root biomass accumulation process of different A.potaninii populations at different altitudes were similar to that of the whole population. However, the root system accumulation and root development was related closely with habitant conditions, and the root forms of different populations at different altitudes were significantly different (P<0.05) abstract At middle altitude (2800～3300m) abstract, the biomass and form of root system could achieve a higher level, and the good harvest of root biomass could be obtained because of the favorable soil and climate conditions, and the less external disturbance of human beings. Therefore, this area could be an important base for A.potaninii population to grow. Whereas at the lower altitude (2600～2800m) abstract, the biomass accumulation and the form development of root system were confined and maintained at a lower level because of the drought climate and the external disturbance of human beings. At the higher altitude (3300～3500m) abstract area with the harsh habitats, especially with lower temperature and lower pH, the root biomass of the mean individuals was significantly lower, and the individual form of root system was smaller, compared with that at middle altitude area. In order to use natural A.potaninii resource sustainablely, all the area should be planned, and the reasonable rotational prohibition of grazing and digging should be carried out.

Diversity and resistance of rhizobia isolated from Caragana intermedia in Maowusu sandland

GAO Lifeng, DENG Xin, WANG Hongxin, HU Zhiang

2004, (1):  44-48. 

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Fifteen rhizobia strains were isolated from wild shrubby legume Caragana intermedia in Maowusu sandland. A dendrogram was constructed based on esterase profiles, showing a rich diversity of these rhizobia. Many biochemical characteristics were detected, including acid or alkali production, catalase activity, utilization of sole carbon sources, and resistance to salt, acid-alkali and temperature variation. The results indicated that all the rhizobia strains isolated from Caragana intermedia could excrete H⁺ on YMA agar and produce catalase. 73.3% strains could tolerate NaCl stress at 3% concentration, and 80% strains could grow at 50℃.Except the difference in lactose and starch utilization, rhizobia strains had no bias on the rest carbon sources. However, the difference in resistance to stress existed among strains, which might be related to the adaptation of rhizobia to diverse landscapes in Maowusu sandland. It was revealed that rhizobia nodulating Caragana intermedia could be used as a new germplasm to fix nitrogen under severe environment.

Estimation of aboveground biomass of desert plants

ZHAO Chengyi, SONG Yudong, WANG Yuchao, JIANG Pinan

2004, (1):  49-52. 

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Based on the research of plant quadrate in Sangong River Basin in Xinjiang, the fitted equations were given, which could be used to estimate the aboveground biomass of typical desert plant by using the thicket characteristics such as length of crown diameter, width of crown diameter, number of basal branch, length of new branch, basal diameter (D) abstract and plant height (H) abstract as parameters. Using the length of crown diameter and the width of crown diameter as parameters, the fitted equation was set up and tested for estimating the aboveground biomass of Reaumuria soongorica Maxim. It had a relatively high accuracy and a fine linear relationship between the predicted values and measured values. Its coefficient and relative standard deviation was 0.9989 and 4.79%～10.12 %, respectively. The results indicated that the fitted equation was easy and available for estimating the aboveground biomass of Reaumuria soongorica Maxim in large scale. The fitted equations were also set up and tested for estimating the aboveground biomass of Haloxylon ammodendron and Tamarix ramosissima by using the basal diameter and height of plant as the parameters. The coefficients and relative standard deviations of these equations were 0.9902, 0.9875 and 6.87% ～19.22%, 7.49%～18.47%, respectively. Therefore, estimating the biomass of Reaumuria soongorica in large scale through crown characteristics was available, and estimating the biomass of Haloxylon Ammodendron and Tamarix ramosissima through crown characteristics would produce certain error.

A preliminary study on salt contents of soil in root-canopy area of halophytes

XI Jinbiao, ZHANG Fusuo, CHEN Yang, MAO Daru, YIN Chuanhua, TIAN Changyan

2004, (1):  53-58. 

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The results showed that among the 27 sampling sites, the salt content in rhizosphere of herbaceous halophytes increased at 7 sites and decreased at 20 sites. The variation of soil salt content in the RUE micro-area of shrubby halophytes was related to the growth status of the plants. The salt content in rhizosphere decreased a little at the early stage of plant development, but that in RUE micro-area tended to increase and accumulated most quickly at the site of the canopy edge soil.An obvious variation of salt components was found in the RUE micro-area of different types of halophytes. The Na⁺/K⁺ ratio tended to decrease in succulent halophytes and salt secrete halophytes. Among 53 sampling sites, only 14 sampling sites had a higher ratio of Na⁺/K⁺ in rhizosphere soil than in background soil, and only 10 sampling sites had a higher ratio of Na⁺/K⁺ in canopy-under soil than in background soil. However, the Na⁺/K⁺ ratio in the canopy edge soil of Tamarix and Nitraria tended to increase when they grew weakly. By contraries, the Na⁺/K⁺ ratio in the rhizosphere was higher than that in background soil at 3 of 4 sampling sites of Phragmites australia, which indicated that the Na⁺/K⁺ ratio in the rhizosphere of exclude halophytes tended to increase. The variation of SO₄^-2/Cl^- ratio in the RUE micro-area was different in the 3 types of halophytes. For salt secrete halophytes, it decreased obviously in rhizosphere soil, canopy-under soil and canopy-edge soil; for succulent herbaceous halophytes, it tended to increase in rhizosphere soil; and for succulent shrubby halophytes, it tended to decrease in rhizosphere and in canopy-under soil, and tended to increase in canopy-edge soil. The SO₄^-2/Cl^- ratio had no big change for exclude-halophytes. The reduction of the salts in rhizosphere of herbaceous halophytes was mainly because of their plant uptake, and the accumulation of salts in the RUE micro-area of shrubby halophytes was because the salt absorbed from the around soil returned to the RUE micro-area again. Because of the selective uptake by plant, the salt component varied with different types of halophytes. Most halophytes except Phragmites australia take more Na⁺, and hence the Na⁺/K⁺ ratio in the rhizosphere tends to decrease. The SO₄^-2/Cl^- ratio in the RUE micro-area of salt secrete halophytes trended reduce, mainly because this type of halophyte can secrete more Cl^- with its growth.

Population development characteristics of rice crop cultivated on aerobic soil with mulching

SHENG Haijun, SHEN Qirong, FENG Ke

2004, (1):  59-62. 

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Field experiments were carried out to study the population development characteristics of rice crop cultivated both on aerobic and waterlogged soil conditions. The results showed that the whole growth duration of rice growing on aerobic soil was one week longer than that on waterlogged soil. Shorter and narrower leaves and smaller LAI of rice population were found on aerobic soil than on waterlogged soil, which resulted in a decreased photosynthesis, smaller amount and lighter weight of rice grains on aerobic soil, compared with those on waterlogged soil. Among the aerobic treatments, more tillers, lower percentage of filled grains and shorter duration of grain forming were found on soils covered with plastic film than on soils covered with semi-decomposed straw or without mulching. The rice grain yield was decreased in the order of waterlogged soil > aerobic soil covered with plastic film > aerobic soil covered with semi-decomposed straw >aerobic soil without mulching.

Effect of short-term drought on leaf water potential,photosynthesis and dry matter partitioning in paddy rice

HU Jichao, JIANG Dong, CAO Weixing, LUO Weihong

2004, (1):  63-67. 

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Pot experiments were conducted to study the effect of short-term drought at four rice growth stages on leaf water potential, photosynthesis and dry matter partitioning in paddy rice. The leaf water potential of rice plant under water stress was lower than that of CK, and the difference increased after midday.The predawn leaf water potential of rice plant decreased significantly when soil water content or soil water potential went down a threshold value, resulted in an obvious decline in the single leaf net photosynthetic rate. In compared with the well-watered treatment, the net photosynthetic rate under severe water stress decreased by more than 50%. The partitioning indexes of leaf, root and spike decreased, while that of stem and sheath increased after short-term drought.

Impact of localized compaction and ridge fertilization on field nitrate transport and nitrate use efficiency

ZHAO Yunge, SHAO Ming'an, ZHANG Xingchang

2004, (1):  68-72. 

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The primary season of nitrate leaching in the Loess Plateau region is the monsoon,which is caused by heavy rainfall during the growth season of corn (Zea mays L.) abstract Nitrate leaching to groundwater is an increasing concern in agriculture,and is one of the major nitrogen losing ways in dryland farming system.Localized compaction and ridge fertilization is a method for nitrogen fertilizer application,by which,less fertilizer leaching would occur.The NO₃^--N transport in soil profile,corn yields and nitrogen use efficiency under localized compaction and ridge fertilization were investigated through two years field study.The factors that affect NO₃^--N transport under localized compaction and ridge fertilization were studied,combined with simulated experiment. The results showed that NO₃^--N was leached to below 90cm in plat fertilization in the year of about 370mm rainfall,a mean precipitation during the season,while the NO₃^--N leakage of the fertilizer zone was reduced by localized compaction and ridge fertilization,as a result that the NO₃^--N concentration below 60cm was less than 10mg·kg^-1,and NO₃^--N accumulated in 20～40cm with a concentration 80～90 mg·kg^-1. There was no significant difference in yield between application methods with 240.0kgN·hm^-2. However,the absorbed amount of nitrogen was improved significantly by localized compaction and ridge fertilization,and the nitrogen use efficiency was increased by 9%. The bulk density of the barriers had an evident effect on NO₃^--N transport under localized compaction and ridge fertilization,but the effect of ridge slope was insignificant.

Effects of soil available silicon on growth,development and physiological functions of soybean

LI Qingfang, MA Chengcang, LI Hanping, XIAO Yunli, LIU Xueyan

2004, (1):  73-76. 

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Soybean plants were planted in pots to investigate the effects of soil available silicon on their growth, development and physiological functions. When the content of soil available silicon was 55.1～202.8 mg·kg^-1, the protease and lipase activities of germinating seed were increased with increasing soil available silicon content, amylase activity had no obvious change, and the respiration rate of seedlings was accelerated. The bioactivity of seed was increased, but the germination rate had no significant change. The photosynthesis rate, root activity, and nitrate reductase activity of soybean seedlings were enhanced, but the chlorophyll content in leaves had no significant change during seedling growth. The transpiration rate was decreased, while the water utilization efficiency and leaf water content were increased, and the capacity of drought-resistance was promoted. When the available silicon content was >202.8 mg·kg^-1, the abovementioned physiological functions had no significant changes. There was a positively linear relationship between the silicon content in soybean seedlings and the available silicon content in soil (r =0.994) abstract It could be concluded that the silicon absorbed from soil improved the physiological functions of soybean germinating seed and seedlings. As a result, the seed germination and seedlings growth rate were enhanced.

Effects of zinc and boron nutrition on balsam pear (Momordica charantia) yield and quality,and polyamines,hormone,and senescence of its leaves

SHI Mutian, CHENG Rukai

2004, (1):  77-80. 

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Field trial and physiological determination on the effects of zinc and boron nutrition on balsam pear (Momordica charantia) abstract yield and quality and on polyamines, hormone, and senescence of its leaves showed that application of ZnSO₄?7H₂O and Na₂B4_O7?10H₂O on Zn and B deficient soils could increase balsam pear yield and its contents of protein, Vc and 17 sorts of amino acids, especially the contents of essential amino acids for human body, but decrease the NO₃^--N content. The reason was that Zn and B could increase polyamines (PAs) abstract, putrescine (Put) abstract, spermidine (Spd) abstract, spermine (Spm) abstract, indole acetic acid (IAA) abstract, gibberellic acid (GA₃) abstract and ascorbic acid (ASA) abstract contents and superoxide dismutase (SOD) abstract, peroxidase (POD) abstract and catalase(CAT) abstract activities, and reduce malondialdehyde (MDA) abstract, abscisic acid (ABA) abstract contents in leaves, which inhibited membrane lipid peroxidation. The results also showed that there was a significant positive correlation between yields and PAs, Put, Spd, Spm, GA₃, SOD, POD, CAT, but a significant negative correlation with MDA and ABA contents in leaves. There was a significant positive correlation between MDA and ABA, but a significant negative correlation with PAs, Put, Spd, Spm, IAA, GA₃, ASA, SOD, POD, and CAT.

Effects of different application rates of humic acid compound fertilizer on pepper and its mechanism of anti-senility and incremental yield

SUN Zhimei, XUE Shichuan, LIANG Wenju, LIU Yuzhu

2004, (1):  81-84. 

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The effects of different application rates of humic acid compound fertilizer (HA) abstract on the yield and physiological characteristics of pepper (Capsicum frutescens L.) abstract were studied in this paper. The results showed that different application rates of (HA) abstract could affect the physiological activities and yield of pepper. The nitrate reductase activity (NRA) abstract and peroxidase (POD) abstract activity were improved with increasing application rate, but the change rate of NRA was reduced gradually. POD activity in inorganic compound fertilizer treatment was improved significantly when the application rate of fertilizer was higher than 0.3 g穔g^-1,but that in HA treatment changed smoothly. Superoxide dismutase (SOD) abstract activity was improved significantly when the application rate of fertilizer was lower than 0.2 g穔g^-1, and decreased gradually when the application rate was higher than 0.2 g穔g^-1. The change of transpiration rate was consistent with that of SOD activity. The relationship between the application rate of fertilizer and the yield of pepper could be described with quadratic curve regression model. According to the equation, the highest application rate of HA should be 0.27 g穔g^-1, and the highest yield of pepper could reach 165.22g per pot.

Temporal and spatial structure of carabid community in agricultural landscape of Dongbeiwang,Beijing

LIU Yunhui, YU Zhenrong, LIU Yun

2004, (1):  85-90. 

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From May to October 2000, the carabid beetles in the habitats of woodland, field margin and crop field in Dongbeiwang agroecosystem in Beijing were investigated by pitfall traps, and the temporal and spatial structure of carabid community was analyzed. The results indicated that the numbers of both carabid species and individuals were much higher in the field margin and woodland than in the crop field. Both dominant species and rare species tended to live in field margin and/or woodland. Field margins had a positive effect on the diversity and richness of carabid community in their adjacent crop fields. The modest disturbance (plowing in autumn) abstract in the field margin was beneficial for the increase of the individual number of carabid community, and the treatments of irrigation, fertilization and straw return in field had no effects on both the individual and species number of carabid community. Furthermore, the threatening condition to some carabid species was discussed, based on the analysis of the temporal and spatial dynamics of carabid community.

Edge effect on the dynamics of pests and natural enemies in cotton agroecosystems

GE Feng, MEN Xingyuan, SU Jianwei, LIU Xinghui, DING Yanqin

2004, (1):  91-94. 

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Investigation on the population dynamics of pests and natural enemies on the cotton plants in the middle and edge of cotton agroecosystems showed that the population of the 2nd generation of cotton bollworms (Heliocopavar armigia) abstract and seedling aphids (Aphis gossyppi) abstract was respectively 1.94 times and 1.09 times higher, but that of the 3rd generation cotton bollworms and summer aphids population was respectively 62.12% and 97.73% lower in the edge than in the middle of cotton agroecosystem. The population of predacious ladybeetles, predacious bugs, spiders and parasites in the edge of cotton agroecosystem was 73.81%, 35.79%, 52.90% and 39.11% of that in the middle of cotton agroecosystem, respectively. The greater diversity of pest community and the less diversity of natural enemies community were found in the edge than in the middle of cotton agroecosystem. The increase of energy utilization efficiency and gross production in the edge of cotton agroecosystems showed the edge effect of cotton agroecosystems.

Effects of imidacloprid on arthropod community structure in tobacco field

WU Houzhang, CHENG Xianian, WEI Chongsheng, ZOU Yunding

2004, (1):  95-98. 

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The effects of imidacloprid on the structure of arthropod community and its sub-communities were analyzed. The results showed that after applied imidacloprid, the species number of arthropod community and its pest sub-community was influenced, but that of its natural insect enemy and spider sub-community was not influenced obviously. The individuals of arthropod community and its pest sub-community in both treatment plot (Ⅱ) abstract and control plot were decreased after the application of imidacloprid on May 23 to June 13, and the decline degree in treatment plot was larger than that in control plot. The individuals of arthropod community and its pest sub-community at treatment plots had a large decrease, and that in control plot had a large increase after imidacloprid application on June 14. Twice applications with imidacloprid did not reduce the number of the individuals of natural insect enemy and spider sub-community obviously. The individuals of tobacco aphids who were dominant in tobacco field decreased obviously within a period of time after application, and hence, the dominant concentration of arthropod community and its pest sub-community declined, and the diversity and stability increased.

Effects of low and subzero temperature on a Plutella xylostella laboratory population

CHEN Feizhou, LIU Shusheng

2004, (1):  99-102. 

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In this study, the effects of low (< 8 ℃) abstract and subzero temperature on the development, survival and reproduction of Plutella xylostella were examined. The mortality of its egg and pupae at 4℃ and 6℃ increased with time, no egg and pupae could complete their development at these low temperatures, and all died after 55 days and 70 days, respectively. When the pupae were placed at 4℃ and 6℃ for various durations and then moved to 16℃ for development, the fecundity of the resultant adults was reduced, and the longer the duration at 4℃ and 6℃, the further the fecundity was reduced, and the fecundity was reduced to zero when the pupae were retained at these low temperatures for 45 days. The survival of this insect was observed following exposure of various stages of this insect to temperatures below 0℃. The results showed that the mortality of all preimaginal stages increased with decreased temperature and prolonged duration. The ability of cold tolerance of the various stages of this insect was in order of the third instar and pupa > the second and forth instars >the first instar and egg. Temporal exposure to temperatures below 0℃ affected the development of subsequent stages at a favorable temperature. Generally, the developmental time of the subsequent stages increased, and the largest increase of development time was observed with the stage next to the stage treated at low temperatures. Exposure of the pupal stage to low temperature also reduced the fecundity of the resultant female adults, and the reduction was positively correlated to lower temperature and longer exposure.

Experimental population ecology of Carcelia matsukarehae Shima (Diptera:Tachinidae)

ZHOU Changqing, WENG Zhongyan

2004, (1):  103-107. 

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This paper dealt with the developmental zero, effective accumulated temperature, adult longevity, adult fecundity and specific life table parameters of tachinid fly Carcelia matsukarehae at temperature 15℃, 18℃, 22℃, 25℃, 29℃, and 32℃, relative humidity 70%～85%, and photoperiod L:D=12:12. The results showed that the developmental zero and effective accumulated temperature for generation were 5.23℃ and 525.73 day-degree, respectively.The adult longevity was 1.35～8.06 days without supplying nutrient but water, and while fed with 30% honey water, their longevity could prolong to 9.63～36.42 days.The optimum temperature for oviposition was 23.6 ℃, maximum eggs laid by a female were 86.The optimum temperature for population growth was 22～25℃. The specific life table parameters of experimental population under temperature 22℃ and 25℃ were calculated. At 22℃, R₀,T₀,r_c and λ were 24.89, 37.33, 0.086 and 1.089, respectively, and at 25℃, they were 20.01, 32.38, 0.09 and 1.10, respectively. The maximum L_xM_x occurred from the 33rd day to the 38th day after adult emergence at temperature 22℃, and from the 29th day to the 34th day at 25℃.

Relationship between occurrence of Dryocosmus kuriphilus and development of cecidum

DING Yuzhou, BI Shoudong, FANG Guofei, HE Lin

2004, (1):  108-110. 

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Dryocosmus kuriphilus is one of the most important pests on chestnut in China, and cecidum is the jeopardized result of Dryocosmus kuriphilus.Under natural condition, the growth status of different cecidum of Dryocosmus kuriphilus was differed, and the weight of individual cecidum was submitted to normal distribution. The zooecium number was positively related to cecidum quality and volume. For three different varieties of chestnut, their resistance to Dryocosmus kuriphilus were different, and the order was Chushuhong > Mifengqiu > Ershuizao. Torymus sinensis Kamijo was the dominant natural enemy. The cecidum-parasitized ratio was 72.7%, and the zooecium-parasitized ratio was 24.06%.

Techniques of diseases,insect pests and weeds control and their efficacy in bio-rational rice production

LI Baotong, SHI Qinghua, FANG Jiahai, PAN Xiaohua

2004, (1):  111-115. 

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Studies on the efficacy of bio-rational pesticides and agricultural methods against the chief diseases, insect pests and weeds of rice showed that the efficacy of the mixtures of jingangmycin and bacillus-cereus, and jingangmycin and polyoxin against rice sheath blight were 75.16%～94.27% after sprayed once at the tiller and boot end stages of rice, respectively, and better than that of chemical fungicide triadimefon. The efficacy of kasugamycin and blasticidin was 50.54%～72.67% on rice leaf blast and 76.66%～87.42% on rice head blast, and equal to the chemical fungicide tricyclazole after sprayed once at the initial stage of rice leaf blast occurrence and the initial and end stages of earing, respectively. The efficacy of bacillus thuringiensis on Chilo suppressalis and Cnaphalocrocis medinalis was better than that of chemical insecticide bisultap, and the efficacy of saponin-nicotine and matrine was equal to that of chemical insecticide bisultap when the three biorational insecticides were sprayed at 1～2 instar larvae of pests. The efficacy of saponin -nicotine and matrine was above 70%, and lower than that of chemical insecticide imidacloprid 3～30d after sprayed at 1～2 instar larvae of Nilaparvata lugens. The occurrence of weeds could be controlled, and the rice yield could be raised when the suitable non-thorough decomposed organism was applied or weeding was carried after the field had been ploughed twice before rice transplant. The rice yield could be raised by using biorational pesticides and agricultural methods against the chief diseases, insect pests and weeds of rice. The residue of pesticides in rice was lower in the bio-control area than in the chemical control area, according with the demands of health target of green food.

Removal of red tide organisms by organo-modified bentonite

DENG Yuesong, XU Zirong, XIA Meisheng, YE Ying, HU Caihong

2004, (1):  116-118. 

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A series of organo-bentonites were synthesized by exchanging cation surfactants such as cyltrimethylammonium bromide and cetyltrimethylammonium to remove red tide organisms Skeletonema costatum.The results showed that the removal rate of Skeletonema costatum by the bentonites was in the order of cyltrimethylammonium surfactant modified iron pillared bentonite>cetyltrimethylammoium surfactant modified iron pillared bentonite>iron pillared bentonite>cyltrimethylammonium surfactant modified sodium bentonite>cetyltrimethylammoium surfactant modified>sodium bentonite. The removal rate of Skeletonema costatum was related to the length of alkyl chains and the amount of cation surfactants exchanged on bentonites.

Effect of copper pollution on seedling growth and activate oxygen metabolism of Trifolium pratense

CHU Ling, LIU Dengyi, WANG Youbao, LI Ying, LIU Huijun

2004, (1):  119-122. 

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The effect of copper (Cu) abstract pollution on the seedling growth and activate oxygen metabolism of Trifolium pratense was studied by water cultivation experiments.The results showed that under low concentration of Cu (<10mg·L^-1) abstract, the growth of Trifolium pratense seedlings could be improved, their fresh/dry weight and the contents of soluble protein and chlorophylls in leaves increased slightly, the MDA content of leaf cells decreased, the activities of SOD, CAT and POD in the activate oxygen metabolism system slightly increased, and the balance of protective enzyme system was hold. However, with the increase of Cu concentration (10～100mg·L^-1) abstract, there existed an obvious negative effect on the growth of Trifolium pratense seedlings. The seedlings under high concentrations of Cu were shorter and smaller, their fibrous roots were shorter and fewer, and their fresh/dry weight and the contents of soluble protein and chlorophylls in leaves decreased drastically. With the increase of Cu concentration, the membrane penetration, electric conductivity and MDA content of leaf cells increased. Furthermore, the activate oxygen metabolism system was destroyed, the balance of protective enzyme system was broken, the activities of SOD and CAT decreased by 26.67% and 71.31%, respectively, while the POD activity increased by 10.6 times.

Heavy metal concentration in Nanjing urban soils and their affecting factors

LU Ying, GONG Zitong, ZHANG Ganlin, ZHANG Bo

2004, (1):  123-126. 

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The concentration and source of heavy metals in Nanjing urban soils and their relationships with soil properties were studied. The results indicated that the soils in Nanjing urban were not obviously polluted by Fe, Ni, Co and V, but polluted by Mn, Cr, Cu, Zn, and Pb to a certain extent. The heavy metals were irregularly distributed in soil profiles. Fe, Ni, Co, and V were originated from soil materials, but Cu, Zn, Pb, and Cr were anthropogenic input. Probably, Mn had different origins in different soils. There were positive correlations among Fe, Cr, Ni, Co, and V concentration, and among Cu, Zn, Pb, and Cr concentration. The Fe, Co, V, and Ni concentration were positively correlated with soil clay content and CEC, and the Cu, Zn and Pb concentration were negatively correlated with clay content. There were positive correlations between Cu, Zn, Pb and Cr concentration and organic C content, and between Pb concentration and soil pH.

Effect of acid rain,copper,and atrazine on soil hydrolase activity

LIU Guangshen, XU Dongmei, LI Kebin, LIU Weiping

2004, (1):  127-130. 

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The effects of acid rain, Cu²⁺ and atrazine on the activities of soil urease, invertase and acid phosphatase were studied by means of orthogonal test. The results showed that the inhibition rate was H⁺>Cu²⁺, and atrazine had no significant influence on urease and intertase. Interaction analysis revealed that Cu ? atrazine exhibited synergism on soil acid phosphatase activity, Cu譎 had antagonism on soil invertase and urease, but atrazine ? H had no interaction within the investigated concentration range. Among the three enzymes, soil acid phosphatase was the most sensitive one to the contaminations.

Accumulation and distribution of lead in Macrobrachium nipponense

LU Xingjia, XI Yilong, LIU Guiyun

2004, (1):  131-135. 

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The accumulation and distribution of lead granules in the major organs of Macrobrachium nipponense were studied by means of histochemistry, transmission electron microscope (TEM) abstract and atomic absorption spectrophotometer (AAS) abstract analysis. The results showed that many high electronic dense lead granules (EDG) abstract were found primarily in the antennal gland of this species exposed to 0.625 mg稬^-1 Pb²⁺ for 10 days. Under TEM, lead granules were deposited in lysosome, then gradually accumulated in cell apex, and finally individually discharged into gland lumen by apocrine secretion and excreted with urine. There was a small quantity of lead granules in the cells of midgut. Many vacuolus were observed in the cytoplasm of the cells, and the nuclear membranes and cristae in mitochondria were disintegrated partially. The structure of hepatopancreas cells basically remained intact, although there were a few of lead granules in the cells. No lead granule was found in the cells of gills, but a few of lead granules adsorbed on the surface of gill filaments among the gill filaments. The highest concentration (637.6 mg穔g^-1) abstract of lead was found in antennal gland by AAS, suggesting that the antennal gland might play an important role in detoxifying process of lead.

Quantification of non-point sources phosphorus pollution in key protection area of Taihu Lake

GUO Hongyan, WANG Xiaorong, ZHU Jianguo

2004, (1):  136-140. 

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The distribution of various kinds of non-point sources phosphorus pollution in Xueyan Town,Wujin city,Taihu area was researched through field experiments and local investigation during rice growth season. The results showed that of all kinds of phosphorus pollution,about 56.2% (1313 kg P) abstract was from farmland,22.2% (518 kg P) abstract was from town residents,18.9% (442 kg P) abstract was from village residents,and 2.7%(62 kg P) abstractwas from livestock. Besides the strict control of the phosphorus pollution from farmland,attention should also be paid on the control of domestic water pollution from towns and villages.

River continuum characteristics of Xiangxi River

TANG Tao, LI Daofeng, PAN Wenbin, QU Xiaodong, CAI Qinghua

2004, (1):  141-144. 

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The density of epilithic algae and concentration of chlorophyll a, Shannon-Wiener index and primary productivity were chosen to study the river continuum characteristics of Xiangxi River.The results showed that in general,the algal density,chlorophyll a concentration and Shannon-Wiener index tended to be increased with increasing stream order,but this trend was not very evident in the first three orders and even reversed. The primary productivity was also higher in the higher than that in the lower stream orders, and reached the maximum in the fourth order, then decreased slightly.The ratio of gross primary productivity to community respiration was the highest in the first stream orders, which means autochthonous productivity was dominant in the river. The results did not absolutely tally with the RCC forecast, therefore,we can conclude that Xiangxi River had been undergone anthropogenic influence.

Allelopathic effects of secalonic acid F produced by Aspergillus japonicus on Zea mays

ZENG Rensen, LUO Shiming, SHI Yuehong

2004, (1):  145-148. 

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Aspergillus japonicus Saito is a common soil-borne fungus, and exists on the surface of some cereal crop seeds. Secalonic acid F (SAF) abstract is the main allelochemical from the fungus. Bioassays showed that SAF significantly stimulated the seedling growth of corn (Zea mays L.) abstract at a concentration of 0.0375 mmol稬^-1. The root length, root numbers and root oxidation activities increased by 31.7%, 13.2%, and 373%, respectively. Secalonic acid F also increased the nutrient absorption of P, K, Ca, Mg, and S at the same concentration. However, SAF inhibited the seedling growth of corn at concentrations of 0.3 mmol稬^-1 and 0.6 mmol稬^-1. The root length, root dry weight, and shoot length were inhibited by 27.7%, 39.1% and 35.8% by 0.3 mmol稬^-1 of SAF, and root activities were inhibited by 72.1% and 100% by 0.3 mmol稬^-1 and 0.6 mmol稬^-1 of SAF, respectively. The nutrient absorption of N, P, K, Ca, Mg and Fe was reduced when the corn seedlings were treated with 0.3 mmol稬^-1 SAF. Transmission electron microscope observations showed that the corn treated with 0.3 mmol稬^-1 of SAF had a swelling and disorderly arrangement chloroplast, and the stratiform structure of chloroplast became unconspicuous.

Bioactivity of volatile oils from Myoporum bontioides on Plutella xylostella

HE Yanbiao, HE Tingyu, GU Wenxiang, XIAN Jidong, ZHANG Maoxin, FENG Liping

2004, (1):  149-152. 

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This study showed that the volatile oils from Myoporum bontioides had a significant repellent action on Plutella xylostella.When Plutella xylostella adults entered into the 4-arm selective olfactometer,the preferred times and average staying duration,in the order from more to less,were 3,1,4,and 2 arms,which showed a tendency of keeping away from the treatment arms. The males were more sensitive to the volatile oils than the females,when the velocity of flow was 200 ml穖in^-1. On the first day of the 3rd bioassay,the oviposition deterrent rate and IIPC of the volatile oils on Plutella xylostella adults was 94.48% and 0.0552,respectively. A liquid component of the volatile oils from Myoporum bontioides was isolated,purified,and identified as myoporone.

Effect of forest litter on microenvironment conditions of forestland

PAN Kaiwen, HE Jing, WU Ning

2004, (1):  153-158. 

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Litter is a very important component in forest ecosystem. This paper made a systematic review on the previous studies about the effects of litter on forestland microsites. Litter significantly reduced the light on the soil surface of forestlands, and the light transmittance was varied with the type, water content and weight of litter. The spectral composition of the light was dramatically shifted to longer wavelengths after transmitted through forest capony, especially through moist litter leaves, intact forest litter, and even the thinner soil layer, which greatly reduced the R/FR ratio and PPFD (photosynthetic photo flux density) abstract beneath litter and surface soil (2 mm depth) abstract, and resulted in a stronginhibitory effect on the germination of photoblastic seeds, and on the growth of seedling and sapling. It was the reason why the appearance of massive numbers of pioneer plants and their successful establishment required relatively large gaps of the forest canopy. Many references concerned the effects of litter on soil nutrient cycling and water and soil conservation. The previous studies indicated that litter could create a moist micro-site above soil, and make soil more moist and fertile. Furthermore, litter could also increase the numbers of arthropods such as Carabidae adults and larvae, crickets, millipedes, spiders, ants and others. An increase in the activity of herbivorous arthropods might produce the negative effects on the establishment of individual seedlings. Although the mechanical barrier of litter was neglected in the paper, litter might act as a mechanical impediment to the emergence of the seedlings of pioneer species with small seeds. The effects of litter on micro-sites were of complexity because it varied greatly with the density, age, structure and species composition of the canopy, sunfleck frequency, presence of gaps, as well as litter thickness, moisture, and species composition, and also with climate and topography factors. The effects of litter were comprehensive, including positive and negative effects on seed germination and seedling growth. Each effect of litter on regeneration was dependent on species physiology, litter physical properties and environmental conditions. Therefore, it should be encouraged to integrate the physical properties (such as changing light, temperature and moisture) abstract of litter with the physiological ecology (including seed, germination and growth natures) abstract of species, and with environment (vegeneration, climate and topography propersities) abstract on the basis of combination of regeneration patterns of litter, understory and gap scales.

Advances in energy analysis of agro-ecosystems

LU Hongfang, LAN Shengfang, CHEN Feipeng, PENG Shaolin

2004, (1):  159-162. 

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The energy analysis of agro-ecosystems from the view point of energy flow is a quantitative study on the function of agro-ecosystem, and is one of the most important aspects in agro-ecosystem study. In this paper, the history and some current progresses of energy analysis on agro-ecosystems were reviewed briefly, and the difference and breakthrough of emergy analysis theory with the traditional energy analysis method, some current challenges in front of emergy analysis of agro-ecosystems, and some of the new trends were discussed. Using the direct and indirect cost of solar energy to evaluate any energy or material, emergy analysis is the new development of energy analysis, not only in concept but also on calculation method. Developing to emergy analysis phase, there were still some deficiencies on energy analysis of agro-ecosystem, such as the complicate calculation of transformation and the vacancy of energy index for sustainable development, etc.How to solve these problems combined with the clearing of the maximum Em-power principle, the combination among energy analysis, emergy analysis, material analysis and landscape analysis has made up of the current and future trends of energy analysis of agro-ecosystem.

Models and determining methods of unsaturated soil hydraulic parameters

LÜ Dianqing, SHAO Ming'an

2004, (1):  163-166. 

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The selection and determination of soil hydraulic parameters is the basis of predicting water movement and solute transfer in soils. Based on the researches at home and abroad, the models of hydraulic parameters, including those of soil water characteristic curve and soil hydraulic conductivity, and their direct and indirect measurement methods were reviewed, and their application and limitation were compared to provide evidence for the selection and determination of soil hydraulic parameters in the study of ecological environment construction and sustainable agriculture development.

Chemical properties of litter in dark coniferous forest of Sejila Mountains in Tibet

ZHONG Guohui, XIN Xuebing

2004, (1):  167-169. 

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The storage and chemical properties of the forest litter in dark coniferous forest of Sejila Mountain were studied. The results showed that the existing storage was 5.863t穐m^-2 and the annual litter fall was 0.3205 t穐m^-2. It implied that the forest litter decomposed slowly and accumulated quickly, and the turnover of nutrient circles was slow. The contents of N, Ca, Na, and Mn nutrient elements in litter layer were in the order of un-decomposed layer (U layer) abstract > semi-decomposed layer (S layer) abstract > decomposed layer (D layer) abstract, those of K, Fe, and Mg were in the order of D layer > S layer > U layer, and P element content was in the order of U layer > D layer > S layer. The pool of elements was 78.483 kg穐m^-2 N, 3.843 kg穐m^-2 P, 48.205 kg穐m^-2 K, 23.115 kg穐m^-2 Ca, 13.157 kg穐m^-2 Na, 30.554 kg穐m^-2 Fe, 2.113 kg穐m^-2 Mn and 27.513 kg穐m^-2 Mg. The turnover of forest litter was the total of nutrient release accumulation. K, Fe, and Mg were enriched, and N, Ca, Na, Mn, and P were released with the turnover rate in the order of N > Ca > Na > Mn >P.

Chemical components of Vetiveria zizanioides volatiles

HUANG Jinghua, LI Huashou, YANG Jun, CHEN Yufen, LIU Yinghu, LI Ning, NIE Chengrong

2004, (1):  170-172. 

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The chemical components of the volatiles from Vetiveria zizanioides were analyzed by SPME and GC-MS. In the roots, the main component was valencene (30.36%) abstract, while in the shoots and leaves, they were 9-octadecenamide (33.50%) abstract, 2,6,10,15,19,23-hexamethyl-2,6,10,14,18,22-tetracosahexaene (27.46%) abstract, and 1,2-benzendicarboxylic acid, diisooctyl ester(18.29%) abstract The results showed that there were many terpenoids in the volatils. In shoot volatiles, there existed 3 monoterpenes, 2 sesquiterpenes and 1 triterpene. Most of the volatiles in roots were sesquiterpenes.

Effects of diet condition on survival and metamorphosis of Charybdis japonica larvae

JIANG Xiamin, WANG Chunlin

2004, (1):  173-175. 

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This paper studied the effects of different kind and density of baits and different starvation duration on Charybdis japonica larvae. The results showed that the preferable baits of zoaea-1 were Chaetoceros sp. and Isochrysis galbana,and their proper feeding density were 20×10⁴ cell·ml^-1.The preferable bait of the larvae after zoaea-1 was Artemia salina nauplius, and its proper feeding density for zoaea-2 and zoaea-3 was 2～3 ind·ml^-1.The point of no-return for zoaea-1 of Charybdis japonica was about 66 hours. 18 hours starvation did not affect the growth of the larvae, but their livability would be decreased, and their metamorphism would be suspended along with the starvation duration.