Table of Content

15 March 2002, Volume 13 Issue 3

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Analysis of natural regeneration barriers of Pinus sylvestris varmongolica plantation on sandy land

ZENG Dehui, YOU Wenzhong, FAN Zhiping, LIU Mingguo

2002, (3):  257-261. 

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By employing comparison analysis,and field experiment of watering and soil covering befroe overwintering for seedlings,the barriers of natural regeneration for Mongolian pine plantations on sandy soil were identified. The experimental area was divided into 3 parts according to the state of natural regeneration. Crown closure,litter,understory coverage,and site condition were the factors which affect natural regeneration. Water deficit,but not low temperature during overwintering,is the key factor that limits survival for 1～2 years old seedlings in plantation area. The water deficit is due to higher air temperature,less accumulated snow,higher soil evaporation,higher plant transpiration in plantation area than in the area in which Mongolian pine is naturally distributed. Based on the above research,it is necessary to take effective artificial measures to promote its natural regeneration so as to guarantee its successful development. The following measures are recommended:1)covering the 1～2 years old seedlings with soil before wintering,2)irrigating seedlings before wintering,3)suitable forest harvest,e.g.,belt clear cutting,or patch cutting,4)planting the pine with broadleaf species,5)protecting forest stands from livestock grazing,seed collecting and litter gathering.

Analysis on the sustainability of Amomum villosum cultivation under the tropical rainforest in Xishuangbanna

GAO Lei, LIU Hongmao, CUI Jingyun, NIE Zelong, DUAN Qiwu

2002, (3):  262-266. 

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Amomum villosum has been cultivated under tropic rainforest in Xishuangbanna area since 1970s. The cultivation area of Amomum villosum had expanded to 5811 hm² by 1998,and the dry fruit yield had reached to 542 t. In this study,the ecological and economical benefits of this cultivation model were analyzed. The results showed that plant diversity,litter,soil humidity,and soil fertility of rainforest decreased at different levels after Amomum villosum cultivated under rainforest,and the distribution of nutrition had been changed in the soil. The economical benefits had an obvious downtrend after 7～8 years cultivating due to irrational management. So,the present cultivation model of Amomum villosum under the tropical rainforest was not sustainable. For the objectives of harmonizing the ecological,economic,and social benefits and sustainable utilization of the rainforest,and improved model was also discussed in this study.

A comparative study on life-form spectra of evergreen broad-leaved forest in different successions in Jinyun Mountain

LEI Ningfei, SU Zhixian, SONG Huixing, ZHANG Yan

2002, (3):  267-270. 

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The life form of plant communities in different succession stages in Jinyun Mountain was studied and the life form spectrum was established. The results showed that according to the characters of life form of plant communities,the vegetation in Jinyun Mountain belonged to typical subtropical evergreen broad leaved forest vegetation. Evergreen phaenerophytes were absolutely dominant in the life form spectrum and its quantity accounted for more than80%. Among phaenerophyte,quantity of microphanerophyte was the most,and quantities of mesophanerophtye and nanophanerophyte were less. Different successions had different life form spectra. With the development of succession,the percentage of phaenerophytes increased,and other life forms decreased correspon dingly. According to the development of life form and comparative analysis of environmental factors in different succession stages,coniferous species would be replaced by evergreen phaenerophytes.

Neighbor diversity and interspecific association of Quercus mongolica

YU Shunli, MA Keping, LIU Canran, CHEN Lingzhi

2002, (3):  271-274. 

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Neighbor diversity and interspecific association of Quercus mongolica were studied through point sample method. With the increase of plots number,species richness and Shannon Wiener (H') diversity index increased. At last they came colse to fixed value. LSvalue (average number of neighboring species) was first introduced in this article. Different sits had different PCvalue (value of interspecific association). According to PCvalue and LSvalue,accompany tree and shrub species of Quercus mongolica were determined. The similar environmental requirement and mutualism were the main reason why they live together. The result of interspecific association between Quercus mongolica and other species in 4 locations was analyzed. The reason why the diffe rences existed was that Quercus mongolica studied was in different succession stages.

Effect of drought stress on apparent resource utilization efficiency of Quercus mongolica

WANG Miao, DAI Limin, JI Lanzhu

2002, (3):  275-280. 

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To study the effect of drought stress on the physiological characteristics and resource utilization effciency of Quercus mongolica,a dominant species in the Korean pine broad leaved forest in Changbai Mountain,a comparative experiment was carried out under three soil moisture gradients as 85%～100%(high water,CK),65%～85%(Medium water,MW),and 45%～65%(low water,LW) of field water bolding capacity. The results showed that net photosynthetic rate,stomatal conduction,transpiration rate,water utilization efficiency,apparent CO₂ utilization efficiency and apparent light utilization efficiency of the seedlings of Quercus mongolica were all significantly influenced by simulated drought stress. Stomatal conduction,water utilization efficiency and net photosynthetic rate of large tress of Quercus mongolica were affected by the soil drought stress,while transpiration rate,apparent CO₂ utilization efficiency,and apparent light utilization efficiency were not influenced. Mode rate soil water condition could greatly increase gas exchange and water utilization efficiency. These results indicated that the responses of gas exchange and resource utilization efficiency to various water stresses were diffe rent. Quercus mongolica was a species with variable resistance to drought stress,and the resistance would be improved by drought stress,especially moderate water stress.

Clutch size,nesting success and breeding success rate in Emberiza jankowskii in the grassland at Baicheng in Jilin Province

TONG Fuchun, GAO Wei, XIAO Yihua, WANG Shaoxian, BAI Hasi, SUN Danting, WANG Qingli

2002, (3):  281-284. 

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In this article,clutch size,nesting success and breeding success rate of Emberiza jankowskii living in grassland habitats in Baicheng Region of Jilin Province were studied from May to July in 1999. The results showed average clutch size was 5.09?0.58 eggs per nest. There was negative correlation between clutch size and initial laying date,brood quantity and initial laying date,clutch size and fresh egg weight. There was exceedingly negative correlation between initial laying date and incubated rate. There was exceedingly positive correlation between nest size and clutch size. There was positive correlation between other attributes of nest and clutch size. Average incubation period was 12?094 days, incubated rate was 36.3%,and breeding success rate was 11.11%. The population size of brood size above seven days was 2.56?1.53. Nestling survival rate was 27.69%.

Quantitative characteristics of degenerative succession in Festuca sinensis sowing grassland in the alpine pastoral area

ZHANG Yaosheng, ZHAO Xinquan

2002, (3):  285-289. 

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Quantitative characteristics of degenerative succession in Festuca sinensis sowing grassland in the alpine pastoral area were studied. The results showed that with the succession developing,number of species,richness index,diversity index,and evenness index were all increased,but ecological dominance was decreased. Analysis on important values,niche width,and niche overlaps proved that some herb species such as Ajania tenuifolia and Polygomum sibiricum were pioneer plants invading sowing grassland in the succession process. The pioneer plants had wider niche widths than other species,and their important values increased with the succession developing.Niche overlaps between Festuca sinensis and other species were smaller than that between two latifoliate herbs species in most case. The invasion of latifoliate herbs was one of the most important factors,which made the sowing grassland more degenerative.

Selection of optimum periods for rice estimation using remote sensing data based on GIS

HUANG Jingfeng, WANG Renchao, JIANG Hengxian, YANG Zhong'en

2002, (3):  290-294. 

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The optimum temporal for rice estimation using remote sensing data included the optimum temporal for rice planting area estimation and the optimum temporal for rice yield estimation. Based on GIS,the rice potential planting area was extracted. Therefore, the study area became smaller and the plant species considered decreased. So the optimum temporal for rice planting area estimation were determined through comparing the crop phonological calendars. In order to select the optimum temporal for rice yield estimation using remote sensing data,the relationships between the rice yield and agronomic parameters,the agronomic parameters and spectral variables,the rice yield and spectral variables for different development stages using field experiment data in1989 and 1990 were studied. The result showed that the key period of rice production was from boot stage to heading stage. At last,the optimum temporal for rice yield estimation using remote sensing data was selected using the rice phenological calendars of 1998.

Morphology of wheat roots under low phosphorus stress

SUN Haiguo, ZHANG Fusuo

2002, (3):  295-299. 

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The morphology of root systems of different wheat(Triticum aestivum L.) genotypes under low phosphorus stress were studied to determine the effects of external factors on components of root system and the early morphological indicators related to phosphorus efficiency. The number of root axes and the length of lateral root of Pdeficient plant were significantly lower than those of Psufficient plant. The length of root axis and root system,and the number of lateral roots were sharply increased under low Pstress. The number and length of root axis were significantly different under different levels of phosphorus supply and among different wheat genotypes under same phosphorus supply. This implied that the two traits (number and length of root axis) were controlled by genotype and external factors. The difference in the characteristics of lateral root of the given wheat genotypes was significant only between different levels of Psupply. It showed that the traits of lateral root mainly depended on external factors. The length and number of root axis, root length,and root angle were significantly different among6 wheat genotypes. There exited significant linear relationships between relative grain yield and the interaction of the morphological traits,and it implied that the traits could be used as early indicators of selec ting high Pefficiency wheat varieties.

Microbial biomass affected by cadmium with the occurrence of organic acids in red soil

LIAO Min, HUANG Changyong

2002, (3):  300-302. 

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Soil microbial biomass carbon and nitrogen were determined after adding fixed concentration of organic acids and changeable concentration of cadmium in pre incubated red soil and 14 day incubation at 25 ℃. The results show that soil microbial biomass carbon and nitrogen in the soil added with organic acids decreased with increasing concentration of cadmium. When the concentration of cadmium was higher than25 mg·kg^-1,the microbial biomass carbon and nitrogen in the soil added with low molecular weight of organic acids (oxalic acid,acetic acid,citric acid,tartaric acid) were lower than those without the addition of oranic acids,indicating that low molecular weight of organic acids could increase the toxicity of cadmium. On the contrary,the microbial biomass carbon and nitrogen in the soil added with low molecular weight of oranic acids were higher than those without the addition of organic acids when the concentration of cadmium was lower than25 mg·kg^-1,indicating that low molecular weight organic acids could decrease the toxicity of cadmium. The microbial biomass carbon and mitrogen in the soil containing humic acid were higher than those without the addition of organic acids,indicating that humic acid could decrease the toxicity of cadmium.However,the C:Nratio of soil microbial biomass was increased with incresing concentration of cadmium. Organic acids could increase microbial biomass carbon and nitrogen when soil was not added with cadmium.

Effects of maize stubble remaining in field on dynamics of soil microbial biomass C and soil enzyme activities

SONG Ri, WU Chunsheng, MOU Jinming, JIANG Yan, GUO Jixun

2002, (3):  303-306. 

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This study dealt with the effects of maize stubble remaining in field on dynamics of soil microbial biomass Cand soil enzyme actvities. The results showed that maize stubble remaining in field could raise soil microbial biomass Cand the actvities of urease,phosphatase,cellulase,and invertase in soil remarkably. According to the dynamics of soil microbial biomass Cand activities of the four enzymes,the five characters reached their maximum values about 60 days after sowing,and the crops were in bloom of growth. The results also showed that maize stubble remaining in field had positive effects on improving fertility and keeping high and steady yield of maize.

Exudation and accumulation of citric acid in common bean in response to Al toxicity stress

SHEN Hong, YAN Xiaolong, ZHENG Shaoling, WANG Xiurong

2002, (3):  307-310. 

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Significant differences in the exudation and accumulation of citric acid in common bean genotypes were observed in response to Al toxicity stress by hydroponic cultural experiments. Secreted citric acid increased with increasing external concentrations of Al³⁺ which ranged from 0 to 50 μmol·L^-1,while ranged from 50 to 80 μmol·L^-1,secreted citric acid decreased with increasing external concentrations of Al³⁺. Among different genotypic common beans,citric acid secreted in G19842 was the largest,while Al uptake per unit dry weight in G19842 was the least. No difference in the accumulation of citric acid in leaves was found among different genotypic common beans,while the size of the content of citric acid in roots was G19842>AFR>ZPV>G5273. The amount of citric acid exuded was smaller induced by phosphorus deficiency than that induced by Al toxicity stress. Exposure to 50 μmol·L^-1 LaCl 3 could not induce the exudation of citric acid,and it implied that the exudation and accumulation of citric acid in common bean was an important physiological response of resistance to Al toxicity stress.

Effects of magnesium deficiency on senescence of Dimocarpus longana leaves

LI Yan, LIU Xinghui

2002, (3):  311-314. 

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180days old Dimocarpus longana seedlings were grown in nutrition solution with three magnesium concentrations as 4 mmol·L^-1 Mg²⁺(sufficient supply),0.4 mmol·L^-1 Mg²⁺(deficient supply),and Mg free (without supply). Leaves were sampled 120 and 150 days later after treatment. With an increase in severity of Mg deficient,the chlorophyll content,PSⅡ activityes,photosynthetic rate,protein,nucleic acid (DNA,RNA),and ZRs contents declined progressively. Whereas the content of H₂O₂,the rate of O₂^-. generation as well as the content of malondialdehyde (MDA) increased. The results suggested that magnesium deficiency had significant effect on the senescence of Dimocarpus longana leaves.

Contribution to vegetable mercury from atmosphere and soil

LIU Deshao, QING Changle

2002, (3):  315-318. 

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In this research,the characteristics of Hg accumulation in vegetable and the contribution of atmosphere and soil to vegetable Hg were studied by field observation and pot experiments.11 kinds of vegetable were experimented in field. The results indicated that the Hg contents in roots and leaves of vegetables were higher than that in stems and fruits.In the natural condition,more than60% of the assimilated Hg was distributed in the up ground edible parts. The results of pot experiments showed that the Hg content of the edible parts of carrot and lettuce exceeded the Food Heath Standard Value (FASV),when the atmospheric Hg content reached 57.6±14.7 ng·m^-3. This result indicted that the contribution of atmosphere and soil to vegetable Hg were 70.4～90.7% and 9.3～29.6% respectively. So, the vegetable Hg was affected mainly by atmosphere Hg.

Changes of soil physical,chemical and ecological factors under mechanized cultivation

XIA Ping, Ren Li

2002, (3):  319-322. 

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Three years agricultural mechanization extension project in Huang Huai Hai regions showed that the application of comprehensive agricultural technologies which included the return of straw and stalk to field by mechanization,deep application of fertilizer, deep plough and soil no tillage with mulch,had an obvious biological effects.In comparing with traditional cultivation,the comprehensive mechanized cultivation could decrease soil bulk density by 0.08 g·cm^-3,increase soil organic mater by 12%,improve moisture utilization by 10.1～13.6%,and increase the grain yields of wheat and corn by 1218 kg·hm^-2.

Ecological economic analysis of a rice-crab model

CHEN Feixing, ZHANG Zengjie

2002, (3):  323-326. 

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Based on field investigation and experimental data analysis,ecological economic principles were applied to study the structure and function,the characteristics of material and energy flows,and the economic and ecological benefits of a rice crab model.The resutls show that rice crab model had a higher integral benifit than rice model,and its net income,cost benefit ratio,and labor productivity were increased by 382%,67.7% and 295%,respectively.In view of the ecological benefits produced,the total nitrogen,alkaline hydrolyzal nitrogen,total phosphorus,rapidly availlable phosphorus,rapidly available potassium,and organic matter in the soil after 1 year carb breeding were increased by 10.6%, 3.3 %,5.8%,11.7%,3.5% and 10.5%,respectively.Moreover,6375 kg N穐m^-2 of non point source pollution load could be cut down annually.

Bioremediation of PAHs contaminated soil using bio-slurry reactor process

LI Peijun, GONG Zongqiang, JING Xin, XU Huaxia, ZHANG Chungui, MA Xuejun, HE Yaowu

2002, (3):  327-330. 

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Studies on bioremediation of PAHs contaminated soil were carried out using bio slurry reactor process.Phenanthrene (PHE) and pyrene (PY) were chosen as the test pollutants.The results showed that the physical and chemical properties of the pollutants were key factor affecting the bio remedying possibility of PAHs in soil.PAHs with less benzene rings and lower molecule weight were easier to be biodegraded.So,phenanthrene had higher bio remedying possibility than pyrene.Temperature and airflow were important control factors in bio slurry reactor process. In this research,the optimized parameters were operating temperature as 20～30℃,ratio between water and soil as 2:1,airflow as 8 L·h^-1·L^-1,and the inoculating amount as 50 g·kg^-1.

Toxicity assessment of soil contaminated by heavy metals using algae growth inhibition test

LI Bin, LI Peijun, WANG Jing, ZHANG Hairong, YANG Guifen, XU Dawei, SU Baoling

2002, (3):  331-334. 

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Scenedesmus obliquus growth inhibiton test was carried out to assess the toxicity of soil contaminated by heavy metals. The results showed that the growth rate of Scenedesmus obliquus was positively related to the concentration of heavy methals added to soil,and it was decreased with the increasing concentration of heavy metals. Two parameters were chosen and the sensivities were compared.It was found that the cell growth rate was more sensitive than OD growth rate. The orders of general detection limit by EC₅₀ of different metals were Pb>Cu>Zn>Cd by using cell growth rate as the test index and Pb>Cu>Cd>Zn by using OD as the test index. This study also indicated that under the complex pollution condition,the toxicity of heavy metals in soil was stronger than that in the case of soil contaminated by single metal.

Agricultural application of sludge dredged from landscape water bodies

ZHU Guangwei, CHEN Yingxu, WANG Fengping, ZHOU Gendi

2002, (3):  335-339. 

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The feasibility and ecological effects of agricultural application of sludge dredged from the Grand Canal (Hangzhou Section) were studied. Applied too much dredged sludge to red soil and paddy soil affected the germination of alpine fescue [Fescuta ovina var. brachyphylla (Schult.) Piper] and colver (Trifolium repens.L) seeds,while there wasn't significantly affects in pot experiment.While the application rate was lower than 270 t穐m^-2,the growth of pakchoi (Brassica chinensis L.) increased as application rate increasing. While the application rate was higher than270 t穐m^-2,the growth of pakchoi decreased. The flowers and grasses in garden were more suitable for the dredged sludge application,and there was significant increase of growth while the application rate was lower than1080 t穐m^-2. Contents of copper and zinc exceed hygiene standard,while the application rate was above 1350 t穐m^-2. While the application rate was lower than450 t穐m^-2,the pollution of the groundwater had not been observed. The results showed that land application was an economical and feasible way for the disposal of sludge dredged from landscape water bodies,and horticultural application was more safe and economical than agricultural application.

Influences of body weight and temperature on standard metabolic rate of Paralichthys olivaceus

XIAN Weiwei, ZHU Xinhua

2002, (3):  340-342. 

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The standard metabolic rate of Paralichthys olivaceus was increased with its increasing body weight,whose relationship could be described as a power function. The rate change with tempreature could be expressed by an exponential function, R_s=02340W^0.6695e^00372T. There was no significant interaction between body weight and temperature in the process of the standard metabolism for the living organism.

Stimulation effect of anthracene on marine microalgae growth

WANG You, TANG Xuexi, LI Yongqi, LIU Yong

2002, (3):  343-346. 

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Two species of marine microalgae, Isochrysis galbana 8701 and Skeletonema costatum,were exposed to low concentration of anthracene,and their cell density,contents of chlorophyll a,carotinoid and protein,and superoxide dismutase (SOD) activity were examined. It was showed that low concentration of anthracene (1.5～6.0μg·L) could obviously stimulate the growth of these microalgae, and their protein,chlorophyll a, and carotinoid contents increased with increasing cell density. SOD of treated groups remained high activity,compared with the controlled group during the whole experiment.

Frontier fields of plant chemical ecology in the21st century

KONG Chuihua

2002, (3):  349-353. 

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It has focused on chemical interactions between plant and other organisms,which mediated by secondary plant metabolites in recent years.Induced chemical defense in plant,plant chemical communication,relationships between secondary plant metabolites and evolution,chemical relationships between plant and human and chemical ecology of marine plant are the frontier fields needed attention of plant chemical ecology in the 21st century.Progress in these frontier fields of plant chemical ecology will play an important role in sustainable development,particular in increasing agricultural production and effective control of pest,disease and weed under ecological security in the 21st century.

On the basic concepts and contents of ecological security

XIAO Duning, CHEN Wenbo, Guo Fuliang

2002, (3):  354-358. 

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Security is the inverse function of risk,generally regarded as safeguard degree expectation state of assessment object, or reliability of prevent imperfect and uncertainty event to happen.Ecological security can defined as mankind's ensure degree un effected by ecological destroy and environmental pollution in yield,living and health,including basic element of water and food security,air quality and green environment. The mostly content of ecological security consists of ecological health diagnosis,regional ecological risk analysis,landscape security pattern,ecological security monitoring and prediction,and ecological security management and guarantee etc. Study on regional ecological security has characteristics of macro scope and pertinence,assessment criterion of relativity and expansibility. Ecological security prediction and design should embody the capability of human activity. At last,authors discuss the measures of the ecological security ensure of inland watershed and ecological security analysis of oasis landscape.

Present status and prospects in research on effect of enhanced UV-B radiation on plants

JI Meiju, FENG Huyuan, AN Lizhe, WANG Xunling

2002, (3):  359-364. 

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Current research status on the effect of enhanced UV Bradiation on plants was reviewed in this paper. The main research fields involved plant growth and morphological structure,plant physiological and biochemical metabolism,plant genetic material,UV Babsorbing compounds and some gene expression,population,and ecosystem. In addition,some issues worthy to be studied in this field in future were proposed.

Ecological effects of cover crops

LIU Xiaobing, SONG Chunyu, Stephen J.Herbert, XING Baoshan

2002, (3):  365-368. 

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This paper reviewed the effects of cover crops in reducing soil loss,surface runoff,NO₃^- leaching and water pollution,and elucidated roles of cover crops in controllling pest insects, weeds and diseases, and increasing soil nu trients. The potential roles and appropriate application of cover crops in sustainable development of agriculture were also discussed.

Microbial reduction of iron,manganese as well as other metals and their individual significance in environmental bioremediation

ZHU Weiqin, LIN Xianyong, ZHANG Yongsong

2002, (3):  369-372. 

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In this paper,microbial reduction of iron,manganese and other metals in soils and waters were discussed. Microorganisms reducing to different metals such as iron,manganese and uranium as well as selenium and their enzymatic and non enzymatic mechanisms for reducing to different metals were summarized. Moreover,the significance of reduction of different microorganisms of metals in the bioremediation of metals contaminated environment was also evaluated.

Impact of root exudates from transgenic plants on soil micro-ecosystems

WANG Zhonghua, YE Qingfu, SHU Qingyao, CUI Hairui, XIA Yingwu

2002, (3):  373-375. 

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With the commercialization of transgenic plants,ecological risk assessment of transgenic plants has been sche duled. Many problems such as gene transfer from transgenic plants to related wild species,production of super weeds and super virus,tolerance to insect resistant transgenic plants,and distruption of biodiversity have been taken place in some transgenic plants. The influences of root exudates from transgenic plants on soil micro ecosystems were reviewed.

Genetics study on photo-and thermo-sensitive genic male sterility of indica rice (Osatival L)

DENG Qiyun, SHENG Xiaobang, LI Xinqi

2002, (3):  376-378. 

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The sterility segregation and its genetic patterns of indica P(T)GMS rice were analyzed mainly based on the investigation of bagged seed set of individuals in reciprocal F₂ population from the crosses between P(T)GMS lines of different origin and typical indica conventional varieties of different ecotype under long day length and high temperature condition by using the software of the maximum likelihood method. The results showed that the sterility of Annong S-1,Hengnong S-1,and W6154S,of which the sterility alteration was mainly induced by temperature fluctuation,was controlled by one major recessive gene. But the sterility of W7415Swas controlled by more than two major recessive genes. Apart from the major recessive gene,there was a group of polygenes in controlling of the sterility segregation in F₂ population. Moreover,the polygenic variance was different from line to line. It implied that the polygenes of W6154S or W7415Swas far more complicated than that of Annong S-1 and Hengnong S-1 according to the maximum likelihood method. All the conventional indica varieties of different ecotypes possessed the major dominant fertility genes. Meanwhile,the genetic background in different ecotype conventional varieties,the essentiality of which lies in the existence of polygenes,was different and influenced the major gene expression deeply. It was also indicated that genetic background of middle season variety Nanjing11 was more complicated than that of early season variety Erjiuqing and late season variety GER 1 as well. Finally,the differences of drift in critical temperature inducing male sterility of P(T)GMS lines (for short term DCT) and the stratgey of breeding practically usable P(T)GMS line with slighter DCT were discussed in the paper.

Effect of phosphorus deficiency on activity of acid phosphatase exuded by wheat roots

SUN Haiguo, ZHANG Fusuo

2002, (3):  379-381. 

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The activity of acid phosphatase exuded by roots,the tissue location of the enzyme, and the relationship between the enzyme activity and phosphorus efficiency of wheat were studied. The results showed that the activity of acid phosphatase exuded by wheat 81(85)5-3-3-3 and NC37 under P-sufficiency treat were lower than those under Pdeficiency, and the enzyme activity of the former variety was significantly higher than that of the latter. There was a significant difference in the enzyme activity among12 wheat genotypes grown under Pdeficiency treat. Acid phosphatase was exuded by epidermis cell of root, especially by epidermal cell of root apex. Thus, there was a linear relationship between the enzyme activity and the surface area of root or the number of root apexes. It implied that the enzyme activity was markedly related to the size of root system. The linear relationship between relative grain yield and acid phosphatase activity was significant. It indicates that the enzyme activity could be used as an early indicator to select P-efficient wheat genotypes.

Effects of enhanced ammonium nutrition on content and accumulation of nitrogen and mineral nutrients in wheat plant

DAI Tingbo, CAO Weixing, SUN Chuanfan

2002, (3):  382-384. 

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The hydroponics experiment was conducted to study the nutrition basis for growth promotion of wheat by Enhanced Ammonium Nutrition(EAN). Compared with fertilizing NO₃^- alone,EAN significantly increased Nconcentration and accumulation in leaves,sheaths,and whole plant,but there were not significant effects on roots. EAN had no significant effects on concentration of Pand K,but decreased that of Ca and Mg in whole plant. EAN increased accumulation of P,K,and Ca in whole plant,and decreased that of Mg,whereas single NH₄⁺ decreased accumulation of all mineral nutrients. EAN had different effects on accumulation of mineral nutrients in different genotypes. Compared with fertilizing NO₃^- alone,EAN increased accumulation of P,K,and Ca of YM158 and LZ953. For the accumulation of JDM,there was little responsive to EAN. These results indicated that EAN promoted Nabsorption and increased accumulation of N,P,K,and Ca in whole plant.

Analysis of natural regeneration barriers of Pinus sylvestris varmongolica plantation on sandy land

ZENG Dehui, YOU Wenzhong, FAN Zhiping, LIU Mingguo

2002, (3):  257-261. 

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By employing comparison analysis,and field experiment of watering and soil covering befroe overwintering for seedlings,the barriers of natural regeneration for Mongolian pine plantations on sandy soil were identified. The experimental area was divided into 3 parts according to the state of natural regeneration. Crown closure,litter,understory coverage,and site condition were the factors which affect natural regeneration. Water deficit,but not low temperature during overwintering,is the key factor that limits survival for 1～2 years old seedlings in plantation area. The water deficit is due to higher air temperature,less accumulated snow,higher soil evaporation,higher plant transpiration in plantation area than in the area in which Mongolian pine is naturally distributed. Based on the above research,it is necessary to take effective artificial measures to promote its natural regeneration so as to guarantee its successful development. The following measures are recommended:1)covering the 1～2 years old seedlings with soil before wintering,2)irrigating seedlings before wintering,3)suitable forest harvest,e.g.,belt clear cutting,or patch cutting,4)planting the pine with broadleaf species,5)protecting forest stands from livestock grazing,seed collecting and litter gathering.

Analysis on the sustainability of Amomum villosum cultivation under the tropical rainforest in Xishuangbanna

GAO Lei, LIU Hongmao, CUI Jingyun, NIE Zelong, DUAN Qiwu

2002, (3):  262-266. 

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Amomum villosum has been cultivated under tropic rainforest in Xishuangbanna area since 1970s. The cultivation area of Amomum villosum had expanded to 5811 hm² by 1998,and the dry fruit yield had reached to 542 t. In this study,the ecological and economical benefits of this cultivation model were analyzed. The results showed that plant diversity,litter,soil humidity,and soil fertility of rainforest decreased at different levels after Amomum villosum cultivated under rainforest,and the distribution of nutrition had been changed in the soil. The economical benefits had an obvious downtrend after 7～8 years cultivating due to irrational management. So,the present cultivation model of Amomum villosum under the tropical rainforest was not sustainable. For the objectives of harmonizing the ecological,economic,and social benefits and sustainable utilization of the rainforest,and improved model was also discussed in this study.

A comparative study on life-form spectra of evergreen broad-leaved forest in different successions in Jinyun Mountain

LEI Ningfei, SU Zhixian, SONG Huixing, ZHANG Yan

2002, (3):  267-270. 

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The life form of plant communities in different succession stages in Jinyun Mountain was studied and the life form spectrum was established. The results showed that according to the characters of life form of plant communities,the vegetation in Jinyun Mountain belonged to typical subtropical evergreen broad leaved forest vegetation. Evergreen phaenerophytes were absolutely dominant in the life form spectrum and its quantity accounted for more than80%. Among phaenerophyte,quantity of microphanerophyte was the most,and quantities of mesophanerophtye and nanophanerophyte were less. Different successions had different life form spectra. With the development of succession,the percentage of phaenerophytes increased,and other life forms decreased correspon dingly. According to the development of life form and comparative analysis of environmental factors in different succession stages,coniferous species would be replaced by evergreen phaenerophytes.

Neighbor diversity and interspecific association of Quercus mongolica

YU Shunli, MA Keping, LIU Canran, CHEN Lingzhi

2002, (3):  271-274. 

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Neighbor diversity and interspecific association of Quercus mongolica were studied through point sample method. With the increase of plots number,species richness and Shannon Wiener (H') diversity index increased. At last they came colse to fixed value. LSvalue (average number of neighboring species) was first introduced in this article. Different sits had different PCvalue (value of interspecific association). According to PCvalue and LSvalue,accompany tree and shrub species of Quercus mongolica were determined. The similar environmental requirement and mutualism were the main reason why they live together. The result of interspecific association between Quercus mongolica and other species in 4 locations was analyzed. The reason why the diffe rences existed was that Quercus mongolica studied was in different succession stages.

Effect of drought stress on apparent resource utilization efficiency of Quercus mongolica

WANG Miao, DAI Limin, JI Lanzhu

2002, (3):  275-280. 

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To study the effect of drought stress on the physiological characteristics and resource utilization effciency of Quercus mongolica,a dominant species in the Korean pine broad leaved forest in Changbai Mountain,a comparative experiment was carried out under three soil moisture gradients as 85%～100%(high water,CK),65%～85%(Medium water,MW),and 45%～65%(low water,LW) of field water bolding capacity. The results showed that net photosynthetic rate,stomatal conduction,transpiration rate,water utilization efficiency,apparent CO₂ utilization efficiency and apparent light utilization efficiency of the seedlings of Quercus mongolica were all significantly influenced by simulated drought stress. Stomatal conduction,water utilization efficiency and net photosynthetic rate of large tress of Quercus mongolica were affected by the soil drought stress,while transpiration rate,apparent CO₂ utilization efficiency,and apparent light utilization efficiency were not influenced. Mode rate soil water condition could greatly increase gas exchange and water utilization efficiency. These results indicated that the responses of gas exchange and resource utilization efficiency to various water stresses were diffe rent. Quercus mongolica was a species with variable resistance to drought stress,and the resistance would be improved by drought stress,especially moderate water stress.

Clutch size,nesting success and breeding success rate in Emberiza jankowskii in the grassland at Baicheng in Jilin Province

TONG Fuchun, GAO Wei, XIAO Yihua, WANG Shaoxian, BAI Hasi, SUN Danting, WANG Qingli

2002, (3):  281-284. 

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In this article,clutch size,nesting success and breeding success rate of Emberiza jankowskii living in grassland habitats in Baicheng Region of Jilin Province were studied from May to July in 1999. The results showed average clutch size was 5.09?0.58 eggs per nest. There was negative correlation between clutch size and initial laying date,brood quantity and initial laying date,clutch size and fresh egg weight. There was exceedingly negative correlation between initial laying date and incubated rate. There was exceedingly positive correlation between nest size and clutch size. There was positive correlation between other attributes of nest and clutch size. Average incubation period was 12?094 days, incubated rate was 36.3%,and breeding success rate was 11.11%. The population size of brood size above seven days was 2.56?1.53. Nestling survival rate was 27.69%.

Quantitative characteristics of degenerative succession in Festuca sinensis sowing grassland in the alpine pastoral area

ZHANG Yaosheng, ZHAO Xinquan

2002, (3):  285-289. 

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Quantitative characteristics of degenerative succession in Festuca sinensis sowing grassland in the alpine pastoral area were studied. The results showed that with the succession developing,number of species,richness index,diversity index,and evenness index were all increased,but ecological dominance was decreased. Analysis on important values,niche width,and niche overlaps proved that some herb species such as Ajania tenuifolia and Polygomum sibiricum were pioneer plants invading sowing grassland in the succession process. The pioneer plants had wider niche widths than other species,and their important values increased with the succession developing.Niche overlaps between Festuca sinensis and other species were smaller than that between two latifoliate herbs species in most case. The invasion of latifoliate herbs was one of the most important factors,which made the sowing grassland more degenerative.

Selection of optimum periods for rice estimation using remote sensing data based on GIS

HUANG Jingfeng, WANG Renchao, JIANG Hengxian, YANG Zhong'en

2002, (3):  290-294. 

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The optimum temporal for rice estimation using remote sensing data included the optimum temporal for rice planting area estimation and the optimum temporal for rice yield estimation. Based on GIS,the rice potential planting area was extracted. Therefore, the study area became smaller and the plant species considered decreased. So the optimum temporal for rice planting area estimation were determined through comparing the crop phonological calendars. In order to select the optimum temporal for rice yield estimation using remote sensing data,the relationships between the rice yield and agronomic parameters,the agronomic parameters and spectral variables,the rice yield and spectral variables for different development stages using field experiment data in1989 and 1990 were studied. The result showed that the key period of rice production was from boot stage to heading stage. At last,the optimum temporal for rice yield estimation using remote sensing data was selected using the rice phenological calendars of 1998.

Morphology of wheat roots under low phosphorus stress

SUN Haiguo, ZHANG Fusuo

2002, (3):  295-299. 

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The morphology of root systems of different wheat(Triticum aestivum L.) genotypes under low phosphorus stress were studied to determine the effects of external factors on components of root system and the early morphological indicators related to phosphorus efficiency. The number of root axes and the length of lateral root of Pdeficient plant were significantly lower than those of Psufficient plant. The length of root axis and root system,and the number of lateral roots were sharply increased under low Pstress. The number and length of root axis were significantly different under different levels of phosphorus supply and among different wheat genotypes under same phosphorus supply. This implied that the two traits (number and length of root axis) were controlled by genotype and external factors. The difference in the characteristics of lateral root of the given wheat genotypes was significant only between different levels of Psupply. It showed that the traits of lateral root mainly depended on external factors. The length and number of root axis, root length,and root angle were significantly different among6 wheat genotypes. There exited significant linear relationships between relative grain yield and the interaction of the morphological traits,and it implied that the traits could be used as early indicators of selec ting high Pefficiency wheat varieties.

Microbial biomass affected by cadmium with the occurrence of organic acids in red soil

LIAO Min, HUANG Changyong

2002, (3):  300-302. 

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Soil microbial biomass carbon and nitrogen were determined after adding fixed concentration of organic acids and changeable concentration of cadmium in pre incubated red soil and 14 day incubation at 25 ℃. The results show that soil microbial biomass carbon and nitrogen in the soil added with organic acids decreased with increasing concentration of cadmium. When the concentration of cadmium was higher than25 mg·kg^-1,the microbial biomass carbon and nitrogen in the soil added with low molecular weight of organic acids (oxalic acid,acetic acid,citric acid,tartaric acid) were lower than those without the addition of oranic acids,indicating that low molecular weight of organic acids could increase the toxicity of cadmium. On the contrary,the microbial biomass carbon and nitrogen in the soil added with low molecular weight of oranic acids were higher than those without the addition of organic acids when the concentration of cadmium was lower than25 mg·kg^-1,indicating that low molecular weight organic acids could decrease the toxicity of cadmium. The microbial biomass carbon and mitrogen in the soil containing humic acid were higher than those without the addition of organic acids,indicating that humic acid could decrease the toxicity of cadmium.However,the C:Nratio of soil microbial biomass was increased with incresing concentration of cadmium. Organic acids could increase microbial biomass carbon and nitrogen when soil was not added with cadmium.

Effects of maize stubble remaining in field on dynamics of soil microbial biomass C and soil enzyme activities

SONG Ri, WU Chunsheng, MOU Jinming, JIANG Yan, GUO Jixun

2002, (3):  303-306. 

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This study dealt with the effects of maize stubble remaining in field on dynamics of soil microbial biomass Cand soil enzyme actvities. The results showed that maize stubble remaining in field could raise soil microbial biomass Cand the actvities of urease,phosphatase,cellulase,and invertase in soil remarkably. According to the dynamics of soil microbial biomass Cand activities of the four enzymes,the five characters reached their maximum values about 60 days after sowing,and the crops were in bloom of growth. The results also showed that maize stubble remaining in field had positive effects on improving fertility and keeping high and steady yield of maize.

Exudation and accumulation of citric acid in common bean in response to Al toxicity stress

SHEN Hong, YAN Xiaolong, ZHENG Shaoling, WANG Xiurong

2002, (3):  307-310. 

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Significant differences in the exudation and accumulation of citric acid in common bean genotypes were observed in response to Al toxicity stress by hydroponic cultural experiments. Secreted citric acid increased with increasing external concentrations of Al³⁺ which ranged from 0 to 50 μmol·L^-1,while ranged from 50 to 80 μmol·L^-1,secreted citric acid decreased with increasing external concentrations of Al³⁺. Among different genotypic common beans,citric acid secreted in G19842 was the largest,while Al uptake per unit dry weight in G19842 was the least. No difference in the accumulation of citric acid in leaves was found among different genotypic common beans,while the size of the content of citric acid in roots was G19842>AFR>ZPV>G5273. The amount of citric acid exuded was smaller induced by phosphorus deficiency than that induced by Al toxicity stress. Exposure to 50 μmol·L^-1 LaCl 3 could not induce the exudation of citric acid,and it implied that the exudation and accumulation of citric acid in common bean was an important physiological response of resistance to Al toxicity stress.

Effects of magnesium deficiency on senescence of Dimocarpus longana leaves

LI Yan, LIU Xinghui

2002, (3):  311-314. 

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180days old Dimocarpus longana seedlings were grown in nutrition solution with three magnesium concentrations as 4 mmol·L^-1 Mg²⁺(sufficient supply),0.4 mmol·L^-1 Mg²⁺(deficient supply),and Mg free (without supply). Leaves were sampled 120 and 150 days later after treatment. With an increase in severity of Mg deficient,the chlorophyll content,PSⅡ activityes,photosynthetic rate,protein,nucleic acid (DNA,RNA),and ZRs contents declined progressively. Whereas the content of H₂O₂,the rate of O₂^-. generation as well as the content of malondialdehyde (MDA) increased. The results suggested that magnesium deficiency had significant effect on the senescence of Dimocarpus longana leaves.

Contribution to vegetable mercury from atmosphere and soil

LIU Deshao, QING Changle

2002, (3):  315-318. 

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In this research,the characteristics of Hg accumulation in vegetable and the contribution of atmosphere and soil to vegetable Hg were studied by field observation and pot experiments.11 kinds of vegetable were experimented in field. The results indicated that the Hg contents in roots and leaves of vegetables were higher than that in stems and fruits.In the natural condition,more than60% of the assimilated Hg was distributed in the up ground edible parts. The results of pot experiments showed that the Hg content of the edible parts of carrot and lettuce exceeded the Food Heath Standard Value (FASV),when the atmospheric Hg content reached 57.6±14.7 ng·m^-3. This result indicted that the contribution of atmosphere and soil to vegetable Hg were 70.4～90.7% and 9.3～29.6% respectively. So, the vegetable Hg was affected mainly by atmosphere Hg.

Changes of soil physical,chemical and ecological factors under mechanized cultivation

XIA Ping, Ren Li

2002, (3):  319-322. 

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Three years agricultural mechanization extension project in Huang Huai Hai regions showed that the application of comprehensive agricultural technologies which included the return of straw and stalk to field by mechanization,deep application of fertilizer, deep plough and soil no tillage with mulch,had an obvious biological effects.In comparing with traditional cultivation,the comprehensive mechanized cultivation could decrease soil bulk density by 0.08 g·cm^-3,increase soil organic mater by 12%,improve moisture utilization by 10.1～13.6%,and increase the grain yields of wheat and corn by 1218 kg·hm^-2.

Ecological economic analysis of a rice-crab model

CHEN Feixing, ZHANG Zengjie

2002, (3):  323-326. 

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Based on field investigation and experimental data analysis,ecological economic principles were applied to study the structure and function,the characteristics of material and energy flows,and the economic and ecological benefits of a rice crab model.The resutls show that rice crab model had a higher integral benifit than rice model,and its net income,cost benefit ratio,and labor productivity were increased by 382%,67.7% and 295%,respectively.In view of the ecological benefits produced,the total nitrogen,alkaline hydrolyzal nitrogen,total phosphorus,rapidly availlable phosphorus,rapidly available potassium,and organic matter in the soil after 1 year carb breeding were increased by 10.6%, 3.3 %,5.8%,11.7%,3.5% and 10.5%,respectively.Moreover,6375 kg N穐m^-2 of non point source pollution load could be cut down annually.

Bioremediation of PAHs contaminated soil using bio-slurry reactor process

LI Peijun, GONG Zongqiang, JING Xin, XU Huaxia, ZHANG Chungui, MA Xuejun, HE Yaowu

2002, (3):  327-330. 

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Studies on bioremediation of PAHs contaminated soil were carried out using bio slurry reactor process.Phenanthrene (PHE) and pyrene (PY) were chosen as the test pollutants.The results showed that the physical and chemical properties of the pollutants were key factor affecting the bio remedying possibility of PAHs in soil.PAHs with less benzene rings and lower molecule weight were easier to be biodegraded.So,phenanthrene had higher bio remedying possibility than pyrene.Temperature and airflow were important control factors in bio slurry reactor process. In this research,the optimized parameters were operating temperature as 20～30℃,ratio between water and soil as 2:1,airflow as 8 L·h^-1·L^-1,and the inoculating amount as 50 g·kg^-1.

Toxicity assessment of soil contaminated by heavy metals using algae growth inhibition test

LI Bin, LI Peijun, WANG Jing, ZHANG Hairong, YANG Guifen, XU Dawei, SU Baoling

2002, (3):  331-334. 

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Scenedesmus obliquus growth inhibiton test was carried out to assess the toxicity of soil contaminated by heavy metals. The results showed that the growth rate of Scenedesmus obliquus was positively related to the concentration of heavy methals added to soil,and it was decreased with the increasing concentration of heavy metals. Two parameters were chosen and the sensivities were compared.It was found that the cell growth rate was more sensitive than OD growth rate. The orders of general detection limit by EC₅₀ of different metals were Pb>Cu>Zn>Cd by using cell growth rate as the test index and Pb>Cu>Cd>Zn by using OD as the test index. This study also indicated that under the complex pollution condition,the toxicity of heavy metals in soil was stronger than that in the case of soil contaminated by single metal.

Agricultural application of sludge dredged from landscape water bodies

ZHU Guangwei, CHEN Yingxu, WANG Fengping, ZHOU Gendi

2002, (3):  335-339. 

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The feasibility and ecological effects of agricultural application of sludge dredged from the Grand Canal (Hangzhou Section) were studied. Applied too much dredged sludge to red soil and paddy soil affected the germination of alpine fescue [Fescuta ovina var. brachyphylla (Schult.) Piper] and colver (Trifolium repens.L) seeds,while there wasn't significantly affects in pot experiment.While the application rate was lower than 270 t穐m^-2,the growth of pakchoi (Brassica chinensis L.) increased as application rate increasing. While the application rate was higher than270 t穐m^-2,the growth of pakchoi decreased. The flowers and grasses in garden were more suitable for the dredged sludge application,and there was significant increase of growth while the application rate was lower than1080 t穐m^-2. Contents of copper and zinc exceed hygiene standard,while the application rate was above 1350 t穐m^-2. While the application rate was lower than450 t穐m^-2,the pollution of the groundwater had not been observed. The results showed that land application was an economical and feasible way for the disposal of sludge dredged from landscape water bodies,and horticultural application was more safe and economical than agricultural application.

Influences of body weight and temperature on standard metabolic rate of Paralichthys olivaceus

XIAN Weiwei, ZHU Xinhua

2002, (3):  340-342. 

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The standard metabolic rate of Paralichthys olivaceus was increased with its increasing body weight,whose relationship could be described as a power function. The rate change with tempreature could be expressed by an exponential function, R_s=02340W^0.6695e^00372T. There was no significant interaction between body weight and temperature in the process of the standard metabolism for the living organism.

Stimulation effect of anthracene on marine microalgae growth

WANG You, TANG Xuexi, LI Yongqi, LIU Yong

2002, (3):  343-346. 

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Two species of marine microalgae, Isochrysis galbana 8701 and Skeletonema costatum,were exposed to low concentration of anthracene,and their cell density,contents of chlorophyll a,carotinoid and protein,and superoxide dismutase (SOD) activity were examined. It was showed that low concentration of anthracene (1.5～6.0μg·L) could obviously stimulate the growth of these microalgae, and their protein,chlorophyll a, and carotinoid contents increased with increasing cell density. SOD of treated groups remained high activity,compared with the controlled group during the whole experiment.

Frontier fields of plant chemical ecology in the21st century

KONG Chuihua

2002, (3):  349-353. 

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It has focused on chemical interactions between plant and other organisms,which mediated by secondary plant metabolites in recent years.Induced chemical defense in plant,plant chemical communication,relationships between secondary plant metabolites and evolution,chemical relationships between plant and human and chemical ecology of marine plant are the frontier fields needed attention of plant chemical ecology in the 21st century.Progress in these frontier fields of plant chemical ecology will play an important role in sustainable development,particular in increasing agricultural production and effective control of pest,disease and weed under ecological security in the 21st century.

On the basic concepts and contents of ecological security

XIAO Duning, CHEN Wenbo, Guo Fuliang

2002, (3):  354-358. 

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Security is the inverse function of risk,generally regarded as safeguard degree expectation state of assessment object, or reliability of prevent imperfect and uncertainty event to happen.Ecological security can defined as mankind's ensure degree un effected by ecological destroy and environmental pollution in yield,living and health,including basic element of water and food security,air quality and green environment. The mostly content of ecological security consists of ecological health diagnosis,regional ecological risk analysis,landscape security pattern,ecological security monitoring and prediction,and ecological security management and guarantee etc. Study on regional ecological security has characteristics of macro scope and pertinence,assessment criterion of relativity and expansibility. Ecological security prediction and design should embody the capability of human activity. At last,authors discuss the measures of the ecological security ensure of inland watershed and ecological security analysis of oasis landscape.

Present status and prospects in research on effect of enhanced UV-B radiation on plants

JI Meiju, FENG Huyuan, AN Lizhe, WANG Xunling

2002, (3):  359-364. 

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Current research status on the effect of enhanced UV Bradiation on plants was reviewed in this paper. The main research fields involved plant growth and morphological structure,plant physiological and biochemical metabolism,plant genetic material,UV Babsorbing compounds and some gene expression,population,and ecosystem. In addition,some issues worthy to be studied in this field in future were proposed.

Ecological effects of cover crops

LIU Xiaobing, SONG Chunyu, Stephen J.Herbert, XING Baoshan

2002, (3):  365-368. 

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This paper reviewed the effects of cover crops in reducing soil loss,surface runoff,NO₃^- leaching and water pollution,and elucidated roles of cover crops in controllling pest insects, weeds and diseases, and increasing soil nu trients. The potential roles and appropriate application of cover crops in sustainable development of agriculture were also discussed.

Microbial reduction of iron,manganese as well as other metals and their individual significance in environmental bioremediation

ZHU Weiqin, LIN Xianyong, ZHANG Yongsong

2002, (3):  369-372. 

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In this paper,microbial reduction of iron,manganese and other metals in soils and waters were discussed. Microorganisms reducing to different metals such as iron,manganese and uranium as well as selenium and their enzymatic and non enzymatic mechanisms for reducing to different metals were summarized. Moreover,the significance of reduction of different microorganisms of metals in the bioremediation of metals contaminated environment was also evaluated.

Impact of root exudates from transgenic plants on soil micro-ecosystems

WANG Zhonghua, YE Qingfu, SHU Qingyao, CUI Hairui, XIA Yingwu

2002, (3):  373-375. 

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With the commercialization of transgenic plants,ecological risk assessment of transgenic plants has been sche duled. Many problems such as gene transfer from transgenic plants to related wild species,production of super weeds and super virus,tolerance to insect resistant transgenic plants,and distruption of biodiversity have been taken place in some transgenic plants. The influences of root exudates from transgenic plants on soil micro ecosystems were reviewed.

Genetics study on photo-and thermo-sensitive genic male sterility of indica rice (Osatival L)

DENG Qiyun, SHENG Xiaobang, LI Xinqi

2002, (3):  376-378. 

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The sterility segregation and its genetic patterns of indica P(T)GMS rice were analyzed mainly based on the investigation of bagged seed set of individuals in reciprocal F₂ population from the crosses between P(T)GMS lines of different origin and typical indica conventional varieties of different ecotype under long day length and high temperature condition by using the software of the maximum likelihood method. The results showed that the sterility of Annong S-1,Hengnong S-1,and W6154S,of which the sterility alteration was mainly induced by temperature fluctuation,was controlled by one major recessive gene. But the sterility of W7415Swas controlled by more than two major recessive genes. Apart from the major recessive gene,there was a group of polygenes in controlling of the sterility segregation in F₂ population. Moreover,the polygenic variance was different from line to line. It implied that the polygenes of W6154S or W7415Swas far more complicated than that of Annong S-1 and Hengnong S-1 according to the maximum likelihood method. All the conventional indica varieties of different ecotypes possessed the major dominant fertility genes. Meanwhile,the genetic background in different ecotype conventional varieties,the essentiality of which lies in the existence of polygenes,was different and influenced the major gene expression deeply. It was also indicated that genetic background of middle season variety Nanjing11 was more complicated than that of early season variety Erjiuqing and late season variety GER 1 as well. Finally,the differences of drift in critical temperature inducing male sterility of P(T)GMS lines (for short term DCT) and the stratgey of breeding practically usable P(T)GMS line with slighter DCT were discussed in the paper.

Effect of phosphorus deficiency on activity of acid phosphatase exuded by wheat roots

SUN Haiguo, ZHANG Fusuo

2002, (3):  379-381. 

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The activity of acid phosphatase exuded by roots,the tissue location of the enzyme, and the relationship between the enzyme activity and phosphorus efficiency of wheat were studied. The results showed that the activity of acid phosphatase exuded by wheat 81(85)5-3-3-3 and NC37 under P-sufficiency treat were lower than those under Pdeficiency, and the enzyme activity of the former variety was significantly higher than that of the latter. There was a significant difference in the enzyme activity among12 wheat genotypes grown under Pdeficiency treat. Acid phosphatase was exuded by epidermis cell of root, especially by epidermal cell of root apex. Thus, there was a linear relationship between the enzyme activity and the surface area of root or the number of root apexes. It implied that the enzyme activity was markedly related to the size of root system. The linear relationship between relative grain yield and acid phosphatase activity was significant. It indicates that the enzyme activity could be used as an early indicator to select P-efficient wheat genotypes.

Effects of enhanced ammonium nutrition on content and accumulation of nitrogen and mineral nutrients in wheat plant

DAI Tingbo, CAO Weixing, SUN Chuanfan

2002, (3):  382-384. 

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The hydroponics experiment was conducted to study the nutrition basis for growth promotion of wheat by Enhanced Ammonium Nutrition(EAN). Compared with fertilizing NO₃^- alone,EAN significantly increased Nconcentration and accumulation in leaves,sheaths,and whole plant,but there were not significant effects on roots. EAN had no significant effects on concentration of Pand K,but decreased that of Ca and Mg in whole plant. EAN increased accumulation of P,K,and Ca in whole plant,and decreased that of Mg,whereas single NH₄⁺ decreased accumulation of all mineral nutrients. EAN had different effects on accumulation of mineral nutrients in different genotypes. Compared with fertilizing NO₃^- alone,EAN increased accumulation of P,K,and Ca of YM158 and LZ953. For the accumulation of JDM,there was little responsive to EAN. These results indicated that EAN promoted Nabsorption and increased accumulation of N,P,K,and Ca in whole plant.