Table of Content

20 December 2008, Volume 19 Issue 12

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Articles

Comparison of light characteristics in different size gaps in eastern Liaoning montane secondary forests.

CHEN Mei^1,2;ZHU Jiao-jun¹;YAN Qiao-ling¹;WU Xiang-yun²;TAN Hui¹

2008, 19(12):  2555-2560 . 

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With three different size gaps (G₁, 670 m²; G₂, 290 m²; and G₃, 90 m²) in eastern Liaoning montane secondary forests of China as test objects, and through a continuous measurement of light intensity, the spatiotemporal distribution of photosynthetic photon flux density (PPFD) in the gaps was compared. The results showed that the diurnal variation of PPFD in the gaps was greater at northern than at southern position. The larger the forest gap, the broader the higher PPFD value area, and the more obvious the heterogeneity. As for the monthly variation of PPFD, the maximum PPFD at each position of the gaps appeared at the beginning of growth season (i.e., in April and May), while the minimum PPFD occurred in different months. The maximum PPFD at the eastern and western positions of each gap was basically appeared in the same months, and the PPFD was significantly higher in spring than in summer and autumn (P<0.05). The mean monthly PPFD at the centers of G₁, G₂, and G₃ was 66.59%, 49.05%, and 30.37% of full sunlight, respectively, and in growth season, the PPFD at gap center was 37.8, 27.9 and 10.3 times higher than that at understory. It was suggested that owing to the different size and shape of forest gap and the effects of landform, the light intensity and its distribution in forest gap were different, being the key factors leading to the heterogeneity of regeneration pattern and the variation of species composition in forest gap.

Microclimatic characteristics of different size gaps in Pinus koraiensis-dominated broadleaved mixed forests.

DUAN Wen-biao; WANG Jing; LI Yan

2008, 19(12):  2561-2566 . 

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By the help of HOBO automatic weather stations, the microclimatic characteristics of different size forest gaps in Pinus koraiensis-dominated broadleaved mixed forests in Xiaoxing’an Mountains were studied during growth season, with closed forest and bare ground as the control. The results showed that the diurnal variation of illumination, ground temperature, and air temperature of the gaps and the controls, as well as the change trend of the microclimatic factors during growth season, all presented a single peak curve. The diurnal variation pattern of relative humidity of the gaps and the control was high-low-high, being higher in early morning and evening and lower at noon. The relative humidity during growth season also presented a single peak curve, and was the highest for closed forest, followed by small, medium, and large forest gaps, and bare ground. The amount and the times of precipitation tended to decrease with increasing forest canopy, and the precipitation amount in large gaps was about 1.4 times as much as that in small gaps. During growth season, the maximum wind speed above bare ground, large, medium, and small gaps, and closed forest was 3.34, 2.97, 2.87, 2.41 and 1.84 m·s^-1, respectively.

Carbon storage maturity age of Larix olgenisis and L. kaempferi.

YIN Ming-fang¹; ZHAO Lin¹; CHEN Xiao-fei²; GAO Song²; HOU Chuan-sheng³

2008, 19(12):  2567-2571 . 

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The successive years and average increments of the volumes of Larix olgensis and L. kaempferi were computed by Trunk Analysis, and the carbon content and carbon density of L. olgensis and L. kaempferi at their different age stages were measured with Germany Vario EL Ⅲ element analyzer, aimed to approach the carbon storage maturity age of the two tree species. The results indicated that L. olgensis and L. kaempferi had a volume maturity age of 48.3 and 49.3 years, respectively, and the change trend of their carbon density was basically identical. The maximum carbon density was presented in the 30th year for L. olgensis and the 35th year for L. kaempfer. The successive years carbon storage of L. kaempferi was larger than that of L. olgensis, but the carbon storage maturity age was in adverse. The average carbon storage of L.kaempferi was also larger than that of L. olgensis. Through simulating the curve equations of successive years and average carbon storages, the carbon storage maturity age of L. olgensis and L. kaempferi were computed as 48.7 years and 47.7 years, respectively.

Characteristics of seed germination of rare plant species Reaumuria trigyna in west Ordos.

ZHANG Ying-juan^1,2;WANG Yu-shan²;LI Qing-feng¹

2008, 19(12):  2572-2576 . 

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Reaumuria trigyna is a relic species in the desert shrubbery vegetation in arid regions of northwestern China, and plays an important role in the maintenance of the stability of desert vegetation. In this paper, the seed traits and germination strategy of R. trigyna under different environmental conditions, e.g., light, temperature, soil moisture, and sand bury, were investigated. The results showed that R. trigyna seed had high vigor and high germination rate, and endured reserve. The seed could germinate either in light or in darkness, and the optimal temperature for germination was 20 ℃-25 ℃ or 15 ℃/25 ℃, with the germination rate being 93%. The seed could start to germinate when soil moisture content was 2%, and the germination rate was the highest (89%) when the moisture content was 12%. The optimal sand burial depth of R. trigyna seed was 1 cm, and no seed would germinate when the sand burial depth was >5 cm. Sand burial depth had significant effects on the seedling’s emergence percentage and growth height, but lesser effects on seedling’s mass. Soil moisture and sand burial depth were the main environmental factors limiting the seed germination and seedling emergence of R. trigyna. The high seed germination rate of R. trigyna enhanced the survival risk of its seedlings, which was unfavorable to its handling with the extreme changes of desert environment. Such a character of R. trigyna seed was one of the factors causing the species endangered.

Population life process and spectral analysis of rare and endangered plant Alsophila spinulosa.

SONG Ping¹;HONG Wei¹;WU Cheng-zhen¹;FENG Lei²;FAN Hai-lan¹

2008, 19(12):  2577-2582 . 

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According to population life table and survival analysis theory, the time-specific life table and the survival function curve of Alsophila spinulosa population were established and drawn based on height class, and the life process of the population was analyzed. The results revealed that the population structure of A. spinulosa was of the type ascending at early stage and stable at late stage. The peak of expected life appeared at the 4th age class, indicating the relative good survival quality at this phase, and the survival curve belonged to the typical form of Deevey-Ⅲ. There existed three death peak phases in the population life process, i.e., the growth stages from 2nd to 3rd age class, from 10th to 11th age class, and from 12th to 13th age class. With the increase of age class, the population survivability dropped down monotonously, and the accumulative mortality rose up correspondently. The variation extent was high in early phase and low in anaphase. The death density function curve displayed the characteristics of descent in early phase and stabilization in anaphase, and the concave point occurred at 4th age class. Spectral analysis showed that the quantitative fluctuation of A.spinulosa population was multi-harmonic superposition with large cycles containing small cycles. The influences of these cycles dropped with the diminishment of cycle length, and the effect of fundamental wave was most prominent.

Biology and phenology of Xanthoceras sorbifolia in Wudan area.

MA Li-ping;WANG Li-hua;YIN Li-ming;LIU Bo; CHEN Wei

2008, 19(12):  2583-2587 . 

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Based on the continuous observation on located trees and branches, the phenology and sexual reproductive process of Xanthoceras sorbifolia Bunge in an annual growth cycle in Wudan area were investigated, and the relationships between fruit growth process of X. sorbifolia and effective accumulative temperature as well as the quantitative dynamics of flowers and fruits were studied. The results showed that the phenology of X. sorbifolia had a significant linear correlation with effective accumulative temperature, and there was a time sequence in the male flower silk elongating and antheral unfolding. The fruits of X. sorbifolia experienced three times of dropping during their growth process. The pollination rate was 26.4%, flower dropping rate was 73.6%, and fruit dropping rate was 92.9%, suggesting that the dropping of flowers and fruits was very serious. The fruits had a quicker vertical growth from early June to mid June and a quicker horizontal growth in the last ten-day of June, with the highest ratio of vertical to horizontal length being 2.17. The individuals of X. sorbifolia had definite differences in their phenology, which was disadvantageous to the cross pollination among the individuals, and the enhancement of pollination rate.

Relationships of soil moisture content with precipitation and evaporation in rehabilitated forests in degraded limestone red-soil region of Jiangxi Province.

LIU Yuan-qiu¹;WANG Hong-sheng¹;GUO Sheng-mao¹;FU Min-ning²

2008, 19(12):  2588-2592 . 

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By using time series analysis, the relationships of 0-40 cm soil moisture content with precipitation and evaporation in four main rehabilitated forests in degraded limestone red-soil region of Xiushui County, Jiangxi Province were studied. The results showed that in the four rehabilitated forests, the previous month’s soil moisture content had stronger effects on the current month’s soil moisture content in 0-40 cm and 20-40 cm layers, but had lesser effects on that in 0-10 cm layer. The soil moisture content in 20-40 cm layer was mainly affected by current month’s precipitation, while that in 0-10 cm layer was mainly affected by current month’s evaporation. The correlation coefficient between current month’s precipitation and soil moisture content was the largest in pure Liquidambar formosana plantation, and the auto-interrelation coefficient of soil moisture content was larger in mixed forests than in pure L. formosana plantation.

Responses of Agriophyllum squarrosum phenotypic plasticity to the changes of soil nutrient and moisture contents and population density.

HUANG Ying-xin^1,2;ZHAO Xue-yong¹;ZHANG Hong-xuan³; LUO Ya-yong^1,2; MAO Wei^1,2

2008, 19(12):  2593-2598 . 

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This paper studied the phenotypic plasticity of Agriophyllum squarrosum under effects of soil nutrient and moisture contents and population density. The results showed that with the increase of soil nutrient content, the root/shoot ratio of A. squarrosum was decreased from 0.135 to 0.073. However, soil moisture content and population density had less effect on the root/shoot ratio. The plasticity of reproductive allocation of A. squarrosum as responding to the changes of soil nutrient and moisture contents was a “real plasticity”, and the allocation was negatively correlated with soil nutrient content but positively correlated with soil moisture content. When soil nutrient content was high or moisture content was low, the reproductive allocation of A.squarrosum changed larger with plant size. Population density had no effects on the reproductive allocation, while plant size conditioned the allocation. Among the three test affecting factors, soil nutrient content had the greatest effects on the morphological characters and biomass of A.squarrosum.

Responses of marsh wetland plant Calamagrostis angustifolia to exogenous nitrogen input.

LIU De-yan^1，2;SONG Chang-chun¹

2008, 19(12):  2599-2604 . 

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Taking the typical marsh wetland plant Calamagrostis angustifolia in Sanjiang Plain of Northeast China as test material, a field control experiment was conducted to study its leaf morphological characters, chlorophyll content, and aboveground biomass under effects of different levels of exogenous nitrogen input in 2004—2007. Four nitrogen (N) fertilization treatments, i.e., 0 (CK), 6 g·m^-2·a^-1 (N₆), 12 g·m^-2·a^-1 (N₁₂) and 24 g·m^-2·a^-1 (N₂₄), were installed. The results showed that there were no significant differences in the leaf length and width among different N fertilization treatments, but the specific leaf area was the smallest (149.54±18.27 cm²·g^-1) under N₁₂, which indicated that the leaves of C. angustifolia were thicker under this N treatment. The leaf chlorophyll content showed a unimodal distribution over the growth season, which increased with the amount of N input before the peak. The peak occurred earlier under N₁₂ and N₂₄ than under N₆ and CK. After the peak, the chlorophyll content declined sharply under N₂₄ but slowly under N₆, indicating that moderate N input could delay leaf senescence. Continuous high N (N₂₄) input might advance plant growth, while leaf senescence would occur earlier. By the end of growth season both in 2005 and in 2007, the aboveground biomass of C. angustifolia increased with increasing N input, but declined by 53.72% after 4 years continuous high N (N₂₄) input (in 2007), compared with that after 2 years treatment (in 2005).

CO₂ exchanges between mangrove-and shoal wetland ecosystems and atmosphere in Guangzhou.

KANG Wen-xing;ZHAO Zhong-hui;TIAN Da-lun;HE Jie-nan;DENG Xiang-wen

2008, 19(12):  2605-2610 . 

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Based on the investigation of biomass and the measurement of CO₂ and CH₄ fluxes, the CO₂ exchanges between mangrove- and shoal wetland ecosystems and atmosphere in Guangzhou were studied, and the CO₂ absorption capability of the wetlands vegetation net productivity as well as the carbon sink function of the wetlands under different waterlogged conditions (perennial, intermittent, and no water-logging) was analyzed. As for mangrove wetland ecosystem, its vegetation net productivity absorbed 33.74 t·hm^-2·a^-1 of CO₂, and soil emitted 12.26 t·hm^-2·a^-1 of CO₂ (including the greenhouse effect amount of CH₄ converted into that of CO₂), illustrating that mangrove wetland had a 21.48 t·hm^-2·a^-1 net absorption of CO₂, being a strong carbon sink. For shoal wetland ecosystem, its vegetation net productivity absorbed 8.54 t·hm^-2·a^-1 of CO₂, and soil emitted 5.88 t·hm^-2·a^-1 of CO₂ and 0.19 t·hm^-2·a^-1 of CH₄. If converting into carbon, the wetland absorbed 2.33 t C·hm^-2·a^-1, and soil emitted 1.74 t C·hm^-2·a^-1 (including the carbon in CH₄), illustrating that shoal wetland fixed 0.59 t C·hm^-2·a^-1, being a weak carbon sink. If the greenhouse effect amount of CH₄ was converted into that of CO₂, the soil emitted 9.78 t·hm^-2·a^-1 of CO₂, which was 1.24 t·hm^-2·a^-1 more than the absorption. As a result, shoal wetland was a weak carbon source. Between the two test greenhouse gases, CH₄ was the main one emitted under perennial water-logging, while CO₂ was that under no water-logging. Moreover, the wetland under perennial water-logging had the strongest carbon sink function, while that under no water-logging was in adverse.

Contribution of soil seed bank to the regeneration of damaged vegetation on floodplain.

WANG Zeng-ru^1,2;XU Hai-liang¹;YIN Lin-ke¹;LI Ji-mei¹;ZHANG Zhan-jiang³;LI Yuan¹

2008, 19(12):  2611-2617 . 

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A field germination experiment of soil seed bank was carried out on two typical floodplains in the lower reaches of Tarim River, and a comparison was made between the soil seed banks and corresponding seedling banks on the two floodplains, aimed to assess the contribution of soil seed bank to the regeneration of damaged vegetation. The results showed that there were 12 plant species in the soil seed banks, and the life forms were mainly perennial herbs and shrubs. The soil seed banks had a density of 282.5 seeds·m^-2 and 173.2 seeds·m^-2, and the seeds in top soil (0-2 cm) accounted for 76.9% and 71.0% of the total, respectively. The soil seed banks had significant effects on the seedlings species composition and density, and 84.7% and 99.4% of the seedlings on the two floodplains were emerged from corresponding soil seed banks. The similarity coefficient between soil seed bank and seedling bank of the two floodplains was 0.72 and 0.63, respectively, and there existed significant positive correlation between seedling density and soil seed bank density, illustrating that soil seed bank made important contribution to the natural regeneration of vegetation.

Roles of nitrogen fertilization in regulating the physiological bases of fiber specific strength formation in cotton bolls bloomed at different dates.

MA Rong-hui;XU Nai-yin;ZHANG Chuan-xi;LI Wen-feng;FENG Ying;QÜ Lei;WANG You-hua;ZHOU Zhi-guo

2008, 19(12):  2618-2626 . 

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To study the roles of nitrogen fertilization in regulating the physiological bases of fiber specific strength formation in cotton bolls bloomed at different dates (July 15, July 25, and September 10; expressed as PSB, SB, and AB, respectively), field experiments were conducted in two sites with different ecological conditions, i.e., Nanjing (middle lower reach of Yangtze River Valley) and Xuzhou (Yellow River Valley). Three treatments (0, 240, and 480 kg N·hm^-2) were installed. The results showed that comparing with applying optimum nitrogen (240 kg N·hm^-2), no N application decreased the N content and increased the C/N in the leaves subtending cotton bolls significantly, and the effects increased with postponing blooming date, which, to a great extent, led to the decreases of the capabilities of the leaves subtending cotton bolls bloomed at SB and AB in the accumulation and transportation of photosynthetic products, the relative growth rate of fiber in cotton bolls, and the activities of key enzymes (sucrose synthetase and β-1,3-glucanase) during the middle-later period of fiber development, and also, the decline of cellulose speedily accumulating duration in cotton fiber and of the fiber specific strength in the bolls bloomed at SB and AB. On the contrary, applying high nitrogen (480 kg N·hm^-2) increased the N content but decreased the C/N in the leaves subtending cotton bolls significantly, and the effects decreased with postponing blooming date, which decreased the distribution proportion of photosynthetic products to fiber, the key enzyme activities during the early-middle period of fiber development, and the momentary rate of cellulose accumulation in the fiber of the bolls blooming at PSB and SB, resulting in a significant decrease of the fiber specific strength. It was suggested that appropriate N application could regulate the ‘source-sink’ relation of cotton, and benefit the high fiber specific strength formation in cotton bolls bloomed at different dates.

Effects of post-anthesis irrigation frequency on the grain quality of strong gluten winter wheat cultivars.

YAO Feng-juan;HE Ming-rong;LI Fei;XU Liang-liang;HUANG Chuan-hua;QU Mu

2008, 19(12):  2627-2631 . 

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In order to investigate the effects of post-anthesis irrigation frequency on the grain quality of strong gluten winter wheat, two cultivars Jimai 20 and Gaocheng 8901 were subjected to a series of irrigation frequencies under rainfall proof conditions, with their grain yield and grain quality (farinograph parameters and loaf volume) and protein composition evaluated. The results indicated that with increasing irrigation frequency, the grain yield of the two cultivars, their wheat flour dough development time, dough stability time, and loaf volume were noted to be increased first but decreased then. The grain yield and quality of Gaocheng 8901 were the highest when irrigated once after anthesis, while those of Jimai 20 were the best when irrigated twice after anthesis, respectively. The contents of monomeric protein, soluble glutenin, insoluble glutenin, total glutenin, flour protein, and wet gluten in the grains displayed the similar trends. Stepwise regression analysis showed that under the test post-anthesis irrigation frequencies, the key factor affecting dough stability time was insoluble glutenin content, and loaf volume was significantly correlated with total glutenin content. It was suggested that to maintain the quality stability of high grade strong gluten winter wheat, irrigation management should take the improvement of grain protein composition, and glutenin in particular, as the target.

Effects of salicylic acid on D₁ protein phosphorylation and PSⅡ performance in wheat leaf chloroplasts under high temperature and high light stress.

MA Pei-fang¹;LI Li-hong² ;YANG Ya-jun¹;ZHAO Hui-jie¹;FU Xiao-ji¹;ZHANG Chao-nan¹

2008, 19(12):  2632-2636 . 

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To study the effects of salicylic acid (SA) on the D₁ protein phosphorylation and PSⅡ performance in wheat (Tritivum aestivum L.) leaf chloroplasts under high temperature and high light, the wheat leaves at grain-filling stage were sprayed with SA solution (0.5 mmol·L^-1) or water (as control), and then subjected to 35 ℃ and 1 600 μmol·m^-2·s^-1 for various hours. The changes in electron transport rate (ETR), net photosynthetic rate, chlorophyll fluorescence parameters, and relative amount of phosphorylated and nonphosphorylated D₁ protein in thylakoid membrane were compared. The results showed that foliar spraying SA effectively inhibited the degradation of D₁ protein under high temperature and high light stress, and maintained the D₁ protein phosphorylation, ETR of whole chain and PSⅡ, F_v/F_m (the maximal photochemical efficiency of PSⅡ), Ф_PSⅡ (the actual photochemical efficiency of PSⅡ), q_P (the photochemical quenching coefficient), and P_n (net photosynthetic rate) at a higher level, indicating that exogenous SA could mitigate the damage effect of high temperature and high light on wheat leaf photosynthetic apparatus and benefit PSⅡperformance via regulating the turnover of D₁ protein in chloroplasts.

Effects of non-sufficient irrigation with saline water on soil water-salt distribution and spring corn yield.

JIANG Jing;FENG Shao-yuan;SUN Zhen-hua;HUO Zai-lin

2008, 19(12):  2637-2642 . 

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A field experiment was conducted to study the effects of sufficient and non-sufficient irrigation with saline water on the soil water-salt distribution and spring corn yield in the middle reach of Shiyanghe River Basin. The results showed that under both sufficient and non-sufficient irrigation, the peak value of soil water content all appeared during irrigation period, and the variation range of the water content was higher under sufficient than under non-sufficient irrigation. Soil salinity was positively correlated with the salinity of irrigation water. At the same salinity of irrigation water, the soil salinity under non-sufficient irrigation was lower than that under sufficient irrigation. Under non-sufficient irrigation, the soil layer with salt accumulation was moved up, but the water and salt contents in 80-100 cm soil layer were less affected by the amount and salinity of irrigation water. Comparing with that under fresh water irrigation, the spring corn yield under saline water irrigation was decreased by 15%-22%. Under non-sufficient irrigation with 9 g·L^-1, 6 g·L^-1, and 3 g·L^-1 of saline water, the average salt content in 1 m soil layer after harvest was decreased by 8.1%, 12.4%, and 18.4%, and the corn yield was only decreased by 3.4%, 6.8%, and 3.0%, respectively, compared with those under sufficient irrigation.

Effects of temperature regime on low-light tolerance of Cucumis sativus seedling leaves in their photosynthesis.

LI Wei^1,2, SUI Xiao-lei¹, ZHANG Zhen-xian¹

2008, 19(12):  2643-2650 . 

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In a phytotron, the effects of three temperature regimes (day/night 25 ℃/18 ℃, optimal temperature; 15 ℃/9 ℃, suboptimal temperature; and 9 ℃/7 ℃, low temperature) on the low-light (75-85 μmol·m^-2·s^-1) tolerance of two Cucumis sativus cultivars (shade-susceptible Jinyan 2 and shade-tolerant Deltastar) seedling leaves in their photosynthesis were studied. The results showed that under low light, the SPAD, net photosynthesis rate (P_n), stomatal conductance (G_s), transpiration rate (T_r), water use efficiency (WUE), actual photochemical efficiency of PSⅡ in the light (Φ_PSⅡ), and photochemical quenching of chlorophyll fluorescence (q_P) of cucumber leaves decreased, with the decrement getting more with decreasing temperature, while the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities were in adverse. During the recovery process after low-light stress relieved, the parameters of gas exchange and chlorophyll fluorescence of the leaves recovered gradually, and the recovery of some gas exchange parameters lagged to that of chlorophyll fluorescence parameters. Under low light, the lower the temperature, the more damage the photosynthesis apparatus suffered, and the lesser tolerance to low light the cucumber leaves had in their photosynthesis. During the low temperature and low light treatment period, the decrease of P_n, Φ_PSⅡ, and q_P was more obvious for Jinyan 2 than for Deltastar; and during the relief period, the recovery of these parameters was slower for Jinyan 2 than for Deltastar. It was indicated that Jinyan 2 had weaker tolerance to low temperature and/or low light in its photosynthesis than Deltastar.

Analysis on quantitative trait loci associated with leaf chlorophyll content and their interactions with environment at late growth stage of rice.

SUN Xiao-xia^1,2; DENG Jia-yao²;JIANG Bao-yue²;JIA Xiao-li²;XIONG Jun^1,2;LIN Wen-xiong^1,2

2008, 19(12):  2651-2655 . 

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By using a population of 123 F₁₂ lines (recombinant inbred lines, RILs) derived from a cross between India variety Dular and Japanica variety Lemont, an analysis of quantitative trait loci (QTL) was conducted for the flag leaf chlorophyll content of rice. The chlorophyll content was determined by SPAD-502 in 2005 and 2006, respectively, and software QTLMapper 1.6 was applied to analyze the QTL, including the additive and epistatic effects and the QTL interactions with environment for chlorophyll content. A total of ten QTL showing additive effects on chlorophyll content (Chl) were detected, which accounted for 73.51% of the phenotypic variation. The percentage of phenotypic variation explained by single QTL was 2.08%-20.14%, and the interactions of 6 QTLs with environment (AE) were significant. Epistasis analysis indicated that there existed 13 significant additive×additive interactions on chlorophyll content, 6 pairs of which were significant in additive×additive interactions with environment (AAE).

Effects of graft and nitrogen supply level on water consumption and water use efficiency of solar greenhouse cucumber under traditional irrigation.

CHEN Xiao-yan¹;WANG Lu¹;WANG Yong-quan²;SUN Huan-ming²;REN Hua-zhong¹

2008, 19(12):  2656-2660 . 

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An experiment was conducted in solar greenhouse to study the effects of graft and different nitrogen (N) supply levels (0, 110, and 331 kg·hm^-2) on the water consumption and water use efficiency (WUE) of cucumber (Cucumis sativus L.) under traditional irrigation. The results showed that when topdressing 331 kg N·hm^-2, the water consumption of grafted cucumber was the highest, being 3 350 m³·hm^-2 and 2 181 m³·hm^-2 in winter-spring and autumn-winter cropping, so did the WUE, being 27.2 kg·m^-3 and 36.9 kg·m^-3, respectively. Comparing with those of self-rooted cucumber, the water consumption, economic yield, and WUE of grafted cucumber under the same N topdressing levels were increased by 3%-6%, 28%, and 20.9%, respectively, and the water consumption and WUE of grafted cucumber were increased with increasing N supply level. The water consumption of self-rooted cucumber also increased with increasing N supply level, but its WUE was the highest when the N supply was 110 kg·hm^-2. It was indicated that graft could markedly promote the water consumption and WUE of cucumber, and the effect was more markedly with increasing N supply level. To increase N supply could also markedly promote the water consumption of self-rooted cucumber, but the WUE would be lower when excessive N was supplied.

Strong stem effect and physiological characteristics of rice plant under rice-duck farming.

WANG Qiang-sheng¹;ZHEN Ruo-hong^1,2;DING Yan-feng¹;WANG Shao-hua¹

2008, 19(12):  2661-2665 . 

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A field plot comparison experiment was conducted to study the strong stem effect and physiological characteristics of rice plant under rice-duck farming. The results showed that under rice-duck farming, the morphology of rice plant changed obviously, and the carbohydrate content and C/N ratio of the plant as well as the dry matter output from rice stem increased significantly, due to the activities of duck in paddy field. In the meantime, the length of basal internodes decreased by 2.88%, while the stem diameter, stem mechanical strength, and stem lodging resistant index increased by 64.90%, 11.78%, and 10.95%, respectively. Rice-duck farming increased the root mass and root vitality in deeper soil layers, and decreased the proportion of black roots by 16.63%. It was indicated that rice-duck farming benefited the formation of strong rice stem and increased the stress resistance of rice plant, which would be favorable to the stable and high-yielding of rice.

Effects of rice-duck farming on paddy field’s methane emission.

ZHAN Ming; CAO Cou-gui; WANG Jin-ping; YUAN Wei-ling; JIANG Yang; GAO Da-wei

2008, 19(12):  2666-2672 . 

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By using closed-chamber technique, the characteristics of CH₄ emission from an integrated rice-duck ecosystem were studied in 2006 and 2007. The results showed that comparing with conventional flooded rice ecosystem (CK), integrated rice-duck system (RD) was distinguished in its high dissolved oxygen (DO) in field surface water and significantly lower CH₄ emission, due to the activities of duck. In 2006, the average CH₄ emission flux and the total CH₄ emission during the whole rice growth period of RD were 6.84±1.49mg·m^-2·h^-1 and 19.34±1.15 g·m^-2, being 32.7% and 26.3% lower than those of CK (10.17±1.25 mg·m^-2·h^-1 and 26.25±2.17 g·m^-2), respectively; while in 2007, the values of the two test items of RD were 7.68±0.74 mg·m^-2·h^-1 and 18.41±1.05 g·m^-2, being 19.0% and 19.3% lower than those of CK (9.53±0.40 mg·m^-2·h^-1 and 22.81±0.75 g·m^-2), respectively. The emission flux of CH₄ had two peaks, being appeared at tillering and heading stages, respectively. The seasonal fluctuations of CH₄ emission flux had significant positive correlations with soil temperature and soil dissolved organic carbon content (DOC), but no obvious correlation with soil total organic carbon.

Analysis on urban spatial expansion process in Shenyang City in 1979-2006.

WANG Hou-jun^1,2;LI Xiao-yu²;ZHANG Zu-lu¹;HE Xing-yuan²;CHEN Wei²;CHEN Yan-bin¹;HU Jian-bo²

2008, 19(12):  2673-2679 . 

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Based on the 1979, 1992, 2001 and 2006 satellite images, the spatial expansion information of Shenyang City was extracted by human-computer interactive method, and the temporal and spatial expansion characteristics of Shenyang City as well as their driving forces were analyzed from the aspects of growth intensity, center coordinates, compact index, fractal index, and elasticity coefficient, with the help of the statistic and analytic functions of GIS for the spatial data. The results showed that in 1979-2006, both the urban build-up area and its expansion rate in Shenyang were increased continuously, and reached the maximum in 2001-2006. The urban expansion showed obvious spatial heterogeneity, with the gravity shifted to the southwest. In the meantime, the compact index was decreasing while the fractal index was increasing, implying that the urban spatial configuration in Shenyang became more and more complex. Natural environmental factors, economic development, population growth, traffic infrastructure construction, and government policy and planning were the main driving forces of the urban expansion.

Differences in urbanization process of catchments in Dongjiang watershed and their effects on landscape pattern.

REN Wen-tao¹;PENG Shao-lin¹;ZHOU Ting¹;LI Yan²

2008, 19(12):  2680-2686 . 

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Based on 1991, 1998, and 2006 TM images, the areas of different land use types and the landscape indices of three catchments (catchment a, b, and c, which represented upper, middle, and lower reaches, respectively) in Dongjiang watershed were analyzed, aimed to study the differences in urbanization process along Dongjiang River, and their effects on landscape pattern. The results showed that the degree and speed of urbanization increased from the upper to the lower reach of Dongjiang River. Urbanization had significantly effects on water and vegetation. Urban land area was positively correlated with water body area, and negatively correlated with forest land area. However, to some extent, urbanization stepped into a relatively high degree might benefit forest recovery. The landscape pattern of catchments a and b kept complicating from 1991 to 2006, while that of catchment c was getting complex from 1991 to 1998 and then becoming simple from 1998 to 2006, indicating that with the development of urbanization, landscape pattern presented a “simple-complex-simple” tendency. Understanding the change patterns of the landscape pattern along Dongjiang River would benefit the management and sustainable development of the watershed as a whole.

Dynamic changes of groundwater level and vegetation in water table fluctuant belt in lower reaches of Heihe River: Coupling simulation.

ZHAO Chuan-yan¹;LI Shou-bo²;JIA Yan-hong³;JIANG Yun-chao³

2008, 19(12):  2687-2692 . 

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Based on the 2006 investigation data in lower reaches of Heihe River, and by using logarithmic normal distribution model, the models about the vegetation cover of Populus euphratica and Tamarix ramossima and the groundwater level in study area were built, and the potential plant of the study area was simulated. The results showed that in the lower reaches of Heihe River, the optimal groundwater level and mean groundwater level for P. euphratica were 2.6 m and 3.6 m, and those for T. ramossima were 2.0 m and 3.0 m, respectively. The high cover P. euphratica distribution area was mainly concentrated in the near-banks of Donghe River and Xihe River, while higher cover T. ramossima was distributed in most parts of the study area. From the aspect of current groundwater level, T. ramossima should be the adaptive species in the study area. The similarities between the potential and actual spatial distribution of P. euphratica and T. ramossima were 43.4% and 55.6%, respectively, and the main reason for the lower similarity was that there existed a gypsum salt pan in soil, which blocked the vertical movement of soil water.

Assessment model of townlet eco-environmental quality based on BP-artificial neural network.

LI Li; ZHANG Hai-tao

2008, 19(12):  2693-2698 . 

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Aiming at the problems in the townlet eco-environmental quality assessment in China, a comprehensive assessment model of townlet ecological environmental quality based on BP-artificial neural network was set up, which contained 20 cryptic layer nodes and 3 layers. The rank classification criterion of eco-environmental quality’s assessment indicator system were chosen as the training sample of the model, the 10% of training sample as well as the middle and critical values were regarded as examining sample, and the monitoring values of assessment region were treated as test sample. Choosing the Dushan Town in Ezhou City as an example, the training and prediction were made by using MATLAB software. The results showed that BP-artificial neural network was not only feasible and dependable, but also could provide acceptable results in accord with the regional realistic eco-environmental feature.

A new type water supplement mode of urban wetland park and its effects in purification and ecology.

ZHANG Li^1,2;ZHU Xiao-dong¹;CHEN Jie^1,3;ZHU Zhao-li⁴; PAN Tao^1,3;LI Yang-fan¹

2008, 19(12):  2699-2705 . 

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With the Rosebush Wetland Park in Changzhou as a case, a new type water supplement mode for urban wetland park, i.e.,“vertical- flow plus horizontal- flow”, was constructed, and its effects in water purification, ecology, and economic advantages were evaluated. The results showed that this water supplement mode could not only improve the landscape of the water bodies in urban wetland park, but also enhance their quality, making it satisfy the requirement for human full-body exposure. Furthermore, the operation cost of the mode was as lower as 5%-25% of direct municipal pipe-water supply and other routine technique solutions, suggesting that this water supplement mode had potential positive ecological effects and economic advantages.

Microclimatic niche of rice sheath blight fungus.

WANG Zi-ying^1，2;TAN Gen-jia²

2008, 19(12):  2706-2710 . 

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By using the principles and methods of niche, the microclimatic niche of rice sheath blight fungus was analyzed. The results showed that the integrative effect of ecological factors light intensity, air temperature, and humidity was higher than the effect of each of the factors, and the combination of light intensity and air temperature had higher effect than the other combinations of the three factors. At the tillering, booting, heading, and waxing stages of rice, the microclimatic niche breadth of the fungus was 0.3112, 0.4012, 0.4326, and 0.7365, respectively, i.e., increased with rice growth, and the microclimatic niche occupied by the fungus was mainly with the low light intensity, low air temperature and high humidity as the prior microclimate type.

Spatial distribution of arbuscular mycorrhizal fungi in Astragalus adsurgens root-zone soil in Mu Us sand land.

HE Xue-li^1,2;BAI Chun-ming²;ZHAO Li-li¹

2008, 19(12):  2711-2716 . 

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This paper studied the spatial distribution of arbuscular mycorrhizal (AM) fungi in Astragalus adsurgens root-zone soil in Mu Us sand land under five different ecological conditions. The results showed that the colonization and spore density of AM fungi differed significantly with sampling sites and soil depths. The highest colonization rate and spore density of AM fungi were found in 10-30 cm soil layer, and the highest spore density was at Dingbian site. Ningtiaoliang and Tawan sites had the highest vesicular colonization, and Tawan site had the highest total and hyphal colonization. The contents of total glomalin (TG) and easily extractable glomain (EEG) were the highest at Tawan site, being 1.18 mg·g^-1 and 0.65 mg·g^-1, respectively. Soil pH had significant positive effects on the vesicular and arbuscular colonization, spore density, TG, and EEG, and the TG and EEG had significant positive correlations with spore density, soil organic carbon (SOC), and soil available N and P. The proportion of glomalin to SOC was higher in desert soils than in agricultural soils, which implied that glomalin could be one of the main origins of SOC in desert ecosystem. Therefore, glomalin could be a useful index for the evaluation of soil AM fungal activity and soil ecology.

Effects of rotation and intercropping on bacterial communities in rhizosphere soil of cucumber.

WU Feng-zhi; WANG Shu; YANG Yang

2008, 19(12):  2717-2722 . 

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By the method of PCR-DGGE, this paper studied the effects of rotation with wheat, soybean, villose vetch, clover, and alfalfa and intercropping with onion and garlic on the bacterial communities in rhizosphere soil of cucumber. The results showed that rotation and intercropping with test plants increased the diversity and evenness indices of bacterial communities in cucumber rhizosphere soil, and also, cucumber yield. The sequencing of DGGE bands indicated that most of the bands had high homology with uncultured bacterial species, and were of Sphingobacterium and Proteobacteria. High bacterium G+C was only detected when cucumber was intercropped with onion. The diversity of soil bacterial communities varied with the growth stages of cucumber, being the highest at vigorous fruiting stage. It was suggested that intercropping with onion and rotation with wheat were the best cultivation modes of cucumber.

Arthropod communities in jujube-grain intercropping system: Composition and time series dynamics.

GAO Fei^1，2;ZHOU Guo-na¹;YUAN Sheng-liang¹;GAO Bao-jia¹

2008, 19(12):  2723-2730 . 

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In order to reveal the correlations between the arthropod communities in two sub-systems (jujube yard and grain field) of jujube-grain intercropping system, an investigation was conducted on the composition and time series dynamics of the communities in the two sub-systems. A total of 14 936 arthropod individuals belonging to 14 orders and 96 families were found, among which, 5 992 individuals of 14 orders and 82 families were in jujube yard and 8 971 of 14 orders and 80 families were in grain field, and some differences were observed in the arthropod community structure between the two sub-systems. The time series dynamics of the arthropod communities could be divided into four periods, according to the optimal cut-apart of time series, i.e., decline period in grain field sub-system, species number increase period in whole system, steady period in whole system, and decline period in whole system. The primary natural enemies in the system showed a characteristic of transferring between the two sub-systems in the four periods, and the parasitical natural enemies in a sub-system could impact the pest insects in another sub-system. The species transferring and mutual effect of the arthropod communities between the two sub-systems could benefit the stability of the jujube-grain intercropping system, and the capability of the system in controlling pest insects.

Comprehensive assessment on management measures of rice insect pests.

LUO Shu-ping^1,2;HUANG Shou-shan¹;LIANG Guang-wen¹;YUAN Wei¹;LIU Jia-li¹;ZHANG Qing-wen²;LIU Xiao-xia²

2008, 19(12):  2731-2737 . 

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Based on the investigation of arthropods biodiversity and insect pests controlling effect in the paddy fields of demonstration area of organic rice production in Guangzhou, a comprehensive assessment on the economic, social, and ecological profits and costs of organic rice production in study area was conducted by using analytic hierarchy process (AHP). The results indicated that among all insect pests controlling measures, organic rice planting had the best comprehensive benefits, with a weight value of 0.5355. Ecological cost played a dominant role in comprehensive costs, and that of traditional pesticide-based insect pests control was most cruel, with a weight value of comprehensive costs being 0.6252. From the viewpoint of the ratio of comprehensive profits to comprehensive costs (RPC), organic rice planting was better than any other insect pests controlling modes, whose RPC was 2.4776, being accorded with the requirement of sustainable development of agriculture.

Cadmium accumulation and its development tendency in black soil under long-term fertilization.

TAN Chang-yin^1,2,3;WU Long-hua¹;LUO Yong-ming¹;XU Jian-ming⁴;HAN Xiao-zeng⁵;QIAO Yun-fa⁵

2008, 19(12):  2738-2744 . 

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Based on the long-term field experiment at Hailun Agro-ecosystem Experimental Station of Chinese Academy of Sciences, this paper studied the cadmium (Cd) accumulation, its development tendency, and Cd availability in black soil under effects of long-term application of chemical N and P fertilizers and pig manure. The results showed that under no fertilization, soil Cd concentration had a slight increase. Long-term chemical N and P fertilization increased soil Cd concentration significantly, but soil Cd accumulation had less difference under different N and P fertilization rates. Applying pig manure increased the Cd accumulation in soil significantly, and the accumulation had a tendency of speed-up. Cd-containing feedstuff additives could be the important source of Cd in pig manure. No significant effects of chemical N and P fertilization were observed on the Cd availability in soil, but long-term application of pig manure increased the Cd availability significantly.

Effects of fungicide chlorothalonil on soil nitrous oxide and carbon dioxide emissions.

LANG Man; CAI Zu-cong

2008, 19(12):  2745-2750 . 

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A 14 d incubation test at 60% WHC and 25 ℃ was conducted to study the effects of fungicide chlorothalonil at its application rates of 0, 5.5 mg·kg^-1(field application rate, FR), 110 mg·kg^-1 (20FR) and 220 mg·kg^-1 (40FR) on the nitrous oxide (N₂O) and carbon dioxide (CO₂) emissions from acidic, neutral, and alkaline soils. The results indicated that the effects of chlorothalonil on the two gases emissions depended on its application rate and soil type. Comparing with no chlorothalonil application, the chlorothalonil at 20FR and 40FR inhibited the N₂O emission from acid soil significantly, while that at FR, 20FR and 40FR stimulated the N₂O emission from neutral soil, with the strongest effect at FR. Higher application rates (20FR and 40FR) of chlorothalonil inhibited the N₂O emission from alkaline soil at the early stage of incubation, but stimulated it at late incubation stage. Chlorothalonil at FR had no obvious effects on the CO₂ emission from test soils, but that at 20FR and 40FR promoted the CO₂ emission from acid soil while inhibited it from neutral and alkaline soils significantly.

Risk assessment of pig manure Cu-contamination of black soil in Northeast China.

ZHU Yi-jun^1,2;ZHENG Yuan-ming³;HE Ji-zheng³;LI Ling-hao¹; ZHANG Lei⁴

2008, 19(12):  2751-2756 . 

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Copper (Cu) is massively used as feed additives in intensive farms, and the discharge and utilization of livestock wastes may cause certain environmental problems. In this paper, a cultivated black soil in Northeast China was sampled, and added with pig manures that contained different concentration of Cu to simulate the vegetable soil under different years of pig manure fertilization. With this soil, a pot experiment was conducted to study the effects of soil Cu accumulation via the application of the pig manures on the aboveground biomass and its Cu concentration of pakchoi (Brassica chinensis L.), soil microbial biomass carbon, and soil enzymes (dehydrogenase, urease, and acid phosphatase) activities. The results showed that pig manure application increased the aboveground biomass of pakchoi significantly, but had no significant effects on the aboveground biomass Cu concentration. Under the application of pig manure, soil dehydrogenase and urease activities increased in a definite period of time, but their activities as well as soil acid phosphatase activity were depressed gradually with the increase of soil Cu concentration. When the soil total Cu concentration reached 301.3 mg·kg^-1, the aboveground biomass of pakchoi, soil microbial biomass carbon, and the activities of dehydrogenase, urease, and acid phosphatase were greatly reducd. The aboveground biomass Cu concentration of pakchoi had significant positive correlations with the concentration of soil total and water soluble Cu (P<0.01), while the aboveground biomass was negatively correlated with soil total Cu concentration (P<0.05). It was suggested that the threshold value of Cu in black soil under vegetable cultivation should be less than 301.3 mg·kg^-1.

Research advances in cadmium pollution of peanut (Arachis hypogaea L.).

WANG Kai-rong;ZHANG Lei

2008, 19(12):  2757-2762 . 

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Peanut (Arachis hypogaea L.) is a major oil-bearing crop in the world, and as well, an important resource of plant protein and a main raw material for food processing. With the increasing of its direct human consumption and food processing, the Cd concentration in peanut kernel has aroused great concern in recent years. China is a main country of the production and exportation of peanut, but the Cd enrichment in peanut kernel is the main obstacle for its peanut export trade. In this paper, the research advances in Cd pollution of peanut kernel were reviewed, based on the characteristics and mechanisms of Cd accumulation and distribution in peanut kernel, the intra-specific variation of kernel Cd content, and the measures in controlling kernel Cd content. Two strategies were put forward for controlling Cd pollution of peanut kernel, i.e., to reduce the Cd uptake by main root system of peanut plant, and to control the transference of Cd from root to fruit (kernel). In order to applying the strategies effectively, researches on the mechanisms of Cd accumulation in peanut kernel should be enhanced in three aspects, i.e., root vitality and its relationship with Cd accumulation in kernel, mechanism of fruit Cd absorption and its contribution to kernel Cd content, and mechanism of Cd transference in plants and its effects on kernel Cd content.

Form transformation of arsenic in soil and corresponding analyzing methods.

HE Qiu-hong; ZENG Xi-bai

2008, 19(12):  2763-2768 . 

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Based on the analysis of the sources and existing forms of soil arsenic, this paper approached the inter-transformation of different arsenic forms in soil. In the meanwhile, the extraction and determination methods of different soil arsenic forms were also compared. It was considered that HPLC-HG-AFS had the advantages of high sensitivity, low detection limit, better selectivity, low operation cost, and less inter-transformation of different arsenic forms, being able to be used as the prior method for the detection of different arsenic forms. Combining with previous research results, the form transformation of arsenic in soil and the promising research aspects were also discussed.

Soil enzyme activities under two forest types as affected by different levels of nitrogen deposition.

ZHAO Yu-tao^1,2;LI Xue-feng¹; HAN Shi-jie¹; HU Yan-ling^1,2

2008, 19(12):  2769-2773 . 

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A simulation test was conducted to study the change trends of soil cellulase, polyphenol oxidase, and sucrase activities under natural broadleaf-Korean pine (Pinus koraiensis) and secondary poplar (Populus davidiana) -birch (Betula platyphylla) mixed forests as affected by 0, 25, and 50 kg·hm^-2·a^-1 of N deposition. The results showed that the effects of elevated N deposition on test enzyme activities varied with forest type, and short-term nitrogen addition could significantly affect the test enzyme activities. High N deposition decreased soil polyphyneol oxidase activity, and correspondingly, soil cellulase and sucrase activities also had a trend of decrease.

Biological process of phosphorus turnover in surface water body of Xiamen Harbor. Ⅱ: Grazing pressure of copepod on phytoplankton.

YANG Wei-di¹;YANG Qing¹;LIN Yuan-shao^1,2;CAO Wen-qing¹

2008, 19(12):  2774-2778 . 

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To understand the roles of copepod in the biogeochemical cycling of phosphorus, gut fluorescence method was applied to examine in situ the grazing rate of copepod on the phytoplankton in Xiamen Time Station (XMTS) in May, August and November 2005 and March 2006. In the meanwhile, the abundance and species composition of copepod were investigated, and the grazing pressure of copepod on the phytoplankton was estimated. The results showed that the annual average grazing rate of copepod was 55.53 μg·m^-3·d^-1, being the highest (108.98 μg·m^-3·d^-1) in autumn and the lowest (7.18 μg·m^-3·d^-1) in summer. Based on the estimation from our experimental data, the daily grazing rate of copepod populations on the phytoplankton in Xiamen Harbor was, on annual average, about 181% of the phytoplankton’s standing stock, with the values in spring, summer, autumn, and winter being 3.22%, 0.06%, 3.52% and 0.46%, respectively.