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Table of Content

    20 June 2008, Volume 19 Issue 06
    Articles
    Simulation of three-dimensional green biomass of urban forests in Shenyang City and the factors affecting the biomass.
    LIU Chang-fu1,2;HE Xing-yuan1;CHEN Wei1;ZHAO Gui-ling2; XUE Wen-duo1
    2008, 19(06):  1173-1178 . 
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    Based on the fractal theory of forest growth, stepwise regression was employed to pursue a convenient and efficient method of measuring the threedimensional green biomass (TGB) of urban forests in small area. A total of thirteen simulation equations of TGB of urban forests in Shen-yang City were derived, with the factors affecting the TGB analyzed. The results showed that the-coefficien-ts of determination (R2) of the 13 simulation equations ranged from 0.612 to 0.842. No evident pattern was shown in residual analysis, and the precisions were all higher than 87% (α=0.05) and 83% (α=0.01). The most convenient simulation equation was lnY=7.468+0.926 lnx1, where Y was the simulated TGB and x1 was basal area at breast height per hectare (SDB). The correlations between the standard regression coefficients of the simulation equations and 16 tree characteristics suggested that SDB was the main factor affecting the TGB of urban forests in Shenyang.
    Effects of silicon on photosynthetic characteristics of Indocalamus barbatus under simulated acid rain stress.
    XIE Yin-feng;YANG Wan-hong;LU Mei-rong;CAI Xian-lei;ZHOU Jian
    2008, 19(06):  1179-1184 . 
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    With Indocalamus barbatus as test material, the effects of silicon on the relative content of chlorophyll, diurnal variations of photosynthesis, and chlorophyll fluorescence were examined under simulated acid rain (pH 3.0) stress. The results showed that under acid rain stress, 20 and 500 mg·L-1 of Na2SiO3 could prohibit the decrease of the relative content of chlorophyll to some extent; 100 mg·L-1 of Na2SiO3 could get best effect, with the relative chlorophyll content being 22.7% higher than the control; while 500 mg·L-1 of Na2SiO3 didn’t have any effect. Under the stress, the midday depression of photosynthesis became more serious. The average daily net photosynthetic rate (Pn), stomatal limitation value (Ls), and stomata conductance (Gs) were all decreased significantly, while the intercellular CO2 concentration (Ci) increased. After treated with 20-100 mg·L-1 of Na2SiO3, the Pn,Ls, and Gs increased to some extent while Ci decreased, and 100 mg·L-1 of Na2SiO3 was most effective, with the average daily Pn increased by 39.2%. The maximum fluorescence of dark adaptation(Fm), maximal photochemical efficiency (Fv/Fm), potential activity (Fv/Fo), effective photochemical efficiency (Fv′/Fm′), maximum fluorescence of light adaptation (Fm′) of PSII, photochemical quenching (qP), non-photochemical quenching (qN), and actual photochemical efficiency of PSII (ΦPSⅡ) were all decreased obviously under simulated acid rain stress, but the minimum fluorescence of dark adaptation (Fo) and the minimum fluorescence of light adaptation (Fo′) increased. 100 mg·L-1 of Na2SiO3 could restrain the changes of fluorescence parameters obviously, with the Fv/Fm, Fv/Fo,Fv′/Fm′ and ΦPSⅡ increased by 35.2%, 146.2%, 55.0% and 24.3%, respectively, compared with the control. It was suggested that applying appropriate concentration of exogenous silicon to I. barbatus could efficiently relieve the decrease of its photosynthetic activity and the damage of its photosynthetic system caused by acid rain, and thus, improve its photosynthetic ability under the stress.
    Response processes of Aralia elata photosynthesis and transpiration to light and soil moisture.
    CHEN Jian1;ZHANG Guang-can1;ZHANG Shu-yong2;WANG Meng-jun1
    2008, 19(06):  1185-1190 . 
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    By using CIRAS-2 portable photosynthesis system, the light response processes of Aralia elata photosynthesis and transpiration under different soil moisture conditions were studied, aimed to understand the adaptability of A. elata to different light and soil moisture conditions. The results showed that the response processes of A. elatanet photosynthetic rate (Pn), transpiration rate (Tr), and water use efficiency (WUE) to photon flux density (PFD) were different. With the increasing PFD in the range of 800-1 800 μmol·m-2·s-1, Pn changed less,Tr decreased gradually, while WUEincreased obviously. The light saturation point (LSP) and light compensation point (LCP) were about 800 and 30 μmol·m-2·s-1, respectively, and less affected by soil water content; while the apparent photosynthetic quantum yield (Ф) and dark respiratory rate (Rd) were more affected by the moisture content. The Pn and WUE had evident threshold responses to the variations of soil water content. When the soil relative water content (RWC) was in the range of 44%-79%, A. elata could have higher levels of Pn and WUE.
    Heavy metals contents and Hg adsorption characteristics of mosses in virgin forest of Gongga Mountain.
    LIANG Peng1;YANG Yong-kui1;HE Lei2;WANG Ding-yong1,3
    2008, 19(06):  1191-1196 . 
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    Seven main moss species in the Hailuogou virgin forest of Gongga Mountain were sampled to determine their heavy metals (Hg, Cr, Cd, Ni, Pb, Cu, Mn, Zn and Fe) content, and two widely distributed species, Pleurozium schreberi(Brid.) Mitt. and Racomitrium laetum Besch., were selected to study their Hg adsorption characteristics. The results showed that the heavy metals contents in the mosses were lower than the background values in Europe and America, except that the Cd had a comparable value, which indicated that the atmosphere in study area was not polluted by heavy metals and good in quality. The Hg adsorption byP. schreberi and R. laetum was an initiative and rapid process, with the equilibrium reached in about two hours, and could be well fitted by Freundlich and Langmuir equations. Based on Langmuir equation, the maximum Hg adsorption capacities of P. schreberi and R. laetum were 15.24 and 8.19 mg·g-1, respectively, suggesting that the two mosses had a good capacity of Hg adsorption, and could be used as the bio-monitors of atmospheric Hg pollution.
    Effects of artificial Ulmus pumila forest on plant diversity of temperate grassland in Inner Mongolia.
    YANG Hong-xiao1;WANG Xue-quan2,3;YANG Wen-bin2,3,4;LU Qi2,3
    2008, 19(06):  1197-1203 . 
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    Based on field survey, the effects of artificial Ulmus pumila forest on the species diversity of temperate grassland in Siziwang Banner of Inner Mongolia were studied. The results showed that U. pumila forest had obvious effects on the species diversity of grassland. With increasing density of U. pumila, the Patrick’s richness, Pielou’s evenness and Shannon-Wiener index of grass species under the forest had a decreasing trend, and were higher nearby the forest than far from the forest. The habitat inside the forest was favorable to Silene jenisseensis, while that nearby the forest was favorable to Heteropappus altaicus, Pocockia ruthenia, Potentilla bifurca, Leymus secalinus and Cleistogenes squarrosa, suggesting that to blindly exclude forestation on grassland could be less scientific, while properly afforesting U. pumila on the sides with relatively abundant soil moisture should be available to the conservation of plant diversity in temperate grassland regions.
    Effects of bio-mulching on rhizosphere soil microbial population, enzyme activity and tree growth in poplar plantation.
    LIU Jiu-jun;FANG Sheng-zuo;XIE Bao-dong;HAO Juan-juan
    2008, 19(06):  1204-1210 . 
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    Coriaria nepalensis, Pteridium aquilinum var. latiuscukum, Imperata cylindrical var. major, and Quercus fabric were used as mulching materials to study their effects on the rhizosphere soil microbial population and enzyme activity and the tree growth in poplar plantation. The results showed that after mulching with test materials, the populations of both bacteria and fungi in rhizosphere soil were more than those of the control. Of the mulching materials, I. cylindrical and Q. fabric had the best effect, with the numbers of bacteria and fungi being 23.56 and 1.43 times higher than the control, respectively. The bacterial and fungal populations in rhizosphere soil increased with increasing mulching amount. When the mulching amount was 7.5 kg m-2, the numbers of bacteria and fungi in rhizosphere soil were 0.5 and 5.14 times higher than the control, respectively. Under bio-mulching, the bacterial and fungal populations in rhizosphere soil had a similar annual variation trend, which was accorded with the annual fluctuation of soil temperature and got to the maximum in July and the minimum in December. The urease and phosphatase activities in rhizosphere soil also increased with increasing mulching amount. As for the effects of different mulching materials on the enzyme activities, they were in the order of C. nepalensis>P. aquilinum >I. cylindrical>Q. fabric. The annual variation of urease and phosphatase activities in rhizosphere soil was similar to that of bacterial and fungal populations, being the highest in July and the lowest in December. Bio-mulching promoted the tree height, DBH, and biomass of poplar trees significantly.
    Coupling effects of water and chemical fertilizers on Hevea brasiliensis latex yield.
    HUA Yuan-gang;CHEN Qiu-bo;LIN Zhao-mu;LUO Wei
    2008, 19(06):  1211-1216 . 
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    Water and nutrient are the two main factors limiting Hevea brasiliensis growth and its latex yield. With 17 yearold Clone SCATC 7-33-97 H. brasiliensis as test material, the coupling effects of water and chemical N, P and K fertilizers on latex yield were studied by general orthogonal rotation design of quadratic regression with four factors and five levels under field condition, and a regressive mathematical model was set up based on the latex yield by quadratic regression analysis. The results showed that all test coupling levels of water and chemical fertilizers had significant effects on the latex yield. The yield-increasing effect of test factors was in the order of N application rate > irrigation amount > P application rate > K application rate, while the coupling effect of water and chemical fertilizers was in the sequence of water and N > N and P> water and P> water and K. There was a negative coupling effect of K application rate and soil moisture content. For latex yield, the optimum application rates of chemical fertilizers were 476.39 kg·hm-2 of urea, 187.70 kg·hm-2 of superphosphate and 225.77 kg·hm-2 of potassium chloride, and the optimum irrigation amount was to have 82.78% soil relative water content.
    Dynamics of initial decomposition of Calamagrostis angustifolia litter in Sanjiang Plain of China.
    QIN Sheng-jin1,2;LIU Jing-shuang1;ZHOU Wang-ming1;CHENG Li3
    2008, 19(06):  1217-1222 . 
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    A 28-day leaching-decomposition experiment was conducted to study the effects of microbial activity and leaching on the initial decomposition of Calamagrostis angustifolia litters taken from the boggy meadow and meadow in Sanjiang Plain of China. The results showed that the mass loss of the litters at their initial decomposition stage accounted for 59% and 22% of yearly mass loss, respectively, and the remaining dry mass decreased significantly after 28-day decomposition. By the end of the experiment, the N content in the litters decreased by 32.65% and 24.55%, and P content decreased by 36.71% and 45.15%, respectively. The N and P contents in the litters treated with chloroform were higher than those of the control, but the difference was not significant. No significant difference was also observed in the N and P release from the litters to the leachates between the treatment of chloroform and CK, which indicated that the initial decomposition of the litters was mainly affected by leaching. There was no significant difference in the decomposition rate and nutrient loss rate between the two litters.
    Monthly dynamics and distribution of major cations in Iris lactea.
    WANG Yong1,2;GUO Ji-xun1;CUI Xi-yan1;HAN De-fu1
    2008, 19(06):  1223-1228 . 
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    The study on the monthly absorption, transportation, and distribution of Na+, K+, Ca2+and Mg2+ in Iris lactea under saline-alkali field conditions showed that the contents of test cations in I. lactea varied with months. After June, the cations contents in plant increased with growth. Root Ca2+ and Na+ contents were the highest in July, being 2.30% and 0.51%, respectively, while root K+ and Mg2+ contents were the highest in September (0.27%) and October (0.28%), respectively. Leaf Na+ content was the highest in July (0.57%), while leaf K+, Ca2+ and Mg2+ contents were the highest in August, being 1.30%, 2.69% and 0.47%, respectively. In July and August, the selective absorption (SA) of K+ was higher than that of Na+, while the selective transport (ST) was in adverse. The cations contents in I. lacteawere significantly higher than those in soil, suggesting that I. lactea had high accumulation capacity to these cations. The cations were mainly accumulated in the 0-30 cm aboveground part and 0-40 cm underground part ofI. lactea, and the average contents of Na+, K+, Ca2+and Mg2+ in aboveground part were 9.11, 4.07, 0.98 and 2.27 times of those in underground part, respectively.
    Effects of waterlogging on ecophysiological characteristics of Salix variegate seedlings.
    CHEN Fang-qing1;GUO Cheng-yuan1;WANG Chuan-hua1;XU Wen-nian;FAN Da-yong2;XIE Zong-qiang2
    2008, 19(06):  1229-1233 . 
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    Salix variegate, a widely distributed species along the riverbank in Three Gorges Reservoir area, plays an important role in soil conservation and riverbank stabilization. Waterlogging from April to May was simulated in 2006 to test the adapting ability and mechanism of S. variegate seedlings to water environment change resulted from the construction of Three Gorges Project. The results showed that under waterlogging, all of the S. variegate seedlings could survive, but their maximum photosynthesis (Pmax), transpiration rate (Tr), water use efficiency (WUE), and stomatal conductance (Gs) decreased significantly with the prolongation of waterlogging. In the early period of waterlogging (20 days), these indices changed little, with the Pmax and Tr decreased by 18.5% and 2.2%, respectively, compared with the control. After 30 days, Pmax and Tr decreased by 53.4% and 23.7%, respectively, and then, kept stable. The contents of chlorophyll and carotenoid and their ratio decreased significantly with the prolongation of waterlogging, while the ratio of chlorophyll a to b increased significantly. The ratio of chlorophyll to carotenoid ranged in 4.873-6.883, and that of chlorophyll a to b ranged in 2.855-3.912. Adventitious roots were developed after waterlogging, which would benefit the oxygen supply for the plants. It was suggested thatS. variegate had good adaptability to waterlogging, and could be used as a pioneer species in the restoration of degraded water-level fluctuation zone.
    Dynamic changes of soil moisture in loess hilly and gully region under effects of different yearly precipitation patterns.
    ZHANG Bei-ying1,2;XU Xue-xuan1,3;LIU Wen-zhao1,3;CHEN Tian-lin1,3
    2008, 19(06):  1234-1240 . 
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    Based on field determinations, the dynamic changes of soil moisture in dry farmland, Robinia pseudoacacia forestland, Hippophae shrubland and Bothriochloa ischaemum grassland in loess hilly and gully region under effects of different yearly precipitation patterns were analyzed. The results showed that yearly precipitation pattern had definite effects on the seasonal variation and profile distribution of soil moisture. In normal year, soil moisture in dry farmland had a gentle seasonal variation; in dry year, it decreased slowly before rainy season but increased markedly after rainy season; while in rainy year, it had an overall increase and the increment was remarkable after rainy season. The soil moisture in R. psendoacacia forestland, Hippophae shrubland, and B. ischaemun grassland decreased as a whole in normal year. In dry year, soil moisture in Hippophae shrubland decreased first and increased then, while that in R. psendoacacia forestland and B. ischaemun grassland varied in “W” type, with the minimum in June and August. In rainy year, the seasonal variation of soil moisture in R. psendoacacia forestland and Hippophae shrubland presented “V” type, and that in B. ischaemu grassland fluctuated markedly, with the minimum in August. In dry farmland, the active and sub-active layers of soil moisture were deeper in dry year than in normal year, and the sub-active layer disappeared in rainy year. In R. psendoacacia forestland and B. ischaemu grassland, the active layer of soil moisture was deeper in dry and rainy years than in normal year; while in Hippophae shrubland, this active layer was shallower in dry and rainy years than in normal year.
    Spatiotemporal variation of soil moisture in a small watershed of loess hilly region.
    WANG Jun1,2;LIU Wen-zhao1;HU Meng-jun3
    2008, 19(06):  1241-1247 . 
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    Based on field determinations, the spatiotemporal variation of soil moisture content in a small watershed of loess hilly region from 2002 to 2005 was studied, with the main affecting factors analyzed. The results showed that in the study area, the mean annual soil moisture profile was in an inverse L shape, with the lowest value at the depth of 1 m. The soil moisture contents between the layers of 0-0.2 m and below 2.4 m in different years, and those between the layers of 0-0.2 m and 1.0-2.4 m in different seasons were significantly different. In drought years, the lack of precipitation increased the spatial heterogeneity of soil moisture content in the layers of 1.0-2.4 m and below 2.4 m significantly; while in rainy years, the supplement of precipitation decreased the spatial heterogeneity of soil moisture content in 0-0.2 m layer, but had less effects on that in the layers of 1.0-2.4 m and below 2.4 m. Slope aspect and land use were the two main factors affecting the spatiotemporal variation of soil moisture content, while slope position had less effects. In drought years or by the end of drought season, the effects of slope aspect on soil moisture content decreased, while those of landuse type increased with soil depth. In rainy years or by the end of rainy season, slope aspect became the most important affecting factor, while land use type only affected upper soil layer.
    Light environment characteristics in maize-soybean strip intercropping system.
    GAO Yang;DUAN Ai-wang;LIU Zu-gui;SHEN Xiao-jun
    2008, 19(06):  1248-1254 . 
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    Observations on the light environment characteristics in maize-soybean narrow strip intercropping system were made in 2006 and 2007 to study the spatial distribution of photosynthetically active radiation (PAR) in intercropped crop canopy, and to analyze the effects of light environment on crop biomass. The results indicated that in early growth period, the light transmittance at the bottom of the edge rows of soybean strips adjacent to maize was higher than that of the inner rows of soybean strips, while it was in adverse for maize strips. The horizontal variation of light transmittance at the bottom of crop canopy did not vary significantly at reproductive stage, and the average light transmittance was less than 7%. In soybean strips, the daily photosynthetic photon flux density (PPFD) above inner rows canopy in early growth period was 10% higher than that above edge rows canopy, and the average light transmittance of edge rows and inner rows in 1∶3 intercropping system (treatment I1) was about 15% higher than that in 2∶3 system (treatment I2), indicating that the shading of maize strips on soybean strips was more serious in treatment I2 than in treatment I1. After flowering, there was a significant difference in the daily PPFD between inner rows and edge rows of soybean strips, but no significant difference was observed between edge rows. The mean light transmittance of edge rows and inner rows of soybean strips was 27% and 38%, respectively, and there was no significant difference between treatment I1 and treatment I2, which indicated that the shading effects of maize strips on soybean strips in treatment I1 and treatment I2 were similar at reproductive stage. The biomass of inner rows of soybean strips was larger than that of edge rows, and there was no significant different between edge rows, indicating that under adequate irrigation, the effects of different narrow strip intercropping systems on crop biomass were primarily due to the changes of light environment.
    Evolution characteristics of flag leaf photosynthesis and grain yield of wheat cultivars bred in different years.
    WANG Shi-hong;JING Qi;DAI Ting-bo;JIANG Dong;CAO Wei-xing
    2008, 19(06):  1255-1260 . 
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    Taking six winter wheat (Triticum aestivum) cultivars, i.e., ‘Wangshuibai’ and ‘Bima 1’ bred in 1950s, ‘Zhengyin 1’ and ‘Yangmai 1’ bred in 1970s, and ‘Yumai 34’ and ‘Ningmai 9’ bred in 1990s, as test materials, field experiments were conducted to study the evolution characteristics of their flag leaf photosynthesis and grain yield. The results showed that compared with those bred in 1950s and 1970s, the cultivars bred in 1990s had higher chlorophyll content, net photosynthetic rate (Pn), PSⅡ maximum photochemical efficiency (Fv/Fm), actual photochemical efficiency (ΦPSⅡ), photochemical quenching coefficient (qP) and nonphotochemical quenching coefficient (qN) at grainfilling stage, their flag leaf had a longer functional duration and senesced slower, and their harvest indices were higher, with the grain yield increased by 25.90% and 11.29%, respectively. It was suggested that in the evolution process of wheat cultivars from 1950s to 1990s, the improved photosynthetic capacity and the lengthened functional duration of flag leaf after anthesis were the key physiological bases for grain yield enhancement.
    Hyperspectral remote sensing diagnosis models of rice plant nitrogen nutritional status.
    TAN Chang-wei1;ZHOU Qing-bo2;QI La3;ZHUANG Heng-yang1
    2008, 19(06):  1261-1268 . 
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    The correlations of rice plant nitrogen content with raw hyperspectral reflectance, first derivative hyperspectral reflectance, and hyperspectral characteristic parameters were analyzed, and the hyperspectral remote sensing diagnosis models of rice plant nitrogen nutritional status with these remote sensing parameters as independent variables were constructed and validated. The results indicated that the nitrogen content in rice plant organs had a variation trend of stem<sheath<spike<leaf. The spectral reflectance at visible light bands was leaf<spike<sheath<stem, but that at nearinfrared bands was in adverse. The linear and exponential models with the raw hyperspectral reflectance at 796.7 nm and the first derivative hyperspectral reflectance at 738.4 nm as independent variables could better diagnose rice plant nitrogen nutritional status, with the decisive coefficients (R2) being 0.7996 and 0.606, respectively; while the model with vegetation index (SDr-SDb)/(SDr+SDb) as independent variable, i.e., y=365.871+639.323((SDr-SDb)/(SDr+SDb)), was most fit rice plant nitrogen content, with R2=0.8755, RMSE=0.2372 and relative error=11.36%, being able to quantitatively diagnose the nitrogen nutritional status of rice.
    Soil N2O flux and its affecting factors under different land use patterns in Three Gorges Reservoir Area of China.
    LIN Shan1;FENG Ming-lei1;RUAN Lei-lei1;HU Rong-gui1;PENG Ye-xuan2;XIAO Hong-yu1;LU Lan1
    2008, 19(06):  1269-1276 . 
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    By using static chamber techniques, the N2O emission from soils under different land use patterns was measured. The results showed that the N2O flux ranged from -21 to 435 μg·m-2·h-1, and the annual N2O flux was decreased in the order of vegetable field>orchard>upland>upland transferred from paddy field>woodland, being 447.14, 313.57, 167.00, 124.875 and 7.24 mg·m-2, respectively. The N2O flux presented significant seasonal fluctuation, with the maximum in spring and summer, followed by in autumn, and the minimum in winter, which was approximately consistent with the changes of air and soil temperature. N2O flux had significant positive correlation with the soil temperature at 5 cm depth and soil NO3-N content, but no significant correlation with soil moisture and NH4+ -N contents.
    N2O emission from ricerapeseed rotation system in Chengdu Plain of Sichun Basin.
    YU Ya-jun1,2;ZHU Bo1;WANG Xiao-guo1;XIANG Hong-yan1;ZHENG Xun-hua3
    2008, 19(06):  1277-1282 . 
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    By using static chamber/gas chromatograph techniques, the N2O emission from rice-rapeseed rotation system in Chengdu Plain of Sichuan Basin was measured from June 2005 to June 2006, with its characteristics and affecting factors investigated. The results showed that the totalemission of N2O in a rotation cycle was (8.3±2.8) kg·hm-2·a-1, and the emission in rice season, rapeseed season and fallow season accounted for 30%, 65%, and 5% of the total, respectively. In rice season, the mean N2O flux was higher during alternative drainage and irrigation than during continuous flooding and drainage, and was roughly the same during continuous flooding and drainage. N application was the main driving factor for the appearance of N2O emission peak, and the lower moisture content in surface soil layer in rapeseed season and fallow season was the main cause inducing soil N2O absorption. Soil moisture, soil temperature, N application, and crop involvement affected the N2O emission to various extents, and soil moisture was the key factor affecting the N2O emission. To avoid the high frequency of dry and wet alternation in rice season or to regulate soil moisture content to a level of 50%-70% WFPS (percentage of water-filled pore space) in rapeseed season and fallow season could effectively decrease the N2O emission from the rice-rapeseed rotation system.
    Effects of elevated carbon dioxide and ozone on the growth and secondary metabolism of spring wheat.
    LI Guo-mei1,2;SHI Yi1;CHEN Xin1
    2008, 19(06):  1283-1288 . 
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    With opentop chamber (OTC), the effects of elevated CO2 (550 μmol·mol-1) and O3 (80 nmol·mol-1) and their combination on the biomass, total phenols, and flavone at different growth stages of spring wheat, as well as the yield components at maturity stage, were studied. The results showed that under elevated CO2, the biomass and yield components were significantly higher than those under ambient CO2 (342 μmol·mol-1), while under elevated O3, these parameters were significantly lower than those under ambient O3 (30 nmol·mol-1). The combination of elevated CO2 and O3 was at the ntermediate place, indicating that CO2 could mitigate the negative effects of O3, while O3 could weaken the positive effects of CO2. Elevated CO2 and O3 increased the content of total phenols in wheat leaves, and the combination of elevated CO2 and O3 had the greatest effect. However, at late growth stage, the increment of total phenols was decreased. At early growth stage, the total content of leaf flavone under elevated CO2 and O3 and their combination was lower than the control, but at maturing stage, it was in adverse.
    Effects of different irrigation patterns on the growth of maize root hair.
    HU Tian-tian1;KANG Shao-zhong1,2;YUAN Li-na1;LI Zhi-jun1;ZHANG Fu-cang1
    2008, 19(06):  1289-1295 . 
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    With split-root pot experiment and using optical and electrical microscopes, the growth of root hair of maize under different irrigation patterns, i.e., irrigated on both halves of the pot (conventional irrigation, CI), on one half only (fixed partial root zone irrigation, FPRI), and on both halves alternatively (alternate partial root zone irrigation, APRI), was observed. The observation after 40 days of treatment showed that in nonirrigated root zone of FPRI, the length proportion of root covered by vestigial root hairs was 20.96%, being higher than that in other zones. In addition to some bletting spots, the root system in irrigated zone of FPRI turned yellow, rootbranching deteriorated to some extent, and the root hair density on the section with thick root hairs was lower than that in nonirrigated zone. However, both the length proportion of root covered by vestigial root hairs (15.72%) and the deterioration of root hair were lower than those in nonirrigated zone. As for CI, the root appearance and root hair growth were similar to those of the FPRI irrigated zone. As for the early and late irrigated root zones of APRI, the root hair density on the section with thick root hairs was high. The length proportion of root covered by vestigial root hairs was 9.77% and 10.38% for these two root zones, respectively, being lower than that in any root zones of FPRI and CI. It was suggested that alternative partial root zone irrigation was more beneficial to the growth of root hair than fixed partial root zone irrigation and conventional irrigation.
    Estimation models of vegetation fractional coverage (VFC) based on remote sensing image at different radiometric correction levels.
    GU Zhu-jun1,2,3;ZENG Zhi-yuan2;SHI Xue-zheng1,3; YU Dong-sheng1;ZHENG Wei2;ZHANG Zhen-long2;HU Zi-fu2
    2008, 19(06):  1296-1302 . 
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    The images of post atmospheric correction reflectance (PAC), top of atmosphere reflectance (TOA), and digital number (DN) of a SPOT 5 HRG remote sensing image of Nanjing, China were used to derive four vegetation indices (VIs),i.e., normalized difference vegetation index (NDVI), transformed vegetation index (TVI), soiladjusted vegetation index (SAVI), and modified soiladjusted vegetation index (MSAVI), and 36 VI-VFC relationship models were established based on these VIs and the VFC data obtained from ground measurement. The results showed that among the models established, the cubic polynomial models based on NDVI and TVI from PAC were the best, followed by those based on SAVI and MSAVI from DN, with the accuracy being slightly higher than that of the former two models whenVFC>0.8. The accuracy of these four models was higher in middle-densely vegetated areas (VFC=0.4-0.8) than in sparsely vegetated areas (VFC=0-0.4). All the stablished models could be used in other places via the introduction of calibration models. In VI-VFC modeling, using VIs derived from different radiometric correction levels of remote sensing image could help mining valuable information from remote sensing image, and thus, improving the accuracy of VFC estimation.
    Effects of land use type and slope position on soil physical properties in loess tableland area.
    LI Zhi1,2; LIU Wen-zhao2;WANG Qiu-xian3
    2008, 19(06):  1303-1308 . 
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    Soil samples under different land use types and at different slope positions in the Wangdonggou watershed of loess tableland area were collected to determine their particle composition, bulk density (ρb), and saturated hydraulic conductivity (Ks), and the effects of land use type and slope position on the soil physical properties were studied in virtue of the variation coefficient and nonparameter tests. The results showed that the physical properties of soil varied in horizontal direction and vertical profile, however at the same slope position or under the same land use type, the ρb and particle composition were similar. In horizontal direction, Ks varied strongly, slit content and ρb varied weakly, and clay and sand contents varied medially. In vertical profile, soil particles had a continuous distribution, but ρband Ks varied greatly in 0-25 cm layer. With the slope degree descended, soil contained more clay and had a higher ρb, and Ks increased. At upper and middle slopes, soil physical properties were similar, and thus, could be merged into one in related researches. There was a significant difference in soil physical properties between grassland and other land use types, which was mainly due to the effects of slope position, but the soil physical properties in farmland and orchard were similar, indicating the important effects of human activities.
    Determination of 13C-enrichment in soil amino acid enantiomers by gas chromatogram/mass spectrometry.
    HE Hong-bo1;ZHANG Wei1,2;DING Xue-li1,2;BAI Zhen1,2;LIU Ning1,2;ZHANG Xu-dong1
    2008, 19(06):  1309-1316 . 
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    The transformation and renewal of amino acid enantiomers is of significance in indicating the turnover mechanism of soil organic matter. In this paper, a method of gas chromatogram/mass spectrometry combined with U-13 -C-glucose incubation was developed to determine the 13C-enrichment in soil amino acid enantiomers, which could effectively differentiate the original and the newly synthesized amino acids in soil matrix. The added U-13-C-glucose was utilized rapidly to structure the amino acid carbon skeleton, and the change of relative abundance of isotope ions could be determined by mass spectrometry. The direct incorporation of U-13C glucose was estimated by the intensity increase of m/z (F+n) to F (F was parent fragment, and n was the carbon number in the fragment), while the total isotope incorporation from the added 13C could be calculated according to the abundance ratio increment summation from m/z (Fa+1) through (Fa+T) (Fa was the fragment containing all original skeleton carbons, and T was the carbon number in the amino acid molecule). The 13C enrichment in the target compound was expressed as atom percentage excess (APE), and that of D-amino acid needed to be corrected by the coefficient of hydrolysisinduced racemization. The13C enrichment reflected the carbon turnover velocity of individual amino acid enantiomers, and was powerful to investigate the dynamics of soil amino acids.
    Landscape pattern change and its driving forces in middle and upper reaches of Dongting Lake watershed.
    LIU Ming1,2;WANG Ke-lin1
    2008, 19(06):  1317-1324 . 
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    Based on GIS and RS, the landscape pattern change in the middle and upper reaches of Dongting Lake watershed from 1980 to 2000 was studied, with its driving forces analyzed. The results showed that there was a remarkable difference in the area change of various landscape types, with the sequence of forest land>mountain paddy field>open forest land. This change mainly occurred in mountainous and hilly areas, and had a decreasing trend from the east to the west, i.e., decreased in the order of Xiangshui River valley>Zishui River valley>Yuanshui River valley>Lishui River valley. The patch shape was simple and regular from 1980 to 1995, but diversified from 1995 to 2000. The main driving forces of the landscape pattern change were the pressure of booming farming population on natural ecosystem, the dependence of watershed’s development on natural resources, the investment to protect and improve the functions of natural ecosystem, and the adjustment of agricultural polices.
    Effects of temperature on development and reproduction of Sylepta derogata Fabricius (Lepidoptera: Pyralidae).
    WU Jian-hui1,2;HUANG Zhen1,2;REN Shun-xiang1,2, ZHOU Hui-ping1,2
    2008, 19(06):  1325-1330 . 
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    By using life table parameters, the effects of seven constant temperature regimes (17, 20, 23, 26, 29, 32 and 35 ℃) on the development and reproduction of Sylepta derogata was investigated. The results indicated that the durations of egglaying, larval, pupal, and adult stages of S. derogata shortened significantly when the temperature increased from 17 ℃ to 26 ℃, but prolonged at 32 ℃ and 35 ℃. The lower development threshold temperature of S. derogata at its all development stages was 12.08 ℃, and the effective accumulative temperature was 436.2 degreedays. The survival rates of all immature stages were the highest at 26 ℃, and would be decreased when the temperature was above or under 26 ℃. The innate capacity to increase (rm), net reproductive rate (R0), and finite rate of increase (λ) reached the maximum at 29, 26 and 32 ℃, with the values being 0.1268, 415.65 and 1.185, respectively. The mean generation time (T) shortened with increasing temperature, with the maximum and minimum values of 89.11 and 28.68 days at 17 ℃ and 35 ℃, respectively.
    Effects of wheatoilseed rape or wheat-garlic intercropping on the population dynamics of Sitobion avenae and its main natural enemies.
    WANG Wan-lei;LIU Yong;JI Xiang-long;WANG guang;ZHOU Hai-bo
    2008, 19(06):  1331-1336 . 
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    Sitobion avenae (Fabricius) is one of the most important pests of winter wheat in China. An investigation was conducted at the experimental farm of Shandong Agricultural University to study the effects of intercropping oilseed rape or garlic with winter wheat on the population dynamics of S. avenae and its main natural enemies. The results showed that in most cases, the population density of S. avenae apterae was significantly lower in wheat-oilseed rape and wheat-garlic intercropping fields than in wheat monoculture field. The population density of ladybeetle and the ratio of ladybeetle to S. avenae were higher in wheat-oilseed rape intercropping field. Before May 2, the population density of aphid parasitoids in wheat-oilseed rape intercropping field was higher than that in wheat-garlic intercropping field and wheat monoculture field; and after May 5, the mummy rate of aphid parasitoids and the ratio of aphid parasitoids to S. avenae in wheat-oilseed rape intercropping field were significantly higher than those in the other two fields. In wheat-garlic intercropping field, S. avenae alatae had a higher population amount, but no significant change was observed in the population amounts of ladybeetle and aphid parasitoids. It was concluded that wheat-oilseed rape or wheat-garlic intercropping could control S. avenae in wheat fields.
    Effects of salinity and Na+/K+ in percolating water from saline-alkali soil on the growth of Litopenaeus vannamei.
    LIU Cun-qi;WANG Jun-xia;ZHANG Ya-juan;LIU Li-jing
    2008, 19(06):  1337-1342 . 
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    In order to develop shrimp farming with the percolating water from coastal saline-alkali soil, the effects of the salinity and Na+/K+ in this percolating water on the survival, growth, metabolism, and glutamic oxaloacetic transaminase (GOT), glutamicpyruvic transaminase (GPT) and Na+-K+-ATPase activities ofLitopenaeus vannameiwere investigated. The shrimps were cultured at the salinity 5, 10 and 15 and at the Na+/K+ ratios of 20, 40, 50, 60, 70 and 90 for 20 days. The results showed that the survival rate, growth rate, and enzyme activities of the shrimps were the highest at salinity 15, and the shrimps had higher survival rate, growth rate, and enzyme activities at the Na+/K+ ratios of 40 and 50, suggesting that after an appropriate preparation, the percolating water from coastal saline-alkali soil was available to culture the shrimps.
    Acute toxicity of DDT and its effects on life table demography of Moina macrocopa.
    LIU Xiao-bo1,2;XI Yi-long1;WANG Jin-xia1;HU Ke1
    2008, 19(06):  1343-1348 . 
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    The 48 h LC50 of DDT to Moina macrocopa was determined by acute toxicity test, and the effects of different concentrations (1, 8, 16, 24, 32 and 40 μg·L-1) of DDT on the life table demography of M. macrocopa was studied by life table demography. The results showed that the 48 h LC50 of DDT to M. macrocopa was 324 μg·L-1. 1-40 μg·L-1 of DDT had no significant effects on the life expectancy at birth, generation time, net reproductive rate, and gross productive rate of M. macrocopa (P>0.05), but significantly affected the intrinsic rate of population increase (rm) (P<0.05). The rm of M. macrocopa increased markedly at 8, 16 and 40 μg·L-1 of DDT, compared with the blank control, indicating that when the life table demography of M. macrocopa was used to monitor the ecological effects of sublethal concentrations of DDT, rm could be a sensitive indicator.
    Kinetic characteristics of Zn uptake by Potentilla griffithii Hook. f. var. velutina Card.
    YING Rong-rong1;DU Suo-jun1;HU Peng-jie1;ZHAO Zhi-hao1;ZHOU Xiao-yong1;TANG Ye-tao1;QIU Rong-liang1,2
    2008, 19(06):  1349-1354 . 
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    The kinetic characteristics of Zn uptake by Potentilla griffithii Hook. f. var. velutina Card. were studied with hydroponic culture under different Zn supply and its exposure time. When the Zn supply was 10 mg·L-1, the Zn concentration in shoot and root reached the peak on the 8th day, being 2.49×103 mg·kg-1 and 2.21×103 mg·kg-1, respectively; while when the supply was 100 mg·L-1, the Zn concentration in shoot reached the maximum (1.23×103 mg·kg-1) on the 16th day, but that in root did not exhibit saturation. The Zn concentration in leaf and leafstalk increased with increasing Zn supply from 0 to 160 mg·L-1, but had no increase or even decreased when the Zn supply was higher than 160 mg·L-1. The Zn concentration in root exhibited a positive correlation with Zn supply and its exposure time, and the kinetic curve of Zn uptake fitted linear-quadratic (LQ) model, i.e., fast linear uptake first and slow saturation uptake later, with the dividing point at about 1.2 hours’ exposure, which could be related with the Zn adsorption on root cell wall and the Zn transportation across the cell membrane.
    Effects of cadmium stress on the antioxidative system in Ganoderma lucidum mycelia.
    WANG Song-hua1;ZHANG-Hua2;CUI Yuan-rong1;HE Qing-yuan1, Z;HANG Qiang1
    2008, 19(06):  1355-1361 . 
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    The study on the effects of different concentration (0, 10,50, 100, 200 and 400 μmol·L-1) cadmium (Cd) on the antioxidative system in Ganoderma lucidum mycelia indicated that with increasing concentration of Cd, the fresh mass and the proline, total polysaccharides, and reduced polysaccharides contents of G. lucidum mycelia decreased, but non-protein thiol (NPT) content increased. At 400 μmol·L-1 of Cd, the NPT content increased dramatically, being 5.7 times higher than control. Within the range of test Cd concentrations, the activities of CAT, GR and POD increased first and decreased then, with the peak at 100 μmol·L-1 of Cd, while the activities of LOX and SOD increased with increasing Cd concentration, with the maximum at 400 μmol·L-1 of Cd. Polyacrylamide gel electrophoresis analysis revealed that 100-400 μmol·L-1 of Cd induced two additional isozymes bands of Mn-SOD, 10-200 μmol·L-1 of Cd increased the intensity of constitutive isozymes of CAT, POD, SOD and LOX, while 400 μmol·L-1 of Cd decreased the intensity of isozymes of POD significantly.
    Chemical forms and ecological effect of soil Mn in liver cancer’s high incidence area in Zhujiang River Delta, China.
    DOU Lei1,2;ZHOU Yong-zhang1,2;LI Yong1,2;MA Jin1,2;AN Yan-fei1,2;DU Hai-yan3;LI Zhan-qiang4
    2008, 19(06):  1362-1368 . 
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    The samples of surface soil, deep soil, and vegetables were collected from the liver cancer’s high and low incidence areas in Zhujiang River Delta to study the relationships between soil Mn forms and vegetables’ Mn enrichment. The results showed that the soil Mn in study area was mainly derived from parent materials, and rarely come from human activities. The average soil Mn content in liver cancer’s high incidence area was 577.65 mg·kg-1, being significantly lower than that of liver cancer’s low incidence area (718.04 mg·kg-1) and whole country (710 mg·kg-1). The Mn forms in high incidence area were mainly of residual Mn and FeMn oxide, and less of water soluble Mn and exchangeable Mn, with the sum of the latter two’s distribution coefficients being not higher than 4%. In low incidence area, the distribution pattern of soil Mn forms was similar to that in high incidence area, but the absolute contents of the Mn forms were significantly higher. Soil total Mn and soil pH had significant effects on soil Mn forms. There existed significant positive correlations between soil total Mn and the Mn forms of Fe-Mn bound, humic acid bound, carbonate bound, and residual, and negative correlations between soil pH and soil water soluble and organic bound Mn forms. Among the test five kinds of vegetables, Youmai lettuce and Chinese cabbage in liver cancer’s high incidence area had a significantly lower Mn content than in low incidence area, while the other three had less difference. The Mn enrichment in test vegetables was positively correlated with to the content of soil available Mn (sum of water soluble Mn and exchangeable Mn), but had no correlations with the contents of soil total Mn and other Mn forms.
    Effects of intercropping different crops with maize on the Cd uptake by maize.
    LI Ning-yu1,2;LI Zhi-an1; DING Yong-zhen1,2;ZOU Bi1;ZHUANG Ping1
    2008, 19(06):  1369-1373 . 
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    A greenhouse experiment was conducted to investigate the effects of intercropping 7 kinds of crops on the Cd uptake by maize (Zea mays L.). The results showed that most intercrops had no significant effects on the growth of maize, only with purple haricot reduced the maize biomass by 32.2% of the control. Legume crops enhanced the total quantity of Cd in maize in a great magnitude, and chickpea worked most efficiently, which doubled the Cd quantity in maize. The 7 intercrops showed different capability of Cd uptake, among which, rape and amaranth absorbed larger amount of Cd, with a Cd level of 53.9 mg·kg-1 and 51.0 mg·kg-1 in their aboveground parts, respectively, and of 91.8 mg·kg-1 in amaranth root when the soil Cd content was 3 mg·kg-1 soil. There was an interaction between maize and intercrops in Cd uptake. Legumes absorbed smaller amount of Cd but significantly increased the Cd uptake by maize, while amaranth was in adverse. Rape had a higher level of Cd concentration in its shoot, but reduced the Cd in aboveground part of maize. It was indicated that if maize was used for phytoremediation of Cdcontaminated soil, a higher efficiency of Cd removal could be achieved by intercropping it with legumes. Rape and amaranth could be the two promising plants for phytoremediation because of their high Cd accumulation.
    Soil biological evaluation on ecological remedy of damaged riparian.
    ZHANG Yu-bo1;YANG Hai-jun1;WANG De-li1;XIAO Zhi-jian2;HAN Ji-yue3
    2008, 19(06):  1374-1380 . 
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    In order to explore the theory and technique about the restoration of damaged riparian ecosystem, this paper evaluated the remedy effect of artificial spotted habitats that have been built for four years on the damaged riparian ecosystem based on soil biological principles. The results showed that in restored area, the quantities of various soil microbial species were significantly higher, and the species, quantity, and biodiversity of soil animal as well as the contents of soil organic matter, nitrogen, phosphorus, and potassium were all higher than those in unrestored area. After successful restoration, the soil conditions in damaged riparian were significantly improved, which resulted in an increase in soil biodiversity and enhanced the stability of this ecosystem. The remedy technique for the damaged riparian by using artificially spotted habitats not only consumed less cost, but also exhibited great ecological, landscape, and social values, providing a new model for the ecological reconstruction of damaged concrete riparian and the approximately natural remediation of damaged riparian.
    Research advances in molecular ecology of ammonia oxidizing bacteria.
    DONG Lian-hua;YANG Jin-shui;YUAN Hong-li
    2008, 19(06):  1381-1388 . 
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    Ammonia oxidizing bacteria (AOB) play an important role in global nitrogen cycle. This paper reviewed the research advances on molecular ecology of ammonia oxidizing bacteria. The analysis of systematic evolution of AOB based on 16S rRNA reveals that the evolution of AOB is quite simple, which belongs to β and γ subgroup of Proteobacteria. This paper also introduced the main molecular ecological methods in the study of AOB, which included denature gradient gel electrophoresis (DGGE), terminal restriction fragment length polymorphism (TRFLP), fluorescence in situ hybridization (FISH), and realtime PCR, summarized the effects of ecological factors on the communities and populations of AOB, and prospected the research directions on molecular ecology of AOB.
    Regulation of soil nitrification with nitrification inhibitors and related mechanisms.
    SUN Zhi-mei1,2;WU Zhi-jie1;CHEN Li-jun1;JIA Li-bin3
    2008, 19(06):  1389-1395 . 
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    To improve the use efficiency of fertilizer N while alleviate its pollution is one of the keys in ensuring the high yield and good quality of agricultural products and the sustainable development of agriculture and environment, for which, applying nitrification inhibitors to retard the course of soil nitrification is an efficient measure. In this review, the definition, screening criteria, major varieties being widely used, and action mechanisms of nitrification inhibitors were introduced, and the existing problems and prospects in related researches were discussed.
    Toxic effect of musk ketone based on the determinations of wheat (Triticum aestivum) seed germination and root elongation.
    FAN Fei1,2;ZHOU Qi-xing1,3;WANG Mei-e1
    2008, 19(06):  1396-1400 . 
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    Through the determinations of wheat (Triticum aestivum) seed germination and seedling growth, the toxic effect of emerging pollutant musk ketone was investigated. The results showed that 10 mg·kg-1 of musk ketone could significantly inhibit the seed germination rate (P<0.05) and the seedling’s root and shoot elongation of wheat (P<0.01), and there existed a significant (P<0.01) doseeffect relationship between musk ketone and root and shoot elongation, suggesting that the seedling’s root and shoot elongation of wheat could indicate the pollution extent of musk ketone in soil. The correlation analysis revealed that under soil musk ketone pollution, there was a significant (P<0.01) positive correlation between root and shoot elongation, and a significant (P<0.01) negative correlation between seed germination and biomass. Besides the solubility in water, the toxicity of organic pollutant was related to its chemical characters, and its action mechanisms to the target organism.
    Effects of residual heat and chlorine in cooling water from coastal power plant on Calanus sinicus. Effects of residual heat and chlorine in cooling water from coastal power planton Calanus sinicus.
    JIANG Zhi-bing1,3;ZENG Jiang-ning1,2;CHEN Quan-zhen1;LIAO Yi-bo1,3;XU Xiao-qun1;SHOU Lu1;LIU Jing-jing1; GAO Ai-gen1
    2008, 19(06):  1401-1406 . 
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    According to the practical operation of coastal power plant cooling system, a simulation study was conducted on the effects of residual heat and chlorine in the cooling water on Calanus sinicus. The results showed that the thermal tolerance of C. sinicus to the cooling water was decreased with increasing exposure duration but increased with increasing acclimation temperature. When the acclimation temperature was 16 ℃-27 ℃, the lethal temperature ofC. sinicus under thermal shock for 15, 30 and 45 min was 29.9 ℃-31.7 ℃, 29.4 ℃-31.0 ℃ and 28.9 ℃-30.3 ℃, and that of C. sinicus continually exposed to increasing temperature for 24 and 48 h was 26.9 ℃-28.5 ℃ and 26.4 ℃-28.0 ℃, respectively. When the acclimation temperature increased to a certain degree, the thermal tolerance of C. sinicus maintained at a stable level. The toxicity of residual chlorine on C. sinicus enhanced with increasing acclimation temperature, temperature increment, and exposure duration.