Table of Content

15 April 2003, Volume 14 Issue 4

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Phosphorus transfer between mixed poplar and black locust seedlings

HE Wei, JIA Liming, HAO Baogang, WEN Xuejun, ZHAI Mingpu

2003, (4):  481-486. 

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In this paper, the ³²P radio-tracer technique was applied to study the ways of phosphorus transfer between poplar (Populus euramericana cv.‘I-214') and black locust (Robinia pseudoacacia). Afive compartment root box (18cm×18cm×26cm) was used for testing the existence of the hyphal links between the roots of two tree species when inoculated with vesicular-arbuscular (VA) mycorrhizal fungus (Glomus mosseae). Populus I-214 (donor) and Robinia pseudoacacia (receiver) were grown in two terminal compartments, separated by a 2 cm root-free soil layer. The root compartments were lined with bags of nylon mesh (38μm) that allowed the passage of hyphae but not roots. The top soil of a mixed stand of poplar and black locust, autoclaved at 121℃ for one hour, was used for growing seedlings for testing. In5 compartment root box, mycorrhizal root colonization of poplar was 34%, in which VAmycorrhizal fungus was inoculated, whereas 26% mycorrhizal root colonization was observed in black locust, the other terminal compartment, 20 weeks after planting. No root colonization was observed in non-inoculated plant pairs. This indicated that the mycorrhizal root colonization of black locust was caused by hyphal spreading from the poplar. Test of tracer isotope of ³²P showed that the radioactivity of the treatment significantly higher than that of the control (P<0.05), 14 days from the tracer applied, to 27 days after, when VAmycorrhizal fungus was inoculated in poplar root. Furthermore, mycorrhizal interconnections between the roots of poplar and black locust seedlings was observed in situ by binocular in root box. All these experiments showed that the hyphal links was formed between the roots of two species of trees inoculated by VAmycorrhizal fungus.Four treatments were designed according to if there were two nets (mesh 38μm), 2 cm apart, between the poplar and black locust, and if the soil in root box was pasteurized. Most significant differences of radioactivity among four treatments appeared 44 days after feeding³²P, the radioactivity of the day was applied to estimating the contribution of the various possible transfer ways to the total amount of nutrient transfer.Level of ³²Pradioactivity was found to be significantly (P<0.05) higher in leaves of the treatment of "no separated and soil non-pasteurized"(17.1 pulse·g^-1·s^-1) than in leaves of "net separated and soil non-pasteurized" ( 5.3 pulse·g^-1·s^-1),and also significantly higher in leaves of "no net separated and soil pasteurized"( 11.5 pulse·g·s^-1) than in leaves of "net separated and soil pasteurized" (2.3 pulse·g^-1·s^-1), and very significantly (P<0.01) higher in leaves of "no net separated and soil non-pasteurized" than in leaves of "net separated and soil pasteurized",whereas the levels of ³²P radioactivity were not significantly different between the other treatments.The results showed that root contact and root exudations were the main ways of phosphorus transfer between the two species and the amount of phosphorus transfer through these two ways accounted for 62% of the total.The activity of the microorganisms including VAmycorrhizal fungi and the interaction between the microorganisms and root contact and root exudations made up 38% of total amount of phosphorus. The effect of mycorrhizal hyphal links in the direct nutrient transfer between poplar and black locust through separate mesh (38μm) was little.

Quantification comparison of spatial pattern of soil seed bank of Fraxinus mandshurica in two stands

HAN Youzhi, WANG Zhengquan

2003, (4):  487-492. 

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The spatial pattern of soil seed bank of Fraxinus mandshurica were examined by geostatistics in two stands with different densities, tree species composition and ground plants, in the Northeast of China. Asampling grid of 559 points, at each point a sample was located, was established according to regular grid design at three spatial scales (cell size were 0.5m×0.5m, 1m×1m, and 2m×2m) in each plot. Spatial pattern were quantified by using semivariance analysis, fractal dimension and Kriging maps. The object of this paper is to quantify the spatial pattern of seed bank, to compare its variations between two stands, and to explore what sort of mechanism would control its variations. The results indicated seed distribution showed appreciable heterogeneity within stand and clearly difference between the two stands.In plot 1 (mixed stand), seed bank, with a mean of 158.1±96.7 seeds·m^-2, higher sill (C₀+C=0.549) and 4.25m scales, has a stronger spatial pattern. There were a high autocorrelated variation (89.4%) and lowly random variation (10.6%) at this scale. However, at scale from 5m to 31.3m, its autocorrelated variation ranged 51.4%～69.8% and random variation ranged 30.2%～47.6%, also has distinctly mosaic patterns. Fractal dimension (D) analysis showed that the Dvalues was relatively lower(1.728～1.865), their coefficient of variation only about 26.7%～68.35%, indicated that there was a high self-similarity of patch shapes of seed bank.In plot 2 (pure stand), with a mean of 57.4±44.7 seed·m^-2, and lower sill (C₀+C=0.125), spatial patterns were not so strong as plot 1, which has a smaller scale (2.59m). Its spatially autocorrelated variation was 56.8% and randomly variation was 43.2%. Over the scale there were no clearly autocorrelated spatial patterns. Fractal dimension analysis showed higher Dvalue (1.906～1.960), and their coefficient of variation varying wildly (69.51%～134.14%), implying highly random variation and more complex patch shapes. The differences of spatial pattern of seed bank between the two stands were likely to be due to spatial heterogeneity at the level of stands.

Acclimation of foliar photosynthetic apparatus of three tropical woody species to growth irradiance

CAI Zhiquan, CAO Kunfang, FENG Yulong, FENG Zhili

2003, (4):  493-496. 

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The photosynthetic characteristics and protective role of leaf antioxidant systems were studied for seedlings of three woody species, Anthocephalus chinensis,Barringtonia pendala,Garcinia hanburyi, acclimated to 8%, 25%, 50% of natural sunlight for four months. As growth irradiance increased, the saturation points,the light compensation points of photosynthesis,the maximum net photosynthetic rate,and the non-photochemical quenching efficiency of three species were increased, while the apparent quantum yield (AQY), the effective quantum efficiency (Fv'/Fm'), and the photochemical quenching efficiency (qP) were decreased.In protective enzymes systems, SOD and APX activities increased with increasing growth irradiance, but CATactivity was not consistent with PFD. As Aexhibited the most dramatic increase in response to growth irradiance. It could be concluded that besides the increase in xanthophyll cycle-dependent energy dissipation, the enhancement of leaf antioxidants was also a protective pathway against high light intensity.

Structure and function of several intercropping ecosystems in newly built orchard

ZENG Fuping, WANG Kelin, LI Lin, SU Yirong, XIAO Runlin, MENG Guanxi, WEI Zhengshe

2003, (4):  497-501. 

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Sloping wildland is the important potential land resource in China. Structures and functions of five optimized models selected from more than10 intercropping patterns in the newly built orchards in the uncultivated sloping field were analyzed in this paper. The results showed that organic matter was increased by 5～20%, total Nby 7～40%, total Pby 8～70%, and total Kby 15～80% yearly. Considering its benefit in soil and water conservation, the intercropping model of peanut and autumn soybean was the best, and followed by spring soybean and autumn soybean, tomato and Chinese cabbage, cayenne and tomato, and drought rice and red turnip. Compared with the control, the average soil erosion module and runoff amount of the 5 models were decreased by 44.19%, 38.24%, 39.52%, 37.56%, 37.30%, and 22.40%, 9.28%, 24.11%, 21.60%, 15.93%, respectively.The intercropping model of cayenne and tomato had the highest biomass, and its annual biomass averaged 100267kg·hm^-2. The biomass of intercropping model of peanut and autumn soybean was the second, and the annual value averaged 77026kg·hm^-2.Intercropping model of peanut and autumn had the highest annual productivity, which averaged 15619kg·hm^-2, and that of intercropping model of tomato and Chinese cabbage was the second,averaged 15394kg·hm^-2.The efficiency of energy introjection was in order of cayenne and tomato, tomato and Chinese cabbage, peanut and autumn soybean, spring soybean and autumn soybean, and dry rice and red turnip, and their values were 3.06, 2.16, 2.15, 2.06, and 0.71, respectively.

Fuzzy decision system for ecological distribution of citrus in north-cultivated-marginal area

ZHU Liwu, LI Shaowen, KONG Juanjuan, JIA Bing

2003, (4):  502-506. 

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The fuzzy decision system for ecological distribution of citrus in north-cultivated-marginal area was established by using the data of mean extreme low temperature, accumulated active temperature (≥12.5℃), mean temperature in coldest month, annual mean temperature integrated with annual precipitation, days with mean extreme low temperature below -9℃,physiognomy, elevation, inland water body, cold air barrier, and soil nutrition and pH value. The complex reasoning model with imprecision was used in the decision system by introduction of L-R fuzzy number and recognition formula, which made the decision system have a wide range of application in practice. An example of applying the decision system was tested in Anhui province. The result showed that the development of the decision system would provide a useful tool for the decision of the ecological distribution of citrus in north-cultivated-marginal area.

Soil water availability in new-cultivated hillside land

SU Yirong, HUANG Yu, WANG Kelin

2003, (4):  507-511. 

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The dynamics of water content in three soil layers (0～20cm, 20～40cm and 40～60cm) were determined at three geographic locations (mesoslope, downgrade, valley) of new-cultivated sugarcane field and uncultivated hillside land at one day before rain, 4 hours, 2, 4, 6 and 8 days after rain during rainy season and dry season in1998 at environmental immigrants settlement area of northwest Guangxi.The result showed that the increment of available soil water content in valley sugarcane field after rain was equal to precipitation, but that in mesoslope sugarcane field and uncultivated hillside land was 80% of precipitation. The distribution of available soil water content in0～60cm soil horizons was uniform after rain during rainy season; however it was concentrated in surface horizon after rain during dry season. The differences of available soil moisture saturation degree between treatments and between soil horizons were significant during rainy season; nevertheless, those of dry season were not significant. The consumption rate of available soil water content in0～60cm soil horizons of uncultivated hillside land was the least among all treatments. Although the consumption rate of available soil water content during dry season was less than that of rainy season, the available soil water content during dry season would be exhausted in15 days after rain.

Variation characteristics and calculation model of evapotranspiration in latored soils on hills

GUO Qingrong, ZHANG Binggang, ZHONG Jihong, TAN Jun, LUO Bosheng, HUANG Xianglan

2003, (4):  512-514. 

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The dynamic characteristics of evapotranspiration in latored soil on hills of subtropics regions in south China was analyzed. The results showed that evapotranspiration presented annual and seasonal fluctuations. The maximum monthly evapotranspiration was 10.80～15.41 times of the monthly minimum. The evapotranspiration in wet season (March to September) accounted for about 77% of annual total evapotranspiration, and that in dry season (October to February of next year) accounted for about 23%. Although the amount of annual rainfalls could balance annual total evapotranspiration, rainfalls were insufficient for evapotranspiration in the dry season, and soil water could be depleted by evapotranspiration. Based on the modified Penman equation, the calculation model of evapotranspiration in latored soil on hills of subtropics regions in south China was set up. By comparing modeling results with experimental data, it was proved that the calculation model was very reliable.

Spatial and temporal characteristics of soil moisture dynamics in Loess Plateau

LI Hongjian, WANG Mengben, CHAI Baofeng

2003, (4):  515-519. 

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Field monitoring results of wasteland soil water content of during growing season of seven years in Zhuanyaogou valley of northwestern Shanxi Province,and the results showed that the seasonal dynamics of the soil water was controlled by annual precipitation and its distribution.The seasonal dynamics of soil water in a normal rainfall year could be divided into three stages,i.e., consumption stage from late spring to early summer,storage stage from late summer to early autumn,and second consumption stage from late autumn to early winter. The relationship equation between soil water content and measuring number was linear (1988, 1990), exponent (1992, 1995) and parabola curve (1993). The vertical profiles of soil water in the wasteland in different rainfall year were different,and the soil water content increased with increasing depth . The equations between soil water content and soil depth in all years were cubic. Taking150cm as a boundary, the ratio of soil water content in lower layers to upper layers was larger than1, and the variance coefficient of soil water decreased with increasing depth. The soil water profile in0～300cm depth for seven year's average could be divided into three layers,i.e., active layer (above 200cm), transitive layer (between200～250cm) and stable layer (below 250cm), and the depth of each layer varied with the annual precipitation and its distribution. The ANOVA result of soil water content in extremely high rainfall showed a great difference with that in other years. The difference between soil water content in wasteland and in Caragana korshinskii plantation was significant, but was not different from that in Populus hopeiensis and Populus simonii plantation respectively. The quantitative analysis methods used in this paper facilitated the comparison of soil moisture in different region and in different vegetation.

Patterns and characteristics of ecological water demand in west arid zone of China -A case study of green corridor in the lower reaches of Tarim River

WANG Ranghui, LU Xinming, SONG Yudong, FAN Zili, MA Yingjie

2003, (4):  520-524. 

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Ecological water demand has some characteristics. The ecological water demand that was used for protection of the green corridor in the lower reaches of Tarim River was chiefly water demand by natural vegetation below Daxihaizi reservoir, and it included gross restoration water amount of ground water level and gross stand water amount in all over the lower reaches of Tarim River. The gross restoration water amount of ground water level mainly included restoration water amount of ground water level and lateral discharge, as well as evaporation of the course. Based on the drainage target of Alagan in2005, gross ecological water demand was the gross water amount of restoration ground water level between Daxihaizi and Alagan, which would be 13.20?10⁸m³. Meanwhile, the annual average water demand would be 2.64?10⁸m³. Because the drainage target and vegetation protection target would be all Taitema lake in2010, the gross ecological water demand included not only the gross water amount of restoration ground water level between Alagan and Taitema lake, but also the ecological stand water amount between Daxihaizi and Taitema lake, which would be 18.32?10⁸m³.Meanwhile, the annual average water demand would be 3.66?10⁸m³. From the year 2010 to 2030, the gross ecological water demand would be consisted of two parts (the gross stand water amount between Daxihaizi and Alagan, and the water demand by increased vegetation of 18.67?104hm²), and the total ecological water demand during the 20 years would be 139.00?10⁸m³.Meanwhile, the annual average water demand would be 6.95?10⁸m³.

Establishment of Chinese eco-agricultural model management information and decision support system

HUANG Jinyong, WANG Zhaoqian

2003, (4):  525-529. 

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According to the experiences of eco-agricultural county construction and research on eco-agricultural model,Access technology was used to build the database system about natural resource, agricultural production, eco-environment, eco-engineering and technology, and eco-agricultural model information of each eco-agricultural county. The relative information of 51 eco-agricultural counties could be offered in the system. On the basis of building database system, object-oriented method was applied to design the knowledge base of eco-agricultural model, and visual C⁺⁺ was used to exploit Chinese eco-agricultural model management information and decision support system. The implement of eco-agricultural model decision with the help of computer was developed primarily.

Individual and modular biomass dynamics of Kingdonia uninflora population in Qinling Mountain

ZHANG Wenhui, LI Hong, LI Jingxia, LU Zhijun, LIU Guobin

2003, (4):  530-534. 

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The individual and modular biomass dynamics of Kingdonia uninflora populations in Qinling Mountain were studied systematically.They could be expressed by Logistic equation. The ratio of leaf to bud biomass of population decreased with its increasing age,whereas the ratio of the root system to the subterranean stem biomass increased. The individual and each modular biomass of different populations at different altitudes were significant different (P<0.05), which were larger at altitude 2700～2900m than at the lower and higher altitudes. The rate of leaf biomass decreased as altitude rose, whereas that of the subterranean stem increased. In the favorable area, the rate of root system biomass was less, whereas the bud biomass was bigger compared with other habitats. The individual growth and modular biomass accumulation were closely related to habitat condition.

Landscape changes of Minqin oasis in Gansu Province and its driving force

SONG Dongmei, XIAO Duning, ZHANG Zhicheng, CAO Yu, MA Mingguo, WANG Jianhua, WANG Jian

2003, (4):  535-539. 

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Based on the technology of GIS, RSand using FRAGSTATS, studies on the landscape changes of Minqin oasis during1987 to 2001 showed that the transitions of landscape patches were complex, and open up wasteland took place during1994 to 1998 in the south of the oasis where the condition of water was better and desertization took place during1998 to 2001 in the north of the oasis where the condition of water was worse.The decreasing of the Shannon's diversity index and the Shannon's evenness index and the increasing of Contagion index showed that human beings reconstructing the landscape of the oasis began stronger than before.Unreasonable land use was changed the landscape pattern, and the condition of water resource accelerated the landscape change.

Landscape ecological assessment and planning in the watershed of Erlong Mountain reservoir in Heilongjiang Province

ZANG Shuying, WAN Luhe, ZHOU Daowei

2003, (4):  540-544. 

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Based on the theories of landscape ecology, the landscape eco-environment in the watershed of Erlong Mountain reservoir in Heilongjiang Province was analyzed and assessed using GIStechnique and statistical model of principal component analysis and spatial cluster analysis. It was found that 100.08km²(36%)of total area was in good state,85.73 km²(31%) was in general state,and 47.26 km²(17%) and 15.48 km²(16%) was in relative poor and ideal states,respectively.According to the landscape ecological structure,three landscape functional areas were designed as agricultural area,the developmental direction of which was eco-agriculture,tour agriculture and high-benefit agriculture;eco-environment protection area,the development direction of which was develop soil and water conservation forest; and area for increasing vegetation cover,the developmental direction of which was rational cut and utilization of forest resources, spatial optimization disposal of forest type, and protection of wildwood.

Field efficacy of emulsifiable suspensions of Beauveria bassiana conidia for control of Myzus persicae population on cabbage

YING Shenghua, FENG Mingguang, XU Shoutao, MA Zaibo

2003, (4):  545-548. 

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The conidial powder of Beauveria bassiana SG8702 produced using a diphasic fermentation technology was formulated into emulsifiable suspention I (ES-I, >10¹⁰ conidia穖l^-1) and ES-II, which resulted from adding1% (W/V) of imidacloprid 10% WP to the ES-I. Three dilutions (10⁷, 10⁶, and 10⁵ conidia穖l^-1 of each were sprayed onto cabbage plants for control of the green peach aphid Myzus persicae population in field plots in Kunming, Yunnan during July 2001. Each dilution and a water spray as control were replicated three times. During a 28 d period of sampling at 3 or 4 d intervals, spray of the ES-IIat 10⁷ conidia穖l^-1 controlled the increase of the aphid population by >90% consistently from day 7 after spray. The efficacy for the ES-Iat the same concentration reached 85% on day 7 after spray, exceeded 70% in the following two weeks, but declined to 64.4% on day 24 and 52.6% on day 28. At the lower concentrations sprayed, both suspensions significantly suppressed the increase of M. persicae population, but the ES-II resulted in higher efficacy than the ES-I. Local summer weather with mild temperature and frequent rainy days was favorable to the use of the formulations for aphid control.

Spatial and temporal niches of Aphis gossypii and its predatory enemies

MIAO Yong, ZOU Yunding, SUN Shanjiao, YE Chengrui, LI Taochun, YE Shilu, XING Jianguo

2003, (4):  549-552. 

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The research results showed that Aphis gossypii had a narrow temporal niche breadth and a wide spatial niche breadth. This implied that the occurrence of A. gossypii population had the characteristics of obvious peak-period and whole-plant damage. The temporal-dynamic spatial niche breadthes of A. gossypii had no relativity to its own population densities. This implied that the damage of A. gossypii was complicated. Among the predatory enemies, Erigonidium graminicola and Propylaea japonica had wider temporal and spatial niche breadthes than other predatory enemies, and it meant that the above two enemies had longer period of occurrence and wider range of distribution. The temporal譻patial niche overlap of the predatory enemies with A. gossypiiwas in order of Theridium octomaculatum>P.japonica>E.graminicola>total of other enemies>Geocoris ochropterus>Misumenops tricuspidatus>Orius minutes, and the order was consistent with that of relational grades of A. gossypiiand its predatory enemy populations. This result showed that the sympatry and synchronism of predatory enemies with A. gossypiihad close relation to the predatory effect of the natural enemies.

Effect of habitat and interspecific competition on Apis cerana cerana colony distribution

YU Linsheng, HAN Shengming

2003, (4):  553-556. 

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Habitat change and interspecific competition were the main factors affecting,Apis cerana cerana colony distribution among Wannan and Wanxi Dabie mountainous areas,Jianghuai area and Huaibei plain.Wannan and Wanxi Dabie mountainous areas were the ideal places for Apis cerana cerana' habitation and propogation,in which,there were integrated natural vegetation,fine ecological condition,abundant nectariferous plants,and Apis cerana cerana had large colony size,wide distribution,high density,no disturbances of natural mating,and was dominant interspecific competition.In Jianghuai area and Huaibei plain,there were small covering of natural vegetation,different degree of degradation of ecological balance,few kinds of nectariferous plants with almost the same blooming periods,natural mating perturbed by Apis mellifera ligustica for Apis cerana cerana,and which was inferior in interspecific competition,colony size sharply decreased,distribution area reduced,and density cut down to a great extent.In Huaibei plain,the negative factors were more conspicuous.

Ontogenetic shifts in sexual dimorphism in head size and food habits of Eremias brenchleyi

XU Xuefeng, JI Xiang

2003, (4):  557-561. 

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Studies on the ontogenetic shifts in sexual dimorphism in head size (head length and width) and food habits of Eremias brenchleyi were studied. The results showed that adult E. brenchleyi had no obvious sexual dimorphism in body size (SVL). Both sexes differed in head size since hatching, with males having larger heads than females. This sexual dimorphism was much more pronounced between adults than between juveniles (including hatchlings), largely because the increase velocity of head size of males with SVL was faster than that of females. Hatchlings had relatively larger heads to SVL than juveniles and adults, presumably because E. brenchleyi embryos allocated relatively more resources for early survival and growth of hatchlings. Head size of both sexes overall showed an allometric growth pattern with SVLincrease ontogeny.Lizards of different sizes and sexes differed, in certain degrees,in food niche breadth and niche overlap. However, no direct evidence showed a noticeable contribution of the divergence in head size to the segregation of food niche between males and females, thereby mitigating the competition between both sexes.

Germplasm characteristics and genetic diversity of Wenchang fowl

GENG Zhaoyu, ZHANG Yunfang

2003, (4):  562-564. 

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Some germplasm characteristics and genetic diversity of Wenchang fowl produced in tropical /subtropical Hainan were tested, and compared with different ecological types of other chickens.The results showed that the feather colors of Wenchang hens are brown, yellow-brown and yellow-spotted,accounted for 80.83%,while the cocks are mainly red, with some mixed black on their back (71.96%). The crura color of Wenchang fowl was mainly yellow. Its growing velocity was slower, with smaller body weights, body length and crura length at 40 weeks of age, and being obviously of tropical/subtropical ecological characteristics than those of other ecological types. Wenchang fowl was precocious. The egg production rate of the hen at 127d and 182d was 5% and 50%,respectively, with an average egg weight of 37.6±3.2g .The egg production of hen in300d was 73. By DNA-RAPDanalysis, the average similarity index of individuals or populations was 0.6071～0.9699 for Wenchang fowl breeds. Thus, Wenchang fowl had a higher homology than other breeds,kept the breed to be pure.

Comparative studies on individual growth and development of three Brachionus angularis strains

HU Haoyuan, XI Yilong, GENG Hong

2003, (4):  565-568. 

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The embryonic developmental period (De), pre-reproductive period (Dp), the least generation time (Tg), body size of juveniles and adults, egg volume and relative egg volume of three strain Brachionus angularis from Qingdao, Guangzhou and Wuhu were studied with Scenedesmus obliquus at 2.4×10⁶cells·ml^-1 as the rotifers' food at 25℃. We found that there were significantly different in De, Dp and Tg of three strains. De of WH strain was the top, and subsequently was GZstrain and QD strain. QD strain had the longest Dp, but GZ strain had the shortest. Tg in GZ strain was the shortest, and QD strain, and WH strain were longer, respectively, but no significantly difference existed in the later two. De tended to decrease as the relative egg volume increased in the three strains. Body size at the same stage in pre-reproductive period of three strains was significantly different. WH strain had the largest body size during all of the stages. The relationships between body size and the age of the juvenile of QD, GZ and WH strain were all curvilinear. The variance of the neonates and the adults was 244.24% in WH strain, and 182.89%, 156.28% in QD and GZ strain, respectively. The adults' body size, egg size, and relative egg size was significantly different in three strains.

Present utilization situation of main fishery resources in Zhoushan fishing ground

NI Haier, LU Jiehua

2003, (4):  569-572. 

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Based on principal component analysis, the present utilization situation of main fishery resources in Zhoushan fishing ground were studied. The results showed that the nine main fishery resources in Zhoushan Fishing Ground could be divided into four categories,i.e.,Pseudosciaena crocea and Sepiella maindroni rochebrune were at the degenerating stage;Trichiurus haumela, Pneumatophorus japonicus and Decapterus maruadsi at the fully-utilized stage;Muraenesox cinereus, Pseudosciaena polyactis and Pampus at the partly-used stage and shrimps and crabs were at the initially-used stage. Therefore, it will be of key importance for the sustainability of fishery resources to utilize the current fishery resources at a reasonable way.

Effects of selenium on soybean chloroplast ultra-structure and microelement content of soybean leaves under continuous cropping stress

YU Ying, LIU Yuanying, LUO Shengguo, PENG Xianlong

2003, (4):  573-576. 

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Pot and field experiments were carried out to study the effect of low Se concentration on soybean chloroplast ultra-structure and on Mg, Fe, Mn and contents in soybean leaves under continuous cropping stress. The results showed that Se could certainly increase the contents of Mg, Fe and Mn in soybean leaves when the application rate of Se was below 0.50mg穔g^-1 in pot experiment, and below 300g穐m^-2 in field experiment.In pot experiment, Se concentration positively correlated with Mg and Fe contents in soybean leaves, but the relationship between Mn and Se was hardly to be quantified.Transmission electron microscopic observation indicated that under continuous cropping stress, application of Se could hold the soybean chloroplast membrane structure in good condition.When Se was not applied,the chloroplast swelled, and its grana disappeared, and even,transformed into etioplast.These experiments indicated that application of low Se could alleviate peroxidative stress resulting from continuous cropping, and keep the soybean grow normally.

Effects of combined pollution of heavy metals on root vitality of wheat seeds

CHEN Suhua, SUN Tieheng, ZHOU Qixing

2003, (4):  577-580. 

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The combined effects of Cu, Cd, Pb and Zn on the growth and activity of the seminal roots of wheat (Triticum aestivum) were studied by the method of quadratic regression revolution design. The mathematical models describing the above relations were established. As for the toxicity to the root vitality, their single effects, marginal utility and combined effects between two heavy metals were analyzed. The results showed that Pb had the most important effect on the activity of root,and then,Cu,Cd and Zn in sequence. The interaction between Cu and Cd, Cu and Zn, Zn and Cd, Cd and Pb had great effects on the activity of seminal roots. Furthermore, among the concentration range of 0 to 20 mg稬^-1, as for Cu and Zn, the lowest density had the biggest marginal utility, while Cd and Pb had the biggest ones at the highest density.

Effect of short-term phenanthrene stress on SOD activities and MDA contents in soybean (Glycine max) seedlings

LIU Wan, LI Peijun, ZHOU Qixing, SUN Tieheng, TAI Peidong, XU Huaxia, ZHANG Hairong

2003, (4):  581-584. 

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Growth of soybean (Glycine max) seedlings, changes of superoxide dismutase (SOD) activities, and malonyldialdehyde (MDA) contents were researched during different concentration phenanthrene stress and following recovery from stress. The results showed that seedling growth was interrupted after 5d in 200μg·g^-1 phenanthrene treatment. However, during the period of recovery, growth was restored, although there was a delay in returning to control levels.The dose-related response of SODactivities were observed in manner of linear for 2d and of parabola for 5d and 8d at 50～200μg·g^-1 phenanthrene. SODactivities of seedling were significantly induced by 100 and 200μg·g^-1 phenanthrene for 2d (P<0.05 and P<0.01), while declined significantly under phenanthrene stress for 8d, and was 88% of control at 200μg·g^-1 phenanthrene (P<0.05). When releasing soybean seedlings from phenanthrene stress for 5d to clear tap water for 2d or 4d,their SODactivities at 50 and 100μg·g^-1 phenanthrene recovered towards control level, while a significant increase in SOD activities was observed at 200μg·g^-1 phenanthrene (P<0.05). The experiments also revealed that a significant increase of MDA contents in seedlings occurred after 5d and 8d in100 and 200μg·g^-1 phenanthrene treatment (P<0.05 and P<0.01), which suggested that the membrane systems were damaged by phenanthrene stress. All of the above results showed that SOD activities of soybean seedling might be suitable to be the biomarkers of phenanthrene stress.

Effects of chlorobenzene stress on seedling growth and cell division of Vicia faba

LIU Wan, ZHOU Qixing, LI Peijun, SUN Tieheng, TAI Peidong, XU Huaxia, ZHANG Chungui, ZHANG Hairong

2003, (4):  585-588. 

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Effects of 1, 2,4-trichlorobenzene (TCB) stress on seedling growth, cell division and chromosomal aberration frequency of root-tip cells of Vicia faba were studied. The results indicated that the growth of the root length and mitotic index of root tip cells were successively decreased and even stopped with the increase of TCBconcentrations and treatment duration. Numerical and structural chromosomal aberrations at metaphase and anaphase of root-tip cells in Vicia faba seedlings were produced by 50～300μg·g^-1TCBtreatment for 12～96h. The percentage of c-mitosis, chromosomal bridge and chromosomal asymmetry array in root tip cells exposed to 50～100μg·g^-1 TCB for 12～24h was up to 1.0～10.3%. The percentage of chromosomal stickiness (S), chromosomal stickiness + chromosomal breakage (S+B), chromosomal stickiness + chromosomal ring (S+R), chromosomal stickiness + chromosomal asymmetry array (S+A) and chromosomal stickiness + chromosomal bridge (S+Be) in root tip cells reached 47.9～88.9%, and 18.1～29.6% for different kinds of chromosomal breakage at 300μg·g^-1 TCB for 12～96h. Thus,the chromosomal aberration of root tip cells in Vicia faba seedlings could be used as a sensitive biomarker of monitoring soil contaminated with TCB.

Effect of inoculation with AM fungi on DBP-pollution of plant

WANG Shuguang, LIN Xiangui, YIN Rui

2003, (4):  589-592. 

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In greenhouse, taking DBPas the object and taking Pigna sinensis inoculated respectively with AM fungi Aculospora lavis and Glomus caledonium as the host plants, a pot experiment was carried out to study the effect of inoculated AM fungi on the dynamics of plant DBP-pollution. The experiment lasted 60d. The results indicated that inoculation with AM fungi could restrain plant from absorbing DBP. Although AM fungi were affected by DBP, they played important roles in decreasing the DBP uptake by plant and the translocation of DBP from roots to aboveground part of plant. After inoculation with AM fungi, the final concentrations of DBP in plants inoculated respectively with Aculospora lavis and Glomus caledonium were decreased, to significant level (P<0.01) with maximum decrease ratios reaching up to 32.7% and 21.7%, respectively when soil-applied DBPconcentration was 4mg穔g^-1, and to significant level (P<0.05) with maximum decrease ratios reaching up to 30.5% and 30.0%, respectively when soil-applied DBPconcentration was 100mg穔g^-1.The translocation of DBPfrom roots to aboveground part of plant was also inhibited by inoculated AM fungi. Therefore, AM was helpful to decrease plant DBP-pollution.

Single and binary-combined toxicity of methamidophos, acetochlor and Cu on earthworm Eisenia foetida

LIANG Jidong, ZHOU Qixing

2003, (4):  593-596. 

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Apopulation of earthworm Eisenia foetida was exposed to single and binary-combined contamination of phaeozem by methamidophos, acetochlor and Cu. The result showed that one of three test chemicals had its toxicity on the earthworm population,and the single toxic sequence of the chemicals was acetochlor > methamidophos > Cu.The values of their LD₅₀ were 0.307, 0.708 and 118.70 mg穔g^-1, respectively. The difference was depended on the biological mechanisms of the earthworm population.Acetochlor and Cu in soil could be absorbed by the earthworm population through penetrating through the skin of an earthworm.The result also showed that Cu could swell the toxicity of methamidophos,whether it was in low or high concentration by the binary-combined toxic effect test.Cu in low concentration could decrease the toxicity of acetochlor, but in high concentration,Cu could increase the acetochlor toxicity in soil. Therefore,these three pollutants were dangerous to the ecological security of soil ecosystem and soil-health quality. Furthermore, when the chemicals in same soil environment act one another, they could boost up the potential danger of soil ecosystem contaminated by the three pollutants.The joint toxic effects of various chemicals were in relation to their different concentration combinations in soil.

Purification efficiency of vertical-flow wetland system constructed by cinder and turf substrate on municipal wastewater

CUI Lihua, ZHU Xizhen, LUO Shiming, LIU Yihu

2003, (4):  597-600. 

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Vertical-flow constructed wetlands (VFCWs) system not only has a higher hydraulic loading rate (54～64cm·d^-1), but also has a good removal efficiency for organics, ammonia nitrogen (AN) and total phosphorus (TP). The removal efficiencies of COD, BOD₅, AN, and TP for septic tank effluent were 76～87%, 82～92%, 75～85% and 77～91%, respectively,and the average effluent concentrations of COD, BOD₅, AN, and TP in the treated effluent were less than 60, 20, 25 and 2.0 mg·L^-1, respectively. Acomparison of planted and unplanted columns showed that plantation of Cyperus alternifolius could increase the removal rates of AN, TN, and TP by 2～3%, 4～6%, and 10～14%, respectively.

Effects of different application dosage of herbicide on rice production

XIAO Hong, ZHOU Qixing, CAO Ying, CAO Zhiqiang

2003, (4):  601-603. 

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Investigations on the effects of different application dosage of Machete and Londax mixture to control weeds in paddy fields showed that applied common and double dosage could effectively control weeds, and the controlling effects exceeded 80% and 90%, respectively, while there were some inhibiting effects to height and branch number of rice, and some resistance of weed had appeared. Weed contest might make rice get some compensation in height and branch under the condition that no herbicide and half dosage were applied, but the rice yield was decreased 36.01% and 54.80%, respectively, mainly because of the decrease of the number of effective panicles and grain number per panicle. The narrow economic benefit of the herbicides should be high.

Effect of temperature on methane production and oxidation in soils

DING Weixin, CAI Zucong

2003, (4):  604-608. 

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The influence of temperature and its mechanism on methane production and oxidation in soils were reviewed in this paper. Temperature can alter the soil ability to produce methane through changing types of dominant methanogens in archaeal community. Dominant methanogen is Methanosarcinaceae at higher temperature which can utilize both H₂/CO₂ and acetate as the precursor to produce methane, while Methanosaetaceae at lower temperature which only use acetate as the precursor and produce far less methane than do Methanosarcinaceae. Increasing soil temperature apparently raises soil ability to produce methane, which is called temperature effectiveness and expressed as Q₁₀ with a range from 1.5 to 28 and an average of 4.1. There is an obviously positive correlation between temperature effectiveness (Q₁₀) on methane production and substrate content. As compared to methane production, effect of temperature on methane oxidation is lower, which may be related to the strong affinity of methanotrophs for methane.

Phylogenetic diversity of microbes and its perspectives in conservation biology

TIAN Chunjie, CHEN Jiakuan, ZHONG Yang

2003, (4):  609-612. 

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Molecular phylogenetic analysis plays a very important role in the study of microbial diversity. For both cultivated and uncultivated microbes, the comparative sequence analysis of 16SrRNAenabled the investigation of phylogenetic relationships among microorganisms in a manner that was not feasible through traditional microbiological methods. As a result, there are drastic revisions in our understanding of microbiology. The phylogenetic diversity based on the comparative sequence analysis of 16SrRNAproduced new insights into the biodiversity conservation.It provides a method for biodiversity judgment and a guideline for biodiversity conservation. Also,it produces the aim of conservation,which is to keep the phylogenetic information as much as possible.In this review, some characters of microbial phylogenetic diversity and the perspectives in conservation biology are outlined.

Ecological significance of arbuscular mycorrhiza biotechnology in modern agricultural system

ZHANG Yong, ZENG Ming, XIONG Bingquan, YANG Xiaohong

2003, (4):  613-617. 

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Mycorrhiza plays a key role in nutrient cycling in ecosystem, and protects host plant against environmental stress.Under natural condition, plant's mycorrhizal structure is a normal phenomenon, and arbuscular mycorrhiza (AM) association is the commonest mycorrhizal type. If well mycorrhizal structure can be formed during plant root system developing process, the quantity and quality of plant production will be improved in large. Because of its effects on plant growth and health, it is accepted that AM symbiosis can reduce chemical fertilizer and pesticide inputs. Consequently, this will lead to a reduction in harmful chemical substance impact on environment. The key effects of AM symbiosis can be summarized as follows: ⑴improving rooting and plant establishment; ⑵improving uptake of low mobile ions; ⑶improving nutrient cycling; ⑷enhancing plant tolerance to (biotic and abiotic) stress; ⑸improving quality of soil structure; and ⑹enhancing plant community diversity. In this paper, the ecological characteristic of arbuscular mycorrhiza fungi (AMF), effects of AM on host plant, and ecologic significance of AM biotechnology in agricultural system were reviewed.

Advances in the research of soil microorganisms and their mediated processes under heavy metal stress

YU Shen, HE Zhenli, HUANG Changyong

2003, (4):  618-622. 

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More and more evidence from both laboratory and field experiments suggested that soil microbes were more sensitive to heavy metal stress than soil animals or plants living in the same soil. This understanding has been gradually accepted as a common point in this field. The history and the latest advances in soil microorganisms and its mediated processes under heavy metal stresses in soils were reviewed in this paper. It is difficult to do any comparison among the results from laboratory, field toxicological experiment and environmental monitoring.So far, a relevantly 'accurate' control soil was rarely available in the environmental monitoring. Much of evidence has indicated that not only microbial population/ biomass was changed under heavy metal stress, but also its structure was varied. Although many molecular methods, such as PLFA, BIOLOGand DNA, have been developed to detect this microbial structural change, they always need many expensive instruments and accessories, and only could be done in laboratory. Therefore, some rapid and easy methods are expected to develop to substitute the traditional plate count. The speciation in the solution phase, ion effect and rhizospheric effect of heavy metal on the toxicity to soil microorganisms and its mediated processes need extent studies and discussion. Finally, the microbial indicator system of assessing heavy metal toxicity to soil microorganisms and its mediated processes need to be established.

Advances in the research of infiltration wetland wastewater treatment systems

CUI Lihua, ZHU Xizhen, LUO Shiming

2003, (4):  623-626. 

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As their high purification efficiency and relatively low capital investment and treatment cost, infiltration wetland wastewater treatment systems have been popular,and are being increasingly applied in many countries. In this paper, the bed structure and filtering media, nitrogen and phosphorus removal processes and purification mechanisms, performance, current design criteria, operation and regulation mechanisms, soil clogging problem and solutions, and combination of vertical-horizontal flow wetlands treatment system and its use in different types of wastewater treatment were introduced and summarized. Finally, the future research directions of this technique were also discussed.

Physiological and molecular biological mechanisms of heavy metal absorption and accumulation in hyperaccumualtors

LI Wenxue, CHEN Tongbin

2003, (4):  627-631. 

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In comparison with normal plants, hyperaccumulators have the ability to accumulate heavy metals in their shoots far exceeding those observed in soil, without suffering from detrimental effects.With the help of molecular technologies, the research on the mechanisms of heavy metal accumulation in hyperaccumulators has been made a great progress. Anumber of trace element transporters have been cloned by functional complementation with yeast mutants defective in metal absorption. The relations between glutathione, phytochelatins metallothioneins, organic acids and heavy metals have been studied by molecular technologies. This review concentrated on the physiological and molecular mechanisms of heavy metal absorption and sequestration in hyperaccumulators.

Phytochelatin and its function in heavy metal tolerance of higer plants

WU Feibo, ZHANG Guoping

2003, (4):  632-636. 

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The biosynthesis pathway of phytochelatins (PC) and its function in heavy metal tolerance of higher plants were summarized in this paper. The toxic heavy metal accumulation in soil would deteriorates crop growth and yield components, and threaten the agro-products security. There were significantly differences in the accumulation and tolerance to heavy metals among plant species and genotypes. The formation of PCin response to the stress caused by heavy metals was one of the truly adaptive responses occurred commonly in higher plants. In the heavy metal tolerant genotypes, there was a much higher accumulation of PCthan the non-tolerant lines. Glutathione (GSH) was the substrate for the synthesis of PC, which chelated the metals. The inactive toxic metal ions of metal-PC chelatins were subsequently transported from cytosol to vacuole before they could poison the enzymes of life-supporting metabolic routes, and transiently stored in vacuole to reduce the heavy metal concentration in cytosol, thus, heavy metal detoxification was attained. The break through of genetic mechanism and bio-chemical pathway of PC synthesis induced by heavy metals would depend on the further study on molecular biology in this field. The isolation of Cd-sensitive cad1 and cad2 mutants of Arabidopsis thaliana, that was deficient in PC, demonstrted the importance of PCfor heavy metal tolerance. The effect of PC on food security and on phytoremediation of soil and water contaminated by heavy metals was also discussed in this paper.

Relationship between climatic factors and radial growth of Pinus massoniana in Dinghushan Mountain

HOU Aimin, ZHOU Guoyi, PENG Shaolin

2003, (4):  637-639. 

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Dendroclimatology method was used to study the relationship between ring index of Pinus massoniana and three climate factors in Dinghushan, South China. The ring indices were negatively correlated with the average temperature in June, August and September, and positively correlated with the average temperature of March, whereas no statistically significant correlation was found with monthly precipitation, showing that high summer temperature could limit the radial growth of the species. Meanwhile, tree ring indices showed a strong positive correlation with the relative humidity of April, June, August, September, October and November, and also with the average humidity of the whole year, indicating that atmospheric moisture could not fully satisfy the growth of Pinus massoniana despite of abundant rainfall. The possible impact of climate change on the growth of Pinus massoniana was discussed accordingly.

Fractal relationship between aboveground biomass and plant length or sheath height of Carex lasiocarpa population

HE Chiquan, ZHAO Kuiyi

2003, (4):  640-642. 

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By using the principles and methods of fractal geometry theory, the relationship between aboveground biomass and plant length or sheath height of Carex lasiocarpa population was studied. The results showed that there was a good static fractal relationship between them, and the resulted fractal dimension was an efficient description of the accumulation of aboveground biomass in each organ. The dynamic fractal relationship showed that during the whole growing season, the increase of aboveground biomass had a self-similarity, being a fractal growth process, and the pattern of its increase was the fractal dimension D. Based on these results, a fractal growth model of Carex lasiocarpa population was established, which regarded the bigger grass as the result of the amplification of seedling growth.

Phosphorus transfer between mixed poplar and black locust seedlings

HE Wei, JIA Liming, HAO Baogang, WEN Xuejun, ZHAI Mingpu

2003, (4):  481-486. 

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In this paper, the ³²P radio-tracer technique was applied to study the ways of phosphorus transfer between poplar (Populus euramericana cv.‘I-214') and black locust (Robinia pseudoacacia). Afive compartment root box (18cm×18cm×26cm) was used for testing the existence of the hyphal links between the roots of two tree species when inoculated with vesicular-arbuscular (VA) mycorrhizal fungus (Glomus mosseae). Populus I-214 (donor) and Robinia pseudoacacia (receiver) were grown in two terminal compartments, separated by a 2 cm root-free soil layer. The root compartments were lined with bags of nylon mesh (38μm) that allowed the passage of hyphae but not roots. The top soil of a mixed stand of poplar and black locust, autoclaved at 121℃ for one hour, was used for growing seedlings for testing. In5 compartment root box, mycorrhizal root colonization of poplar was 34%, in which VAmycorrhizal fungus was inoculated, whereas 26% mycorrhizal root colonization was observed in black locust, the other terminal compartment, 20 weeks after planting. No root colonization was observed in non-inoculated plant pairs. This indicated that the mycorrhizal root colonization of black locust was caused by hyphal spreading from the poplar. Test of tracer isotope of ³²P showed that the radioactivity of the treatment significantly higher than that of the control (P<0.05), 14 days from the tracer applied, to 27 days after, when VAmycorrhizal fungus was inoculated in poplar root. Furthermore, mycorrhizal interconnections between the roots of poplar and black locust seedlings was observed in situ by binocular in root box. All these experiments showed that the hyphal links was formed between the roots of two species of trees inoculated by VAmycorrhizal fungus.Four treatments were designed according to if there were two nets (mesh 38μm), 2 cm apart, between the poplar and black locust, and if the soil in root box was pasteurized. Most significant differences of radioactivity among four treatments appeared 44 days after feeding³²P, the radioactivity of the day was applied to estimating the contribution of the various possible transfer ways to the total amount of nutrient transfer.Level of ³²Pradioactivity was found to be significantly (P<0.05) higher in leaves of the treatment of "no separated and soil non-pasteurized"(17.1 pulse·g^-1·s^-1) than in leaves of "net separated and soil non-pasteurized" ( 5.3 pulse·g^-1·s^-1),and also significantly higher in leaves of "no net separated and soil pasteurized"( 11.5 pulse·g·s^-1) than in leaves of "net separated and soil pasteurized" (2.3 pulse·g^-1·s^-1), and very significantly (P<0.01) higher in leaves of "no net separated and soil non-pasteurized" than in leaves of "net separated and soil pasteurized",whereas the levels of ³²P radioactivity were not significantly different between the other treatments.The results showed that root contact and root exudations were the main ways of phosphorus transfer between the two species and the amount of phosphorus transfer through these two ways accounted for 62% of the total.The activity of the microorganisms including VAmycorrhizal fungi and the interaction between the microorganisms and root contact and root exudations made up 38% of total amount of phosphorus. The effect of mycorrhizal hyphal links in the direct nutrient transfer between poplar and black locust through separate mesh (38μm) was little.

Quantification comparison of spatial pattern of soil seed bank of Fraxinus mandshurica in two stands

HAN Youzhi, WANG Zhengquan

2003, (4):  487-492. 

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The spatial pattern of soil seed bank of Fraxinus mandshurica were examined by geostatistics in two stands with different densities, tree species composition and ground plants, in the Northeast of China. Asampling grid of 559 points, at each point a sample was located, was established according to regular grid design at three spatial scales (cell size were 0.5m×0.5m, 1m×1m, and 2m×2m) in each plot. Spatial pattern were quantified by using semivariance analysis, fractal dimension and Kriging maps. The object of this paper is to quantify the spatial pattern of seed bank, to compare its variations between two stands, and to explore what sort of mechanism would control its variations. The results indicated seed distribution showed appreciable heterogeneity within stand and clearly difference between the two stands.In plot 1 (mixed stand), seed bank, with a mean of 158.1±96.7 seeds·m^-2, higher sill (C₀+C=0.549) and 4.25m scales, has a stronger spatial pattern. There were a high autocorrelated variation (89.4%) and lowly random variation (10.6%) at this scale. However, at scale from 5m to 31.3m, its autocorrelated variation ranged 51.4%～69.8% and random variation ranged 30.2%～47.6%, also has distinctly mosaic patterns. Fractal dimension (D) analysis showed that the Dvalues was relatively lower(1.728～1.865), their coefficient of variation only about 26.7%～68.35%, indicated that there was a high self-similarity of patch shapes of seed bank.In plot 2 (pure stand), with a mean of 57.4±44.7 seed·m^-2, and lower sill (C₀+C=0.125), spatial patterns were not so strong as plot 1, which has a smaller scale (2.59m). Its spatially autocorrelated variation was 56.8% and randomly variation was 43.2%. Over the scale there were no clearly autocorrelated spatial patterns. Fractal dimension analysis showed higher Dvalue (1.906～1.960), and their coefficient of variation varying wildly (69.51%～134.14%), implying highly random variation and more complex patch shapes. The differences of spatial pattern of seed bank between the two stands were likely to be due to spatial heterogeneity at the level of stands.

Acclimation of foliar photosynthetic apparatus of three tropical woody species to growth irradiance

CAI Zhiquan, CAO Kunfang, FENG Yulong, FENG Zhili

2003, (4):  493-496. 

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The photosynthetic characteristics and protective role of leaf antioxidant systems were studied for seedlings of three woody species, Anthocephalus chinensis,Barringtonia pendala,Garcinia hanburyi, acclimated to 8%, 25%, 50% of natural sunlight for four months. As growth irradiance increased, the saturation points,the light compensation points of photosynthesis,the maximum net photosynthetic rate,and the non-photochemical quenching efficiency of three species were increased, while the apparent quantum yield (AQY), the effective quantum efficiency (Fv'/Fm'), and the photochemical quenching efficiency (qP) were decreased.In protective enzymes systems, SOD and APX activities increased with increasing growth irradiance, but CATactivity was not consistent with PFD. As Aexhibited the most dramatic increase in response to growth irradiance. It could be concluded that besides the increase in xanthophyll cycle-dependent energy dissipation, the enhancement of leaf antioxidants was also a protective pathway against high light intensity.

Structure and function of several intercropping ecosystems in newly built orchard

ZENG Fuping, WANG Kelin, LI Lin, SU Yirong, XIAO Runlin, MENG Guanxi, WEI Zhengshe

2003, (4):  497-501. 

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Sloping wildland is the important potential land resource in China. Structures and functions of five optimized models selected from more than10 intercropping patterns in the newly built orchards in the uncultivated sloping field were analyzed in this paper. The results showed that organic matter was increased by 5～20%, total Nby 7～40%, total Pby 8～70%, and total Kby 15～80% yearly. Considering its benefit in soil and water conservation, the intercropping model of peanut and autumn soybean was the best, and followed by spring soybean and autumn soybean, tomato and Chinese cabbage, cayenne and tomato, and drought rice and red turnip. Compared with the control, the average soil erosion module and runoff amount of the 5 models were decreased by 44.19%, 38.24%, 39.52%, 37.56%, 37.30%, and 22.40%, 9.28%, 24.11%, 21.60%, 15.93%, respectively.The intercropping model of cayenne and tomato had the highest biomass, and its annual biomass averaged 100267kg·hm^-2. The biomass of intercropping model of peanut and autumn soybean was the second, and the annual value averaged 77026kg·hm^-2.Intercropping model of peanut and autumn had the highest annual productivity, which averaged 15619kg·hm^-2, and that of intercropping model of tomato and Chinese cabbage was the second,averaged 15394kg·hm^-2.The efficiency of energy introjection was in order of cayenne and tomato, tomato and Chinese cabbage, peanut and autumn soybean, spring soybean and autumn soybean, and dry rice and red turnip, and their values were 3.06, 2.16, 2.15, 2.06, and 0.71, respectively.

Fuzzy decision system for ecological distribution of citrus in north-cultivated-marginal area

ZHU Liwu, LI Shaowen, KONG Juanjuan, JIA Bing

2003, (4):  502-506. 

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The fuzzy decision system for ecological distribution of citrus in north-cultivated-marginal area was established by using the data of mean extreme low temperature, accumulated active temperature (≥12.5℃), mean temperature in coldest month, annual mean temperature integrated with annual precipitation, days with mean extreme low temperature below -9℃,physiognomy, elevation, inland water body, cold air barrier, and soil nutrition and pH value. The complex reasoning model with imprecision was used in the decision system by introduction of L-R fuzzy number and recognition formula, which made the decision system have a wide range of application in practice. An example of applying the decision system was tested in Anhui province. The result showed that the development of the decision system would provide a useful tool for the decision of the ecological distribution of citrus in north-cultivated-marginal area.

Soil water availability in new-cultivated hillside land

SU Yirong, HUANG Yu, WANG Kelin

2003, (4):  507-511. 

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The dynamics of water content in three soil layers (0～20cm, 20～40cm and 40～60cm) were determined at three geographic locations (mesoslope, downgrade, valley) of new-cultivated sugarcane field and uncultivated hillside land at one day before rain, 4 hours, 2, 4, 6 and 8 days after rain during rainy season and dry season in1998 at environmental immigrants settlement area of northwest Guangxi.The result showed that the increment of available soil water content in valley sugarcane field after rain was equal to precipitation, but that in mesoslope sugarcane field and uncultivated hillside land was 80% of precipitation. The distribution of available soil water content in0～60cm soil horizons was uniform after rain during rainy season; however it was concentrated in surface horizon after rain during dry season. The differences of available soil moisture saturation degree between treatments and between soil horizons were significant during rainy season; nevertheless, those of dry season were not significant. The consumption rate of available soil water content in0～60cm soil horizons of uncultivated hillside land was the least among all treatments. Although the consumption rate of available soil water content during dry season was less than that of rainy season, the available soil water content during dry season would be exhausted in15 days after rain.

Variation characteristics and calculation model of evapotranspiration in latored soils on hills

GUO Qingrong, ZHANG Binggang, ZHONG Jihong, TAN Jun, LUO Bosheng, HUANG Xianglan

2003, (4):  512-514. 

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The dynamic characteristics of evapotranspiration in latored soil on hills of subtropics regions in south China was analyzed. The results showed that evapotranspiration presented annual and seasonal fluctuations. The maximum monthly evapotranspiration was 10.80～15.41 times of the monthly minimum. The evapotranspiration in wet season (March to September) accounted for about 77% of annual total evapotranspiration, and that in dry season (October to February of next year) accounted for about 23%. Although the amount of annual rainfalls could balance annual total evapotranspiration, rainfalls were insufficient for evapotranspiration in the dry season, and soil water could be depleted by evapotranspiration. Based on the modified Penman equation, the calculation model of evapotranspiration in latored soil on hills of subtropics regions in south China was set up. By comparing modeling results with experimental data, it was proved that the calculation model was very reliable.

Spatial and temporal characteristics of soil moisture dynamics in Loess Plateau

LI Hongjian, WANG Mengben, CHAI Baofeng

2003, (4):  515-519. 

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Field monitoring results of wasteland soil water content of during growing season of seven years in Zhuanyaogou valley of northwestern Shanxi Province,and the results showed that the seasonal dynamics of the soil water was controlled by annual precipitation and its distribution.The seasonal dynamics of soil water in a normal rainfall year could be divided into three stages,i.e., consumption stage from late spring to early summer,storage stage from late summer to early autumn,and second consumption stage from late autumn to early winter. The relationship equation between soil water content and measuring number was linear (1988, 1990), exponent (1992, 1995) and parabola curve (1993). The vertical profiles of soil water in the wasteland in different rainfall year were different,and the soil water content increased with increasing depth . The equations between soil water content and soil depth in all years were cubic. Taking150cm as a boundary, the ratio of soil water content in lower layers to upper layers was larger than1, and the variance coefficient of soil water decreased with increasing depth. The soil water profile in0～300cm depth for seven year's average could be divided into three layers,i.e., active layer (above 200cm), transitive layer (between200～250cm) and stable layer (below 250cm), and the depth of each layer varied with the annual precipitation and its distribution. The ANOVA result of soil water content in extremely high rainfall showed a great difference with that in other years. The difference between soil water content in wasteland and in Caragana korshinskii plantation was significant, but was not different from that in Populus hopeiensis and Populus simonii plantation respectively. The quantitative analysis methods used in this paper facilitated the comparison of soil moisture in different region and in different vegetation.

Patterns and characteristics of ecological water demand in west arid zone of China -A case study of green corridor in the lower reaches of Tarim River

WANG Ranghui, LU Xinming, SONG Yudong, FAN Zili, MA Yingjie

2003, (4):  520-524. 

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Ecological water demand has some characteristics. The ecological water demand that was used for protection of the green corridor in the lower reaches of Tarim River was chiefly water demand by natural vegetation below Daxihaizi reservoir, and it included gross restoration water amount of ground water level and gross stand water amount in all over the lower reaches of Tarim River. The gross restoration water amount of ground water level mainly included restoration water amount of ground water level and lateral discharge, as well as evaporation of the course. Based on the drainage target of Alagan in2005, gross ecological water demand was the gross water amount of restoration ground water level between Daxihaizi and Alagan, which would be 13.20?10⁸m³. Meanwhile, the annual average water demand would be 2.64?10⁸m³. Because the drainage target and vegetation protection target would be all Taitema lake in2010, the gross ecological water demand included not only the gross water amount of restoration ground water level between Alagan and Taitema lake, but also the ecological stand water amount between Daxihaizi and Taitema lake, which would be 18.32?10⁸m³.Meanwhile, the annual average water demand would be 3.66?10⁸m³. From the year 2010 to 2030, the gross ecological water demand would be consisted of two parts (the gross stand water amount between Daxihaizi and Alagan, and the water demand by increased vegetation of 18.67?104hm²), and the total ecological water demand during the 20 years would be 139.00?10⁸m³.Meanwhile, the annual average water demand would be 6.95?10⁸m³.

Establishment of Chinese eco-agricultural model management information and decision support system

HUANG Jinyong, WANG Zhaoqian

2003, (4):  525-529. 

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According to the experiences of eco-agricultural county construction and research on eco-agricultural model,Access technology was used to build the database system about natural resource, agricultural production, eco-environment, eco-engineering and technology, and eco-agricultural model information of each eco-agricultural county. The relative information of 51 eco-agricultural counties could be offered in the system. On the basis of building database system, object-oriented method was applied to design the knowledge base of eco-agricultural model, and visual C⁺⁺ was used to exploit Chinese eco-agricultural model management information and decision support system. The implement of eco-agricultural model decision with the help of computer was developed primarily.

Individual and modular biomass dynamics of Kingdonia uninflora population in Qinling Mountain

ZHANG Wenhui, LI Hong, LI Jingxia, LU Zhijun, LIU Guobin

2003, (4):  530-534. 

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The individual and modular biomass dynamics of Kingdonia uninflora populations in Qinling Mountain were studied systematically.They could be expressed by Logistic equation. The ratio of leaf to bud biomass of population decreased with its increasing age,whereas the ratio of the root system to the subterranean stem biomass increased. The individual and each modular biomass of different populations at different altitudes were significant different (P<0.05), which were larger at altitude 2700～2900m than at the lower and higher altitudes. The rate of leaf biomass decreased as altitude rose, whereas that of the subterranean stem increased. In the favorable area, the rate of root system biomass was less, whereas the bud biomass was bigger compared with other habitats. The individual growth and modular biomass accumulation were closely related to habitat condition.

Landscape changes of Minqin oasis in Gansu Province and its driving force

SONG Dongmei, XIAO Duning, ZHANG Zhicheng, CAO Yu, MA Mingguo, WANG Jianhua, WANG Jian

2003, (4):  535-539. 

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Based on the technology of GIS, RSand using FRAGSTATS, studies on the landscape changes of Minqin oasis during1987 to 2001 showed that the transitions of landscape patches were complex, and open up wasteland took place during1994 to 1998 in the south of the oasis where the condition of water was better and desertization took place during1998 to 2001 in the north of the oasis where the condition of water was worse.The decreasing of the Shannon's diversity index and the Shannon's evenness index and the increasing of Contagion index showed that human beings reconstructing the landscape of the oasis began stronger than before.Unreasonable land use was changed the landscape pattern, and the condition of water resource accelerated the landscape change.

Landscape ecological assessment and planning in the watershed of Erlong Mountain reservoir in Heilongjiang Province

ZANG Shuying, WAN Luhe, ZHOU Daowei

2003, (4):  540-544. 

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Based on the theories of landscape ecology, the landscape eco-environment in the watershed of Erlong Mountain reservoir in Heilongjiang Province was analyzed and assessed using GIStechnique and statistical model of principal component analysis and spatial cluster analysis. It was found that 100.08km²(36%)of total area was in good state,85.73 km²(31%) was in general state,and 47.26 km²(17%) and 15.48 km²(16%) was in relative poor and ideal states,respectively.According to the landscape ecological structure,three landscape functional areas were designed as agricultural area,the developmental direction of which was eco-agriculture,tour agriculture and high-benefit agriculture;eco-environment protection area,the development direction of which was develop soil and water conservation forest; and area for increasing vegetation cover,the developmental direction of which was rational cut and utilization of forest resources, spatial optimization disposal of forest type, and protection of wildwood.

Field efficacy of emulsifiable suspensions of Beauveria bassiana conidia for control of Myzus persicae population on cabbage

YING Shenghua, FENG Mingguang, XU Shoutao, MA Zaibo

2003, (4):  545-548. 

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The conidial powder of Beauveria bassiana SG8702 produced using a diphasic fermentation technology was formulated into emulsifiable suspention I (ES-I, >10¹⁰ conidia穖l^-1) and ES-II, which resulted from adding1% (W/V) of imidacloprid 10% WP to the ES-I. Three dilutions (10⁷, 10⁶, and 10⁵ conidia穖l^-1 of each were sprayed onto cabbage plants for control of the green peach aphid Myzus persicae population in field plots in Kunming, Yunnan during July 2001. Each dilution and a water spray as control were replicated three times. During a 28 d period of sampling at 3 or 4 d intervals, spray of the ES-IIat 10⁷ conidia穖l^-1 controlled the increase of the aphid population by >90% consistently from day 7 after spray. The efficacy for the ES-Iat the same concentration reached 85% on day 7 after spray, exceeded 70% in the following two weeks, but declined to 64.4% on day 24 and 52.6% on day 28. At the lower concentrations sprayed, both suspensions significantly suppressed the increase of M. persicae population, but the ES-II resulted in higher efficacy than the ES-I. Local summer weather with mild temperature and frequent rainy days was favorable to the use of the formulations for aphid control.

Spatial and temporal niches of Aphis gossypii and its predatory enemies

MIAO Yong, ZOU Yunding, SUN Shanjiao, YE Chengrui, LI Taochun, YE Shilu, XING Jianguo

2003, (4):  549-552. 

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The research results showed that Aphis gossypii had a narrow temporal niche breadth and a wide spatial niche breadth. This implied that the occurrence of A. gossypii population had the characteristics of obvious peak-period and whole-plant damage. The temporal-dynamic spatial niche breadthes of A. gossypii had no relativity to its own population densities. This implied that the damage of A. gossypii was complicated. Among the predatory enemies, Erigonidium graminicola and Propylaea japonica had wider temporal and spatial niche breadthes than other predatory enemies, and it meant that the above two enemies had longer period of occurrence and wider range of distribution. The temporal譻patial niche overlap of the predatory enemies with A. gossypiiwas in order of Theridium octomaculatum>P.japonica>E.graminicola>total of other enemies>Geocoris ochropterus>Misumenops tricuspidatus>Orius minutes, and the order was consistent with that of relational grades of A. gossypiiand its predatory enemy populations. This result showed that the sympatry and synchronism of predatory enemies with A. gossypiihad close relation to the predatory effect of the natural enemies.

Effect of habitat and interspecific competition on Apis cerana cerana colony distribution

YU Linsheng, HAN Shengming

2003, (4):  553-556. 

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Habitat change and interspecific competition were the main factors affecting,Apis cerana cerana colony distribution among Wannan and Wanxi Dabie mountainous areas,Jianghuai area and Huaibei plain.Wannan and Wanxi Dabie mountainous areas were the ideal places for Apis cerana cerana' habitation and propogation,in which,there were integrated natural vegetation,fine ecological condition,abundant nectariferous plants,and Apis cerana cerana had large colony size,wide distribution,high density,no disturbances of natural mating,and was dominant interspecific competition.In Jianghuai area and Huaibei plain,there were small covering of natural vegetation,different degree of degradation of ecological balance,few kinds of nectariferous plants with almost the same blooming periods,natural mating perturbed by Apis mellifera ligustica for Apis cerana cerana,and which was inferior in interspecific competition,colony size sharply decreased,distribution area reduced,and density cut down to a great extent.In Huaibei plain,the negative factors were more conspicuous.

Ontogenetic shifts in sexual dimorphism in head size and food habits of Eremias brenchleyi

XU Xuefeng, JI Xiang

2003, (4):  557-561. 

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Studies on the ontogenetic shifts in sexual dimorphism in head size (head length and width) and food habits of Eremias brenchleyi were studied. The results showed that adult E. brenchleyi had no obvious sexual dimorphism in body size (SVL). Both sexes differed in head size since hatching, with males having larger heads than females. This sexual dimorphism was much more pronounced between adults than between juveniles (including hatchlings), largely because the increase velocity of head size of males with SVL was faster than that of females. Hatchlings had relatively larger heads to SVL than juveniles and adults, presumably because E. brenchleyi embryos allocated relatively more resources for early survival and growth of hatchlings. Head size of both sexes overall showed an allometric growth pattern with SVLincrease ontogeny.Lizards of different sizes and sexes differed, in certain degrees,in food niche breadth and niche overlap. However, no direct evidence showed a noticeable contribution of the divergence in head size to the segregation of food niche between males and females, thereby mitigating the competition between both sexes.

Germplasm characteristics and genetic diversity of Wenchang fowl

GENG Zhaoyu, ZHANG Yunfang

2003, (4):  562-564. 

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Some germplasm characteristics and genetic diversity of Wenchang fowl produced in tropical /subtropical Hainan were tested, and compared with different ecological types of other chickens.The results showed that the feather colors of Wenchang hens are brown, yellow-brown and yellow-spotted,accounted for 80.83%,while the cocks are mainly red, with some mixed black on their back (71.96%). The crura color of Wenchang fowl was mainly yellow. Its growing velocity was slower, with smaller body weights, body length and crura length at 40 weeks of age, and being obviously of tropical/subtropical ecological characteristics than those of other ecological types. Wenchang fowl was precocious. The egg production rate of the hen at 127d and 182d was 5% and 50%,respectively, with an average egg weight of 37.6±3.2g .The egg production of hen in300d was 73. By DNA-RAPDanalysis, the average similarity index of individuals or populations was 0.6071～0.9699 for Wenchang fowl breeds. Thus, Wenchang fowl had a higher homology than other breeds,kept the breed to be pure.

Comparative studies on individual growth and development of three Brachionus angularis strains

HU Haoyuan, XI Yilong, GENG Hong

2003, (4):  565-568. 

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The embryonic developmental period (De), pre-reproductive period (Dp), the least generation time (Tg), body size of juveniles and adults, egg volume and relative egg volume of three strain Brachionus angularis from Qingdao, Guangzhou and Wuhu were studied with Scenedesmus obliquus at 2.4×10⁶cells·ml^-1 as the rotifers' food at 25℃. We found that there were significantly different in De, Dp and Tg of three strains. De of WH strain was the top, and subsequently was GZstrain and QD strain. QD strain had the longest Dp, but GZ strain had the shortest. Tg in GZ strain was the shortest, and QD strain, and WH strain were longer, respectively, but no significantly difference existed in the later two. De tended to decrease as the relative egg volume increased in the three strains. Body size at the same stage in pre-reproductive period of three strains was significantly different. WH strain had the largest body size during all of the stages. The relationships between body size and the age of the juvenile of QD, GZ and WH strain were all curvilinear. The variance of the neonates and the adults was 244.24% in WH strain, and 182.89%, 156.28% in QD and GZ strain, respectively. The adults' body size, egg size, and relative egg size was significantly different in three strains.

Present utilization situation of main fishery resources in Zhoushan fishing ground

NI Haier, LU Jiehua

2003, (4):  569-572. 

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Based on principal component analysis, the present utilization situation of main fishery resources in Zhoushan fishing ground were studied. The results showed that the nine main fishery resources in Zhoushan Fishing Ground could be divided into four categories,i.e.,Pseudosciaena crocea and Sepiella maindroni rochebrune were at the degenerating stage;Trichiurus haumela, Pneumatophorus japonicus and Decapterus maruadsi at the fully-utilized stage;Muraenesox cinereus, Pseudosciaena polyactis and Pampus at the partly-used stage and shrimps and crabs were at the initially-used stage. Therefore, it will be of key importance for the sustainability of fishery resources to utilize the current fishery resources at a reasonable way.

Effects of selenium on soybean chloroplast ultra-structure and microelement content of soybean leaves under continuous cropping stress

YU Ying, LIU Yuanying, LUO Shengguo, PENG Xianlong

2003, (4):  573-576. 

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Pot and field experiments were carried out to study the effect of low Se concentration on soybean chloroplast ultra-structure and on Mg, Fe, Mn and contents in soybean leaves under continuous cropping stress. The results showed that Se could certainly increase the contents of Mg, Fe and Mn in soybean leaves when the application rate of Se was below 0.50mg穔g^-1 in pot experiment, and below 300g穐m^-2 in field experiment.In pot experiment, Se concentration positively correlated with Mg and Fe contents in soybean leaves, but the relationship between Mn and Se was hardly to be quantified.Transmission electron microscopic observation indicated that under continuous cropping stress, application of Se could hold the soybean chloroplast membrane structure in good condition.When Se was not applied,the chloroplast swelled, and its grana disappeared, and even,transformed into etioplast.These experiments indicated that application of low Se could alleviate peroxidative stress resulting from continuous cropping, and keep the soybean grow normally.

Effects of combined pollution of heavy metals on root vitality of wheat seeds

CHEN Suhua, SUN Tieheng, ZHOU Qixing

2003, (4):  577-580. 

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The combined effects of Cu, Cd, Pb and Zn on the growth and activity of the seminal roots of wheat (Triticum aestivum) were studied by the method of quadratic regression revolution design. The mathematical models describing the above relations were established. As for the toxicity to the root vitality, their single effects, marginal utility and combined effects between two heavy metals were analyzed. The results showed that Pb had the most important effect on the activity of root,and then,Cu,Cd and Zn in sequence. The interaction between Cu and Cd, Cu and Zn, Zn and Cd, Cd and Pb had great effects on the activity of seminal roots. Furthermore, among the concentration range of 0 to 20 mg稬^-1, as for Cu and Zn, the lowest density had the biggest marginal utility, while Cd and Pb had the biggest ones at the highest density.

Effect of short-term phenanthrene stress on SOD activities and MDA contents in soybean (Glycine max) seedlings

LIU Wan, LI Peijun, ZHOU Qixing, SUN Tieheng, TAI Peidong, XU Huaxia, ZHANG Hairong

2003, (4):  581-584. 

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Growth of soybean (Glycine max) seedlings, changes of superoxide dismutase (SOD) activities, and malonyldialdehyde (MDA) contents were researched during different concentration phenanthrene stress and following recovery from stress. The results showed that seedling growth was interrupted after 5d in 200μg·g^-1 phenanthrene treatment. However, during the period of recovery, growth was restored, although there was a delay in returning to control levels.The dose-related response of SODactivities were observed in manner of linear for 2d and of parabola for 5d and 8d at 50～200μg·g^-1 phenanthrene. SODactivities of seedling were significantly induced by 100 and 200μg·g^-1 phenanthrene for 2d (P<0.05 and P<0.01), while declined significantly under phenanthrene stress for 8d, and was 88% of control at 200μg·g^-1 phenanthrene (P<0.05). When releasing soybean seedlings from phenanthrene stress for 5d to clear tap water for 2d or 4d,their SODactivities at 50 and 100μg·g^-1 phenanthrene recovered towards control level, while a significant increase in SOD activities was observed at 200μg·g^-1 phenanthrene (P<0.05). The experiments also revealed that a significant increase of MDA contents in seedlings occurred after 5d and 8d in100 and 200μg·g^-1 phenanthrene treatment (P<0.05 and P<0.01), which suggested that the membrane systems were damaged by phenanthrene stress. All of the above results showed that SOD activities of soybean seedling might be suitable to be the biomarkers of phenanthrene stress.

Effects of chlorobenzene stress on seedling growth and cell division of Vicia faba

LIU Wan, ZHOU Qixing, LI Peijun, SUN Tieheng, TAI Peidong, XU Huaxia, ZHANG Chungui, ZHANG Hairong

2003, (4):  585-588. 

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Effects of 1, 2,4-trichlorobenzene (TCB) stress on seedling growth, cell division and chromosomal aberration frequency of root-tip cells of Vicia faba were studied. The results indicated that the growth of the root length and mitotic index of root tip cells were successively decreased and even stopped with the increase of TCBconcentrations and treatment duration. Numerical and structural chromosomal aberrations at metaphase and anaphase of root-tip cells in Vicia faba seedlings were produced by 50～300μg·g^-1TCBtreatment for 12～96h. The percentage of c-mitosis, chromosomal bridge and chromosomal asymmetry array in root tip cells exposed to 50～100μg·g^-1 TCB for 12～24h was up to 1.0～10.3%. The percentage of chromosomal stickiness (S), chromosomal stickiness + chromosomal breakage (S+B), chromosomal stickiness + chromosomal ring (S+R), chromosomal stickiness + chromosomal asymmetry array (S+A) and chromosomal stickiness + chromosomal bridge (S+Be) in root tip cells reached 47.9～88.9%, and 18.1～29.6% for different kinds of chromosomal breakage at 300μg·g^-1 TCB for 12～96h. Thus,the chromosomal aberration of root tip cells in Vicia faba seedlings could be used as a sensitive biomarker of monitoring soil contaminated with TCB.

Effect of inoculation with AM fungi on DBP-pollution of plant

WANG Shuguang, LIN Xiangui, YIN Rui

2003, (4):  589-592. 

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In greenhouse, taking DBPas the object and taking Pigna sinensis inoculated respectively with AM fungi Aculospora lavis and Glomus caledonium as the host plants, a pot experiment was carried out to study the effect of inoculated AM fungi on the dynamics of plant DBP-pollution. The experiment lasted 60d. The results indicated that inoculation with AM fungi could restrain plant from absorbing DBP. Although AM fungi were affected by DBP, they played important roles in decreasing the DBP uptake by plant and the translocation of DBP from roots to aboveground part of plant. After inoculation with AM fungi, the final concentrations of DBP in plants inoculated respectively with Aculospora lavis and Glomus caledonium were decreased, to significant level (P<0.01) with maximum decrease ratios reaching up to 32.7% and 21.7%, respectively when soil-applied DBPconcentration was 4mg穔g^-1, and to significant level (P<0.05) with maximum decrease ratios reaching up to 30.5% and 30.0%, respectively when soil-applied DBPconcentration was 100mg穔g^-1.The translocation of DBPfrom roots to aboveground part of plant was also inhibited by inoculated AM fungi. Therefore, AM was helpful to decrease plant DBP-pollution.

Single and binary-combined toxicity of methamidophos, acetochlor and Cu on earthworm Eisenia foetida

LIANG Jidong, ZHOU Qixing

2003, (4):  593-596. 

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Apopulation of earthworm Eisenia foetida was exposed to single and binary-combined contamination of phaeozem by methamidophos, acetochlor and Cu. The result showed that one of three test chemicals had its toxicity on the earthworm population,and the single toxic sequence of the chemicals was acetochlor > methamidophos > Cu.The values of their LD₅₀ were 0.307, 0.708 and 118.70 mg穔g^-1, respectively. The difference was depended on the biological mechanisms of the earthworm population.Acetochlor and Cu in soil could be absorbed by the earthworm population through penetrating through the skin of an earthworm.The result also showed that Cu could swell the toxicity of methamidophos,whether it was in low or high concentration by the binary-combined toxic effect test.Cu in low concentration could decrease the toxicity of acetochlor, but in high concentration,Cu could increase the acetochlor toxicity in soil. Therefore,these three pollutants were dangerous to the ecological security of soil ecosystem and soil-health quality. Furthermore, when the chemicals in same soil environment act one another, they could boost up the potential danger of soil ecosystem contaminated by the three pollutants.The joint toxic effects of various chemicals were in relation to their different concentration combinations in soil.

Purification efficiency of vertical-flow wetland system constructed by cinder and turf substrate on municipal wastewater

CUI Lihua, ZHU Xizhen, LUO Shiming, LIU Yihu

2003, (4):  597-600. 

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Vertical-flow constructed wetlands (VFCWs) system not only has a higher hydraulic loading rate (54～64cm·d^-1), but also has a good removal efficiency for organics, ammonia nitrogen (AN) and total phosphorus (TP). The removal efficiencies of COD, BOD₅, AN, and TP for septic tank effluent were 76～87%, 82～92%, 75～85% and 77～91%, respectively,and the average effluent concentrations of COD, BOD₅, AN, and TP in the treated effluent were less than 60, 20, 25 and 2.0 mg·L^-1, respectively. Acomparison of planted and unplanted columns showed that plantation of Cyperus alternifolius could increase the removal rates of AN, TN, and TP by 2～3%, 4～6%, and 10～14%, respectively.

Effects of different application dosage of herbicide on rice production

XIAO Hong, ZHOU Qixing, CAO Ying, CAO Zhiqiang

2003, (4):  601-603. 

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Investigations on the effects of different application dosage of Machete and Londax mixture to control weeds in paddy fields showed that applied common and double dosage could effectively control weeds, and the controlling effects exceeded 80% and 90%, respectively, while there were some inhibiting effects to height and branch number of rice, and some resistance of weed had appeared. Weed contest might make rice get some compensation in height and branch under the condition that no herbicide and half dosage were applied, but the rice yield was decreased 36.01% and 54.80%, respectively, mainly because of the decrease of the number of effective panicles and grain number per panicle. The narrow economic benefit of the herbicides should be high.

Effect of temperature on methane production and oxidation in soils

DING Weixin, CAI Zucong

2003, (4):  604-608. 

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The influence of temperature and its mechanism on methane production and oxidation in soils were reviewed in this paper. Temperature can alter the soil ability to produce methane through changing types of dominant methanogens in archaeal community. Dominant methanogen is Methanosarcinaceae at higher temperature which can utilize both H₂/CO₂ and acetate as the precursor to produce methane, while Methanosaetaceae at lower temperature which only use acetate as the precursor and produce far less methane than do Methanosarcinaceae. Increasing soil temperature apparently raises soil ability to produce methane, which is called temperature effectiveness and expressed as Q₁₀ with a range from 1.5 to 28 and an average of 4.1. There is an obviously positive correlation between temperature effectiveness (Q₁₀) on methane production and substrate content. As compared to methane production, effect of temperature on methane oxidation is lower, which may be related to the strong affinity of methanotrophs for methane.

Phylogenetic diversity of microbes and its perspectives in conservation biology

TIAN Chunjie, CHEN Jiakuan, ZHONG Yang

2003, (4):  609-612. 

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Molecular phylogenetic analysis plays a very important role in the study of microbial diversity. For both cultivated and uncultivated microbes, the comparative sequence analysis of 16SrRNAenabled the investigation of phylogenetic relationships among microorganisms in a manner that was not feasible through traditional microbiological methods. As a result, there are drastic revisions in our understanding of microbiology. The phylogenetic diversity based on the comparative sequence analysis of 16SrRNAproduced new insights into the biodiversity conservation.It provides a method for biodiversity judgment and a guideline for biodiversity conservation. Also,it produces the aim of conservation,which is to keep the phylogenetic information as much as possible.In this review, some characters of microbial phylogenetic diversity and the perspectives in conservation biology are outlined.

Ecological significance of arbuscular mycorrhiza biotechnology in modern agricultural system

ZHANG Yong, ZENG Ming, XIONG Bingquan, YANG Xiaohong

2003, (4):  613-617. 

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Mycorrhiza plays a key role in nutrient cycling in ecosystem, and protects host plant against environmental stress.Under natural condition, plant's mycorrhizal structure is a normal phenomenon, and arbuscular mycorrhiza (AM) association is the commonest mycorrhizal type. If well mycorrhizal structure can be formed during plant root system developing process, the quantity and quality of plant production will be improved in large. Because of its effects on plant growth and health, it is accepted that AM symbiosis can reduce chemical fertilizer and pesticide inputs. Consequently, this will lead to a reduction in harmful chemical substance impact on environment. The key effects of AM symbiosis can be summarized as follows: ⑴improving rooting and plant establishment; ⑵improving uptake of low mobile ions; ⑶improving nutrient cycling; ⑷enhancing plant tolerance to (biotic and abiotic) stress; ⑸improving quality of soil structure; and ⑹enhancing plant community diversity. In this paper, the ecological characteristic of arbuscular mycorrhiza fungi (AMF), effects of AM on host plant, and ecologic significance of AM biotechnology in agricultural system were reviewed.

Advances in the research of soil microorganisms and their mediated processes under heavy metal stress

YU Shen, HE Zhenli, HUANG Changyong

2003, (4):  618-622. 

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More and more evidence from both laboratory and field experiments suggested that soil microbes were more sensitive to heavy metal stress than soil animals or plants living in the same soil. This understanding has been gradually accepted as a common point in this field. The history and the latest advances in soil microorganisms and its mediated processes under heavy metal stresses in soils were reviewed in this paper. It is difficult to do any comparison among the results from laboratory, field toxicological experiment and environmental monitoring.So far, a relevantly 'accurate' control soil was rarely available in the environmental monitoring. Much of evidence has indicated that not only microbial population/ biomass was changed under heavy metal stress, but also its structure was varied. Although many molecular methods, such as PLFA, BIOLOGand DNA, have been developed to detect this microbial structural change, they always need many expensive instruments and accessories, and only could be done in laboratory. Therefore, some rapid and easy methods are expected to develop to substitute the traditional plate count. The speciation in the solution phase, ion effect and rhizospheric effect of heavy metal on the toxicity to soil microorganisms and its mediated processes need extent studies and discussion. Finally, the microbial indicator system of assessing heavy metal toxicity to soil microorganisms and its mediated processes need to be established.

Advances in the research of infiltration wetland wastewater treatment systems

CUI Lihua, ZHU Xizhen, LUO Shiming

2003, (4):  623-626. 

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As their high purification efficiency and relatively low capital investment and treatment cost, infiltration wetland wastewater treatment systems have been popular,and are being increasingly applied in many countries. In this paper, the bed structure and filtering media, nitrogen and phosphorus removal processes and purification mechanisms, performance, current design criteria, operation and regulation mechanisms, soil clogging problem and solutions, and combination of vertical-horizontal flow wetlands treatment system and its use in different types of wastewater treatment were introduced and summarized. Finally, the future research directions of this technique were also discussed.

Physiological and molecular biological mechanisms of heavy metal absorption and accumulation in hyperaccumualtors

LI Wenxue, CHEN Tongbin

2003, (4):  627-631. 

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In comparison with normal plants, hyperaccumulators have the ability to accumulate heavy metals in their shoots far exceeding those observed in soil, without suffering from detrimental effects.With the help of molecular technologies, the research on the mechanisms of heavy metal accumulation in hyperaccumulators has been made a great progress. Anumber of trace element transporters have been cloned by functional complementation with yeast mutants defective in metal absorption. The relations between glutathione, phytochelatins metallothioneins, organic acids and heavy metals have been studied by molecular technologies. This review concentrated on the physiological and molecular mechanisms of heavy metal absorption and sequestration in hyperaccumulators.

Phytochelatin and its function in heavy metal tolerance of higer plants

WU Feibo, ZHANG Guoping

2003, (4):  632-636. 

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The biosynthesis pathway of phytochelatins (PC) and its function in heavy metal tolerance of higher plants were summarized in this paper. The toxic heavy metal accumulation in soil would deteriorates crop growth and yield components, and threaten the agro-products security. There were significantly differences in the accumulation and tolerance to heavy metals among plant species and genotypes. The formation of PCin response to the stress caused by heavy metals was one of the truly adaptive responses occurred commonly in higher plants. In the heavy metal tolerant genotypes, there was a much higher accumulation of PCthan the non-tolerant lines. Glutathione (GSH) was the substrate for the synthesis of PC, which chelated the metals. The inactive toxic metal ions of metal-PC chelatins were subsequently transported from cytosol to vacuole before they could poison the enzymes of life-supporting metabolic routes, and transiently stored in vacuole to reduce the heavy metal concentration in cytosol, thus, heavy metal detoxification was attained. The break through of genetic mechanism and bio-chemical pathway of PC synthesis induced by heavy metals would depend on the further study on molecular biology in this field. The isolation of Cd-sensitive cad1 and cad2 mutants of Arabidopsis thaliana, that was deficient in PC, demonstrted the importance of PCfor heavy metal tolerance. The effect of PC on food security and on phytoremediation of soil and water contaminated by heavy metals was also discussed in this paper.

Relationship between climatic factors and radial growth of Pinus massoniana in Dinghushan Mountain

HOU Aimin, ZHOU Guoyi, PENG Shaolin

2003, (4):  637-639. 

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Dendroclimatology method was used to study the relationship between ring index of Pinus massoniana and three climate factors in Dinghushan, South China. The ring indices were negatively correlated with the average temperature in June, August and September, and positively correlated with the average temperature of March, whereas no statistically significant correlation was found with monthly precipitation, showing that high summer temperature could limit the radial growth of the species. Meanwhile, tree ring indices showed a strong positive correlation with the relative humidity of April, June, August, September, October and November, and also with the average humidity of the whole year, indicating that atmospheric moisture could not fully satisfy the growth of Pinus massoniana despite of abundant rainfall. The possible impact of climate change on the growth of Pinus massoniana was discussed accordingly.

Fractal relationship between aboveground biomass and plant length or sheath height of Carex lasiocarpa population

HE Chiquan, ZHAO Kuiyi

2003, (4):  640-642. 

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By using the principles and methods of fractal geometry theory, the relationship between aboveground biomass and plant length or sheath height of Carex lasiocarpa population was studied. The results showed that there was a good static fractal relationship between them, and the resulted fractal dimension was an efficient description of the accumulation of aboveground biomass in each organ. The dynamic fractal relationship showed that during the whole growing season, the increase of aboveground biomass had a self-similarity, being a fractal growth process, and the pattern of its increase was the fractal dimension D. Based on these results, a fractal growth model of Carex lasiocarpa population was established, which regarded the bigger grass as the result of the amplification of seedling growth.