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Table of Content

    18 January 2012, Volume 23 Issue 01
    Articles
    Effects of Eucalyptus grandis leaf litter decomposition on the growth and photosynthetic characteristics of Cichorium intybus.
    2012, 23(01):  1-8. 
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    A pot experiment was conducted to study the effects of Eucalyptus grandis leaf litter during its early stage decomposition on the growth and the photosynthesis of Cichorium intybus. Each pot contained 12 kg soil mixed with different amounts of E. grandis leaf litter (30 g·pot-1, A1; 60 g·pot-1, A2; 90 g·pot-1, A3; and 0 g·pot-1, CK), and sowed with C. intybus. The growth indicators and the photosynthetic characteristics of C. intybus were measured after the third leaf of C. intybus seedlings fully expanded in treatment A3. At the early stage of leaf litter decomposition, the C. intybus biomass accumulation, leaf area growth, and synthesis of photosynthetic pigments were inhibited significantly, and the inhibition effect was getting stronger with the increasing amount of the leaf litter addition. The intercellular CO2 concentration of C. intybus was increased by litter addition, while the net photosynthetic rate, stomatal conductance, and transpiration rate were significantly lower than those of the control. With the increase of leaf litter addition, all the parameters of C. intybus light response and CO2 response except CO2 compensation point showed an obvious downward trend, and there existed significant differences between the treatments of litter additions and the control. It was suggested that during the decomposition of E. grandis leaf litter, its allelopathic substances released gradually and acted on receptor plants, inhibited the synthesis of photosynthetic pigments and the photosynthesis of the receptors, decreased the receptors environmental adaptation ability, and accordingly, inhibited the growth of C. intybus.
    Litter decomposition of dominant plantations in Guangxi and its effects on leachate quality. 
    2012, 23(01):  9-16. 
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    To understand the decomposition characteristics of the litters in different forest plantations and the effects of released substances during litter decomposition on the leachate quality, litter samples (leaf, shoot, and cortices) were collected from five forest plantations (1 year-old Eucalyptus urophylla × E. grandis,  EU1; 4 year-old Eucalyptus urophylla × E. grandis, EU4; 7 year-old Acacia mangium × A. auriculaef, AM; 13 year-old Pinus massoniana Lamb, PL; and mixed broadleaved softwood, BL), and incubated at 28 ℃, using water leached for 255 days. In the first 105 days, the litter leachates of EU1 and EU4 had significantly higher coloration and N and P contents and lower pH than those of AM, PL, and BL. On the 255th day, the cumulative chemical oxygen demand (COD) in the leaf litters leachates of EU1 and EU4 was 193.9  and 212.8 g·kg-1, being 4.2, 4.0, and 4.3 times and 5.3, 4.4, and 4.7 times higher than that of AM, PL, and BL, respectively. The mass loss rate and the N and P leaching rate of the leaf litter of EU1 were significantly higher than those of AM, PL, and BL. The mass loss rate of cortices of EU1 was significantly higher than that of PL. No significant difference was observed for the leaching rate of the shoot litters between AM, PL, and BL.Among the litter samples, leaf litter was easiest to be decomposed,while shoot litter was most difficult to be decomposed. The pH value of the litter leachates of Eucalyptus plantations was significantly negatively correlated with leachate chroma and COD, and the COD had significant positive correlations with the concentrations of total N and P in the leachates.
    Seasonal variations of soil CH4 uptake rate in Castanopsis carlesii forest in mid-subtropical China.
    2012, 23(01):  17-22. 
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    A monthly measurement of soil CH4 uptake rate (VCH4) in a natural Castanopsis carlesii forest in Wanmulin Natural Reserve of Fujian Province, East China was conducted from March 2010 to February 2011. The VCH4 showed a pronounced seasonal fluctuation, being higher in summer-autumn than in winter-spring, with the maximum value (95.13 μg·m-2·h-1) in September and the minimum value (9.13μg·m-2·h-1) in March. With the increase of soil temperature and moisture, the VCH4 showed an increasing and a decreasing trend, respectively, but the correlations of the VCH4 with soil temperature and moisture were not significant. The annual soil CH4 flux of the forest (3.93 kg·hm-2·a-1) was higher than the average value of global natural forests (2.4 kg·hm-2·a-1) and of Asian tropical natural forests (2.07 kg·hm-2·a-1), but lower than that of Asian temperate natural forests (8.12 kg·hm-2·a-1).
    Effects of different disturbance modes on the morphological characteristics and aboveground biomass of Alhagi sparsifolia in oasis-desert ecotone.
    2012, 23(01):  23-28. 
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    Taking Cele oasis at the southern fringe of Taklimakan Desert as a case, this paper studied the effects of different disturbances (burning in spring, cutting in spring, and cutting in fall) on the morphological characteristics and aboveground biomass of natural vegetation Alhagi sparsifolia in the ecotone of oasis-desert. Burning in spring decreased the A. sparsifolia plant height, crown width, and biomass significantly, being harmful to the regeneration and growth of the vegetation. Cutting in spring decreased the A. sparsifolia plant height, crown width, and biomass but increased the leaf biomass, thorn length, and thorn diameter, whereas cutting in fall decreased the plant height and crown width but increased the ramification amount and biomass of A. sparsifolia. Moderate cutting in fall could benefit the protection of A. sparsifolia at the southern fringe of Taklimakan Desert.
    Estimation of soil carbon sequestration potential in typical steppe of Inner Mongolia and associated uncertainty.
    2012, 23(01):  29-37. 
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    Based on the measurements in the enclosure and uncontrolled grazing plots in the typical steppe of Xilinguole, Inner Mongolia, this paper studied the soil carbon storage and carbon sequestration in the grasslands dominated by Leymus chinensis, Stipa grandis, and Stipa krylovii, respectively, and estimated the regional scale soil carbon sequestration potential in the heavily degraded grassland after restoration. At local scale, the annual soil carbon sequestration in the three grasslands all decreased with increasing year of enclosure. The soil organic carbon storage was significantly higher in the grasslands dominated by L. chinensis and Stipa grandis than in that dominated by Stipa krylovii, but the latter had much higher soil carbon sequestration potential, because of the greater loss of soil organic carbon during the degradation process due to overgrazing. At regional scale, the soil carbon sequestration potential at the depth of 0-20 cm varied from -0.03×10 to 3.71×104 kg C·a-1, and the total carbon sequestration potential was 12.1×108 kg C·a-1. Uncertainty analysis indicated that soil gravel content had less effect on the estimated carbon sequestration potential, but the estimation errors resulted from the spatial interpolation of climate data could be about ±4.7×109 kg C·a-1. In the future, if the growth season precipitation in this region had an average variation of -3.2 mm·(10 a)-1, the soil carbon sequestration potential would be decreased by 1.07×108  kg C·(10 a)-1.
    Effects of different irrigation minima on green period and cold-resistance physiological indices of Festuca arundinacea.
    2012, 23(01):  38-44. 
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    A pot experiment was conducted to study the effects of different irrigation minima [80% field capacity (FC), 70% FC, 60% FC and 50% FC] from late autumn to early winter on the green period and cold-resistance of Festuca arundinacea.  Under the low temperature in winter, treatments 80% FC and 70% FC made the leaf relative water content, POD, CAT, and SOD activities, and chlorophyll, soluble sugar, and free proline contents of F. arundinacea maintained at a higher level, but made the MDA content and electrolyte leakage decreased, resulting in an increased cold-resistance of F. arundinacea. Treatment 80% FC made the green period of F. arundinacea prolonged by 4, 22 and 28 days, as compared with treatments 70% FC, 60% FC, and 50% FC, respectively, and made F. arundinacea have the shortest time to wither in winter and to turn green in spring, with the longest green period. Taking water-saving and water use efficiency into consideration, 70% FC would be the optimum irrigation low limit from late autumn to early winter for F. arundinacea.
    Effects of aluminum stress on ecophysiological  characteristics of male and female Populus cathayana seedlings.
    2012, 23(01):  45-50. 
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    This paper studied the sex-specific differences of male and female Populus cathayana seedlings in their ecophysiological characteristics and photosynthesis under the stress of aluminum (216 mg Al3+·kg-1). Under the effects of aluminum, the malonaldehyde (MDA) and soluble protein (Pr) contents of the male and female seedlings increased significantly (P<0.001), and the males had a significantly lower MDA content and a significantly higher Pr content than the females. The peroxidase (POD) activity of the males increased but the superoxide dismutase (SOD) activity decreased significantly, while the POD and SOD activities of the females had no significant variation. The net photosynthetic rate (Pn) of both male and female seedlings decreased significantly (P=0.001), and the transpiration rate (Tr) of the female seedlings decreased (P=0.007) and the instant water use efficiency (WUEi) increased significantly, while no significant variations were observed in the Tr and WUEi of the male seedlings. The total chlorophyll and chlorophyll a contents and chlorophyll a/b ratio of the females decreased significantly, resulting in a significantly higher chlorophyll a/b ratio of the males. The specific leaf area (SLA) of the females decreased but that of the males increased significantly. No significant variation was observed on the leaf- and stem dry mass. Comparing with the females, the males had higher Pr and chlorophyll contents and higher active antioxidant enzymes activity to maintain higher Pn, and thus, had greater resistance against aluminum stress.
    Fire behavior of Mongolian Oak leaves fuel-bed under no-wind and zero-slope conditions. I. Factors affecting fire spread rate and modeling.
    2012, 23(01):  51-59. 
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    Aimed to understand the fire behavior of  Mongolian oak leaves fuel-bed under field condition, the leaves of a secondary Mongolian oak forest  in Northeast Forestry University experimental forest farm were collected and brought into laboratory to construct fuel-beds with varied loading, height, and moisture content, and a total of 100 experimental fires were burned under no-wind and zero-slope conditions. It was observed that the fire spread rate of the fuel-beds was less than 0.5 m·min-1. Fuel-bed loading, height, and moisture contents all had significant effects on the fire spread rate. The effect of fuel-bed moisture content on the fire spread had no significant correlations with fuel-bed loading and height, but the effect of fuel-bed height was related to the fuel-bed loading. The packing ratio of fuel-beds had less effect on the fire spread rate. Taking the fuel-bed loading, height, and moisture content as predictive variables, a prediction model for the fire spread rate of Mongolian oak leaves fuel-bed was established, which could explain 83% of the variance of the fire spread rate, with a mean absolute error 0.04 m·min-1 and a mean relative error less than 17%.
    Differences in phosphorus utilization efficiency among wheat cultivars.
    2012, 23(01):  60-66. 
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    A pot experiment was conducted to study the differences in the biomass, phosphorus concentration, phosphorus use efficiency for dry matter, and phosphorus use efficiency for grain yield among different wheat cultivars under low phosphorus supply, aimed to screen the wheat varieties with high phosphorus use efficiency. For the test cultivars, their biomass per plant at tillering, jointing, flowering, and maturing stages was 0.46-1.09, 0.85-2.10, 3.00-7.00, and 3.85-12.88 g, and their phosphorus concentration was 2.21-4.26, 2.38-4.42, 2.44-4.96, and 1.30-5.09 mg·g-1,respectively. From tillering to maturing stages, the phosphorus accumulation in plant and the phosphorus use efficiency for dry matter displayed a decreasing effect on the biomass formation. Significant differences were observed in the phosphorus use efficiency for dry matter (tillering stage CV=16.3%, jointing stage CV=15.0%, and flowering stage CV=13.3%) and in the phosphorus use efficiency for grain yield (maturing stage CV=20.5%) among the cultivars. The cultivars CD1158-7 and Sheng A3 Yi 03-4 had higher phosphorus use efficiency for dry matter and phosphorus use efficiency for grain yield, while the Yu 02321 was in adverse. The phosphorus concentration in the cultivars with high phosphorus use efficiency was significantly lower than that in the cultivars with low phosphorus use efficiency, and the grain yield of CD1158-7 and Sheng A3 Yi 03-4 was 0.98 times and 0.78 times higher than that of Yu 02321.
    Effects of sulfur- and polymer-coated controlled release urea fertilizers on wheat yield and quality and fertilizer nitrogen use efficiency.
    2012, 23(01):  67-72. 
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    A field experiment was conducted to study the effects of sulfur- and polymer-coated controlled release urea fertilizers on wheat yield and its quality, plow layer soil inorganic nitrogen (N) contents, and fertilizer N use efficiency. Compared with traditional urea fertilizer, both sulfur- and polymer-coated controlled release urea fertilizers increased the grain yield by 10.4%-16.5%, and the grain protein and starch contents by 5.8%-18.9% and 0.3%-1.4%, respectively. The controlled release urea fertilizers could maintain the topsoil inorganic N contents to meet the N requirement for the wheat, especially during its late growth stage. In the meantime, the fertilizer N use efficiency was improved by 58.2%-101.2%. Polymer-coated urea produced better wheat yield and higher fertilizer N use efficiency, compared with sulfur-coated controlled release urea.
    Estimation of winter wheat leaf nitrogen accumulation based on coupling ground- and space- remotely sensed information.
    2012, 23(01):  73-80. 
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    By coupling the SPOT-5 multi-spectral RS images, ground-spectrum, and field measured data of different winter wheat ecological zones, a pure pixel spectrum extraction method was developed based on spectral response function and pixel unmixed, and the quantitative relationships between leaf nitrogen accumulation (LNA) and simulated, measured, and pure pixel spectra were analyzed. The estimation accuracy for LNA was in the sequence of simulated pixel spectra > pure pixel spectra > measured pixel spectra. However, the LNA monitoring model based on simulated pixel spectra couldn’t be extrapolated directly to spatial level. The results of model verification also indicated that the monitoring model based on pure pixel spectra performed well in two different wheat ecological zones. Therefore, the pure pixel spectrum extraction method could be applied to other varied and remotely sensed data with different spatial and spectral resolutions by making use of the merits of ground- and space- remote sensing simultaneously, which provided a technological basis for estimating winter wheat nitrogen status in regional scale.
    Mechanisms for the increased fertilizer nitrogen use efficiency of rice in wheat-rice rotation system under combined application of inorganic and organic fertilizers.
    2012, 23(01):  81-86. 
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    A pot experiment was conducted to study the effects of combined application of organic and inorganic fertilizers on the nitrogen uptake by rice and the nitrogen supply by soil in a wheat-rice rotation system, and approach the mechanisms for the increased fertilizer nitrogen use efficiency of rice under the combined fertilization from the viewpoint of microbiology. Comparing with applying inorganic fertilizers, combined application of organic and inorganic fertilizers decreased the soil microbial biomass carbon and nitrogen and soil mineral nitrogen contents before tillering stage, but increased them significantly from heading to filling stage. Under the combined fertilization, the dynamics of soil nitrogen supply matched best the dynamics of rice nitrogen uptake and utilization, which promoted the nitrogen accumulation in rice plant and the increase of rice yield and biomass, and increased the fertilizer nitrogen use efficiency of rice significantly. Combined application of inorganic and organic fertilizers also promoted the propagation of soil microbes, and consequently, more mineral nitrogen in soil was immobilized by the microbes at rice early growth stage, and the immobilized nitrogen was gradually released at the mid and late growth stages of rice, being able to better satisfy the nitrogen demand of rice in its various growth and development stages.
    Effects of different fertilization modes on paddy field topsoil organic carbon content and carbon sequestration duration in South China.
    2012, 23(01):  87-95. 
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    Based on the organic carbon data of 222 topsoil samples taken from 38 paddy field experiment sites in South China, calculations were made on the relative annual change of topsoil organic carbon content (RAC) and carbon sequestration duration in the paddy fields in South China under five fertilization modes (inorganic nitrogen fertilization, N; inorganic nitrogen and phosphorus fertilization, NP; inorganic nitrogen, phosphorus, and potassium fertilization, NPK; organic fertilization, O; and inorganic plus organic fertilization, OF). The RAC under the fertilizations was 0-0.4 g·kg-1·a-1, with an increment of 0.20 and 0.26 g·kg-1·a-1 in double and triple cropping systems, respectively. The RAC was higher in treatments O and OF than in treatments N, NP, and NPK, being the highest (0.32 g·kg-1·a-1) in treatment OF. The topsoil organic carbon accumulation rate decreased with increasing time, and the carbon sequestration duration in treatments N, NP, NPK, O, and OF was about 22, 28, 38, 57, and 54 years, respectively. Inorganic plus organic fertilization was the most effective practice for soil carbon sequestration in the paddy fields in South China.
    Effects of transgenic Bt rice on soil dissolved organic carbon and nitrogen contents and microbiological properties.
    2012, 23(01):  96-102. 
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    A two-year field experiment (2009 and 2010) was conducted to evaluate the effects of three transgenic Bt rice lines (KMD, HH1, and BtSY63) and their non-Bt lines (XSD, MH63, and SY63) on soil dissolved organic carbon (DOC) and nitrogen (DON) and microbiological properties. All the measured indices changed significantly with sampling time. Comparing with their corresponding non-Bt lines, the test transgenic Bt lines had little effects on the soil DOC, DON, and microbial biomass nitrogen (MBN). The transgenic Bt lines had significant effects on the soil microbial biomass carbon (MBC), basal respiration (BR), and microbial metabolic quotient (qCO2) in certain periods of time in the first year, but no effects in the second year. Among the soils planted with the three non-Bt rice lines, no difference was observed in the DOC, DON, and microbiological properties, whereas in the soil planted with BtSY63, the MBC and BR were significantly higher, but the qCO2 was significantly lower, as compared with those in the soils planted with KMD and HH1. In sum, two years’ planting transgenic Bt rice had little effects on the soil DOC, DON, and microbiological properties, but the differences of soil microbiological properties induced by the planting of different transgenic Bt rice lines were larger than those induced by the planting of different non-Bt lines, implying that long term monitoring would help to reveal the effects of transgenic Bt rice on the structure and function of soil ecosystem.
    Effects of combined application of maize- and horsebean straws on the straws decomposition and soil nutrient contents. 
    2012, 23(01):  103-108. 
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    A laboratory incubation experiment was conducted to study the straw decomposition and soil nutrient contents after single and combined applications of maize- and horsebean straws. With the single application of maize straw, the mineralization rates of the straw and soil organic C were lower, and the immobilization of soil mineral N sustained longest. Combined application of maize- and horsebean straws promoted the mineralization of the straws organic C and soil immobilized N. Both single and combined application of the straws increased the contents of soil microbial biomass C and N significantly. It was suggested that a combined application of gramineous and leguminous straws could promote the straws decomposition and harmonize the soil nutrient supply.
    Effects of organic material amendment on vegetable soil nitrate content and nitrogenous gases emission under flooding condition.
    2012, 23(01):  109-114. 
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    Applying large amount of nitrogen fertilizer into vegetable field can induce soil NO3--N accumulation, while rapidly removing the accumulated NO3--N can improve vegetable soil quality and extend its service duration. In this study, a vegetable soil containing 360 mg N·kg-1 was amended with 0, 2500, 5000, and 7500 kg C·hm-2 of ryegrass (noted as CK, C2500, C5000,and C7500), respectively, and incubated in a thermostat at 30 for 240 h under flooding condition, aimed to investigate the effects of organic material amendment on vegetable soil nitrate concentration and nitrogenous gases emission. By the end of the incubation, the soil NO3--N concentration in CK was still up to 310 mg N·kg-1. Ryegrass amendment could remove the accumulated NO3--N effectively. In treatments C2500, C5000,and C7500, the duration for the soil NO3--N concentration dropped below 10 mg N·kg-1 was 240 h, 48 h, and 24 h, respectively. After the amendment of ryegrass, soil pH increased significantly, and soil EC decreased, with the increment and decrement increased with increasing amendment amount of ryegrass. The cumulative emissions of soil N2O and N2 in ryegrass amendment treatments amounted to 270-378 mg N·kg-1, and the N2O/N2 ratio ranged from 0.6 to 1.5. Incorporating with ryegrass under flooding condition could rapidly remove the accumulated NO3--N in vegetable soil, but the high N2O emission during this process should be attached importance to.
    Distribution and accumulation characteristics of nutrients in solar greenhouse soil in Ji’nan, Shandong Province of East China.
    2012, 23(01):  115-124. 
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    Taking the solar greenhouses with different cultivating years and vegetables in Ji’nan  as test objects, this paper studied the amounts and frequency distribution of soil nutrients and the relationships between cultivating years and soil nutrients accumulation characteristics, and analyzed the factors causing soil salinization and acidification by fitting soil nutrients contents with cultivating years and vegetables. In the greenhouses, the contents of soil alkali-hydrolysable nitrogen, available phosphorus, available potassium, organic matter, and electrical conductivity were significantly higher than those in the open field, with an increment of 135.3%, 475.2%, 290.1%, 97.7%, and 188.7%, respectively, but the soil pH value was 0.31 lower than that of open field. The frequency distribution of soil nutrients presented a normal curve. Differences were observed in the soil nutrients contents in the greenhouses with different cultivating vegetables. The soil alkali-hydrolysable nitrogen content and electrical conductivity were in the order of tomato > cucumber > sweet pepper, soil organic matter content and pH value were cucumber > sweet pepper > tomato, soil available phosphorus content was cucumber > tomato > sweet pepper, and soil available potassium content was tomato > cucumber > sweet pepper. There was a mild tendency of soil acidification in the greenhouses, and the aggravation of soil salinization was primarily caused by the accumulation of soil alkali-hydrolysable nitrogen and available potassium. The decrease of soil pH was closely related to the accumulation of alkali-hydrolysable nitrogen. The soil nutrients accumulation in the greenhouses had the similar patterns, i.e., rapid accumulation in the first two cultivating years, slowed down in the third and fourth year, and kept stable later, demonstrating a dynamic balance on the whole. All the nutrients contents were positively accumulated, while soil pH presented negatively. In the greenhouses with different cultivating vegetables, there was a significant correlation between soil nutrients and cultivating years, which could be fitted by conic curve or cubic curve.
    Effects of different cropping modes on crop root growth, yield, and rhizosphere soil microbes’ number. 
    2012, 23(01):  125-132. 
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    A multi-year field experiment was conducted to study the variation features of rhizosphere environment and crop root growth under the cropping modes of wheat-soybean (A1), wheat-sweet potato (A2), maize (A3), wheat/maize/soybean (A4), and wheat/maize/sweet potato (A5).Among the five modes,A4 increased the plant biomass, root activity, and root dry mass of wheat, maize, and soybean at their flowering and maturing stages, and the quantity of rhizosphere soil bacteria, fungi, and actinomycetes. The biomass and quantity of rhizosphere soil microbes were relay strip intercropping > single cropping, soybean > sweet potato, and fringe row > center row. It was suggested that wheat/maize/soybean relay trip intercropping could improve rhizosphere environment, promote the crops root growth and increase their aboveground biomass, and accordingly, realize yield-increasing.
    Effects of high- and low temperature stress on the leaf PSⅡ functions and physiological characteristics of tree peony (Paeonia suffruticosa cv. ‘Roufurong’). 
    2012, 23(01):  133-139. 
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    Taking the detached leaves of tree peony (Paeonia suffruticosa cv. ‘Roufurong’) as test materials, this paper studied the effects of high temperature (40 ℃) and low temperature (15 ℃) stresses on the PSⅡ functions and physiological characteristics of peony leaves under strong light intensity (1400 μmol·m-2·s-1), with 25 ℃ as the control. With the increasing time of high- and low temperature stress, the maximal photochemical efficiency (Fv/Fm), actual quantum yield of photosystemⅡ(ΦPSⅡ), and efficiency of excitation capture of open PSⅡ center (Fv′/Fm′) all decreased continuously. After recovered in the dark for 4 hours, the Fv/Fm in treatments 15 ℃ and 25 ℃ quickly recovered, but that in treatment 40 ℃ only recovered to 75.5% of non-treatment, even if the leaves were treated in the dark for 15 hours. At 40 ℃, the balance of excited energy between PSⅠand PSⅡunder strong light intensity was perturbed seriously. Treatment 40 ℃ inhibited the superoxide dismutase (SOD) activity, enhanced the production of  O2-·, H2O2, and MDA, and reduced the contents of chlorophyll and soluble protein. This study revealed that strong light combined with high temperature impaired the photosynthetic apparatus of the tree peony irreversibly, whereas strong light plus low temperature had weaker impact.
    Effects of exogenous 24-epibrassinolide on the leaf photosynthetic characteristics and polyamines content of cucumber seedlings under hypoxia stress.
    2012, 23(01):  140-146. 
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    A water culture experiment with 1/2 Hoagland solution was carried out to study the effects of exogenous 24-epibrassinolide (EBR) on the leaf photosynthetic characteristics and polyamines (PAs) content of cucumber seedlings under hypoxia stress. Under the stress, the leaf net photosynthetic rate (Pn), stomatal conductance (gs), transpiration rate (Tr), and intercellular CO2 concentration (Ci) decreased significantly while the chlorophyll content was in adverse, and the seedling growth was inhibited. Hypoxia stress increased the leaf Put, Spd, and Spm contents and Put/PAs ratio significantly, but decreased the (Spd+Spm)/Put. Under the stress, exogenous EBR not only increased the Pn, gs, Tr, and chlorophyll content significantly, but also increased the contents of free Spm, conjugated Spd and Spm,and bound Put, Spd, and Spm significantly. Meanwhile, the PAs content and (Spd+Spm)/Put ratio were further increased, and the Put/PAs ratio decreased. The results suggested that exogenous EBR could regulate the formation and form transformation of PAs in cucumber seedling leaf, made the leaf keep a higher photosynthetic performance, promote the increase of leaf area and dry mass, and alleviate the damage of hypoxia stress.
    Physiological responses of cucumber seedlings grafted on different salt-tolerant rootstocks to NaCl stress. 
    2012, 23(01):  147-153. 
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    Based on the salt-tolerance identification of a series of cucumber rootstock varieties, the cucumber cultivar ‘Xintaimici’ grafted on different salt-tolerant rootstock varieties ‘Sherpa’, ‘Shintosa’, ‘Tielizhen’, and ‘Figleaf gourd’ was selected to study its seedlings physiological responses to NaCl stress, taking the self-rooted ones as the control. Under the stress of 100 mmol NaCl·L-1, the leaf electrolyte leakage rate and malondialdehyde (MDA) content of the grafted seedlings were significantly lower than those of self-rooted seedlings, and the seedlings grafted on ‘Figleaf gourd’ showed the lowest electrolyte leakage rate and malondialdehyde (MDA) content, followed by the seedlings grafted on ‘Tielizhen’, ‘Shintosa’, and ‘Sherpa’. The leaf proline and soluble sugar contents and peroxidase (POD), superoxide dismutase (SOD), catalase (CAT), and ascorbate peroxidase (APX) activities of the grafted seedlings were significantly higher than those of the self-rooted seedlings, and the POD, SOD, CAT, and APX activities were the highest for the seedlings grafted on ‘Figleaf gourd’ and the lowest for the seedlings grafted on ‘Sherpa’, but had no significant differences for the seedlings grafted on ‘Tielizhen’ and ‘Shintosa’. The leaf Na+ content of the seedlings grafted on different rootstock varieties ranked as ‘Figleaf gourd’<‘Tielizhen’<‘Shintosa’<‘Sherpa’, while the leaf K+ content had little difference for the seedlings grafted on ‘Figleaf gourd’, Tielizhen ’, and ‘Shintosa’ but was significantly higher than that for the seedlings grafted on ‘Sherpa’. The self-rooted seedlings had the highest leaf Na+ content but the lowest leaf K+ content. The leaf Na+ /K+ ratio of grafted seedlings was significantly lower than that of self-rooted ones, and the seedlings grafted on ‘Figleaf gourd’ had the lowest leaf Na+/K+ ratio.
    Effects of arbuscular mycorrhiza fungi (AMF) on the plant growth, fruit yield, and fruit  quality of cucumber under salt stress. 
    2012, 23(01):  154-158. 
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    By adopting organic substrate culture, and  salt-sensitive cucumber variety ‘Jinchun No.2’ was used as test material, this paper studied the effects of inoculating arbuscular mycorrhiza fungi (AMF) on the plant growth, fruit yield, and fruit  quality of cucumber under salt stress. AMF-inoculation could effectively promote the plant growth and nutrient uptake, and improve the fruit yield and fruit nutrient quality, compared with ordinary cultivation. Under salt stress, the plant growth was inhibited, and the plant N, P, K, Cu, and Zn contents and K+/Na+ ratio, fruit yield, and fruit soluble protein, total sugar, vitamin C, and nitrate contents decreased, while inoculation with AMF could mitigate the inhibitory effect of salt stress on the plant growth, made the plant N, P, K, Cu, and Zn contents increased by 7.3%, 11.7%, 28.2%, 13.5%, and 9.9%, respectively, and made the plant K+/Na+ ratio, fruit yield, and fruit soluble protein, total sugar, and vitamin C contents have an obvious increase and the fruit nitrate content have a significant decrease. It was suggested that AMF could promote the plant growth and nutrient uptake of cucumber under salt stress, increase the plant salt-tolerance, and improve the fruit yield and its nutrient quality.
    Effects of organic manure application on dry land soil organic matter and water stable aggregates.
    2012, 23(01):  159-165. 
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    A four-year (2007-2010) field experiment was conducted to study the effects of applying different amounts (7500, 15000, and 22500 kg·hm-2) of organic manure on the organic matter content, aggregate particle size distribution, and aggregate stability in different soil layers in a continuously cropped maize field on the Weibei Dry Land, Shaanxi Province of Northwest China. In 0-20 cm soil layer, the organic matter content in treatment 22500 kg·hm-2 of organic manure was 4.1%-4.6% higher than that in treatment 7500 kg·hm-2 of organic manure (P<0.05), and the organic matter content in treatments 15000 and 22500 kg·hm-2 of organic manure was 4.6%-11.2% higher than that in CK (chemical fertilization) (P<0.05). In the fourth year (2010) of applying 7500 kg·hm-2 of organic manure, the organic matter content in 0-20 cm soil layer was 4.7%-6.3% higher than that of CK (P<0.05). In 0-30 cm soil layer, all treatments with organic manure application had an increased amount of soil water stable aggregates (>5 mm), and the amount of the aggregates increased significantly with the increasing application rate of organic manure. Applying organic manure increased the amount of soil water stable aggregates (>0.25 mm), aggregate mean mass diameter, and aggregate stability in 0-30 cm soil layer, as compared with CK, and these three indices increased significantly with increasing organic manure application rate.
    Effects of nitrification inhibitors DCD and DMPP on cinnamon soil’s gross nitrogen mineralization and nitrification rates.
    2012, 23(01):  166-172. 
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    By using 15N pool dilution technique in combining with in situ soil cultivation, this paper studied the effects of nitrification inhibitors dicyandiamide (DCD) and 3,4-dimethylpyrazole phosphate (DMPP) on the gross nitrogen (N) mineralization and nitrification rates in a saline-alkali cinnamon soil in North China. The experiment was carried out in a maize-wheat rotation field in Yuncheng City of Shanxi Province, and three treatments were installed, i.e., urea, urea + DCD, and urea + DMPP. In the first two weeks after fertilization, DCD and DMPP made the gross N mineralization rate and gross N nitrification rate decreased by 25.5% and 7.3%, and by 60.3% and 59.1%, respectively, with a significant difference in the gross N mineralization rate but less difference in the gross N nitrification rate between the effects of DCD and DMPP. However, significant difference was observed in the gross N nitrification rate between the effects of DCD and DMPP after seven weeks of fertilization. The gross N mineralization and nitrification rates and the NH4+ and NO3- consumption rates after two weeks of fertilization were 7.2-10.0, 5.5-21.5, 9.1-12.2, and 5.1-8.4 times of those before fertilization, respectively, possibly due to the stimulating effect of N fertilization. DCD and DMPP made the fertilizer urea N more maintained in NH4+-N form and less accumulated in NO3--N form in soil. The decreases of the gross N mineralization and nitrifications rate in the test soil due to the effects of the inhibitors would benefit the reduction of N2O emission from the soil.
    Water stability of biological soil crusts in hilly regions of Loess Plateau, Northwest China.
    2012, 23(01):  173-177. 
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    By using an improved wet sieving method, this paper studied the water stability of biological soil crusts with different biological components and biomass in the hilly regions of Loess Plateau. The water stability of the biological soil crusts was related to the crusts’ biological components. Moss-dominated crust had significantly higher water stability than cyanobacteria-dominated crust. After 390 shakings, the thickness- and mass losses of moss-dominated crust were only 47.3% and 40.1% of those of cyanobacteria-dominated crust, respectively. Moss-dominated crust had the highest water stability when the moss coverage was up to 60%, and the thickness- and mass losses were 22.7% and 28.6% of those of cyanobacteria-dominated crust (no moss coverage), respectively. The horizontal stability of the biological soil crusts was significantly higher than the vertical stability. After 390 shakings, the area loss of moss-dominated crust was only 6.4% of thickness loss. The biological soil crusts had a layer structure with strong stability in horizontal direction, which increased the crusts’ resistance against wind- and water erosion.
    Nitrogen cycling in rice-duck mutual ecosystem during double cropping rice growth season.
    2012, 23(01):  178-184. 
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    Raising duck in paddy rice field is an evolution of Chinese traditional agriculture.In May-October 2010, a field experiment was conducted in a double cropping rice region of Hunan Province, South-central China to study the nitrogen (N) cycling in rice-duck mutual ecosystem during early rice and late rice growth periods, taking a conventional paddy rice field as the control. Input-output analysis method was adopted. The N output in the early rice-duck mutual ecosystem was 239.5 kg·hm-2, in which, 12.77 kg·hm-2 were from ducks, and the N output in the late rice-duck mutual ecosystem was 338.7 kg·hm-2, in which, 23.35 kg·hm-2 were from ducks. At the present N input level, there existed soil N deficit during the growth seasons of both early rice and late rice. The N input from duck sub-system was mainly from the feed N, and the cycling rate of the duck feces N recycled within the system was 2.5% during early rice growth season and 3.5% during late rice growth season. After late rice harvested, the soil N sequestration was 178.6 kg·hm-2.
    Effects of spatial heterogeneity on spatial extrapolation of sampling plot data. 
    2012, 23(01):  185-192. 
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    By using model combination method, this paper simulated the changes of response variable (tree species distribution area at landscape level under climate change) under three scenarios of environmental spatial heterogeneous level, analyzed the differentiation of simulated results under different scenarios, and discussed the effects of environmental spatial heterogeneity on the larger spatial extrapolation of the tree species responses to climate change observed in sampling plots. For most tree species, spatial heterogeneity had little effects on the extrapolation from plot scale to class scale; for the tree species insensitive to climate warming and the azonal species,spatial heterogeneity also had little effects on the extrapolation from plot-scale to zonal scale. By contrast, for the tree species sensitive to climate warming,spatial heterogeneity had effects on the extrapolation from plot scale to zonal scale, and the effects could be varied under different scenarios.
    Dynamics of regional ecological frangibility under natural hazard stress: A case study in Qingping Town of Sichuan Province, Southwest China.
    2012, 23(01):  193-198. 
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    By using the aerial remote sensing images after May 12, 2008 (the date of catastrophic Wenchuan Earthquake) and the unmanned aircraft vehicle remote sensing images after August 13, 2010 (the date of extraordinary debris flow), and in combining with the land use map (1∶10000), topographic map (1∶50000),and collected field investigation data of Qingping Town,Mianzhu City of Sichuan Province in 2006, this paper analyzed and evaluated the ecological frangibility of the Town. In the Town, the slightly, lightly, moderately, heavily, and extre〖JP2〗mely fragile ecological zones after the extraordinary debris flow occupied 1.9%, 7.9%, 18.7%, 23.0%, and 48.5%, respectively,with the area of heavily and extremely fragile ecological zones accounting for 71.5 % of the total, being 238.45 km2, i.e., the ecological environment was overall very fragile. Under the impact of the two natural hazards, the ecological frangibility degree of the Town increased obviously. As compared with that before the Earthquake, the area of heavily and extremely fragile ecological zones after the Earthquake increased by 12.4%, and the area of extremely fragile ecological zone was 1.67 times larger. The dynamic evolution of the ecological frangibility of the Town was mainly manifested in the conversion of heavily fragile ecological zone into extremely fragile ecological zone. Complex terrain was the key factor of the ecological frangibility of the Town.
    Influence of land use change on vegetation cover dynamics in Dapeng Peninsula of Shenzhen, Guangdong Province of South China.
    2012, 23(01):  199-205. 
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    To study the vegetation cover dynamics under urbanization is of significance to direct regional ecological conservation. Based on the 1995-2007 remote sensing data and the investigation data of 1996 and 2007 land use change in Shenzhen, and by using NDVI index tracking and algebraic overlay calculation, this paper analyzed the vegetation types and their spatial differentiation, land use change pattern, and the relationships between land use change and vegetation cover dynamics in Dapeng Peninsula of Shenzhen. In 1995-2007, the vegetation cover in 65% of the study area changed significantly, with an overall increasing trend. Land use change was mainly caused by the development of urbanization and commercial agriculture, with 31% of the land surface changed in land use function. The land use change was one of the main causes of vegetation cover dynamics,and about 35% of the region where vegetation cover significantly degraded was related to land use change. 55% of the region where land use function changed due to mechanical disturbance caused the degradation of vegetation cover, but by the end of the study period, the vegetation cover in most of the degraded region had being improved significantly.
    Habitat assessment of giant panda in Qingmuchuan Nature Reserve, Shaanxi Province of Northwest China.
    2012, 23(01):  206-212. 
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    Based on field survey and data collection, this paper studied the characteristics of habitat selection of giant panda(Ailuropoda melanoleuca)in Qingmuchuan National Nature Reserve, and assessed the  core and buffer zones of habitats from the aspects of topography, vegetation, food, and human disturbance, with the assistance of hierarchy analysis and Geographic Information System software (ArcMap and ArcView). In the study area, the suitable and secondary suitable habitats for Ailuropoda melanoleuca covered 62.1% and 31.0%, respectively, and the unsuitable habitats covered 6.9%. The suitable habitats were mainly distributed in the west and north parts with high altitudes, while the unsuitable habitats were mainly affected by vegetation coverage, bamboo distribution, and human disturbance. To reduce the unsuitable habitats, management mechanism should be further improved, e.g., controlling human disturbances, especially the grazing, bamboo-cutting, and firewood collection in the regions with altitude 900-1600 m.
    An approach for integrated assessment of eco-risk in coastal waters based on catastrophe theory: Taking Luoyuan Bay as a case.
    2012, 23(01):  213-221. 
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    Based on catastrophe theory, this paper established an index system and catastrophe progression model for the integrated assessment of eco-risk in coastal waters, including three risk types of “eutrophication-heavy metal pollution-organic pollution” and three dimensions of “water-sediment-organism”. According to the related quality standards, a four-level evaluation standard of eco-risk (zero, low, medium, and high) was proposed, and by using the monitoring data of 2007 and 2009, an integrated assessment of the eco-risk in Luoyuan Bay was conducted. In 2007-2009, the spatial variation of the eco-risk in Luoyuan Bay had a downward trend from bayhead to baymouth, and the risk level in 2009 was overall lower than that in 2007.The key factor of the eco-risk in the Bay was eutrophication.The approach established in this paper could identify the spatiotemporal variation characteristics of eco-risk in coastal waters, and better reflect the key eco-risk factor, providing a basic approach for effective forecasting and early warning of eco-risk in coastal waters.
    An  evaluation of potential occurrence of grasshopper plague in Xianghuangqi grasslands of Inner Mongolia, North China.
    2012, 23(01):  222-234. 
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    In this study, the key climatic factors in spawning, overwintering,and hatching periods of grasshopper were taken as the main factors to establish the climatic suitability index of potential occurrence of grasshopper (POG) in Inner Mongolia, and an  evaluation was conducted on the climatic suitability of POG in Xianghuangqi County of Inner Mongolia in 2010. Based on the field investigation data collected in early and mid July 2010, seven relatively stable habitat factors including elevation, aspect, soil type, soil sand content, vegetation type, vegetation coverage, and land cover type were selected, and the habitat suitability for POG throughout the County was estimated by using fuzzy evaluation combining with 3S (GIS, RS, and GPS) technology. The POG ranks in 2010 were estimated by integrating the climatic and habitat suitability for POG. The simulated locations where grasshopper occurred were verified by the field investigation data in 2010, and the simulated areas infected by grasshopper were verified by historical data from 2001 to 2010. The results confirmed that the estimated POG ranks were reliable. The climatic suitability for POG was very homogeneous over the study area, and the vast majority of the study area was in the rank of “suitable”. The spatial heterogeneity of the potential locations where the grasshopper might occur was mainly related to habitat factors. The highest POG rank was found at the locations with elevation 1300-1400 m, flat or aspect of east or south, typical chestnut soil, soil sand content 60%-80%, and vegetation coverage 30%-50% in temperate bunchgrass steppe.
    Screening, identification, and phosphate-solubilizing capability of phosphate-solubilizing bacterial strain B25.
    2012, 23(01):  235-239. 
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    Various phosphate-solubilizing bacterial strains were isolated from the Hippochaete ramosissimum rhizosphere in Tongguanshan copper tailings in Tongling of Anhui Province, East China. After many times of screening and purification, a strain B25 with stronger phosphate-solubilizing capability was obtained, which  belonged to Bacillus genus, as identified by transmission electron microscope and DNA molecular approaches. A culture experiment was conducted to study the phosphate-solubilizing capability of the B25 within 168 h and the variations of the medium pH and B25 growth as well as the phosphate-solubilizing capability of B25 under different culture conditions. A weak correlation was observed between the phosphate-solubilizing capability of B25 and the medium pH. The B25 displayed a better phosphate-solubilizing capability when the carbon source was glucose, medium initial pH was 7.0, and culture temperature was 30 ℃.
    Analysis of conserved flanking elements associated with antibiotic resistance genes dissemination. 
    2012, 23(01):  240-246. 
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    The overuse of antibiotics in medicine, animal husbandry, and aquiculture industry increases the emergence of antibiotic resistant bacteria and antibiotic resistance genes (ARGs), and also, accelerates the dissemination of ARGs within environmental bacteria. In this study, the total DNA was directly extracted from environmental samples, and the upstream and downstream of antibiotic resistance genes were directly amplified by thermal asymmetric interlaced PCR (Tail-PCR) technique.By optimizing the Tail-PCR program, the multiple flanking sequences of tetW,including 6 upstream sequences and 9 downstream sequences, were simultaneously acquired. Through the bioinformatics analysis, the upstream of tetW presented a perfect inverted repeat (IR), a known tetW regulator peptide, and an insertional sequence (IS), whereas the downstream of tetW presented a most conservative fragment and a common open reading frame (ORF) coding methyltransferase. This study not only revealed several conserved flanking tetW gene modules, but also supplied a highly-efficient and convenient methodology for the research of tetW's dissemination within bacteria, i.e., several flanking sequences could be concisely obtained from one sample by using Tail-PCR program.
    Macrobenthos community structure of macrobenthos and bioassessment of  water quality in main stream of Songhua River.
    2012, 23(01):  247-254. 
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    An investigation was conducted on the community structure of macrozoobenthos in the main stream of Songhua River in spring (April and May), summer (July and August), and autumn (from September to November), and the water quality of the main stream was assessed with biotic indices. A total of 116 species of macrobenthos were collected, belonging to 36 families and 16 orders, among which, aquatic insects had the largest number, with 74 species (63.8% of the total) belonging to 21 families and 6 orders. The annual average density and biomass of the macrobenthos were 66.80 ind·m-2 and 24.30 g·m-2, respectively. The average density was the highest (90.52 ind·m-2) in spring, followed by in autumn (61.26 ind·m-2), and in summer (48.63 ind·m-2), while the average biomass was the highest (35.35 g·m-2) in autumn, followed by in summer (23.12 g·m-2), and in spring (14.41 g·m-2). The Shannon index, Pielou index, and Simpson index were the highest in spring, and were nearly the same in summer and autumn. Few species inhabited in the same types of microhabitats in all river sections. The species similarity in all sections was lower, with the largest similarity being only 60%. The species quantity of each functional feeding group was near, with 26 shredders, 32 collectors, 28 scrapers, and 30 predators. The water quality assessed with biotic index (BI) and family biotic index (FBI) was basically coincident with each other, and was accordant with chemical monitoring. The water quality above the Harbin Section of Songhua River was fair, and that below the Harbin Section was contaminated or seriously contaminated. It was presumed that the macrobenthos species composition and community structure had been affected due to the building of ship-electricity hinge in Dadingzi Mountain.
    Synergistic effects of water temperature and salinity on the growth and liver antioxidant enzyme activities of juvenile GIFT Oreochromis niloticus.
    2012, 23(01):  255-263. 
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    By adopting two-factor central composite design (CCD) and response surface methodology (RSM), this paper studied the synergistic effects of water temperature (16-37 ℃) and salinity (0-18) on the specific growth rate (SGR) and liver superoxide dismutase (SOD) and catalase (CAT) activities of juvenile GIFT Oreochromis niloticus. Water temperature and salinity had significant linear and quadratic effects on the SGR (P<0.05), respectively. With increasing water temperature or salinity, the SGR decreased after an initial increase.There existed significant synergistic effects between water temperature and salinity (P<0.05). The SGR was higher at 16-20 ℃ and salinity 9-10, at 27-32 ℃ and salinity 3-5, and at 35-37 ℃ and in freshwater. The SOD and CAT activities were higher at 28-30 ℃ and salinity 6-8. The linear of temperature and quadratic of salinity had significant effects on the two enzymes (P<0.05), and there was a significant synergistic effect on CAT activity.High temperature and high salinity were not favorable to the expression of SOD and CAT activities.The coefficients of determination of quadratic regression equations for SGR, SOD and CAT activities reached to 0.954, 0.831, and 0.942 (P<0.05), respectively, and could be used for prediction. The growth and antioxidant enzyme activities were more affected by water temperature than by water salinity. In the culture practice of O. niloticus, it would be necessary to optimize culture environment and reduce oxidative stress to promote the growth and disease- resistance of the tilapia.
    Phosphorus threshold for the shift between grass- and algae-stable states in Dahong Harbor of Gehu Lake.
    2012, 23(01):  264-270. 
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    Taking the macrophytes remaining area in Dahong Harbor of Gehu Lake as test object, this paper studied the phosphorus threshold for the shift between grass- and algae-stable states under natural conditions. The correlation analysis on the environmental factors showed that the total phosphorous in water body had better liner relationships with phytoplankton chlorophyll a and Secchi depth, and principal component analysis indicated that total phosphorous and nitrogen in the water body were the two main components affecting the water quality, among which, total phosphorous was the maximum weight source and played a determinant role in the shift between grass- and algae-stable states. The Harbor was in grass-stable state in winter, shifted to grass-algae intermediate state in spring, and kept the intermediate state in summer and autumn. The total phosphorous threshold for grass-stable state shifting to grass-algae intermediate state was 61 μg·L-1,and that for grass-algae intermediate state shifting to algae-stable state was 115 μg·L-1. In order to make the ecosystem shift from algae-stable state to grass-stable state, some measures such as cutting and controlling the Lake’s nutrient sources, removing the sediment rich in organic matter, and constructing submerged macrophytes areas should be adopted to make the total phosphorous threshold in the water body dropped to below 61 μg·L-1.
    Development of insecticide resistance and its effect factors in  field population of Bemisia tabaci in Fujian Province,  East China.
    2012, 23(01):  271-277. 
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    The development of insecticide resistance in field populations of Bemisia tabaci from different regions of Fujian Province, China were monitored with adult leaf-dipping bioassay. Compared with bioassay data of 2005, all field populations tested in 2009 still had high levels of resistance to the lambda-cyhalothrin, fenpropathrin and chlorpyrifos, low levels of resistance to methomyl, and no resistance to abamectin. However, resistance to the neonicotinoids imidacloprid and thiamethoxam had increased from moderate levels (23 folds and 25 folds, respectively) in 2005 to high levels (103 folds and 228 folds, respectively) in 2009 in Zhangzhou population, and low levels (1.5-3.3 folds and 1.7-5.5 folds,respectively) in 2005 to moderate levels (23-33 folds and 29-49 folds, respectively) in 2009 for other populations. The biotype of eight B. tabaci populations collected from different regions and hosts were determined according to the mitochondria cytochrome oxidase I (mtCO I ) sequence, and two different biotypes (B-biotype and indigenous whitefly) were detected. The samples collected from geographical regions and hosts showed a prevalence of the B-biotype, and indigenous whitefly (unknown biotype) existed only in croton of Zhangzhou. Host plants and temperature had limited effects on insecticide development in B. tabaci, while extensive and high frequent use of neonicotinoids could be the most important factors responsible for rapid development of insecticide resistance in field populations of B-biotype B. tabaci.
    Impact of fish aggregation devices on tropical tuna’s behavioral pattern: A review.
    2012, 23(01):  278-284. 
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    Tuna prefers to aggregate around floating objects. Based on this behavioral characteristic, people developed fish aggregation devices (FADs) to trap tuna, and made the catch and fishing efficiency of tuna purse seine fisheries improved greatly. However, there still exist uncertainties whether the FADs can attract tuna and what’s the potential impact of widely applying FADs in tuna purse seine fishery on tuna resources and oceanic pelagic ecosystem. Aiming at these uncertainties, scientists  conducted a great deal experiments to study the behavioral biology of tuna around FADs. This paper reviewed the related classic and more credible experiments in the past 30 years, and summed up five behavioral patterns of the tunas around drifting and anchored FADs, i.e., tropism behavior, schooling behavior, association behavior, feeding behavior, and vertical movement pattern. The related main research methods currently in use were introduced, and the issues on this subject needed to be paid great attention to were discussed.
    Eco-physiological functions of mycorrhizal fungi.
    2012, 23(01):  285-292. 
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    Mycorrhizal fungi are an important member of soil microorganisms, not only rich in genetic diversity and species diversity,  but also in functional diversity, which mainly manifest in: 1) affecting the origin, evolution, and distribution of terrestrial plants, 2) promoting plant growth and development, 3) enhancing plant tolerance against environmental stress, 4) remedying polluted and degraded soils, 5) promoting agricultural, forestry, and animal husbandry production, and 6) maintaining ecological equilibrium and stabilizing ecosystem and its sustainable productivity. With the development of technique and research, more functions contributed by mycorrhizal fungi would be discovered.