Table of Content

15 August 2005, Volume 16 Issue 8

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Articles

Net primary productivity of several mangrove species under controlled habitats

PENG Yougui^1,2,CHEN Guizhu¹，WU Pengfei¹,MIAO Shenyu³,YIN Min¹, SHE Zhongming ⁴

2005, 16(08):  1383-1388 . 

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Three mangrove species Sonneratia caseolaris,Kandelia candel and Aegiceras corniculatum were planted in different fishponds in April 2002 with three planting—breeding area proportions of 45∶55,30∶70 and 15∶85, respectively,and the growth of test mangrove plants were surveyed during 2 years after planting.The results showed that S.caseolaris and A.comiculatum could grow well in the coupling system,while K.candel could not.The survival percentage of S.caseolaris,K.candel and A.corniculatum was 92.9%,93.9% and 44.7%,respectively.During the 2 years,the height of S.caseolaris increased 457.0 cm,and its basal diameter increased from 12.6 mm to 98.7 mm. A.corniculatum had an increment of 26.1 cm in height and 36.5 mm in basal diameter,while K.candel only had an increment of 20.4 cm in height and 26.4 mm in basal diameter.Based on the height,basal diameter,and biomass of trunk,branch,leaf and root,regressive equations of the four organs' biomass were obtained,and the whole biomass of standing trees in the coupling system was calculated.The average biomass of S.caseolaris was 5 597.8 g·m^-2 in April 2004,being increased 5 559.5 g·m^-2 in 2 years.At the same period,the standing biomass of A.corniculatum and K.cand of 932.7 g·m^-2 and 57.0 g·m^-2, respectively.The biomass of plant organs was in the order of stem > branch > root > leaf for S.caseolaris,leaf > branch > stem > root for A.corniculatum,and stem > root > leaf > branch for K.candel.The litter fall production of mangrove plants in 2 years was 1 149.2 g·m^-2,170.8 g·m^-2 and 7.1 g·m^-2 for S.caseolaris,A.corniculatum and K.candel,respectively.Leaf litter took up more than half of the whole litter fall.From April 2002 to April 2004,the net primary production of S.caseolaris,A.corniculatum and K.candel was 7 048.9 g·m^-2,1 105.9 g·m^-2 and 93.0 g·m^-2,respectively.The litter fall production occupied 20.5% of the net primary production for S.caseolaris,15.4% for A.corniculatum, and 7.6% for K.candel,which meant that high productivity was accompanied by high return rate.

Seasonal variation of Tamarix ramosissima and Populus euphratica water potentials in southern fringe of Taklamakan Desert

ZENG Fanjiang ¹,ZHANG Ximing ¹,LI Xiangyi ¹,Andrea Foetzki ²,Michael Runge ²

2005, 16(08):  1389-1393 . 

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The measurement of the seasonal and diurnal variations of Tamarix ramosissima and Populus euphratica water potentials in the southern fringe of Taklamakan Desert indicated that there was no apparent water stress for the two species during their growth period,with little change of predawn water potential and some extent decrease of midday water potential. Irrigation once or thinning had no significant effects on the water status of the plants,while groundwater appeared to be a prerequisite for the survival and growth of these species.It is very important to ensure a stable groundwater table for the restoration of Tamarix ramosissima and Populus euphratica in this area.

Population characteristics of Coptis chinensis var.brevisepala in Anhui Province and its endangering mechanism

ZHANG Li,ZHANG Xiaoping

2005, 16(08):  1394-1398 . 

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The study on the distribution pattern,population size,and age structure of C.chinensis var.brevisepala in Anhui Province showed that C.chinensis var.brevisepala mainly distributed in the southern mountain areas such as Mts.Jiuhuashan,Guniujiang,Huangshan and Qingliang Peak.The habitats had two kinds,i.e.,under woods and beside water ditches,both of which were shady and humid,with loose and acidic soils containing abundant organic matter.The shading degree surpassed 70%,air humidity reached 70%～90%,and soil water content was more than 30%.The distribution pattern of existing C.chinensis var.brevisepala populations was clustering,with illogical age structure and small population size.It was suggested that the populations of C.chinensis var.brevisepala in Anhui Province were in an unsteady stage.Serious destroy of natural habitat and excessive digging and gathering adult individuals were the main causes of the rapid decrease of the individuals in some populations,which threatened the existence of C.chinensis var.brevisepala populations seriously.

Effects of nitrate application on alleviating photosynthesis restriction of Cinnamomum burmannii leaves under elevated CO2 concentration and enhanced temperature

SUN Guchou,ZHAO Ping,RAO Xingquan,CAI Xi'an,ZENG Xiaoping

2005, 16(08):  1399-1304 . 

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In this study,potted C.burmannii saplings were cultured in a top-closed cha mber with elevated CO₂(CO₂，365 μmol·mol-1) and ambient CO₂ (CO₂,365 μmol·mol^-1),and at diurnal temperature(day/night) 25/23 ℃ and 32/25 ℃,respectively.The gas exchange,calculated photosynthesis parameter, Rubisco content,and activated state of Rubisco were examined.The results showed that under +CO₂and at 25/23 ℃,the mean photosynthetic rate(Pnsat) of sapling leaves was 5.1%higher than that under +CO₂and at 32/25 ℃.Temperature enhancement declined Pnsat,while nitrate addition increased it.Under +CO₂,saplings had lower Vcmax and Jmax at 32/25 ℃ than at 25/23 ℃.Temperatureenhancement under +CO₂ also declined Vcmax and Jmax. Under +CO₂,lower photorespiration rate(Rp) occurred in leaves，but temperature enhancement could increase Rp.Under +CO2,Rubisco content(NR) and its active site per unit leaf area(M) decreased as diurnal temperature changed from 25/23 ℃ to 32/25 ℃.Meanwhile,nitrate addition could increase NR and M.It may be suggested that nitrate addition could alleviate the restriction of photosynthesis under elevated CO₂ concentration and enhanced temperature.

Quantitative characteristics of soil aggregates under different vegetations in upper reach of Minjiang River

NING Lidan¹,SHI Hui²,ZHOU Haijun¹,LIU Shirong³

2005, 16(08):  1405-1410 . 

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Quantitative analysis on the soil aggregates under dark coniferous forest, coniferous and broad-leaved mixed forest,fargesia under the gap of dark coniferous forest,and sclerophyllous oaks (Quercus semicarpifolia) at Wolong Natural Reserve in the upper reach of Minjiang River showed that wet-sieving soil aggregates were of logarithmic-normal distribution,and the geometric mean diameters were negatively correlated to geometric standard deviation.The aggregates under coniferous and broad-leaved mixed forest and sclerophyllous oaks had larger sizes than those under other vegetations. The range of fractal dimension of soil aggregates was 2.40～2.78,along with more aggregates less than 0.25 mm in size.The fractal dimension of soil aggregates under dark coniferous forest and fargesia were larger than that under other vegetations.The soil aggregates with 3～1 mm and 1～0.5 mm in size had a higher stability,while those with >10 mm and 0.5～0.25 mm in size were in adverse.The aggregate stability index of soil under coniferous and broad-leaved mixed forest was the highest,followed by that under sclerophyllous oaks,fargesia under the gap of dark coniferous forest, and dark coniferous forest,which meant that coniferous and broadleaf mixed forest and sclerophyllous oaks were favorable for soil aggregate stability. Significant correlations were found among the three quantitative characteristics, which could be used to indicate the stability of soil aggregates.

Effects of replacing natural secondary broad?leaved forest with unninghamia lanceolata plantation on soil biological activities

HU Yalin ^1，2,WANG Silong ¹,YAN Shaokui ¹,GAO Hong ¹

2005, 16(08):  1411-1416 . 

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This paper studied the effects of replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation in the south,central and upstate areas of subtropical China on the changes of soil chemical and biological properties.The results showed that after replacing with Cunninghamia lanceolata plantation,the total organic carbon (TOC) content in surface soil decreased by 31.51%～58.24%,and the contents of soil total N and P,pH value,C/N and C/P also decreased to different degree.Soil microbial amount was less than that under natural secondary broad?leaved forest,soil urease,invertase,catalase and dehydrogenase activities decreased,while soil polyphenol oxidase activity increased by 8%～40%.The respiration rate of Cunninghamia lanceolata soil was 51.15%～54.48% lower than that of natural secondary broad?leaved forest soil.The correlation between soil TOC and polyphenol oxidase activity was negative (R=-0.723,n=18), while those between soil TOC,N,P and other enzyme activities were positive.It could be concluded that replacing natural secondary broad?leaved forest with Cunninghamia lanceolata plantation worsened soil quality,and the loss of soil organic matter in Cunninghamia lanceolata plantation ecosystem might be one of the important factors resulted in the decrease of soil nutrients and enzyme activities.

Effects of different ground clearance on soil fertility of Chinese fir stands

XUE Li ^1,2,3,XIANG Wenjing ²,HE Yuejun ²,LI Yan ²,WU Min ²,XU Yan ²,QU Ming ²

2005, 16(08):  1417-1421 . 

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The study on the soil physical properties,nutrient contents,microbial amounts and enzyme activities of clear cutting and controlled burning Chinese fir stands showed that in comparing with the control,soil non?capillary porosity of clear cutting stand increased by 23%,whereas soil natural water capacity and capillary moisture capacity decreased by 25%.In controlled burning stand,soil bulk density increased by 10%,while soil non-capillary porosity, natural water capacity and capillary moisture capacity decreased by 61%,48% and 26%,respectively.The contents of soil organic matter,total N,total P and total K in clear cutting stand decreased by 14%,14%,35% and 22%,and in controlled burning stand,they decreased by 37%,37%,47% and 7%,respectively.Soil alkalized N and available K in clear cutting stand increased by 24% and 31%,respectively,but soil available P decreased by 15%.The contents of soil alkalized N,available P and available K in controlled burning stand decreased by 25%,43% and 40%,respectively.In clear cutting stand,the amounts of soil bacteria,fungi and actinomyces increased by 1.4,11.3 and 0.8 times,respectively,but in controlled burning stand,the amounts of soil bacteria decreased by 24%,while those of soil fungi and actinomyces increased by 5.0 and 0.5 times,respectively.The activities of soil urease,catalase and cellulase in clear cutting stand increased by 1.9,1.6 and 2.1 times,and in controlled burning land,they were 35%,90% and 106% of the control,respectively.Damp soil had higher contents of organic matter,total N and total P,whereas porous soil was favorable for the accumulation of alkalized N,available P and available K and for the increase of soil urease activity.The amount of soil fungi decreased with increasing soil capillary porosity.Aerated soil was favorable for the increase of soil catalase activity.

Ecological distribution patterns of soil microbes under artificial Eucalyptus Grandis stand

FENG Jian,ZHANG Jian

2005, 16(08):  1422-1426 . 

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In order to find out the ecological distribution patterns of soil microbes under artificial Eucalyptus grandis stand,the amount and distribution of soil bacteria,fungi and actinomycetes in Hongya County of Sichuan Province were investigated in 2004.The results showed that soil microbial population under Eucalyptus grandis stand varied with seasons,being the maximum in autumn,fewer in spring,and the minimum in summer.The numbers were decreased in order of bacteria＞actinomycetes＞fungi,which were mainly concentrated in 0～20 cm soil layer,andrapidly decreased with increasing soil depth.In 0～60 cm soil layer,the numbers of aerobic bacteria were 0.31×10 ⁶～14.39×10 ⁶,actinomycetes were 0.06×10 ⁶～0.79×10 ⁶,fungi were 0.06×10 ⁶～0.79×10 ⁶,and anaerobes were 0.05×106～3.22×106 CFU·g^-1. Comparing with artificial C.glauca stand and farming land,Eucalyptus grandis stand had a larger number of soil microbes,suggesting that Eucalyptus grandis was benefit for soil microbial activity.The Simpson and ShannonWiener index of the physiological groups of bacteria was 0.773 and 1.896, respectively.

Spatial pattern relationships between emerald ash borer larvae and their natural enemies

WANG Xiaoyi,YANG Zhongqi

2005, 16(08):  1427-1431 . 

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The investigation on the spatial patterns of emerald ash borer (EAB) larvae, parasitoid Spathius agrili,and EAB?preying woodpecker pecks in ash forests showed that in horizontal direction,EAB larvae,parasitoid S.agriliand woodpecker pecks were in negative binomial distribution,while in vertical direction,EAB larvae were distributed on ash trunks from above ground to 3.37 m in height,with a peak around the 1.50 m.Their natural enemies also favored this range.

Growth characteristics of rock plant Pogonatherum paniceum

WANG Haiyang ¹,PENG Li ¹,LI Shaocai ²,BAI Baowei ¹

2005, 16(08):  1432-1436 . 

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The study on the growth characters,above and underground biomass,and root-shoot ratio of Pogonatherum paniceum grown on three types of substrates and five types of habitats in Chongqing showed that there were significant differences in plant growth characters,including stalk basal diameter,plant canopy and height,root system area and depth,and maximum root length among five habitats.For shoot growth,though the plants grown on purple soil had the maximum stalk basal diameter (15.18 cm),canopy (3 086.77 cm²) and height (6.58 cm) while those grown on purple sandy rock had the minimum values (stalk basal diameter 10.89 cm,canopy 1 868.79 cm2,and height 60.75 cm).There were no significant differences among three types of substrates.As for root system,there were significant differences between sandy rocks and purple soil,the plants grown on sandy rocks having higher means of root system area (1 389.14 cm² and 1 487.14 cm²) and maximum root length (45.83 cm and 39.24 cm) than those grown on purple soil (root system area 717.09 cm²,maximum root length 21.42 cm).The plants grown on sandy rock allocated more biomass to root system,and had higher root?shoot ratio,which was helpful for its fixation on rock and its endurance on the desiccation and arid of rock substrate.

Spatial variability of nutrients in cultivated soils of Xinhui District,Jiangmen City

GAN Haihua,PENG Lingyun

2005, 16(08):  1437-1442 . 

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Employing geostatistical methods and GIS technology,this paper studied the spatial distribution characteristics of pH,organic matter,CEC,total nitrogen,available phosphorus and slowly available potassium in cultivated soils of Xinhui District,Jiangmen City.All the test variables were normally or log normally distributed.Semivariogram analysis showed that soil nutrients were moderately spatially-dependent in a given spatial range,except that soil total nitrogen was strongly spatially-dependent.It was shown from Kriging analysis that soil pH and CEC was the highest in the northeast,and soil organic matter content was higher in the middle and northeast investigation region.The area with 1.5～2.0 g·kg^-1 soil total nitrogen content accounted for 75.7% of the investigated region,mainly distributed in the west and east,that with >40 mg·kg^-1 soil available phosphorus content was accounted for 48.7%,mainly distributed in the west and northeast,and the area that slowly available potassium content was 160～350 mg·kg^-1 accounted for 48.1%,mainly distributed in the east,northeast and the middle.

Soft?ridged bench terrace design in hilly loess region

CAO Shixiong ¹,CHEN L i ²,GAO Wangsheng ¹

2005, 16(08):  1443-1449 . 

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Reconfiguration of hillside field into terrace is regarded as one of the key techniques for water and soil conservation in mountainous regions.On slopes exceeding 30°,the traditional techniques of terracing are difficult to apply as risers(i.e.,backslopes),and if not reinforced,are so abrupt and easy to collapse under gravity alone,thus damaging the terrace.To improve the reconfiguration of hillside field into terrace,holistic techniques of soft-ridged bench terrace engineering,including revegetation with trees and planting grasses on riser slopes,were tested between 1997 and 2001 in Xiabiangou watershed of Yan'an,Shaanxi Province. A “working with Nature” engineering approach,riser slopes of 45°,similar to the pre-existing slope of 35°,was employed to radically reduce gravity-erosion.Based on the concepts of biodiversity and the principles of landscape ecology,terrace hes,bunds,and risers were planted with trees,shrubs,forage grasses,and crops,serving to generate a diverse array of plants,a semi-forested area,and to stabilize terrace bunds.Soft-ridged bench terrace made it possible to significantly reduce hazards arising from gravity erosion,and reduce the costs of individual bench construction and maintenance by 24.9% and 55.5% of the costs under traditional techniques,respectively.Such a construction allowed an enrichment and concentration of nutrients in the soils of terrace bunds,providing an ideal environment for a range of plants to grow and develop.The terrace riser could be planted with drought?resistant plants ranging from forage grasses to trees,and this riser vegetation would turn the exposed bunds and risers existing under traditional techniques into plant?covered belts,great green ribbons decorating farmland and contributing to the enhancement of the landscape biology.

Effects of irrigation and nitrogen fertilization on winter wheat yield under straw mulch

GAO Yajun¹,LI Shengxiu¹,LI Shiqing¹,TIAN Xiaohong¹,WANG Zhaohui¹, ZHENG Xianfeng¹,DU Jianjun ²

2005, 16(08):  1450-1454 . 

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A field experiment was conducted on a Hongyou soil of Yangling to investigate the effects of irrigation and nitrogen fertilization on wheat yield under straw mulch.The results showed that under straw mulch,N fertilization contributed more to the increase of wheat yield than irrigation,because soil moisture condition was improved greatly.The interaction between irrigation and nitrogen fertilization was negative in no-mulch treatment,but positive under straw mulch.For dryland,more attention should be paid to the input of nutrients when straw mulch was applied.High moisture content in soil profile before sowing and sufficient N input were essential for good harvest when field was not mulched.Under straw mulch,the irrigation rate for a maximum yield was reduced,and the optimum time of irrigation was postponed.Wheat grain yield had no relation to the irrigation during jointing stage in both no-mulch and straw mulch treatments.

Relationships between red soil enzyme activity and fertility

XUE Dong,YAO Huaiying,HE Zhenli,HUANG Changyong

2005, 16(08):  1455-1458 . 

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Correlation and cluster analyses on the enzyme activities and chemical-biological properties of eight red soils showed that soil urease, invertase, phosphatase and catalase activities correlated significantly with soil organic carbon,total nitrogen and total phosphorous.Similar results of soil fertility evaluation were obtained by using soil enzyme activities and by using soil chemical-biological properties,indicating that soil enzyme activity could be used as an index of evaluating red soil fertility.The enzyme activities of fresh soil were generally greater than those of air-dried sample,and more closely correlated with soil fertility.

Dynamics of water retaining capacity and chlorophyll content of two-line hybrid rice during heading-grain filling stage and their relations with grain yield

CHEN Xiaorong ¹,ZHONG Lei ¹,ZUO Qingfan ²

2005, 16(08):  1459-1464 . 

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The study with 25 two-line hybrid rice strains showed that their water retaining capacity was different with their combinations.On the whole,the water content in leaf and stem-sheath decreased during heading-grain filling stage,while that in panicle increased first and then decreased,with a peak at 7th day after heading.Stem-sheath was the main organ for water retaining. The correlation of panicle yield with both leaf and stem-sheath water content was positive at the 1st day after heading but became negative later,and that with whole stem-plant water content was positive after heading.The chlorophyll content of the two-line hybrids increased first and then decreased,with a peak at the 7th day after heading.Comparing with normal rice (male parent),the chlorophyll content of most two-line hybrids was lower,and the decreasing rate was faster than that of normal rice after heading. For two-line hybrid rice breeding,it should preferentially consider to select those hybrids which have a clearer dominance of plant water retaining capacity and a higher chlorophyll content at earlier and middle heading-grain filling stage,and an obvious dry matter transportation from leaf and stem-sheath at later heading?grain filling stage.For two?line hybrid rice planting,it should not only pay attention to the supply of water and nutrients,especially nitrogen at earlier and middle heading-grain filling stage,but also control nitrogen and water in time to prevent leaf green clinging and to promote dry matter transportation from leaf and stem-sheath to grain at later heading-grain filling stage.

Effects of shading at blossoming and boll?forming stages on cotton fiber quality

WANG Qingcai ¹,WANG Zhenlin ¹,SONG Xianliang ¹,LI Yujing ¹,GUO Ying ¹, WANG Jian ²,SUN Xuezhen ¹

2005, 16(08):  1465-1468 . 

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The study on the effects of different shading level at blossoming and boll-forming stages on cotton fiber quality of Zhongmiansuo No.41 and Lumianyan No.18 showed that with increasing shading,the maximum fiber length of cotton decreased,while the elongation period increased. The fiber length in 70% shading treatment was 1.01 mm shorter than that in 40% shading treatment. Without shading,the fiber reached its maximum length 25 days after anthesis,while in shading treatments,the fiber reached its maximum length 35 days after anthesis. Fiber gauge tenacity was also decreased with increasing shading. Comparing with the control,both 40% and 70% shading significantly decreased the fiber maturation and maturity. Two test cotton varieties presented the same change trend under shading condition.

Representativeness of Northeast China spring soybeans and their genetic diversity at SSR loci

LUAN Weijiang ^1,2,LIU Zhangxiong ¹,GUAN Rongxia ¹,CHANG Ruzhen ¹,HE Beiru ²,QIU Lijuan ¹

2005, 16(08):  1469-1476 . 

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A total of 283 accessions were selected from the total 3 226 Northeast China spring soybeans,which represented >80% of the whole based on their qualitative and quantitative traits.The representative samples were analyzed by 61 SSR loci,and a total of 534 alleles were detected,ranging 2～16 alleles per locus,with an average of 8.75 alleles per locus.Among the accessions,the Simpson diversity index (SDI) for each locus ranged from 0.406 to 0.886,with a mean of 0.704,which was relatively lower since there were dominant alleles at most of loci in the representative samples.35 accessions had specific alleles,which distributed among 29 loci.The differentiation coefficient was lower than 9.27% in 61 loci among the three provinces of Northeast China,which might be caused by lots of common alleles shared among these provinces.The genetic diversity in Jilin and Liaoning provinces was nearly equal,but was higher than that in Heilongjiang Province.The landraces of the representative samples at 61 loci had a higher genetic diversity than that of the released cultivars.The genetic diversity appeared within and between the provinces could be used to broaden the genetic base of modern cultivars,and also,the landraces were the major source for soybean breeding because of their high genetic diversity.

Physiological and ecological effects of inter?and mixed cropping rape with milk vetch

ZHOU Kejin ¹,XING Jun ²,BO Yuhong ³,SANG Yasong ³,WU Shelan ¹,SONG Guoliang ¹

2005, 16(08):  1477-1481 . 

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The investigation on the growth,yield and benefit of rape inter-and mixed cropped with milk vetch showed that comparing with sowing rape under zero tillage,the physiological and ecological characters of transplanted rape, including its height,leaf size,root diameter,opening degree and yield were obviously improved.Under zero tillage,mixed cropping had an obvious advantage than inter-and single cropping.After tillage,the yield of transplanted rape under mixed cropping was 11.9% more than that under single cropping with zero tillage.The benefit of transplanting rape under mixed cropping with tillage was the biggest,followed by single cropping rape with zero tillage.It could be concluded that the patterns of transplanting rape under mixed cropping after tillage and zero tillage had the best physiological and ecological effects,not only increasing rape yield and income,but also improving soil fertility.

Root activity and nitrogen assimilation of rice(Oryza sativa)under Free-Air CO₂ Enrichment

PANG Jing ^1,2,ZHU Jianguo ¹,XIE Zubin ¹,LIU Gang ¹,CHEN Gaiping ¹,ZHANG Yali ¹

2005, 16(08):  1482-1486 . 

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With Free-Air CO₂ Enrichment(FACE)technique,this paper studied the root activity and amino acid(aa) synthesis of rice(Oryza sativa)at low N(LN,150 kgN·hm^-2)and normal N(NN,250 kgN·hm^-2)under ambient air and elevated atmospheric CO₂(Ambient+200 μmol·mol^-1).Under elevated CO₂,the xylem exudates per hill changed little,while the xylem exudates per stem declined by 1.4%～21.7% as the result of greater tiller numbers.At tillering and heading stages,elevated CO₂ increased aa N/inorganic N in xylem exudates by 11.1%～143.1%,but did not affect the aa concentration in xylem exudates and the total amount of aa in roots significantly.However,at 35 days after heading,the aa N/inorganic N ratio decreased by 38.1%(LN)and 29.2%(NN)under elevated CO2.FACE also declined the aa concentration in xylem exudates by 34.0%(LN)and 44.7%(NN),and the total amount of aa by 50.8%(LN) and 40.0%(NN),which meant the retarded capability of aa synthesis in roots.N amendment led to a decrease of aa N/inorganic N in xylem exudates by 19.5%(Ambient) and 36.8%(FACE) at heading stage,as the result of unaffected aa and increased inorganic N concentration.There existed a significantly antagonistical CO2×N interaction on aa N/inorganic N at heading stage.

Effects of simulated acid rain and its acidified soil on soluble sugar and nitrogen contents of wheat seedlings

TONG Guanhe,LIANG Huiling

2005, 16(08):  1487-1492 . 

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The study showed that the cation release of simulated rain caused soil acidification and base ions release.With the decrease of simulated acid rain pH from 5.6 to 2.5,the acid rain?leached soil pH decreased from 6.06 to 3.41,and its total amount of exchange base ions decreased from 56.5 to 41.1 mmol·kg^-1.Spraying simulated acid rain on the shoots of wheat seedlings planted on such acidified soils caused a rapid decrease in the soluble sugar and nitrogen contents of wheat seedlings,and reduced some of their physiological activities.The effect of spraying simulated acid rain on the soluble sugar,nitrogen,and chlorophyll contents and photosynthetic rate of wheat stems and leaves was larger than that of acidified soil,while the effect of the latter on the soluble sugar and nitrogen contents and the physiological activity of NR and GOGAT in root system of wheat seedlings was larger than that of the former.The intensive acid rain of pH≤3.0 and the corresponding acidified soil had an obvious harm to the growth and physiological activity of wheat seedlings.

Effects of fungicide on temporal and spatial niches of Rhizoctonia solani

WANG Ziying ^1,3,TAN Genjia ²

2005, 16(08):  1493-1496 . 

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This paper studied the variation of the temporal and spatial niches of rice sheath blight-causing Rhizoctonia solani under spraying fungicide.The results showed that between fungicide treatments and control,the spatial niche breadth of Rhizoctonia solani was different,while its temporal niche breadth was similar.The spatial niche breadth of Rhizoctonia solani was 0.5240 when spraying fungicide at booting and full heading stages,0.5742 at booting and milkfilling stages,and 0.8577 at tillering stage,while the control was 0.8563.Spraying fungicide had little effect on temporal niche breath.The spatial niche breath,percentage of diseased leaves and sheathes,index of disease,and control effect all suggested that spraying fungicide two times in rice growth period was better than spraying it one time.Spraying fungicide at booting and full heading stages and at booting stage and milkfilling stages had the best effects.Fungicide could not only narrow the spatial niche breadth, limit the spread of Rhizoctonia solani on top leaves which were important for the yield,but also narrow the temporal niche breadth,limit the spread of Rhizoctonia solani during the yield formation period of rice. But, spraying fungicide only changed the distribution of the fungus niches and narrowed the niches during rice yield formation period,with no changes in the whole niches of Rhizoctonia solani.

Effects of alkali?stress on Aneurolepidium chinense and Helianthus annuus

YAN Hong ¹,ZHAO Wei ²,SHENG Yanmin ³,SHI Decheng ¹,ZHOU Daowei ¹

2005, 16(08):  1497-1501 . 

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Employing monocotyledon Aneurolepidium chinense and dicotyledon Helianthus annuus,the two species with high alkali-saline resistance as test materials,and stressing them with neutral,alkalic,and mixed salts,this paper studied the characteristics of various stresses and their interrelations,with relative growth rate (RGR) as the main strain index.The results showed that under the same concentration,alkalic salt had a stronger effect than neutral salt,and the RGR of A.chinense and H.annuus was decreased with increasing salt concentration under the same kind of salt stress and pH conditions. When the pH was higher,the RGR decreased more obviously.In addition,the proline and citric acid contents in test plants were increased with increasing stress.The transformation of proline in A.chinense was greater than that in H.annuus,while that of citric acid was in adverse.In a word,alkalic salt stress was different from neutral salt stress in stressing plants and in plant responses. Alkalic salt stress and neutral salt stress were actually two distinct kinds of stresses.The former was better called “alkali-stress”,while “salt-stress” only meant neutral salt stress.The key difference between them was their different pH value.It was reasonable to consider the buffer capacity as the strength value of alkali-stress,and the salinity as the strength value of salt-stress.An interactive effect between salt-stress and alkali-stress could be seen under mixed saline and alkali stress.

Effects of eutrophication on distribution and population density of Corbicula fluminea and Bellamya sp.in Chaohu Lake

DENG Daogui^1，3,LI Hongyuan²,HU Wanming²,ZHOU Qiong¹,GUO Longgen¹

2005, 16(08):  1502-1506 . 

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The investigation on the distribution and population density of C.fluminea and Bellamya sp.in Chaohu Lake during September 2001 and September 2002 showed that in the west region of the lake where was seriously eutrophic,the density and biomass of C.fluminea were 5.1 ind.·m^-2 and 17.87 g·m^-2 in 2001,and 8.8 ind.·m^-2 and 47.29 g·m^-2 in 2002,while those of Bellamya sp.were 13.3 ind.·m^-2 and 45.45 g·m^-2 in 2001,and 3.8 ind.·m^-2 and 12.56 g·m^-2 in 2002,respectively.In the east region of the lake where was eutrophic,the density and biomass of C.fluminea were 23.8 ind.·m^-2 and 67.86 g·m^-2 in 2001,and 29.2 ind.·m^-2 and 96.18 g·m^-2 in 2002,while those of Bellamya sp.were 10.1 ind.·m^-2 and 32.00 g·m^-2 in 2001,and 9.4 ind.·m^-2 and 31.21 g·m^-2 in 2002,respectively.The density and biomass of C.fluminea and Bellamya sp.were declined with increasing eutrophication.In hypertrophic region,C.fluminea and Bellamya sp.were absent.The density and biomass of the two species were obviously higher in littoral than in pelagic region.The distribution type of C.fluminea was core-model,while that of Bellamya sp.was random.The correlation between the density and biomass of C.fluminea and Bellamya sp.and water depth was not significant(P>0.05).The biomass of Bellamya sp.was negatively correlated with water TN(P＜0.01),NO₃-N(P＜0.05),TP(P＜0.01) and PO₄-P(P＜0.05),while that of C.fluminea only had a significantly negative correlation with PO₄-P(P＜0.05).Compared with 1981,there was fewer C.fluminea in the lake nowadays. The effects of other environmental factors on the population distribution and growth of C.fluminea and Bellamya sp.were also discussed.

Relationships between antioxidant activities and heat-resistant features of two Laminaria japonica strains

WANG You ^1,2,TANG Xuexi ¹

2005, 16(08):  1507-1512 . 

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The study on the relationships between antioxidant activities and heat-resistant features of two Laminaria japonica gametophyte mutants Kelp 901(abbreviated as 901)and Rongcheng No.1(abbreviated as RC)under different temperature conditions showed that under normal temperature condition(10 ℃),there were no positive relationships between the basal antioxidant activities and heat-resistant features of 901 and RC,while under heat stress(18 ℃),the reactive oxygen species(ROS)contents kept constant in 901,but accumulated rapidly in RC,suggesting that ROS played an essential role in oxidative stress.The enzyme activities in RC were more vulnerable to high temperature,and its antioxidant enzyme activities decreased more sharply under heat stress.Ascorbic acid(ASA),vitamin E,superoxide dismutase(SOD)and glutathione peroxidase(Gpx)might play important roles in kelp's heat-resistance.Chlorophyll a was sensitive to heat stress,and its 50% nocuity time could be used as an indicator to distinguish kelp strains with different heat-resistance.It was suggested that the antioxidant system's responses to heat stress instead of its basic activities accounted for the kelp's heat-resistance.

Factor analysis of Beijing north ring water system eutrophication

ZENG Yong,YANG Zhifeng,LIU Jingling

2005, 16(08):  1513-1517 . 

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Eutrophication is caused by hydrological,physical or chemical factors such as temperature,illumination,or shapes of waters.It is very important to identify the main factors to understand and control the process of eutrophication.In this paper,Beijing north circle water system was divided into river subsystem and lake subsystem by cluster analysis.Factor analysis indicated that the main factors of river subsystem eutrophication were TP,TN and NH₄－N, while those for lake subsystem were TN and NH₄－N,which meant that in the study area,the main cause for eutrophication was the overload of nutrients. Stepwise regression was introduced to build forecasting model,and the choice results of independent variables in the regression model inferred that the type of eutrophication in river subsystem was P limited,while that of lake was N limited.Two main causes for nutrient load were found from water quantity and quality analysis of the study area,one was the ecological water demands be not able to satisfy from 1990 to 1998 except 1998,and the other was the increase of nutrient load coming from domestic waste and nonpoint pollutant,resulting from the rapid population increase and city expansion.The measures to control the eutrophication process were put forward.

Effects of atrazine and its degrader Exiguobaterium sp.BTAH1 on soil microbial community

HU Jiang,DAI Xianzhu,LI Shunpeng

2005, 16(08):  1518-1522 . 

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The study showed that the application of atrazine stimulated soil microorganisms obviously.In comparing with control(without atrazine),the respiration intensity of soil applied with 50 mg atrazine·kg^-1 soil increased greatly,the concentrations of soil NH₄⁺-N and NO₃^--N changed significantly,and the individuals of soil microbes,especially bacteria and fungi,also increased greatly.The application of strain BTAH1 could degrade 98% of applied atrazine within one week,and led to the decrease of soil respiration intensity.Under BTAH1 application,the individuals of actinomyces and fungi decreased,while those of bacteria did not,and the concentrations of soil NH₄⁺-Nand NO₃^--N came back to the level of the control.ARDRA analysis on the 16s rDNA library of soil bacteria suggested that the application of atrazine could decrease the biodiversity of soil microorganisms, while applying BTAH1 could recover the biodiversity.

Effects of Bt toxin Cry1Ac on biochemical responses of Eisenia fetida in an artificial soil

XIAO Nengwen,GE Feng,LIU Xianghui

2005, 16(08):  1523-1526 . 

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Bt toxin Cry1Ac could be introduced into soil by pollen,root exudates,and plant residues.To investigate its toxic effects,the Bt toxin was added into an earthworm-cultured artificial soil,and the survival,growth rate,sperm count, protein content,and activities of acetylcholinesterase (AchE),catalase (CAT), glutathione-S-transferase (GST) and cellulase in Eisenia fetida were determined. The results suggested that Bt toxin Cry1Ac had little effects on the biomass and physiological characteristics of E.fetida,with no acute and subchronic toxicity,and was safe for earthworm at field dose level.

Acute toxicological effects of excessive Cu and Zn-containing in pig manure on earthworm

JIA Xiuying ¹,LUO Ancheng ²,LI Ximei ¹

2005, 16(08):  1527-1530 . 

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Cu and Zn are popularly used as additives in animal feed in China,which could result in their excessive accumulation in manure to a toxic level,and thus,possibly threaten the environment when the manure is applied to farmland.In this paper,the acute and sub?acute lethal effects of pig manure with excessive Cu and Zn on earthworm were studied,and the results indicated that the concentration of Cu and Zn in pig manure had a significantly positive correlation with the mortality of earthworm,while a significantly negative correlation with earthworm growth rate.The individuals of earthworm had different tolerance to excessive Cu and Zn,with the threshold values causing death being 250 mg·kg^-1 and 400 mg·kg^-1 for Cu and Zn,respectively.The LD50 was 646.68 mg·kg^-1 for Cu,and 947.38 mg·kg^-1 for Zn.A strong synergistic effect was observed under the combined pollution of 250 mg·kg^-1 for Cu and 500 mg·kg^-1 for Zn,whereas antagonistic effect happened when 750 mg·kg-1 for Cu was supplied, suggesting that the joint toxic effects of Cu and Zn on earthworm were closely correlated to their concentrations in pig manure.

Forest ecosystem service and its evaluation in China

JIN Fang,LU Shaowei,YU Xinxiao,RAO Liangyi,NIU Jianzhi,XIE Yuanyuan,ZHAG Zhenming

2005, 16(08):  1531-1536 . 

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Facing the relative lag of forest ecosystem service and estimation in China, this paper proposed to quickly carry out the research on the evaluation of forest ecosystem service.On the basis of the classification of forest ecosystem types in China,the service of artificial and semi-artificial forest ecosystems was investigated,which was divided into eight types,i.e.,timber and other products,recreation and eco?tourism,water storage,C fixation and O2 release,nutrient cycling,air quality purifying,erosion control,and habitat provision.According to the assessment index system for global ecosystem service proposed by Costanza et al.,a series of assessment index system suitable for Chinese forest ecosystem service was set up,by which,the total value of forest ecosystem service in China was estimated to be 30 601.20×108 yuan·yr-1,including direct and indirect economic value about 1 920.23×108 and 28 680.97×108 yuan·yr^-1,respectively.The indirect value was as 14.94 times as the direct one.The research aimed to bring natural resources and environment factors into the account system of national economy quickly,and to realize the green GDP at last,which would be helpful to realize sustainable development and environment protection.

Discussion on hydrologic scaling

ZHONG Ye ^1,2,JIN Changjie ¹,PEI Tiefan ¹

2005, 16(08):  1537-1540 . 

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Hydrologic scaling is the hotspot and frontier of today's hydrologic research, which includes three different meanings distinguished from each other,i.e., process scale,observation scale and modelling scale.As a characteristic of hydrologic scale,dominant process scale has been paid more attention. Hydrologic scaling includes the scaling of hydrologic models,parameters,state variables and inputs,which owns special research methods respectively.The difficulty of hydrologic scaling mainly comes from the organized complexity of hydrologic systems,the heterogeneity and variability in space and time,and the insufficiency of data.The ubiquitous selfsimilarity of natural river networks makes itself an important part of hydrologic scaling research.The combination of various techniques and theories is needed to motivate hydrologic scaling research.

Nematodes as bioindicator of soil health:methods and applications

LI Yujuan,WU Jihua,CHEN Huili,CHEN Jiakuan

2005, 16(08):  1541-1546 . 

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This paper summarized the advantages of using nematodes as soil health bioindicator.A review of commonly used indices and analyzing methods by means of nematodes was presented,with emphases on Maturity Index,as well as the indices and analyzing methods based on their trophic groups. Compared with other indices,Maturity Index can reflect the stressed degree of soil more sensitively,and the indices and analyzing methods based on their trophic groups can well reveal the state of soil health based on ecosystem functioning.The applications of nematodes as bioindicator in agriculture, forest,grassland,and other ecosystems were also outlined.In view of some practical limitations in the methods,prospective researches and applications were suggested,i.e.,intensify the ecological studies to advance the understanding on the characteristics of soil nematodes,such as their life histories and feeding habits,consummate the indication system by integrating various nematode indices and analyzing methods,and extend the applications of soil nematodes in different ecosystems and in different regions at large scales.

Affecting factors of soil microorganism and root respiration

JIA Bingrui ^1,2,ZHOU Guangsheng ¹,WANG Fengyu ^1,2,WANG Yuhui ¹

2005, 16(08):  1547-1552 . 

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Soil respiration is an important part of the carbon cycle in terrestrial ecosystems, and its contribution to the global carbon budget has been the focus of wide concern.Researches on the affecting factors of soil microorganism and root respiration,the main components of soil respiration, contribute to the understanding of the role of soil respiration on global carbon cycle,and to the accurate evaluation of global carbon budget.This paper reviewed the direct and indirect affecting factors of soil microorganism and root respiration,including climate factors,soil properties,vegetation and litterfall,air CO2 concentration,and human activities.These affecting factors were interactive,and their contributions to soil microorganism and root respiration varied in temporal and spatial scales.The study on natural and anthropogenic factors of soil microorganism and root respiration was emphasized,and some related research tasks in the future were also proposed.

Research advances on eco?chemical behaviors and toxicological effects of cadmium in root－soil interface

JIN Caixia ^1,2,ZHOU Qixing ¹,SUN Ruilian ^1,2,REN Liping ¹

2005, 16(08):  1553-1557 . 

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Many active substances such as organic acids and enzymes excreted by living plant roots could induce a great difference of Eh and pH values between root-soil interface and non?rhizosphere soil,forming a special root-soil interface miniature environment.As a mini-type ecological area with most frequent exchanges of substances,root-soil interface plays a crucial role in their absorption,transformation,migration and eco-toxicological effects.In this paper,the eco-chemical behaviors of Cd in root-soil interface affected by the change of pH,Eh and root secretion,and its eco-toxicological effects on microorganisms and enzymes in root-soil interface were reviewed,based on the related research advances in recent decade.The shortages in relevant fields were pointed out,and the scientific problems to be researched in the future were suggested.

Advances in research and application of water-treatment flocculants

LIU Rui ^1,3,ZHOU Qixing ²,ZHANG Lanying ¹，WANG Bing ⁴，SUN Piwu ⁵

2005, 16(08):  1558-1562 . 

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Water-treatment flocculants are being developed from traditional to inorganic, from inorganic to organic,from natural organic to synthetic organic, from synthetic organic to modified natural organic,from inorganic or organic to inorganic organic,and from chemical to biological with ecological safety.In order to promote the rapid development and practical application of water-treatment flocculants,the research progress and application situation of flocculants for water treatment at home and abroad were reviewed.In particular,the characteristics of two important flocculant types,chemical and microbiological flocculants,as well as their application processes in water treatment were summarized,their development orientations were analyzed and evaluated,and the future research directions aimed to overcome the current shortages in developing and applying flocculants in China were put forward.

Recycling rate of N and P through a feeding-composting cycle and their recoveries in agro-ecosystems

YU Wantai ¹,GUAN Yan ^1，2,LI Jiandong ²,ZHANG Lu ¹,MA Qiang ¹

2005, 16(08):  1563-1565 . 

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A five-year experiment indicated that the average loss rate of N and P in harve sted products through a feeding-composting cycle was about 50% and 15%,respectively.Under high yield condition,the amount of recycled N and P from 80% harvested products and through a feeding-composting cycle in farming systems was about37～51 and 8～14 kg·hm^-2,equivalent to 25%～34% of N and 32%～56% of P from chemical fertilizers applied each year to the systems.The apparent recoveries of N and P in organic manure increased with the prolongation of fertilization,indicating a synergetic residual effect existed,and was 61% and 39% in average in the five-year experiment.The use of nutrients recycled in the farming systems could not only improve soil fertility,but also increase the recoveries of nutrients and reduce the use of chemical fertilizers.

Biodegradation of di?n?butyl phthalate by mangrove microorganism Rhodococcus ruber 1K

LI Kuixiao ¹,GU Jidong ^1,2

2005, 16(08):  1566-1568 . 

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A di-n-butyl phthalate (DBP)degrading bacterium Rhodococcus rubber was isolated from mangrove soil,and its degrading characteristics were studied.The results showed that the bacterium could grow well on the substrate with DBP as the sole source of carbon and energy,and the DBP of 50 mg·L^-1 could be completely degraded after 48 h.Under aerobic condition,the tentative pathway proposed for DBP degradation was through monoester initially,then phthalic acid,and finally CO₂ and H₂O.

Characteristics of Yunnan Province rice landrace core collections under phosphorus deficiency

SHEN Shiquan,ZENG Yawen,PU Xiaoying,DU Juan,LI Shenchong

2005, 16(08):  1569-1572 . 

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Soil phosphorus (P) deficiency is a major yield-limiting factor in rice production.Employing 526 rice landrace accessions from 5 rice-planting regions and 16 prefectures in Yunnan Province,this paper studied their P?deficiency tolerance characteristics by comparing the relative plant dry weight under acid red soil condition.The results showed that Northwest Yunnan cold highland japonica rice-planting region was most abundant in P?deficiency tolerance core collection of indica,and there was no significant difference in japonica among five ecological zones of rice landraces. Nujiang,Lijiang, Dehong, Wenshan,Xishuangbana and Yuxi were most abundant in P-deficiency tolerance core collection of indica,and Lijiang,Wenshan and Chuxiong were most abundant in P?deficiency tolerance core collection of japonica.Indica had a higher P-deficiency tolerance than japonica.The P-deficiency tolerance of rice was significantly related with its genetic diversity, rice breeding and acid red soils.

Extraction of active substance from Chlorella vulgaris cells and its physiological effects on Saccharomyces cerevisiae

HU Kaihui,ZHOU Shanyong

2005, 16(08):  1573-1576 . 

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The study showed that freezing-thawing method could have a higher cellwall breakage rate,and a light injury to the active substance,which could not only increase the cell fission and growth,delay the death of Saccharomycete cells, but also enhance CO₂ production rate and quicken fermentation process when the cells were exposed to the medium with 0.5% active substance.

Application effect of most probable number(MPN)method in photosynthetic bacteria counting

CUI Zhanli ¹,WANG Pingping ²,WANG Qiuju ¹

2005, 16(08):  1577-1580 . 

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The application of most probable number(MPN)method in counting the numbers of photosynthetic bacteria(PSB)showed that this method was suitable for PSB counting under illumination and anaerobic condition,which remedied the shortages of other methods.With this method,the sensitivity and accuracy of the counting could be enhanced when more replicated tubes and lower dilution times for fewer bacteria samples were applied.When PSB were not dominant in soil and water,MPN method could be used instead of other methods.PSB agent could only survive 6～9 days,and not be dominant in the environment in a long term.Its application time and oxygen level affect the numbers of PSB significantly,which were the largest in a short application time and under anaerobic condition.

Net primary productivity of several mangrove species under controlled habitats

PENG Yougui, CHEN Guizhu, WU Pengfei, MIAO Shenyu, YIN Min, SHE Zhongming

2005, 16(8):  1383-1388. 

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Three mangrove species Sonneratia caseolaris,Kandelia candel and Aegiceras corniculatum were planted in different fishponds in April 2002 with three planting-breeding area proportions of 4555,3070 and 1585,respectively,and the growth of test mangrove plants were surveyed during 2 years after planting.The results showed that Aegiceras corniculatum and A.comiculatum could grow well in the coupling system,while K.candel could not.The survival percentage of Aegiceras corniculatum,K.candel and A.corniculatum was 92.9%,93.9% and 44.7%,respectively.During the 2 years,the height of Aegiceras corniculatum increased 457.0 cm,and its basal diameter increased from 12.6 mm to 98.7 mm.A.corniculatum had an increment of 26.1 cm in height and 36.5 mm in basal diameter,while K.candel only had an increment of 20.4 cm in height and 26.4 mm in basal diameter.Based on the height,basal diameter,and biomass of trunk,branch,leaf and root,regressive equations of the four organs' biomass were obtained,and the whole biomass of standing trees in the coupling system was calculated.The average biomass of Aegiceras corniculatum was 5 597.8 g穖^-2 in April 2004,being increased 5 559.5 g穖^-2 in 2 years.At the same period,the standing biomass of A.corniculatum and K.candel was 962.5 g穖^-2 and 66.0 g穖^-2,with an increase of 932.7 g穖^-2 and 57.0 g穖^-2,respectively.The biomass of plant organs was in the order of stem > branch > root > leaf for Aegiceras corniculatum,leaf > branch > stem > root for A.corniculatum,and stem > root > leaf > branch for K.candel.The litter fall production of mangrove plants in 2 years was 1 149.2 g穖^-2,170.8 g穖^-2 and 7.1 g穖^-2 for Aegiceras corniculatum,A.corniculatum and K.candel,respectively.Leaf litter took up more than half of the whole litter fall.From April 2002 to April 2004,the net primary production of Aegiceras corniculatum,A.corniculatum and K.candel was 7 048.9 g穖^-2,1 105.9 g穖^-2 and 93.0 g穖^-2,respectively.The litter fall production occupied 20.5% of the net primary production for Aegiceras corniculatum,15.4% for A.corniculatum,and 7.6% for K.candel,which meant that high productivity was accompanied by high return rate.

Seasonal variation of Tamarix ramosissima and Populus euphratica water potentials in southern fringe of Taklamakan Desert

ZENG Fanjiang, ZHANG Ximing, LI Xiangyi, Andrea Foetzki, Michael Runge

2005, 16(8):  1389-1393. 

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The measurement of the seasonal and diurnal variations of Tamarix ramosissima and Populus euphratica water potentials in the southern fringe of Taklamakan Desert indicated that there was no apparent water stress for the two species during their growth period,with little change of predawn water potential and some extent decrease of midday water potential.Irrigation once or thinning had no significant effects on the water status of the plants,while groundwater appeared to be a prerequisite for the survival and growth of these species.It is very important to ensure a stable groundwater table for the restoration of Tamarix ramosissima and Populus euphratica in this area.

Population characteristics of Coptis chinensis varbrevisepala in Anhui Province and its endangering mechanism

ZHANG Li, ZHANG Xiaoping

2005, 16(8):  1394-1398. 

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The study on the distribution pattern,population size,and age structure of C.chinensis var.brevisepala in Anhui Province showed that C.chinensis var.brevisepala mainly distributed in the southern mountain areas such as Mts.Jiuhuashan,Guniujiang,Huangshan and Qingliang Peak.The habitats had two kinds,i.e.,under woods and beside water ditches,both of which were shady and humid,with loose and acidic soils containing abundant organic matter.The shading degree surpassed 70%,air humidity reached 70%～90%,and soil water content was more than 30%.The distribution pattern of existing C.chinensis var.brevisepala populations was clustering,with illogical age structure and small population size.It was suggested that the populations of C.chinensis var.brevisepala in Anhui Province were in an unsteady stage.Serious destroy of natural habitat and excessive digging and gathering adult individuals were the main causes of the rapid decrease of the individuals in some populations,which threatened the existence of C.chinensis var.brevisepala populations seriously.

Effects of nitrate application on alleviating photosynthesis restriction of Cinnamomum burmannii leaves under elevated CO₂ concentration and enhanced temperature

SUN Guchou, ZHAO Ping, RAO Xingquan, CAI Xi'an, ZENG Xiaoping

2005, 16(8):  1399-1404. 

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In this study,potted C.burmannii saplings were cultured in a top-closed chamber with elevated CO₂(+CO₂,731 μmol·mol^-1) and ambient CO₂(CO₂,365 μmol·mol^-1),and at diurnal temperature(day/night) 25/23 and 32/25,respectively.The gas exchange,calculated photosynthesis parameter,Rubisco content,and activated state of Rubisco were examined.The results showed that under +CO₂ and at 25/23,the mean photosynthetic rate(Pnsat) of sapling leaves was 5.1%higher than that under +CO₂ and at 32/25.Temperature enhancement declined Pnsat,while nitrate addition increased it.Under +CO₂,saplings had lower V_cmax and J_max at 32/25 than at 25/23.Temperatureenhancement under +CO₂ also declined V_cmax and J_max.Under +CO₂,lower photorespiration rate(R_p) occurred in leaves,but temperature enhancement could increase R_p.Under +CO₂,Rubisco content(N_R) and its active site per unit leaf area(M) decreased as diurnal temperature changed from 25/23 to 32/25.Meanwhile,nitrate addition could increase N_R and M.It may be suggested that nitrate addition could alleviate the restriction of photosynthesis under elevated CO₂ concentration and enhanced temperature.

Quantitative characteristics of soil aggregates under different vegetations in upper reach of Minjiang River

NING Lidan, SHI Hui, ZHOU Haijun, LIU Shirong

2005, 16(8):  1405-1410. 

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Quantitative analysis on the soil aggregates under dark coniferous forest,coniferous and broad-leaved mixed forest,fargesia under the gap of dark coniferous forest,and sclerophyllous oaks (Quercus semicarpifolia) at Wolong Natural Reserve in the upper reach of Minjiang River showed that wet-sieving soil aggregates were of logarithmic-normal distribution,and the geometric mean diameters were negatively correlated to geometric standard deviation.The aggregates under coniferous and broad-leaved mixed forest and sclerophyllous oaks had larger sizes than those under other vegetations.The range of fractal dimension of soil aggregates was 2.402.78,along with more aggregates less than 0.25 mm in size.The fractal dimension of soil aggregates under dark coniferous forest and fargesia were larger than that under other vegetations.The soil aggregates with 31 mm and 10.5 mm in size had a higher stability,while those with >10 mm and 0.50.25 mm in size were in adverse.The aggregate stability index of soil under coniferous and broad-leaved mixed forest was the highest,followed by that under sclerophyllous oaks,fargesia under the gap of dark coniferous forest,and dark coniferous forest,which meant that coniferous and broadleaf mixed forest and sclerophyllous oaks were favorable for soil aggregate stability.Significant correlations were found among the three quantitative characteristics,which could be used to indicate the stability of soil aggregates.

Effects of replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation on soil biological activities

HU Yalin, WANG Silong, YAN Shaokui, GAO Hong

2005, 16(8):  1411-1416. 

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This paper studied the effects of replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation in the south,central and upstate areas of subtropical China on the changes of soil chemical and biological properties.The results showed that after replacing with Cunninghamia lanceolata plantation,the total organic carbon (TOC) content in surface soil decreased by 31.51%～58.24%,and the contents of soil total N and P,pH value,C/N and C/P also decreased to different degree.Soil microbial amount was less than that under natural secondary broad-leaved forest,soil urease,invertase,catalase and dehydrogenase activities decreased,while soil polyphenol oxidase activity increased by 8%～40%.The respiration rate of Cunninghamia lanceolata soil was 51.15%～54.48% lower than that of natural secondary broad-leaved forest soil.The correlation between soil TOC and polyphenol oxidase activity was negative (R=-0.723,n=18),while those between soil TOC,N,P and other enzyme activities were positive.It could be concluded that replacing natural secondary broad-leaved forest with Cunninghamia lanceolata plantation worsened soil quality,and the loss of soil organic matter in Cunninghamia lanceolata plantation ecosystem might be one of the important factors resulted in the decrease of soil nutrients and enzyme activities.

Effects of different ground clearance on soil fertility of Chinese fir stands

XUE Li, XIANG Wenjing, HE Yuejun, LI Yan, WU Min, XU Yan, QU Ming

2005, 16(8):  1417-1421. 

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The study on the soil physical properties,nutrient contents,microbial amounts and enzyme activities of clear cutting and controlled burning Chinese fir stands showed that in comparing with the control,soil non-capillary porosity of clear cutting stand increased by 23%,whereas soil natural water capacity and capillary moisture capacity decreased by 25%.In controlled burning stand,soil bul穔 density increased by 10%,while soil non-capillary porosity,natural water capacity and capillary moisture capacity decreased by 61%,48% and 26%,respectively.The contents of soil organic matter,total N,total P and total K in clear cutting stand decreased by 14%,14%,35% and 22%,and in controlled burning stand,they decreased by 37%,37%,47% and 7%,respectively.Soil al穔alized N and available K in clear cutting stand increased by 24% and 31%,respectively,but soil available P decreased by 15%.The contents of soil al穔alized N,available P and available K in controlled burning stand decreased by 25%,43% and 40%,respectively.In clear cutting stand,the amounts of soil bacteria,fungi and actinomyces increased by 1.4,11.3 and 0.8 times,respectively,but in controlled burning stand,the amounts of soil bacteria decreased by 24%,while those of soil fungi and actinomyces increased by 5.0 and 0.5 times,respectively.The activities of soil urease,catalase and cellulase in clear cutting stand increased by 1.9,1.6 and 2.1 times,and in controlled burning land,they were 35%,90% and 106% of the control,respectively.Damp soil had higher contents of organic matter,total N and total P,whereas porous soil was favorable for the accumulation of al穔alized N,available P and available K and for the increase of soil urease activity.The amount of soil fungi decreased with increasing soil capillary porosity.Aerated soil was favorable for the increase of soil catalase activity.

Ecological distribution patterns of soil microbes under artificial Eucalyptus Grandis stand

FENG Jian, ZHANG Jian

2005, 16(8):  1422-1426. 

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In order to find out the ecological distribution patterns of soil microbes under artificial Eucalyptus grandis stand,the amount and distribution of soil bacteria,fungi and actinomycetes in Hongya County of Sichuan Province were investigated in 2004.The results showed that soil microbial population under Eucalyptus grandis stand varied with seasons,being the maximum in autumn,fewer in spring,and the minimum in summer.The numbers were decreased in order of bacteria>actinomycetes>fungi,which were mainly concentrated in 020 cm soil layer,and rapidly decreased with increasing soil depth.In 060cm soil layer,the numbers of aerobic bacteria were 0.3110⁶14.3910⁶,actinomycetes were 0.0610⁶0.7910⁶,fungi were 0.0610⁶0.7910⁶,and anaerobes were 0.0510⁶3.2210⁶ CFU穏^-1.Comparing with artificial C.glauca stand and farming land,Eucalyptus grandis stand had a larger number of soil microbes,suggesting that Eucalyptus grandis was benefit for soil microbial activity.The Simpson and Shannon-Wiener index of the physiological groups of bacteria was 0.773 and 1.896,respectively.

Spatial pattern relationships between emerald ash borer larvae and their natural enemies

WANG Xiaoyi, YANG Zhongqi

2005, 16(8):  1427-1431. 

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The investigation on the spatial patterns of emerald ash borer (EAB) larvae,parasitoid Spathius agrili,and EAB-preying woodpecker pecks in ash forests showed that in horizontal direction,EAB larvae,parasitoid S.agrili and woodpecker pecks were in negative binomial distribution,while in vertical direction,EAB larvae were distributed on ash trunks from above ground to 3.37 m in height,with a peak around the 1.50 m.Their natural enemies also favored this range.

Growth characteristics of rock plant Pogonatherum paniceum

WANG Haiyang, PENG Li, LI Shaocai, BAI Baowei

2005, 16(8):  1432-1436. 

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The study on the growth characters,above and underground biomass,and root-shoot ratio of Pogonatherum paniceum grown on three types of substrates and five types of habitats in Chongqing showed that there were significant differences in plant growth characters,including stal穔 basal diameter,plant canopy and height,root system area and depth,and maximum root length among five habitats.For shoot growth,though the plants grown on purple soil had the maximum stal穔 basal diameter (15.18 cm),canopy (3 086.77 cm²) and height (6.58 cm) while those grown on purple sandy rock had the minimum values (stal穔 basal diameter 10.89 cm,canopy (1 868.79) cm²,and height 60.75 cm).There were no significant differences among three types of substrates.As for root system,there were significant differences between sandy rocks and purple soil,the plants grown on sandy rocks having higher means of root system area (1 389.14 cm² and 1 487.14 cm²) and maximum root length (45.83 cm and 39.24 cm) than those grown on purple soil (root system area 717.09 cm²,maximum root length 21.42 cm).The plants grown on sandy rock allocated more biomass to root system,and had higher root-shoot ratio,which was helpful for its fixation on rock and its endurance on the desiccation and arid of rock substrate.

Spatial variability of nutrients in cultivated soils of Xinhui District,Jiang穖en City

GAN Haihua, PENG Lingyun

2005, 16(8):  1437-1442. 

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Employing geostatistical methods and GIS technology,this paper studied the spatial distribution characteristics of pH,organic matter,CEC,total nitrogen,available phosphorus and slowly available potassium in cultivated soils of Xinhui District,Jiangmen City.All the test variables were normally or log normally distributed.Semivariogram analysis showed that soil nutrients were moderately spatially-dependent in a given spatial range,except that soil total nitrogen was strongly spatially-dependent.It was shown from Kriging analysis that soil pH and CEC was the highest in the northeast,and soil organic matter content was higher in the middle and northeast investigation region.The area with 1.5～2.0 g·kg^-1 soil total nitrogen content accounted for 75.7% of the investigated region,mainly distributed in the west and east,that with >40 mg·kg^-1 soil available phosphorus content was accounted for 48.7%,mainly distributed in the west and northeast,and the area that slowly available potassium content was 160350 mg·kg^-1 accounted for 48.1%,mainly distributed in the east,northeast and the middle.

Soft-ridged bench terrace design in hilly loess region

CAO Shixiong, CHEN Li, GAO Wangsheng

2005, 16(8):  1443-1449. 

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Reconfiguration of hillside field into terrace is regarded as one of the key techniques for water and soil conservation in mountainous regions.On slopes exceeding 30,the traditional techniques of terracing are difficult to apply as risers(i.e.,backslopes),and if not reinforced,are so abrupt and easy to collapse under gravity alone,thus damaging the terrace.To improve the reconfiguration of hillside field into terrace,holistic techniques of soft-ridged bench terrace engineering,including revegetation with trees and planting grasses on riser slopes,were tested between 1997 and 2001 in Xiabiangou watershed of Yan'an,Shaanxi Province. A "working with Nature" engineering approach,riser slopes of 45,similar to the pre-existing slope of 35,was employed to radically reduce gravity-erosion.Based on the concepts of biodiversity and the principles of landscape ecology,terrace benches,bunds,and risers were planted with trees,shrubs,forage grasses,and crops,serving to generate a diverse array of plants,a semi-forested area,and to stabilize terrace bunds.Soft-ridged bench terrace made it possible to significantly reduce hazards arising from gravity erosion,and reduce the costs of individual bench construction and maintenance by 24.9% and 55.5% of the costs under traditional techniques,respectively.Such a construction allowed an enrichment and concentration of nutrients in the soils of terrace bunds,providing an ideal environment for a range of plants to grow and develop.The terrace riser could be planted with drought-resistant plants ranging from forage grasses to trees,and this riser vegetation would turn the exposed bunds and risers existing under traditional techniques into plant-covered belts,great green ribbons decorating farmland and contributing to the enhancement of the landscape biology.

Effects of irrigation and nitrogen fertilization on winter wheat yield under straw mulch

GAO Yajun, LI Shengxiu, LI Shiqing, TIAN Xiaohong, WANG Zhaohui, ZHENG Xianfeng, DU Jianjun

2005, 16(8):  1450-1454. 

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A field experiment was conducted on a Hongyou soil of Yangling to investigate the effects of irrigation and nitrogen fertilization on wheat yield under straw mulch.The results showed that under straw mulch,N fertilization contributed more to the increase of wheat yield than irrigation,because soil moisture condition was improved greatly.The interaction between irrigation and nitrogen fertilization was negative in no-mulch treatment,but positive under straw mulch.For dryland,more attention should be paid to the input of nutrients when straw mulch was applied.High moisture content in soil profile before sowing and sufficient N input were essential for good harvest when field was not mulched.Under straw mulch,the irrigation rate for a maximum yield was reduced,and the optimum time of irrigation was postponed.Wheat grain yield had no relation to the irrigation during jointing stage in both no-mulch and straw mulch treatments.

Relationships between red soil enzyme activity and fertility

XUE Dong, YAO Huaiying, HE Zhenli, HUANG Changyong

2005, 16(8):  1455-1458. 

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Correlation and cluster analyses on the enzyme activities and chemical-biological properties of eight red soils showed that soil urease,invertase,phosphatase and catalase activities correlated significantly with soil organic carbon,total nitrogen and total phosphorous.Similar results of soil fertility evaluation were obtained by using soil enzyme activities and by using soil chemical-biological properties,indicating that soil enzyme activity could be used as an index of evaluating red soil fertility.The enzyme activities of fresh soil were generally greater than those of air-dried sample,and more closely correlated with soil fertility.

Dynamics of water retaining capacity and chlorophyll content of two-line hybrid rice during heading-grain filling stage and their relations with grain yield

CHEN Xiaorong, ZHONG Lei, ZUO Qingfan

2005, 16(8):  1459-1464. 

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The study with 25 two-line hybrid rice strains showed that their water retaining capacity was different with their combinations.On the whole,the water content in leaf and stem-sheath decreased during heading-grain filling stage,while that in panicle increased first and then decreased,with a peak at 7th day after heading.Stem-sheath was the main organ for water retaining.The correlation of panicle yield with both leaf and stem-sheath water content was positive at the 1st day after heading but became negative later,and that with whole stem-plant water content was positive after heading.The chlorophyll content of the two-line hybrids increased first and then decreased,with a peak at the 7th day after heading.Comparing with normal rice (male parent),the chlorophyll content of most two-line hybrids was lower,and the decreasing rate was faster than that of normal rice after heading.For two-line hybrid rice breeding,it should preferentially consider to select those hybrids which have a clearer dominance of plant water retaining capacity and a higher chlorophyll content at earlier and middle heading-grain filling stage,and an obvious dry matter transportation from leaf and stem-sheath at later heading-grain filling stage.For two-line hybrid rice planting,it should not only pay attention to the supply of water and nutrients,especially nitrogen at earlier and middle heading-grain filling stage,but also control nitrogen and water in time to prevent leaf green clinging and to promote dry matter transportation from leaf and stem-sheath to grain at later heading-grain filling stage.

Effects of shading at blossoming and boll-forming stages on cotton fiber quality

WANG Qingcai, WANGZhenlin, SONG Xianliang, LI Yujing, GUO Ying, WANG Jian, SUN Xuezhen

2005, 16(8):  1465-1468. 

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The study on the effects of different shadinglevel at blossoming and boll-formingstages on cottonfiber quality ofZhongmiansuo No.41 and Lumianyan No.18 showed that withincreasing shading,the maxi mumfiber length ofcotton decreased,while the elongation period increased. The fiber length in 70 %shading treatment was 1.01mmshorter than that in 40 %shading treatment. Without shading,the fiber reached its maxi mumlength 25days after anthesis,while in shading treatments,the fiber reached its maxi mumlength 35 days after anthesis.Fiber gauge tenacity was also decreased with increasing shading. Comparing with the control,both 40 % and70 %shading significantly decreased the fiber maturation and maturity. Two test cotton varieties presented thesame change trend under shading condition.

Representativeness of Northeast China spring soybeans and their genetic diversity at SSR loci

LUAN Weijiang, LIU Zhangxiong, GUAN Rongxia, CHANG Ruzhen, HE Beiru, QIU Lijuan

2005, 16(8):  1469-1476. 

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A total of 283 accessions were selected from the total 3 226 Northeast China spring soybeans,which represented >80% of the whole based on their qualitative and quantitative traits.The representative samples were analyzed by 61 SSR loci,and a total of 534 alleles were detected,ranging 216 alleles per locus,with an average of 8.75 alleles per locus.Among the accessions,the Simpson diversity index (SDI) for each locus ranged from 0.406 to 0.886,with a mean of 0.704,which was relatively lower since there were dominant alleles at most of loci in the representative samples.35 accessions had specific alleles,which distributed among 29 loci.The differentiation coefficient was lower than 9.27% in 61 loci among the three provinces of Northeast China,which might be caused by lots of common alleles shared among these provinces.The genetic diversity in Jilin and Liaoning provinces was nearly equal,but was higher than that in Heilongjiang Province.The landraces of the representative samples at 61 loci had a higher genetic diversity than that of the released cultivars.The genetic diversity appeared within and between the provinces could be used to broaden the genetic base of modern cultivars,and also,the landraces were the major source for soybean breeding because of their high genetic diversity.

Physiological and ecological effects of inter-and mixed cropping rape with milk vetch

ZHOU Kejin, XING Jun, BO Yuhong, SANG Yasong, WU Shelan, SONG Guoliang

2005, 16(8):  1477-1481. 

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The investigation on the growth,yield and benefit of rape inter-and mixed cropped with milk vetch showed that comparing with sowing rape under zero tillage,the physiological and ecological characters of transplanted rape,including its height,leaf size,root diameter,opening degree and yield were obviously improved.Under zero tillage,mixed cropping had an obvious advantage than inter-and single cropping.After tillage,the yield of transplanted rape under mixed cropping was 11.9% more than that under single cropping with zero tillage.The benefit of transplanting rape under mixed cropping with tillage was the biggest,followed by single cropping rape with zero tillage.It could be concluded that the patterns of transplanting rape under mixed cropping after tillage and zero tillage had the best physiological and ecological effects,not only increasing rape yield and income,but also improving soil fertility.

Root activity and nitrogen assimilation of rice(Oryza sativa)under Free-Air CO₂ Enrichment

PANG Jing, ZHU Jianguo, XIE Zubin, LIU Gang, CHEN Gaiping, ZHANG Yali

2005, 16(8):  1482-1486. 

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With Free-Air CO₂ Enrichment(FACE)technique,this paper studied the root activity and amino acid(aa) synthesis of rice(Oryza sativa)at low N(LN,150 kgN·hm^-2)and normal N(NN,250 kgN·hm^-2)under ambient air and elevated atmospheric CO₂(Ambient+200 μmol·mol^-1).Under elevated CO₂,the xylem exudates per hill changed little,while the xylem exudates per stem declined by 1.4%～21.7% as the result of greater tiller numbers.At tillering and heading stages,elevated CO₂ increased aa N/inorganic N in xylem exudates by 11.1%～143.1%,but did not affect the aa concentration in xylem exudates and the total amount of aa in roots significantly.However,at 35 days after heading,the aa N/inorganic N ratio decreased by 38.1%(LN)and 29.2%(NN)under elevated CO₂.FACE also declined the aa concentration in xylem exudates by 34.0%(LN)and 44.7%(NN),and the total amount of aa by 50.8%(LN) and 40.0%(NN),which meant the retarded capability of aa synthesis in roots.N amendment led to a decrease of aa N/inorganic N in xylem exudates by 19.5%(Ambient) and 36.8%(FACE) at heading stage,as the result of unaffected aa and increased inorganic N concentration.There existed a significantly antagonistical CO₂N interaction on aa N/inorganic N at heading stage.

Effects of simulated acid rain and its acidified soil on soluble sugar and nitrogen contents of wheat seedlings

TONG Guanhe, LIANG Huiling

2005, 16(8):  1487-1492. 

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The study showed that the cation release of simulated rain caused soil acidification and base ions release.With the decrease of simulated acid rain pH from 5.6 to 2.5,the acid rain-leached soil pH decreased from 6.06 to 3.41,and its total amount of exchange base ions decreased from 56.5 to 41.1 mmol穔g^-1.Spraying simulated acid rain on the shoots of wheat seedlings planted on such acidified soils caused a rapid decrease in the soluble sugar and nitrogen contents of wheat seedlings,and reduced some of their physiological activities.The effect of spraying simulated acid rain on the soluble sugar,nitrogen,and chlorophyll contents and photosynthetic rate of wheat stems and leaves was larger than that of acidified soil,while the effect of the latter on the soluble sugar and nitrogen contents and the physiological activity of NR and GOGAT in root system of wheat seedlings was larger than that of the former.The intensive acid rain of pH3.0 and the corresponding acidified soil had an obvious harm to the growth and physiological activity of wheat seedlings.

Effects of fungicide on temporal and spatial niches of Rhizoctonia solani

WANG Ziying, TAN Genjia

2005, 16(8):  1493-1496. 

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This paper studied the variation of the temporal and spatial niches of rice sheath blight-causing Rhizoctonia solani under spraying fungicide.The results showed that between fungicide treatments and control,the spatial niche breadth of Rhizoctonia solani was different,while its temporal niche breadth was similar.The spatial niche breadth of Rhizoctonia solani was 0.5240 when spraying fungicide at booting and full heading stages,0.5742 at booting and milkfilling stages,and 0.8577 at tillering stage,while the control was 0.8563.Spraying fungicide had little effect on temporal niche breath.The spatial niche breath,percentage of diseased leaves and sheathes,index of disease,and control effect all suggested that spraying fungicide two times in rice growth period was better than spraying it one time.Spraying fungicide at booting and full heading stages and at booting stage and milkfilling stages had the best effects.Fungicide could not only narrow the spatial niche breadth,limit the spread of Rhizoctonia solani on top leaves which were important for the yield,but also narrow the temporal niche breadth,limit the spread of Rhizoctonia solani during the yield formation period of rice.But,spraying fungicide only changed the distribution of the fungus niches and narrowed the niches during rice yield formation period,with no changes in the whole niches of Rhizoctonia solani.

Effects of al穔ali-stress on Aneurolepidium chinense and Helianthus annuus

YAN Hong, ZHAO Wei, SHENG Yanmin, SHI Decheng, ZHOU Daowei

2005, 16(8):  1497-1501. 

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Employing monocotyledon Aneurolepidium chinense and dicotyledon Helianthus annuus,the two species with high alkali-saline resistance as test materials,and stressing them with neutral,alkalic,and mixed salts,this paper studied the characteristics of various stresses and their interrelations,with relative growth rate (RGR) as the main strain index.The results showed that under the same concentration,alkalic salt had a stronger effect than neutral salt,and the RGR of A.chinense and H.annuus was decreased with increasing salt concentration under the same kind of salt stress and pH conditions.When the pH was higher,the RGR decreased more obviously.In addition,the proline and citric acid contents in test plants were increased with increasing stress.The transformation of proline in A.chinense was greater than that in H.annuus,while that of citric acid was in adverse.In a word,alkalic salt stress was different from neutral salt stress in stressing plants and in plant responses.Alkalic salt stress and neutral salt stress were actually two distinct kinds of stresses.The former was better called "alkali-stress",while "salt-stress" only meant neutral salt stress.The key difference between them was their different pH value.It was reasonable to consider the buffer capacity as the strength value of alkali-stress,and the salinity as the strength value of salt-stress.An interactive effect between salt-stress and alkali-stress could be seen under mixed saline and alkali stress.

Effects of eutrophication on distribution and population density of Corbicula fluminea and Bellamya spin Chaohu Lake

DENG Daogui, LI Hongyuan, HU Wanming, ZHOU Qiong, GUO Longgen

2005, 16(8):  1502-1506. 

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The investigation on the distribution and population density of C.fluminea and Bellamya sp.in Chaohu Lake during September 2001 and September 2002 showed that in the west region of the lake where was seriously eutrophic,the density and biomass of C.fluminea were 5.1 ind.m^-2 and 17.87 g穖^-2 in 2001,and 8.8 ind.m^-2 and 47.29 g穖^-2 in 2002,while those of Bellamya sp.were 13.3 ind.m^-2 and 45.45 g穖^-2 in 2001,and 3.8 ind.m^-2 and 12.56 g穖^-2 in 2002,respectively.In the east region of the lake where was eutrophic,the density and biomass of C.fluminea were 23.8 ind.m^-2 and 67.86 g穖^-2 in 2001,and 29.2 ind.m^-2 and 96.18 g穖^-2 in 2002,while those of Bellamya sp.were 10.1 ind.m^-2 and 32.00 g穖^-2 in 2001,and 9.4 ind.m^-2 and 31.21 g穖^-2 in 2002,respectively.The density and biomass of C.fluminea and Bellamya sp.were declined with increasing eutrophication.In hypertrophic region,C.fluminea and Bellamya sp.were absent.The density and biomass of the two species were obviously higher in littoral than in pelagic region.The distribution type of C.fluminea was core-model,while that of Bellamya sp.was random.The correlation between the density and biomass of C.fluminea and Bellamya sp.and water depth was not significant(P>0.05).The biomass of Bellamya sp.was negatively correlated with water TN(P<0.01),NO₃-N(P<0.05),TP(P<0.01) and PO₄-P(P<0.05),while that of C.fluminea only had a significantly negative correlation with PO₄-P(P<0.05).Compared with 1981,there was fewer C.fluminea in the lake nowadays.The effects of other environmental factors on the population distribution and growth of C.fluminea and Bellamya sp.were also discussed.

Relationships between antioxidant activities and heat-resistant features of two Laminaria japonica strains

WANG You, TANG Xuexi

2005, 16(8):  1507-1512. 

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The study on the relationships between antioxidant activities and heat-resistant features of two Laminaria japonica gametophyte mutants Kelp 901(abbreviated as 901)and Rongcheng No.1(abbreviated as RC)under different temperature conditions showed that under normal temperature condition(10 ),there were no positive relationships between the basal antioxidant activities and heat-resistant features of 901 and RC,while under heat stress(18 ),the reactive oxygen species(ROS)contents kept constant in 901,but accumulated rapidly in RC,suggesting that ROS played an essential role in oxidative stress.The enzyme activities in RC were more vulnerable to high temperature,and its antioxidant enzyme activities decreased more sharply under heat stress.Ascorbic acid(ASA),vitamin E,superoxide dismutase(SOD)and glutathione peroxidase(Gpx)might play important roles in kelp's heat-resistance.Chlorophyll a was sensitive to heat stress,and its 50% nocuity time could be used as an indicator to distinguish kelp strains with different heat-resistance.It was suggested that the antioxidant system's responses to heat stress instead of its basic activities accounted for the kelp's heat-resistance.

Factor analysis of Beijing north ring water system eutrophication

ZENG Yong, YANG Zhifeng, LIU Jingling

2005, 16(8):  1513-1517. 

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Eutrophication is caused by hydrological,physical or chemical factors such as temperature,illumination,or shapes of waters.It is very important to identify the main factors to understand and control the process of eutrophication.In this paper,Beijing north circle water system was divided into river subsystem and lake subsystem by cluster analysis.Factor analysis indicated that the main factors of river subsystem eutrophication were TP,TN and NH₄-N,while those for lake subsystem were TN and NH₄-N,which meant that in the study area,the main cause for eutrophication was the overload of nutrients.Stepwise regression was introduced to build forecasting model,and the choice results of independent variables in the regression model inferred that the type of eutrophication in river subsystem was P limited,while that of lake was N limited.Two main causes for nutrient load were found from water quantity and quality analysis of the study area,one was the ecological water demands be not able to satisfy from 1990 to 1998 except 1998,and the other was the increase of nutrient load coming from domestic waste and non-point pollutant,resulting from the rapid population increase and city expansion.The measures to control the eutrophication process were put forward.

Effects of atrazine and its degrader Exiguobaterium spBTAH1 on soil microbial community

HU Jiang, DAI Xianzhu, LI Shunpeng

2005, 16(8):  1518-1522. 

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The study showed that the application of atrazine stimulated soil microorganisms obviously.In comparing with control(without atrazine),the respiration intensity of soil applied with 50 mg atrazine穔g^-1soil increased greatly,the concentrations of soil NH₄⁺-N and NO₃^--N changed significantly,and the individuals of soil microbes,especially bacteria and fungi,also increased greatly.The application of strain BTAH1 could degrade 98% of applied atrazine within one week,and led to the decrease of soil respiration intensity.Under BTAH1 application,the individuals of actinomyces and fungi decreased,while those of bacteria did not,and the concentrations of soil NH₄⁺-N and NO₃^--N came back to the level of the control.ARDRA analysis on the 16s rDNA library of soil bacteria suggested that the application of atrazine could decrease the biodiversity of soil microorganisms,while applying BTAH1 could recover the biodiversity.

Effects of Bt toxin Cry1Ac on biochemical responses of Eisenia fetida in an artificial soil

XIAO Nengwen, GE Feng, LIU Xianghui

2005, 16(8):  1523-1526. 

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Bt toxin Cry1Ac could be introduced into soil by pollen,root exudates,and plant residues.To investigate its toxic effects,the Bt toxin was added into an earthworm-cultured artificial soil,and the survival,growth rate,sperm count,protein content,and activities of acetylcholinesterase (AchE),catalase (CAT),glutathione-S-transferase (GST) and cellulase in Eisenia fetida were determined.The results suggested that Bt toxin Cry1Ac had little effects on the biomass and physiological characteristics of E.fetida,with no acute and subchronic toxicity,and was safe for earthworm at field dose level.

Acute toxicological effects of excessive Cu and Zn-containing in pig manure on earthworm

JIA Xiuying, LUO Ancheng, LI Ximei

2005, 16(8):  1527-1530. 

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Cu and Zn are popularly used as additives in animal feed in China,which could result in their excessive accumulation in manure to a toxic level,and thus,possibly threaten the environment when the manure is applied to farmland.In this paper,the acute and sub-acute lethal effects of pig manure with excessive Cu and Zn on earthworm were studied,and the results indicated that the concentration of Cu and Zn in pig manure had a significantly positive correlation with the mortality of earthworm,while a significantly negative correlation with earthworm growth rate.The individuals of earthworm had different tolerance to excessive Cu and Zn,with the threshold values causing death being 250 mg穔g^-1 and 400 mg穔g^-1for Cu and Zn,respectively.The LD₅₀ was 646.68 mg穔g^-1 for Cu,and 947.38 mg穔g^-1 for Zn.A strong synergistic effect was observed under the combined pollution of 250 mg穔g^-1 for Cu and 500 mg穔g^-1 for Zn,whereas antagonistic effect happened when 750 mg穔g^-1 for Cu was supplied,suggesting that the joint toxic effects of Cu and Zn on earthworm were closely correlated to their concentrations in pig manure.

Forest ecosystem service and its evaluation in China

JIN Fang, LU Shaowei, YU Xinxiao, RAO Liangyi, NIU Jianzhi, XIE Yuanyuan, ZHAG Zhenming

2005, 16(8):  1531-1536. 

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Facing the relative lag of forest ecosystem service and estimation in China,this paper proposed to quickly carry out the research on the evaluation of forest ecosystem service.On the basis of the classification of forest ecosystem types in China,the service of artificial and semi-artificial forest ecosystems was investigated,which was divided into eight types,i.e.,timber and other products,recreation and eco-tourism,water storage,C fixation and O₂ release,nutrient cycling,air quality purifying,erosion control,and habitat provision.According to the assessment index system for global ecosystem service proposed by Costanza et al.,a series of assessment index system suitable for Chinese forest ecosystem service was set up,by which,the total value of forest ecosystem service in China was estimated to be 30 601.2010⁸ yuan穣r^-1,including direct and indirect economic value about 1 920.2310⁸ and 28 680.9710⁸ yuan穣r^-1,respectively.The indirect value was as 14.94 times as the direct one.The research aimed to bring natural resources and environment factors into the account system of national economy quickly,and to realize the green GDP at last,which would be helpful to realize sustainable development and environment protection.

Discussion on hydrologic scaling

ZHONG Ye, JIN Changjie, PEI Tiefan

2005, 16(8):  1537-1540. 

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Hydrologic scaling is the hotspot and frontier of today's hydrologic research,which includes three different meanings distinguished from each other,i.e.,process scale,observation scale and modelling scale.As a characteristic of hydrologic scale,dominant process scale has been paid more attention.Hydrologic scaling includes the scaling of hydrologic models,parameters,state variables and inputs,which owns special research methods respectively.The difficulty of hydrologic scaling mainly comes from the organized complexity of hydrologic systems,the heterogeneity and variability in space and time,and the insufficiency of data.The ubiquitous self-similarity of natural river networks makes itself an important part of hydrologic scaling research.The combination of various techniques and theories is needed to motivate hydrologic scaling research.

Nematodes as bioindicator of soil health:methods and applications

LI Yujuan, WU Jihua, CHEN Huili, CHEN Jiakuan

2005, 16(8):  1541-1546. 

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This paper summarized the advantages of using nematodes as soil health bioindicator.A review of commonly used indices and analyzing methods by means of nematodes was presented,with emphases on Maturity Index,as well as the indices and analyzing methods based on their trophic groups.Compared with other indices,Maturity Index can reflect the stressed degree of soil more sensitively,and the indices and analyzing methods based on their trophic groups can well reveal the state of soil health based on ecosystem functioning.The applications of nematodes as bioindicator in agriculture,forest,grassland,and other ecosystems were also outlined.In view of some practical limitations in the methods,prospective researches and applications were suggested,i.e.,intensify the ecological studies to advance the understanding on the characteristics of soil nematodes,such as their life histories and feeding habits,consummate the indication system by integrating various nematode indices and analyzing methods,and extend the applications of soil nematodes in different ecosystems and in different regions at large scales.

Affecting factors of soil microorganism and root respiration

JIA Bingrui, ZHOU Guangsheng, WANG Fengyu, WANG Yuhui

2005, 16(8):  1547-1552. 

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Soil respiration is an important part of the carbon cycle in terrestrial ecosystems,and its contribution to the global carbon budget has been the focus of wide concern.Researches on the affecting factors of soil microorganism and root respiration,the main components of soil respiration,contribute to the understanding of the role of soil respiration on global carbon cycle,and to the accurate evaluation of global carbon budget.This paper reviewed the direct and indirect affecting factors of soil microorganism and root respiration,including climate factors,soil properties,vegetation and litterfall,air CO₂ concentration,and human activities.These affecting factors were interactive,and their contributions to soil microorganism and root respiration varied in temporal and spatial scales.The study on natural and anthropogenic factors of soil microorganism and root respiration was emphasized,and some related research tasks in the future were also proposed.

Research advances on eco-chemical behaviors and toxicological effects of cadmium in root-soil interface

JIN Caixia, ZHOU Qixing, SUN Ruilian, REN Liping

2005, 16(8):  1553-1557. 

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Many active substances such as organic acids and enzymes excreted by living plant roots could induce a great difference of Eh and pH values between root-soil interface and non-rhizosphere soil,forming a special root-soil interface miniature environment.As a mini-type ecological area with most frequent exchanges of substances,root-soil interface plays a crucial role in their absorption,transformation,migration and eco-toxicological effects.In this paper,the eco-chemical behaviors of Cd in root-soil interface affected by the change of pH,Eh and root secretion,and its eco-toxicological effects on microorganisms and enzymes in root-soil interface were reviewed,based on the related research advances in recent decade.The shortages in relevant fields were pointed out,and the scientific problems to be researched in the future were suggested.

Advances in research and application of water-treatment flocculants

LIU Rui, ZHOU Qixing, ZHANG Lanying, WANG Bing, SUN Piwu

2005, 16(8):  1558-1562. 

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Water-treatment flocculants are being developed from traditional to inorganic,from inorganic to organic,from natural organic to synthetic organic,from synthetic organic to modified natural organic,from inorganic or organic to inorganic-organic,and from chemical to biological with ecological safety.In order to promote the rapid development and practical application of water-treatment flocculants,the research progress and application situation of flocculants for water treatment at home and abroad were reviewed.In particular,the characteristics of two important flocculant types,chemical and microbiological flocculants,as well as their application processes in water treatment were summarized,their development orientations were analyzed and evaluated,and the future research directions aimed to overcome the current shortages in developing and applying flocculants in China were put forward.

Recycling rate of N and P through a feeding-composting cycle and their recoveries in agro-ecosystems

YU Wantai, GUAN Yan, LI Jiandong, ZHANG Lu, MA Qiang

2005, 16(8):  1563-1565. 

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A five-year experiment indicated that the average loss rate of N and P in harvested products through a feeding-composting cycle was about 50% and 15%,respectively.Under high yield condition,the amount of recycled N and P from 80% harvested products and through a feeding-composting cycle in farming systems was about 37～51 and 8～14 kg·hm^-2,equivalent to 25%～34% of N and 32%～56% of P from chemical fertilizers applied each year to the systems.The apparent recoveries of N and P in organic manure increased with the prolongation of fertilization,indicating a synergetic residual effect existed,and was 61% and 39% in average in the five-year experiment.The use of nutrients recycled in the farming systems could not only improve soil fertility,but also increase the recoveries of nutrients and reduce the use of chemical fertilizers.

Biodegradation of di-n-butyl phthalate by mangrove microorganism Rhodococcus ruber 1K

LI Kuixiao, GU Jidong

2005, 16(8):  1566-1568. 

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A di-n-butyl phthalate (DBP)degrading bacterium Rhodococcus ruber was isolated from mangrove soil,and its degrading characteristics were studied.The results showed that the bacterium could grow well on the substrate with DBP as the sole source of carbon and energy,and the DBP of 50 mg稬^-1 could be completely degraded after 48 h.Under aerobic condition,the tentative pathway proposed for DBP degradation was through monoester initially,then phthalic acid,and finally CO₂ and H₂O.

Characteristics of Yunnan Province rice landrace core collections under phosphorus deficiency

SHEN Shiquan, ZENG Yawen, PU Xiaoying, DU Juan, LI Shenchong

2005, 16(8):  1569-1572. 

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Soil phosphorus (P) deficiency is a major yield-limiting factor in rice production.Employing 526 rice landrace accessions from 5 rice-planting regions and 16 prefectures in Yunnan Province,this paper studied their P-deficiency tolerance characteristics by comparing the relative plant dry weight under acid red soil condition.The results showed that Northwest Yunnan cold highland japonica rice-planting region was most abundant in P-deficiency tolerance core collection of indica,and there was no significant difference in japonica among five ecological zones of rice landraces.Nujiang,Lijiang,Dehong,Wenshan,Xishuangbana and Yuxi were most abundant in P-deficiency tolerance core collection of indica,and Lijiang,Wenshan and Chuxiong were most abundant in P-deficiency tolerance core collection of japonica.Indica had a higher P-deficiency tolerance than japonica.The P-deficiency tolerance of rice was significantly related with its genetic diversity,rice breeding and acid red soils.

Extraction of active substance from Chlorella vulgaris cells and its physiological effects on Saccharomyces cerevisiae

HU Kaihui, ZHOU Shanyong

2005, 16(8):  1573-1576. 

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The study showed that freezing-thawing method could have a higher cellwall breakage rate,and a light injury to the active substance,which could not only increase the cell fission and growth,delay the death of Saccharomycete cells,but also enhance CO₂ production rate and quicken fermentation process when the cells were exposed to the medium with 0.5% active substance.

Application effect of most probable number(MPN)method in photosynthetic bacteria counting

CUI Zhanli, WANG Pingping, WANG Qiuju

2005, 16(8):  1577-1580. 

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The application of most probable number(MPN)method in counting the numbers of photosynthetic bacteria(PSB)showed that this method was suitable for PSB counting under illumination and anaerobic condition,which remedied the shortages of other methods.With this method,the sensitivity and accuracy of the counting could be enhanced when more replicated tubes and lower dilution times for fewer bacteria samples were applied.When PSB were not dominant in soil and water,MPN method could be used instead of other methods.PSB agent could only survive 69 days,and not be dominant in the environment in a long term.Its application time and oxygen level affect the numbers of PSB significantly,which were the largest in a short application time and under anaerobic condition.