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    20 April 2009, Volume 20 Issue 04
    Provenance difference in stable carbon isotope discrimination of Schima superba.
    LIN Lei1;ZHOU Zhi-chun1;FAN Hui-hua2;JIN Guo-qing1;CHEN Yi-liang3;HONG Gui-mu4
    2009, 20(04):  741-746 . 
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    The difference in leaf stable carbon isotope discrimination (Δ) of 18 representative Schima superba provenances was investigated based on three p rove nance trails located at Jian’ou of Fujian Province and Chun’an and Qingyuan of Zhejiang Province, and the geographic variation pattern and the effects of trial site and provenances growth rate were studied. Significant differences in leaf Δ were observed among the provenaces, and the differences in leaf Δ value betw een the highest and lowest provenances reached 69%, 30%, and 37% in 3 exper imental sites, respectively. A classic latitudinal clinal variation pattern was found, because there were significant correlations between the leaf Δ value and the latitude of seed sources in all the 3 sites while no significant correlatio ns were observed between the leaf Δ value and the longitude of the seed sources . The southern provenances showed higher leaf Δ value than the northern provena nces, indicating that the water use efficiency (WUE) was lower in southern prove nances. The leaf Δ value of different provenances was demonstrated to be greatl y affected by the environment of trial sites. The leaf Δ value increased signif icantly with the improvement of site environment and with the increase of annual rainfall. Significant positive correlations were observed between the leaf Δ v alue and the growth traits including tree height, DBH, total number of lateral b ranches, and length of the strongest lateral branch, which indicated that the pr ovenances with higher growth rate and denser crown had larger leaf Δ value. Two and four superior provenances with high growth rate and low leaf Δ value (or h igh WUE) were selected for Jian’ou of Fujian and Chun’an of Zhejiang, respecti vely.
    Effects of fertilization on nutrient concentrations of different root orders’ fine roots in Larix kaempferi plantation.
    YU Li-zhong1;DING Guo-quan2;ZHU Jiao-jun1;ZHANG Na1;ZHANG Xiao-peng1;YING Hui1
    2009, 20(04):  747-753 . 
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    With the 16 years old Larix kaempferi plantation in eastern mountain area of Liaoning Province, China as test object, this paper studied the effects of fertilization on the nutrient concentrations of five root orders’ fine roots. Under fertilization, less difference was observed in the total C concentration of the fine roots. Among the five orders’ fine roots, the first order’s had the lowest concentration of non-structural carbohydrate (TNC) and the highest ones of N and P, while the fifth order’s was in adverse. The TNC concentration increased with increasing root order, while the N and P concentrations decreased correspondingly. Fertilization only had significant effects on the N and P concentrations of the first order’s fine roots. The C/N/P ratio in different orders’ fine roots had significant differences, being 423∶〖KG-*2〗16∶〖KG-*2〗1 and 726∶〖KG-*2〗16∶〖KG-*2〗1 in the first and the fifth order’s fine roots, respectively. With the increase of root order, the proportion of C increased significantly, while that of N varied little. N fertilization didn’t change the proportion of C, while P or P+N fertilization decreased the proportions of C and N in the first three orders’ fine roots at 0〖KG-*2〗-〖KG-*7〗10 cm soil depth or in the first two orders’ fine roots at 10〖KG-*2〗-〖KG-*7〗20 cm soil depth.
    Effects of phosphorus stress on the growth and nitrogen and phosphorus absorption of different Formosan sweet gum provenances.
    LENG Hua-ni1,2;CHEN Yi-tai1;DUAN Hong-ping2;RAO Long-bing1;WANG Yong-jun3;HU Yun-xue4
    2009, 20(04):  754-760 . 
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    Aiming at the ecological value of Formosan sweet gum (Liquidambar formosana) as a pioneer species and the status of red soil phosphorus (P) deficiency, a sand culture experiment of split design was conducted to study the responses of three-leaf stage seedlings of seven Formosan sweet gum provenances from Yixing of Jiangsu, Jingxian of Anhui, Yongkang of Zhejiang, Nanchang of Jiangxi, Shaowu of Fujian, Yanping of Fujian, and Nandan of Guangxi to four levels of P (P0, P1/2, P1, P2). With increasing P stress, the biomass and the N and P absorption of test provenances decreased, whereas the utilization efficiency increased. In higher P treatments, the provenances from Nanchang and Yixing had higher biomass and higher N and P absorption but lower utilization efficiency, while the provenance from Nandan had lower N and P absorption but higher utilization efficiency. In lower P treatments, the biomass and the P absorption and utilization efficiency of the provenances from Nanchang and Nandan were all higher. All the results illustrated that the provenances with high biomass had high P absorption at high P level, and had both high P absorption and high utilization efficiency at low P level. The provenance from Nanchang could be considered to be an excellent P stress-resistant provenance, followed by that from Nandan. Phosphorus was not a limiting nutritional factor of Formosan sweet gum, biomass, leaf Δ(N/P) ratio and P efficiency could be used as the indicators of P stress-tolerance of Formosan sweet gum provenances.
    Responses of mulberry seedlings photosynthesis and antioxidant enzymes to chilling stress after low-temperature acclimation.
    XU Nan;SUN Guang-yu
    2009, 20(04):  761-766 . 
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    Taking the seedlings of mulberry (Morus alba) variety ‘Qiuyu’ as test materials, this paper studied the changes of their leaf photosynthesis and antioxidant enzymes during low-temperature acclimation, chilling stress, and normal temperature recovery. The results showed that low-temperature acclimation at 12 ℃ for 3 days markedly increased the cold resistance of mulberry seedlings. After the acclimation, the leaf net photosynthetic rate (Pn), stomatal conductance (Gs), and maximum photochemical efficiency of photosystem II (Fv/Fm) under the chilling stress at 3 ℃ for 3 days increased obviously and recovered rapidly, compared with the control non-acclimation. During the period of the low-temperature acclimation and chilling stress, the leaf proline and soluble sugar contents increased. After the acclimation, the leaf malondialdehyde (MDA) content was obviously lower while the leaf ascorbate peroxidase (APX) activity was obviously higher than the control, illustrating that the increase of osmolytes content and APX activity played important roles in the cold resistance of mulberry seedlings.
    Absorption and allocation characteristics of K+, Ca2+, Na+ and Cl-in different organs of Broussonetia papyrifera seedlings under NaCl stress.
    YANG Fan;DING Fei;DU Tian-zhen
    2009, 20(04):  767-772 . 
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    One-year-old Broussonetia papyrifera seedlings were subjected to 04, 1, 2, 3, and 4 g·kg-1 of soil NaCl stress, and their biomass accumulation, leaf plasma membrane permeability, and the absorption, allocation and translocation of K+, Ca2+, Na+, and Cl-, as well as the symptoms of salt injury, were studied and investigated. The leaf plasma membrane permeability increased with the increase of soil NaCl concentration and of the duration of soil NaCl stress, and the seedling’s root/shoot ratio also increased with increasing soil NaCl concentration. When the soil NaCl concentration exceeded 3 g·kg-1, leaf plasma membrane permeability and seedling’s biomass accumulation were affected significantly. The Na+ and Cl- concentrations in different organs of seedlings increased with increasing soil NaCl concentration while the K+ and Ca2+ concentrations were in adverse, and the ion contents in leaves were always much higher than those in other organs, illustrating that soil NaCl stress affected the K+ and Ca2+ absorbing capability of roots, and inhibited the selective translocation of K+ and Ca2+ to aboveground parts. As a result, the K+ and Ca2+ concentrations in leaves and stems decreased. The study showed that B. papyrifera could effectively resist the injury of osmotic stress from soil salt via absorbing and accumulating Na+ and Cl-, but excessive accumulation of Na+ and Cl- could induce salt toxicity. As a non-halophyte species with relatively strong salt resistance, the aboveground parts of B. papyrifera did not have significant salt-exclusion effect.
    Coarse woody debris loading capacity and its environmental gradient in Huzhong forest area of Great Xing’an Mountains.
    WANG Wen-juan1,2;CHANG Yu1;LIU Zhi-hua1,2;CHEN Hong-wei1,2;JING Guo-zhi3;ZHANG Hong-xin3;WANG Jin-hai4
    2009, 20(04):  773-778 . 
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    The coarse woody debris (CWD) loading capacity of main forest types and of different larch forest communities in Huzhong area of Great Xing’〖KG-*4〗an Mountains was investigated, with its environmental gradient analyzed by Detrended Canonical Correspondence Analysis (DCCA). The CWD loading capacity varied significantly with forest type, being the highest (020 m3·hm-2) in spruce forest (Picea koraiensis). Different larch forest (Larix gmelinii) communities had a CWD loading capacity from 0 to 028 m3·hm-2, with the highest in Pinus pumila-Larix gmelinii (028 m3·hm-2) and the lowest in Sphagnum magellanicum-Ledum palustre-Larix gmelinii (0), but the differences were not significant. The CWD loading capacity across the study area was complicated, which might result from the complex interplay of affecting factors. The main factors affecting the spatial pattern of the CWD loading capacity were topographic factors (elevation and slope position) and stand structure (age, canopy cover, and others), and the interaction between topographic factors and stand structure expressed the spatial gradient of CWD loading capacity in Huzhong area of Great Xing’an Mountains.
    Growth analysis on modules of Cynodon dactylon clones in Yili River Valley Plain of Xinjiang.
    ZHAO Yu1,2;Janar2;LI Hai-yan1;LIU Ying2;YANG Yun-fei1
    2009, 20(04):  779-784 . 
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    By the method of randomly digging up whole ramet tuft while maintaini ng natural integrity, large samples of Cynodon dactylon clones were collecte d from a grape orchard abandoned for 2 years without any management in the Yili River Valley Plain of Xinjiang, aimed to quantitatively analyze the growth patte rns of their modules. The results showed that the average ramet number of test 3 0 clones reached 2726±1866, among which, vegetative ramets occupied 823%, being 43 times higher than reproductive ones. The total biomass of the clones was 454±400 g, in which, rhizomes accounted for 544%, while the vegetati ve ramets, stolons, and reproductive ramets occupied 210%, 148%, and 94% o f the total, respectively. The accumulative length of rhizomes and stolons reached 51±47 m and 33±34 m, while the bud number on stolons and rhizomes was 2915±2468 and 788±874, respectively. The bud number on stolons and rhizomes was positively correlated to the quantitative characters of vegetative rame ts, reproductive ramets, stolons, and rhizomes (P<001), indicating that in Yili River Valley Plain, C. dactylon clone could achieve and maintain its c ontinuous renovation via rhizome buds.
    Impact of climate warming on phenophase of Populus tomentosa in Inner Mongolia.
    WU Rui-fen1;SHEN Jian-guo2;YAN Wei-xiong1;ZHANG Hua1
    2009, 20(04):  785-790 . 
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    Based on the 1982〖KG-*2〗-〖KG-*7〗2006 data of air temperature and of the phen ophase of Populus tomentosa in spring and autumn from 17 phenological observ ation stations in Inner Mongolia, the change trend of the phenophase of P. tom entosa in spring and autumn was studied, and its relations to climate warming were analyzed. The models for predicting the date change of P. tomentosa fir st flowering and defoliating were constructed by stepwise regression method. It was shown that from 1982 to 2006, the air temperature in study area was increase d, and the date of first flowering and defoliating of P. tomentosa was advan ced and postponed, respectively. The first flowering of P. tomentosa was neg atively related to the air temperature in spring and winter, and the main affect ing factor was the air temperature from March to April; while the first defoliat ing of P. tomentosa was positively related to the air temperature in autumn, and the main affecting factor was the air temperature from August to October. A ccording to the national assessment report on climate change, the air temperatur e in Inner Mongolia in spring and autumn would be raised by 15 ℃〖KG-*2〗-〖KG-* 7〗54 ℃ and 12 ℃〖KG-*2〗-〖KG-*7〗44 ℃, and the first flowering and de foliating of P. tomentosa would advance 39〖KG-*2〗-〖KG-*7〗178 days and po stpone 30〖KG-*2〗-〖KG-*7〗124 days, respectively.
    Effects of NaCl stress on Hippophae rhamnoides and Shepherdia argentea seedlings growth and photosynthetic characteristics.
    QIN Jing1;HE Kang-ning1;TAN Guo-dong1;WANG Zhan-lin2;CHEN Jing1
    2009, 20(04):  791-797 . 
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    With two-year old seedlings of Hippophea rhamnoides and Shepherdia argentea as test materials, this paper studied their growth and photosynthetic characteristics under the stress of different concentration (0, 200, 400 and 600 mmol·L-1) NaCl. The results showed that the biomass and total leaf area per plant of H. rhamnoides and S. argentea seedlings decreased significantly with increasing NaCl concentration. Comparing with the control, the root/shoot ratio of H. rhamnoides and S. argentea seedlings under NaCl stress increased obviously, while the leaf mass per area (LMA) decreased slightly. When the NaCl concentration increased and the stress time prolonged, the net photosynthetic rate (Pn), transpiration rate (Tr), and stomatal conductance (Gs) of H. rhamnoides and S. argentea seedlings declined markedly, the intercellular CO2 concentration (Ci) increased after an initial decrease, whereas the water use efficiency (WUE) and stomatal limiting value (Ls) decreased after an initial increase. The dynamic changes of Gs, Ci and Ls indicated that the decline of Pn was mainly caused by the stomatal limitation in a short-term stress, and by non-stomatal limitation in a long-term stress. The poorer the salt tolerance of tree species and the higher the NaCl concentration, the earlier the transition from stomatal limitation to non-stomatal limitation would occur. As for H. rhamnoides, its morphological symptoms of salt injury appeared on the 10th day, and all of its seedlings were died on the 22th day under 600 mmol NaCl·L-1 stress. In contrast, S. argentea could tolerate 600 mmol NaCl·L-1 stress for above 30 days, illustrating that S. argentea, as an introduced tree species, had higher salt tolerance than H. rhamnoides, and could be planted widely in saline regions of China.
    Recovery effect of tomato leaves photosynthesis and chloroplast ultrastructure after a short-term low nocturnal temperature.
    LI Guo-qiang2;LI Tian-lai1;LIU Ai-qun2
    2009, 20(04):  798-804 . 
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    Tomato seedlings were treated with 15 ℃ (control), 12 ℃, 9 ℃, and 6 ℃ at night for seven days to study the changes of their leaf photosynthesis an d chloroplast ultrastructure, aimed to make sure the recovery effect of the phot osynthesis of tomato leaves after a short-term low nocturnal temperature. The r esults showed that short-term low nocturnal temperature was favorable to the ph otosynthesis of tomato leaves at recovery stage. The chlorophyll content could r ecover to the normal level as control under the treatments of 12 ℃ and 9 ℃, bu t not under the treatment of 6 ℃. The formation of stoma was not seriously inhi bited by low nocturnal temperature. On the contrary, the stoma formation and its growth were stimulated at recovery stage. Under the treatment of 6 ℃, chloropl ast grana layers arranged loosely, and their number reduced. In the seven days o f recovery, the lower the treatment temperature, the smaller and the fewer the s tarch grains were, and the more compact and tidy the chloroplast grana became. I n addition, the transportation of photosynthesis products was promoted after sho rt-term low nocturnal temperature.
    Effects of shading on wheat grain starch quality and redistribution of pre-anthesis stored nonstructural carbohydrates.
    MU Hui-rong1,2;JIANG Dong1,2;DAI Ting-bo1,2;ZHANG Chuan-hui1,2;JING Qi1,2;CAO Wei-xing1,2
    2009, 20(04):  805-810 . 
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    This paper studied the effects of shading in the period from jointing to maturit y on the grain yield, starch content, and starch paste traits of two winter whea t (Triticum aestivum L.) cultivars, shading-tolerant Yangmai 158 and s hading-intolerant Yangmai 11, and analyzed the relationships of the redistribu tion of total soluble sugars stored before anthesis in vegetative organs with th e grain yield, starch content, and starch paste parameters of the cultivars. The results showed that shading decreased the redistribution of pre-anthesis store d total soluble sugars in vegetative organs to reproductive organ, resulting in the decrease of grain yield, and significantly decreased the amylopectin content but had no effects on the amylose content in grains, inducing a significant dec rease in the ratio of amylopectin to amylase content in the grains. Shading also decreased the grain starch peak viscosity of the cultivars. Under shading, Yang mai 11 had a decrease of its grain starch through viscosity and an increase of s tarch pasting temperature, while Yangmai 158 had lesser responses in the two par ameters.
    Interactive effects of drought and salt stresses on winter wheat seedlings growth and physiological characteristics of stress-resistance.
    CHEN Cheng-sheng;XIE Zhi-xia;LIU Xiao-jing
    2009, 20(04):  811-816 . 
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    In a hydroponic culture, different concentrations of PEG-6000 (0, 83%, and 12 6%, W/V) and NaCl (0, 25, and 50 mmol·L-1) were added to simulate diffe rent degrees of drought and salt stresses, aimed to study their interactive effe cts on the winter wheat (cv. Cang-6001) seedlings growth and physiological cha racteristics of stress-resistance. The results showed that under the conditions of adding 83% and 126% of PEG-6000, the addition of 25 mmol NaCl ·L -1 increased the dry matter accumulation and water content in plant, the c ontents of soluble sugar and soluble protein in leaf and the Na+ content in sh oot and root, while decreased the MDA and proline contents in leaf and the K+ content in shoot and root, compared with no NaCl addition. Adding 126% of PEG-6000 and 50 mmol ·L-1 of NaCl more inhibited plant growth, compared with no NaCl added. It was suggested that under drought stress, applying definite amount of salt could alleviate the deleterious effects of drought stress on winter wheat seedlings growth.
    Effects of returning straw to soil and different tillage methods on paddy field soil fertility and microbial population.
    REN Wan-jun1;LIU Dai-yin1,2;WU Jin-xiu1;WU Ju-xian1;CHEN De-chun1;YANG Wen-yu1
    2009, 20(04):  817-822 . 
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    A field experiment was conducted on a paddy field to study the effects of returning straw to soil and different tillage methods (no-tillage + returning straw, no-tillage, tillage + returning straw, and tillage) on the fertility level and microbial quantities of different soil layers. The results showed that in upper soil layer, the organic matter content in treatment ‘no-tillage + returning straw’ was 533, 279, and 537 g·kg-1 higher than that in treatments ‘no-tillage’, ‘tillage+returning straw’, and ‘tillage’, respectively, and the contents of total and available N, P and K in treatment ‘no-tillage+returning straw’ were also the highest, followed by in treatments ‘no-tillage’ and ‘tillage+returning straw’, and in treatment ‘tillage’. In deeper soil layer, all the fertility indices were higher in treatment ‘tillage+returning straw’. Treatments of ‘returning straw to soil’ had the highest quantities of soil microbes. The quantities of bacteria, fungi, and actinomycetes in upper soil layer were the highest in treatment ‘no-tillage + returning straw’, and thus, the cellulose decomposition intensity in this treatment at maturity period was 2644%, 7901%, and 9815% higher than that in treatments ‘tillage+returning straw’, ‘no-tillage’, and ‘tillage’, respectively. In deeper soil layer, the quantities of bacteria, fungi, and actinomycetes were the highest in treatment ‘tillage+returning straw’. Treatment ‘no-tillage+returning straw’ had the features of high fertility and abundant microbes in surface soil layer. The quantities of soil bacteria and actinomycetes and the decomposition intensity of soil cellulose were significantly positively correlated with soil fertility level.
    Effects of palygorskite application on volatilization and leaching losses of urea nitrogen in loess soil.
    LIU Xue-zhou;LIN Hai-ming;WANG Di;ZHANG Jing-zhen;ZHAO Ya-li;ZHAO Deng-xing
    2009, 20(04):  823-828 . 
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    By the methods of adsorption and soil column leaching, a laboratory simulation test was conducted to study the effects of palygorskite application on the volatilization and leaching losses of urea nitrogen in loess soil. Comparing with applying urea fertilizer alone, the addition of palygorskite could decrease the volatilization rate of soil urea N at peak time, with the ammonia volatilization loss decreased by 136%〖KG-*2〗-〖KG-*7〗150%. When the palygorskite application rate was 03 and 06 g·kg-1, the leaching rate of soil NH4+-N and NO3--N decreased, with the leaching loss of soil mineral N decreased by 137% and 136%, respectively. Applying 09 g·kg-1 of palygorskite application increased the leaching rate of soil NH4+-N and NO3--N, with the leaching loss of soil mineral N increased by 61%. Applying 03 g·kg-1 of palygorskite increased soil NH4+-N content by 020 mg·kg-1, while applying 09 g·kg-1 of palygorskite decreased soil NH4+-N content by 042 mg·kg-1. Palygorskite application increased soil NO3--N content by 124〖KG-*2〗-〖KG-*7〗252 mg·kg-1. It was concluded that the application of palygorskite could decrease the volatilization rate of urea N, and applying appropriate amounts of palygorskite could decrease the leaching loss of soil mineral N and increase the contents of soil NH4+-N and NO3--N.
    Changes of soil biological characters beneath greenhouse cucumber under different cultivation systems.
    ZHANG Xue-yan;TIAN Yong-qiang;LIU Jun;GAO Li-hong
    2009, 20(04):  829-835 . 
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    A 3-year pot experiment with 8-year continuously cropped greenhouse cucumber soil was conducted to study the effects of different cultivation systems on the soil quality, soil nematode quantity, and crop yields. The third year’s data were taken into analysis. Comparing with traditional cultivation system (two seasons planting cucumber with fallowing in summer), planting leafy vegetable and garlic in summer increased the yields of the two crops and the soil microbial biomass carbon content, total microbial population, and sucrase activity, decreased the amounts of soil nematode and root-knot nematode, and maintained a relative high Shannon-Weaver index. Planting crown daisy, garlic, and spinach in summer increased soil sucrase activity by 89%, 895%, and 369%, and the planting of crown daisy and garlic also increased the Shannon-Weaver index by 77% and 94%, respectively. All the results suggested that catching crop and rotation had definite restoration effects on the soil quality under continuously cropping of cucumber, and the effects of planting crown daisy and garlic were more significant.
    Antifeedant and antioviposition activities of Momordica charantia leaf ethanol extract against Liriomyza sativae.
    LING Bing1;XIANG Ya-lin1,2;WANG Guo-cai3;CHEN Shao-hua 1;ZHANG Mao-xin1
    2009, 20(04):  836-842 . 
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    Liriomyza sativae Blanchard (Diptera: Agromyzidae) is one of the important pests harming a wide variety of vegetables and ornamental plants throughout the world. The leaf ethanol extract of Momordica charantia at the concentration of 2000〖KG-*2〗-〖KG-*7〗4000 μg·ml-1 displayed significant antifeedant and antioviposition activities against L. sativae adults. For further purifying the extract, four solvents, i.e., cyclohexane, ethyl acetate, n-butanol and water, were used to extract the ethanol extract, and the antifeedant and antioviposition activities of the extracts against L. sativae adults were te sted. The results showed that after treated with the extracts at the concentration of 1000 μg·ml-1 for 2 days, the antifeedant index (AFI) of cyclohexane-, ethyl acetate-, n-butanol- and water extracts against L. sativae adults was 1108%, 3489%, 2299% and 0, and the antioviposition index (AOI ) was 0, 3091%, 645% and 0, respectively. Ethyl acetate extract had the highest bioactivity. At the concentration of 4000 μg·ml-1, the AFI and AOI of ethyl acetate extract were 7095% and 6949%, respectively. The ethyl acetate extract was then isolated by silica gel column chromatography, a nd three compounds, i.e., (19S, 23E)-5β,19-epoxy-19-methoxy-cucurbita-6,23-dien-3β and 25-diol (compound 1), (19R, 23E)-5β,19-epoxy-19-methoxy-cucurbita-6,23-dien-3β and 25-diol (compound 2), and 3β,7β,25-trihydroxycucurbita-5,23-dien-19-al-3-O-β-D-glucopyranoside (compound 3), were obtained. These three compounds at concentration of 100〖KG-*2〗-〖KG-*7〗400 μg·ml-1 all had inhibitory effects on the feeding and oviposition of L. sativae. At the concentration of 400 μg·ml-1, the AFI and AOI were 6689%, 5353% and 7802%, and 7632%, 5836% and 7836% for compound 1, 2 and 3, respectively.
    Risk assessment and control strategies of pests in Lycium barbarum fields under different managements.
    ZHAO Zi-hua1,2;ZHANG Rong2;HE Da-han1;WANG Fang2;ZHANG Ting-ting1;ZHANG Zong-shan2
    2009, 20(04):  843-850 . 
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    In the risk assessment of pests, both the community structure and the environmental factors should be considered at the same time, because of their mutu al effects on the outbreak of disaster pests. This paper established a comprehen sive assessment system, including 2 sub-systems, 5 respects, and 14 indices. In the meanwhile, risk assessment indices and experience formula were used to anal yze the risk degree of pests in Lycium barbarum fields under different manag ements. It was found that using risk assessment indices and experience formula c ould obtain similar results. In abandoned field, Aceria palida, Aphis sp., a nd Paratrioza sinica were the frequent disaster pests, Lema decempunctata, Neoceratitis asiatica, Jaapiella sp., and Phthorimaea sp. were the incidental disaster pests, and Psylliodes obscurofaciata and Phthorimaea sp. were general pests. In organic field, the frequent disaster pests were the same species as t hose in abandoned field, while P. indicus, Jaapiella sp. and Phthorimaea sp. were the incidental disaster pests. In chemical control field, A. palida, Aphis sp., P. sinica, and P. indicus were the frequent disaster pests , while Jaapiella sp. and Phthorimaea sp. were the incidental disaster p ests. Optimal 5 separations most fitted the division of pest sub-communities in L. barbarum fields, which were infancy period (from March 28 to April 15), outbreak Ⅰ period (from April 15 to July 18), dormancy period (from July 18 to September 8), outbreak Ⅱ period (from September 8 to October 15), and recession period (after October 15). The matrix of correlation coefficient showed that th e dynamics of pests in L. barbarum fields under different managements were s ignificantly correlated with each other, suggesting that the dynamics of pest po pulations was similar in different L. barbarum fields, which had two populat ion establishment stages and one exponential growth stage in every year. The opt imal controlling stages were from late infancy period to early and middle outbre ak Ⅰ periods, and from late dormancy period to early outbreak Ⅱ period, which were very critical for pest control.
    Quantitative analysis of insect pest and natural enemy communities in Red Fuji apple orchard.
    ZHENG Fang-qiang1;ZHANG Xiao-hua2;QU Cheng-huai3;LIU Xue-qian4;QU Shu-juan5
    2009, 20(04):  851-856 . 
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    The insect pest and natural enemy communities in Red Fuji apple orcha rd in Mouping District of Yantai City were quantitatively analyzed by multivariat e analysis. The temporal structure of the communities was grouped into five cont inuous stages by using optimal sorting method, and the community characteristics at each stage were described. The dominant pests and natural enemies were deter mined at different growth stages of apple trees through analyzing the sub-commu nities of the insect pests and the predatory and parasitic enemies by principal component analysis and factor analysis. Canonical correlation analysis showed th at there were significant correlations between the dominant insect pests and the dominant natural enemies, especially between Lithocolletis ringoniella and its parasitoids, between Aphis citricola and its parasitoids, and between Tetr anychus viennensis and its obligatory predatory enemies, Stethorus punctillu m and Amblyseius orientalis.
    UP-PCR diversity analysis of Fusarium population isolated from greenhouse melon soils.
    ZHAO Bai-xia;GAO Zeng-gui;ZHUANG Jing-hua;ZHANG Xiao-fei;ZHAO Hui
    2009, 20(04):  857-862 . 
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    A total of 112 Fusarium isolates were obtained from 36 soil samples collected from the greenhouse melon fields of Liaoning Province, among which, 11 species were identified by traditional morphological classification and rDNA sequence analysis. Universally Primed PCR (UP-PCR) was conducted to analyze the 25 strains of test Fusarium isolates and 3 strains of positive control Fu sarium isolates. The results indicated that a total of 73 bands appeared after amp lification by using 6 primers, and 66 bands (904%) were polymorphic. The isola tes were clustered into eight groups at the similarity of 0736 by cluster anal ysis, among which, 14 isolates were clustered into one group. It was concluded t hat UP-PCR could present the genetic relationship and difference among Fusari um strains, being able to be used as an assistant method for Fusarium clas sificati on.
    Soil bacterial community structure in primeval forest and degraded ecosystem in Karst region.
    CHEN Xiang-bi1,2;SU Yi-rong1;HE Xun-yang1;WEI Wen-xue1;WEI Ya-wei1,2;DAI Xiao-yan1,3
    2009, 20(04):  863-871 . 
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    By using PCR-RFLP, this paper studied the 16S rDNA gene diversity and phylogenesis of soil bacteria in primeval forest and degraded ecosystem in Karst region of Northwest Guangxi. More genotypes and higher diversity index were observed in the soil of primeval forest than in that of degraded ecosystem, and only two common genotypes were observed in the two soils. A clone from each genotype was randomly selected as representative for sequencing. The obtained 16S rDNA gene sequences had a similarity of 87%〖KG-*2〗-〖KG-*7〗100% with those in the GenBank (www.ncbi.nlm.nih.gov), and more than half of them had a similarity lower than 97%, being of new species. Based on phylogenetic analysis, the bacteria in the two soils were classified into 10 groups, with 5 groups in common. The dominant bacterial groups in the two soils differed obviously. In primeval forest soil, the dominant group was Proteobacteria, which had 39 genotypes, occupying 580% of all the clones; while in the soil of degraded ecosystem, the dominant groups were Acidobacteria and Proteobacteria, which had 19 and 15 genotypes, occupying 325% and 305% of all the clones, respectively. In the soil of degraded ecosystem, Proteobacteria group decreased while Acidobacteria group increased markedly, compared with those in primeval forest soil. Soil physical and chemical properties and environmental factors should be responsible for the difference of soil bacterial community between the two soils.
    Prediction of winter wheat yield based on crop biomass estimation at regional scale.
    REN Jian-qiang1,2;LIU Xing-ren3;CHEN Zhong-xin1,2;ZHOU Qing-bo1,2;TANG Hua-jun1,2
    2009, 20(04):  872-878 . 
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    Based on the 2004 in situ data of crop yield, remote sensing inversed photosynt hetically active radiation (PAR), fraction of photosynthetically active radiatio n (fPAR), climate, and soil moisture in 83 typical winter wheat sampli ng field of 45 counties in Shijiazhuang, Hengshui, and Xingtai of Hebei Province , a simplified model for calculating the light use efficiency (ε) of winter wheat in Huanghuaihai Plain was established. According to the crop accumulated b iomass from March to May and corrected by harvest index, the quantitative relati onship between crop biomass and crop yield for winter wheat was set up, and appl ied in the 235 counties in Huanghuaihai Plain region of Hebei Province and Shand ong Province and validated by the official crop statistical data at county level in 2004. The results showed that the root mean square error (RMSE) of predicted winter wheat yield in study area was 2385 kg·hm-2, and the relative er ror was 428%, suggesting that it was feasible to predict winter wheat yield by crop biomass estimation based on remote sensing data.
    Modeling of cotton boll maturation period and cottonseed biomass accumulation.
    LI Wen-feng1,2;MENG Ya-li1,2;ZHAO Xin-hua1,2;CHEN Bing-lin1,2;XU Nai-yin1,2;ZHOU Zhi-guo1,2
    2009, 20(04):  879-886 . 
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    Field experiments with different maturity cotton cultivars and sowing dates were conducted at different sites to quantitatively study the effects of c ultivar characteristics, weather conditions (air temperature and solar radiation ), and crop management variable (N application rate) on the cotton boll maturation period and cottonseed biomass accumulation. The cotton boll maturation period was simulated by using the scale of physiological development time. Based on t he hypothesis of sink-determined, the cottonseed biomass accumulation model was then developed. The subtending leaf N concentration of cotton boll was simulate d with a semi-empirical equation, and used as the direct indicator of the N nut rition effect on cottonseed growth and development. The model was tested by inde pendent field data obtained in the Yellow River Valley (Xuzhou and Anyang) and t he lower reaches of Yangtze River Valley (Huaian) in 2005. The simulated values of boll maturation period showed reasonable agreement with observed values, with a root mean square error (RMSE) of 225 days for cultivar DSC-1, of 261 day s for cultivar KC-1, and of 275 days for cultivar AC-33B. The RMSE of cotton seed dry mass prediction was 95 mg·seed-1 for KC-1 and 82 mg·seed -1 for AC-33B, indicating that the model had a good prediction precision.
    Effects of air temperature change on spring wheat growth at different altitudes in northwest arid area.
    ZHAO Hong1,2;LI Feng-min2;XIONG You-cai2;ZHANG Qiang1;WANG Run-yuan1;YANG Qi-guo1
    2009, 20(04):  887-893 . 
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    Based on the 1981〖KG-*2〗-〖KG-*7〗2006 observation data from agricultural meteorological stations at Minle (high altitude) and Zhangye (low altitude) in northwest arid area, the effects of air temperature change at the two altitudes on the growth and yield of spring wheat were studied. It was shown that during study period, the air temperature at the two altitudes had an increasing trend, and the increment was greater at high altitude than at low altitude. At high altitude, the growth duration of spring wheat shortened but the grain yield increased; while at low altitude, the growth duration shortened and the yield decreased. When the mean daily air temperature during spring wheat growth period increased by 1 ℃, the growth duration shortened by 83 days at high altitude and by 38 days at low altitude. The growth duration and grain yield of spring wheat at high altitude had a slight increase when the maximum air temperature during growth period was below 304 ℃, but decreased when the maximum air temperature was above 304 ℃.
    Assessment of farmland soil quality under different utilization intensity in arid area.
    GUI Dong-wei1,2,3;MU Gui-jin1,3;LEI Jia-qiang1,3;ZENG Fan-jiang1,3;WANG Hui1,2,4
    2009, 20(04):  894-900 . 
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    Based on the 2005〖KG-*2〗-〖KG-*7〗2007 experimental data in Cele oasis in the southern margin of Tarim Basin of Xinjiang, the soil quality of four typical types of farmland with different utilization intensity, i.e., farmland with high input, farmland with normal input, newly reclaimed farmland, and farmland in oasis’ interior, was analyzed and assessed by using sustainable yield index, soil improvement index, and soil quality synthesis index. Among the farmlands, there were significant differences in the contents of soil organic matter, available nitrogen, and available phosphorus. Newly reclaimed farmland had the lowest level of soil quality, while the farmland in oasis’ interior had relatively higher soil quality. This study could help the reasonable exploitation and utilization of farmlands in Cele oasis, and the protection of local farmland eco-environment.
    Spatiotemporal dynamics and landscape pattern of alien species Spartina alterniflora in Yancheng coastal wetlands of Jiangsu Province, China.
    LIU Chun-yue1,2;ZHANG Shu-qing1;JIANG Hong-xing3;WANG Hui4
    2009, 20(04):  901-908 . 
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    Based on the 1992〖KG-*2〗-〖KG-*7〗2007 remote sensing images and field survey data, and by using the landscape ecology theories and the method of conversion m atrix, the spatiotemporal dynamics and landscape pattern of Spartina alternifl ora in Yancheng coastal wetlands were analyzed by GIS. The results showed that the total area of S. alterniflora along the whole coastal beaches of Yanche ng increased from 3561 hm2 in 1992 to 14491 hm2 in 2007, with a growth rate of 30694%. In 1992〖KG-*2〗-〖KG-*7〗2007, the total area of S. alterniflora  conversion-in and conversion-out was 26291 hm2 and 15361 hm2, respectiv ely, and the S. alterniflora community in the core area of Yancheng National Nature Reserve expanded from 597 hm2 to 2814 hm2, with an annual growth rat e of 2474%. The S. alterniflora community transformed from scattered patch es in estuarine regions into continuous belt pattern mainly distributed in the p eriphery of coastal wetlands from Sheyang River to Liangduo River. Its centroid moved to the southeast, with a distance of 292 km. The average area of patches increased from 1992 to 2002, and then decreased from 2002 to 2007. The largest patch index and area-weighted contiguity index increased year by year, and the shape of patches tended to be more regular.
    Neighborhood relationships of land use spatial pattern in Qixia City.
    LI Le1;QI Wei1;ZHANG Xin-hua2;QU Yan-bo1
    2009, 20(04):  909-915 . 
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    By using the modules of neighborhood statistics and spatial analysis in ArcGIS software, an analysis was conducted with neighborhood factors on the spatiotemporal variation trend of the neighborhood relationships among main land use types in Qixia City of Shandong Province from 1987 to 2003. The results indicated that the neighborhood relationships between different land use types increased with increasing neighborhood distance, while those among the same land use types manifested congregation, which decreased with increasing neighborhood distance. From 1987 to 2003, the neighborhood relationships between construction land and orchard land, and between woodland and orchard land presented decreasing trend, while those of construction land with woodland and grassland were in adverse. Some measures such as controlling construction land area, protecting cultivated land, and decreasing the disturbances of human activities on woodland and grassland should be carried out to realize the harmonious development of economic and ecological benefits in Qixia City.
    Population dynamics of Alexandrium tamarense and its relations with environmental factors in Nanji Islands sea area of Zhejiang Province.
    LI Yang1;LÜ Song-hui1,2;JIANG Tian-jiu1,2;LI Huan1;XIAO Yun-pu3;YOU Sheng-pao4
    2009, 20(04):  916-922 . 
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    Based on the investigation in Nanji Islands sea area of Zhejiang Province from A pril 2006 to March 2007, the dynamics of Alexandrium tamarense and its relations with environmental factors were studied. In the study sea area, A. tamarense cells could only be found in spring (from April to June), and t he cell abundance was of single peak curve, with the highest (12250 cells·L -1) in surface water on 8th of May. Higher cell abundance of A. tamarense was found at the water temperature of 185 ℃〖KG-*4〗-〖KG-*7〗195 ℃, salin ity of 295‰〖KG-*4〗-〖KG-*7〗310‰, and lower PO4-P concentration, but no correlation was observed between A. tamarense cell abundance and water d issolved inorganic N concentration. Linear stepwise regression revealed that the re was a significant positive correlation between the cell abundance of A. tamarense and the ratio of water dissolved inorganic N to PO4-P.
    Seasonal dynamics of macrozoobenthos community structure in Xiangxi River.
    JIANG Wan-xiang1,2;JIA Xing-huan1,3;ZHOU Shu-chan1;LI Feng-qing1;TANG Tao1;CAI Qing-hua1
    2009, 20(04):  923-928 . 
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    To study the seasonal dynamics of macrozoobenthos community in Xiangxi River, the individuals of macrozoobenthos in the River were quantitatively moni tored. A total of 197 taxa belonging to 6 class and 68 families were collected, among which, Baetis spp., Epeorus spp., and Nemoura spp. were the do minant group s, and their compositions varied with seasons. The macrozoobenthos community was most complicated in winter, followed by in spring and autumn, and the simplest in summer. Gather-collector was the main component of functional feeding groups in Xiangxi River system, followed by scraper, predator, and filter-collector, while shredder only accounted for a small part. Canonical correspondence analysi s showed that the factors affecting the macrozoobenthos community were dissimila r among seasons. In summer and autumn, nutrients had greater effects; and in all seasons, water depth had definite effects.
    Structural characteristics of chironomid community and their indicative significance in bioassessment of water quality in Mingzhu Lake of Chongming Island, Shanghai.
    HU Zhong-jun;LIU Qi-gen;CHEN Li-jing;PENG Zi-ran
    2009, 20(04):  929-936 . 
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    The structural characteristics of chironomid (Diptera: Chironomidae) c ommunity in Mingzhu Lake of Chongming Island, Shanghai, China were studied from July 2006 to April 2008. A total of eleven chironomid species belonging to 10 ge nera and 3 subfamilies were collected, among which, Propsilocerus akamusi an d Microchironomus sp. were predominant. Based on clustering analysis (CA) and importance value (IV), it was found that the dominant species shifted seasonally, wi th Microchironomus sp. in spring and summer, Tanypus chinensis in autumn, an d P. akamusi in winter. There was a significant seasonal difference in the S hannon-Weaver diversity index (H′) of the chironomid community, with the l owest in summer and higher in the other three seasons. The H′ was significa ntly correlated with species richness (S) and evenness (J), and more strongly go verned by J. The average density and biomass of the chironomid community wer e the highest in winter, with a minimum density in autumn and a lower biomass in the other seasons. Among the three dominant species, P. akamusi and Micro chironomus sp. had more obvious seasonal fluctuations in their population dyna mics than T. chinensis. Based on the bioassessment methods of water quality, e.g., H′ and Hilsenhoff biotic index (BI), the Mingzhu Lake wa s considered to be moderately organically polluted and eutrophicated.
    Effects of Pb and Ni stress on antioxidant enzyme system of Thuidium cymbifolium.
    SUN Shou-qin1;HE Ming2;CAO Tong3;CHENG Song1;SONG Hong-tao1
    2009, 20(04):  937-942 . 
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    This paper studied the accumulation and scavenging of active oxygen radicals, injury of photosynthetic system and membrane system, and changes of antioxidant enzyme system in Thuidium cymbifolium cells under single and combined stress of Pb and Ni. Under low concentration of Pb and Ni (Pb<01 mmol·L-1,Ni<001 mmol·L-1), the chlorophyll content of T. cymbifolium increased; while under high concentration of Pb and Ni (Pb>01 mmol·L-1, Ni>001 mmol·L-1), it was in adverse. There was a dose-dependent accumulation of reactive oxide species (ROS) and malondialdehyde (MDA) under combined Pb and Ni stress. The superoxide dismutase (SOD) and catalase (CAT) activities decreased while the peroxidase (POD) activity increased with increasing Pb and Ni concentration, indicating the important role of POD in eliminating ROS under Pb and Ni stress. The dose-dependent change of MDA content and CAT activity under Pb and Ni stress suggested that T. cymbifolium could be used as a biomarker in pollution monitoring of these two heavy metals.
    Effects of exogenous tetracycline on rape soil enzyme activity and rape quality.
    LIU Ji-qiang1;ZHUGE Yu-ping1;CUI Li-na2
    2009, 20(04):  943-948 . 
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    This paper studied the effects of applying different concentration (0, 030, 0 60, and 090 mg·kg-1) tetracycline on the soil enzyme activities and rape quality. The results showed that soil urease activity after applied 030, 060, and 090 mg·kg-1 of tetracycline and soil su crase activity after applied 090 mg·kg-1 of tetracycline were inhibited in the whole cultivating period, while the soil sucrase activity after applied 030 and 060 mg·kg-1 of tetracycline showed a trend of activation-inh ibition-activation. Soil proteinase activity showed a trend of inhibition-acti vation, and the extent and duration of the inhibition and activation had signifi cant positive correlations with tetracycline concentration (r=0950** ). Soil catalase activity showed activation first and turned to irregular then. The action duration of tetracycline on the activities of soil urease, catalase, sucrase and proteinase were 7 weeks, 6〖KG-*2〗-〖KG-*7〗8 wee ks, 7 weeks, and 6〖KG-*2〗-〖KG-*7〗7 weeks, respectively. At harvest time, the soluble sugar contents in rape leaves after applying 030, 060, and 090 mg ·kg-1 of tetracycline decreased dramatically by 9199%, 8792%, 9012% , while the soluble protein content increased by 2647%, 2813%, and 2322%, respectively, compared to the control.
    Effects of enrofloxacin on DNA sequence diversity of soil cultural bacterial community.
    MA Yi1,2;CHEN Zhang-liu1
    2009, 20(04):  949-954 . 
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    In order to understand the effects of remained enrofloxacin (ENR) in e nvironment on the diversity of soil microbial communities, amplified ribosomal D NA restriction analysis (ARDRA) approach and genomic fingerprinting technique en terobacterial repetitive intergenic consensus sequence-polymerase chain reactio n (ERIC-PCR) were used to analyze the molecular diversity of 16S rDNA from soil bacteria after ENR addition. The results showed that after the ENR addition for 35 days, the total count of soil bacteria was less than that of CK, and decreas ed with increasing ENR concentration. The ARDRA divided the separated soil bacte ria into different operational taxonomic units (OTU) groups, and the count of gr oupⅠ to group Ⅵ was 15, 13, 10, 8, 6, and 6, respectively. Genomic fingerprint ing analysis indicated that the Shannon-Wiener index of group Ⅰ to group Ⅵ wa s 278, 214, 178, 111, 069 and 031, respectively, and the Margalef in dex, Simpson index, and Pielou index of soil microbial community in CK were high er than that in the soils in which ENR was added.
    Relationships between economic growth and industrial pollutant discharge of Suzhou: How about the EKC
    LING Hong1,2;ZHU Xiao-dong1;WANG Hui-zhong2;YIN Rong-yao1;WANG Xiang-hua2;ZHAO Wen-jun1
    2009, 20(04):  955-962 . 
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    Based on the study of the relationships between economic growth and in dustrial pollutant discharge of Suzhou City in 1991〖KG-*2〗-〖KG-*7〗2005, the environmental Kuznets curve (EKC) of the City was estimated by several kinds of function, with the cause analyzed. The results showed that the EKC of Suzhou was not a typical one. The industrial pollution of the City increased dramatically by scale effect of economic growth and the clear environmental benefit of indust rial structure adjustment was not received obviously, while generalized discharg e reduction technologies showed great results. In general terms, the pollution i ncrease was comparatively slower than the GDP growth. As a whole, the environmen tal policy of Suzhou was in effect. However, the relationships between economic growth and industrial pollutant discharge had not been a benign development yet. In order to achieve win-win situation of economic growth and pollution reducti on, Suzhou needed to optimize its industry structure, push the energy conservati on and discharge reduction policy deeply, increase environmental investment, and enforce the strictest environmental and industrial policy. In doing these, Suzh ou could turn the traditional ∩-shaped EKC into ∧-shaped EKC.
    Dynamics of suspended solids in Xiangxi Bay of Three Gorges Reservoir during spring algal bloom period.
    XU Yao-yang1,2;WANG Lan1,2;HAN Xin-qin1,2;CAI Qing-hua1
    2009, 20(04):  963-969 . 
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    The dynamics of total suspended solids (TSS) in Xiangxi Bay of Three Gorges Rese rvoir (TGR) during the period of spring algal bloom were weekly investigated. Th e results showed that the TSS in the Bay ranged from 066 to 13492 mg ·L-1, with a median of 680 mg·L-1, and tended to be increased fr om headwater to down-lake zones. The spatial pattern of non-volatile suspended solids (NVSS) was similar to that of TSS, while volatile suspended solids (VSS) showed obviously different pattern from TSS and followed the spatial pattern of chlorophyll a. Regression analysis indicated that in the mid-zone of the Bay, chlorophyll a was significantly related to TSS and VSS, and explained 667% 〖KG-*2〗-〖KG-*7〗967% and 589%〖KG-*2〗-〖KG-*7〗855% of the variance in TSS and VSS, respectively. In the headwater and down-lake zones, there were no significant relationships between chlorophyll a and TSS (including NVSS and VSS ). The TSS in mid-lake had more close relationship with VSS than with NVSS, while that in headwater and down-lake had more close relationsh ip with NVSS than with VSS, implying that the mid-lake of Xiangxi Bay was a mor e autochthonous system than the headwater and down-lake where allochthonous inf luences were the more determinant factors.
    Effects of drip irrigation under mulching on cotton root and shoot biomass and yield.
    YAN Ying-yu1;ZHAO Cheng-yi2;SHENG Yu2;LI Ju-yan2;PENG Dong-mei1;LI Zi-liang3;FENG Sheng-li4
    2009, 20(04):  970-976 . 
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    By using bidirectional sampling method with soil drill, the effects of different amounts of drip irrigation (2618, 2947, 3600 and 4265 m3·hm-2) under mulching on the root distribution, aboveground growth, and yield of cotton was studied in field. The results indicated that irrigation amount affected the root and shoot growth significantly. In all irrigation treatments, cotton root was m ainly distributed in mulched area, occupying 6065%〖KG-*2〗-〖KG-*7〗7345% o f total root biomass, while only 3935%〖KG-*2〗-〖KG-*7〗2655% was distribut ed in bare area. Water stress increased rooting depth, root biomass, and the ext ent of lateral rooting. Significant differences were observed in the biological characteristics and the biomass accumulation and allocation of cotton plant amon g different irrigation treatments. Over-irrigation (4265 m3·hm-2) incr eased plant height, width of inverse fourth leaf, and amounts of branch and bud, and thus, accelerated biomass accumulation rate. Over-irrigation also increase d the root/shoot ratio and the proportion of biomass allocated to vegetative org ans, but increased the fruit abscission rate and therefore reduced the economic yield. It was suggested that both excessive soil moisture content and water stre ss could affect the biomass accumulation and allocation in different cotton orga ns and at various life stages. Under the conditions of our experiment, 3600 m3 ·hm-2 was the optimal irrigation amount.
    Environmental behavior and effect of biomass-derived black carbon in soil: A review.
    LIU Yu-xue1;LIU Wei1;WU Wei-xiang1;ZHONG Zhe-ke2;CHEN Ying-xu1
    2009, 20(04):  977-982 . 
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    Biomass-derived black carbon, also named biochar, has the characteris tics of high stability against decay and high capability of adsorption, and can affect the environment through its interactions with climate and geology, playin g a significant role in global climate change, carbon biogeochemical cycle, and environmental system. In recent years, more and more researchers in the fields o f atmospheric sciences, geology, and environmental science focused on the enviro nmental behavior and effect of biochar. As one possible source of the components with high aromatic structure in soil humus, biochar is of great importance in i ncreasing soil carbon storage and improving soil fertility, and in maintaining t he balance of soil ecosystem. This paper offered the latest information regardin g the characteristics and biotic and abiotic oxidation mechanisms of biochar, it s effects on global climate change, and the environmental effect of biochar in s oil. Research prospects were briefly discussed on the environmental behavior and effect of biochar in soil ecosystem.
    Research progress on index system of regional ecological risk assessment.
    MENG Ji-jun;ZHAO Chun-hong
    2009, 20(04):  983-990 . 
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    Regional ecological risk assessment (RERA) covers the assessments of m ultiple risk sources, receptors, and endpoints, while the selection of assessmen t indices is quite complicated, being a hotspot in regional environment manageme nt research. Domestic and international researches on RERA revealed that three p rocesses in RERA are of vital, i.e., risk probability assessment measured by ris k probability index, status and value assessment of ecosystem at regional scale indicated by ecological index, and vulnerability assessment of each ecosystem in a region under risk measured by vulnerability index. The main problems in the e stablishment of RERA index system are the strong subjectivity and poor comparabi lity, and thus, the index system should be set up in the three key processes und er the principles of objectivity, integration, hierarchy, and comparability. Due to the fact that the status and value assessment of ecosystem is most complicat ed, the index system should be formulated by compulsory and optional components to increase the comparability of RERA results between regions.
    Present status, mechanisms, and control techniques of nitrogen and phosphorus non-point source pollution from vegetable fields.
    HUANG Dong-feng1,2;WANG Guo2;LI Wei-hua1;QIU Xiao-xuan1
    2009, 20(04):  991-1001 . 
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    Chemical fertilizers are often excessively applied on vegetable field s to pursue higher yields. In some areas, the fertilization rates are several ti mes of those needed by vegetables. Nitrogen and phosphorous are obviously accumu lated in the vegetable soils, resulting in the malnutrition, excessive nitrate, and poor quality of vegetables. Furthermore, a series of environmental problems, e.g., deterioration of vegetable soil physical and chemical properties, nitrate pollution of groundwater, and eutrophication of surface water, are produced. Th is paper reviewed the present status of nitrogen and phosphorous non-point sour ce pollution from vegetable soils (accumulation characteristics of nitrogen and phosphorous and their pollution risks to water environment and vegetables), poll ution mechanisms (sources, transformation, and losses of nitrogen and phosphorou s), and control techniques (fertilization, chemical addition, nitrogen catch cro p cultivation, optimal planting system, spatial matching of source and sink land scapes, and grass buffer strip technology), aimed to supply references for the f urther study on the nitrogen and phosphorous non-point source pollution from ve getable fields.
    Effects of UV-radiation on biological characteristics of different body-color biotypes of Sitobion avenae (Fab.)
    HU Zu-qing1;ZHAO Hui-yan1;KANG Ju-xia2;HU Xiang-shun1;LI Dong-hong1
    2009, 20(04):  1002-1006 . 
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    UV-radiation exerts strong selection stress on the evolution of aphid populations, and thus, leads to their genetic differentiation. However, the effects of UV-radiation on different body-color biotypes of aphids are still ambiguous. In this study, new-born nymphae of red and green biotypes of Sitobion avenae were placed on two wheat varieties (Xiaoyan-22 and Astron), bred in an artificial bioclimatic chamber under strict controlled conditions (at 15 ℃, 20 ℃, and 25 ℃, and treated with 30 W lamp of UV-B for 30 min per day for 5 days), and their development duration, mass, and mean relative growth rate were measured. The results showed that at lower temperature, UV-radiation delayed the growth of green biotype aphid on Xiaoyan-22 and Astron significantly; while at higher temperature, UV-radiation significantly delayed the growth of red biotype aphid on Xiaoyan-22, but had lesser effects on the growth of the two biotypes on Astron, illustrating that different biotypes of aphids had different responses to UV-radiation, and the responses were correlated to temperature and wheat varieties.