Table of Content

18 June 2011, Volume 22 Issue 06

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Articles

Effects of forest gap on tree species regeneration and diversity of mixed broadleaved Korean pine forest in Xiaoxing’an Mountains.

2011, 22(06):  1381-1388. 

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This paper studied the quantitative characteristics of main tree species along a forest gap gradient (gap center-near gap center-gap border) of mixed broadleaved Korean pine forest in Xiaoxing’an Mountains, as well as the effects of forest gap size on the regeneration of the tree species. In forest gap, the density of shrub species was obviously larger than that in non-gap, and the density ratio of the same shrub species in forest gap to in non-gap ranged from 1.08 to 18.15. With the increase of gap size, the regeneration density of tree seedlings increased, and that of saplingⅠ(H≥1 m, DBH≤2 cm) and saplingⅡ(H≥1 m, 2 cm＜DBH≤5 cm) exhibited multiple peak curve. The overall regeneration density of shrubs in forest gaps varied mainly with the amounts of tree seedlings and saplingⅠ. The mean height, mean basal diameter, species density, and individual density of trees in different locations of forest gaps were all different. From gap center to non-gap, the importance value of tree species seedlings in regeneration layer was ranked in gap center > near gap center > gap border > non-gap, the tree species evenness presented a variation of high-low-high, and the species diversity decreased in the order of early phase gap > mid phase gap > late phase gap.

Leaf litter decomposition and nutrient release of different stand types in a shelter belt in Xinjiang arid area.

2011, 22(06):  1389-1394. 

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From October 2007 to November 2008, an in situ mesh bag experiment was conducted to study the leaf litter decomposition and nutrient release of forest stands Populus alba var. pyramidalis, Amorpha fruticosa, and P. alba  var. pyramidalis + A. fruticosa in a shelter belt in Karamay, Xinjiang. It was observed that the mass loss rate of leaf litter differed with tree species, and was significantly affected by leaf litter composition. The leaf litter of P. alba var. pyramidalis + A. fruticosa was more easily decomposed than that of the other two mono-dominance forest trees. The analysis with improved Olson’s exponential model indicated that P. alba var. pyramidalis leaf litter had the lowest decomposition coefficient (k=0.167), while P. alba var. pyramidalis + A. fruticosa leaf litter had the highest one (k=0.275). According to the model, it would cost for about 2.41-4.19 years and 10.79-17.98 years to have 50% and 95% decomposition of the three kind leaf litters, respectively. The residual rates of nitrogen, phosphorus, and potassium in the three kind leaf litters differed with decomposition period. After one year decomposition, potassium was wholly released, while nitrogen and phosphorus were immobilized or enriched via the absorption from surrounding environment. Except that the A. fruticosa leaf litter had a decreased organic carbon decomposition rate in the mid period of decomposition, the leaf litters of P. alba var. pyramidalis and P. alba var. pyramidalis + A. fruticosa all had an increasing organic carbon decomposition rate with the decomposition, which was about 35.5%-44.2% after one year decomposition. The C/N value of the leaf litters had a decreasing trend, and the decrement was smaller in the early and mid periods but larger in the late period of decomposition.

Photosynthetic parameters and chlorophyll fluorescence characteristics of Pleioblastus kongosanensis f. aureostriaus under drought stress.

2011, 22(06):  1395-1402. 

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A pot experiment was conducted to study the variations of Pleioblastus kongosanensis f. aureostriaus plant morphology, leaf water content (LWC), leaf
water potential (LWP), photosynthetic parameters, chlorophyll fluorescence parameters, and soil water content (SWC) under natural drought stress, as well as the relationships between these variations and environmental factors. On the 17th day under the stress, the P. kongosanensis presented damaged symptom. Its leaves dehydrated, drooped, and wrap-formed. On the 43rd day, the aboveground part of the plant died from dehydration. When the plant was re-watered for 10 days, the chlorophyll fluorescence parameters had no significant differences with those on the 43rd day under the stress. The SWC decreased significantly in 0-21 d of the stress, and the LWP and LWC dropped rapidly and significantly after 17 d and 29 d, respectively. With the increase of drought stress, the leaf transpiration rate (T_r) and stomatal conductance (g_s) had a persistent decline, photosynthetic rate (P_n) had a greater fluctuation, and instantaneous water use efficiency (PWUE) decreased after an initial increase. After 17 d drought stress, the limiting factor of P_n was from stomatal to non-stomatal, and the actual photosynthetic efficiency (Φ_PSⅡ) declined significantly; after 25 d, the photosynthetic organ was damaged, and the maximum photochemical efficiency of PSⅡ (F_v/F_m) and non-photochemical quenching (q_N) changed significantly from 0.64 to -0.11 and from 0.79 to 0.33, respectively. The T_r,g_s, and PWUE had close correlations with LWP; the P_n, T_r, and g_s were sensitive to air relative humidity (RH); and the g_s was the main factor causing the diurnal variations of photosynthetic parameters. It was suggested that P. kongosanensis could grow well on the soil with relative moisture content ≥12% and drought duration less than 25 d. 

Effects of domestic wastewater slow infiltration on the growth of poplar ‘Zhonglin 2001’ plantation.

2011, 22(06):  1403-1408. 

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A slow infiltration experiment with different hydraulic loads (0, 3, 6, 9, 12, and 15 cm per week) of domestic wastewater was conducted in a ‘Zhonglin 2001’ poplar plantation to study the effects of the wastewater slow infiltration on the growth of the plantation. Comparing with the control (0 cm), the other five treatments increased the soil organic matter, total N, total P, total K, and Na⁺ contents in the plantation averagely by 1.940 g·kg^-1, 0.115 g·kg^-1, 0.029 g·kg^-1, 1.454 g·kg^-1 and 0.030 g·kg^-1, respectively At lower hydraulic loads (3-12 cm per week), the poplar biomass growth and the N, P and Na⁺ contents in different poplar organs averagely increased by 17.583 t·hm^-2·a^-1, 3.086 g·kg^-1, 0.645 g·kg^-1, and 0.121 g·kg^-1, with the maximum (36.252 t·hm^-2·a^-1, 13.162 g·kg^-1, 5.137 g·kg^-1, and 0.361 g·kg^-1, respectively) at hydraulic loads 6-12 cm per week. The further increase of the hydraulic load decreased the poplar biomass growth and the N, P and Na⁺ contents in different poplar organs. The K content in different poplar organs decreased with increasing hydraulic load. Treating with domestic wastewater increased the leaf length, decreased the leaf asymmetry, and delayed leaf- falling. At high hydraulic load (15 cm per week), the higher soil Na⁺ and water contents would threat the poplar growth. The proper domestic wastewater hydraulic loads for the growth of poplar ‘Zhonglin 2001’ plantation would be 3-12 cm per week.

Photosynthetic mechanisms of northern boundary formation of Quercus wutaishanica forest in Loess Plateau of northern Shaanxi Province.

2011, 22(06):  1409-1415. 

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Aimed to understand the causes of the boundary formation of Quercus wutaishanica forest, four sites were chosen along a precipitation and thermal gradient from Qinling Mountain to Loess Plateau of northern Shaanxi Province, i.e., north slope of Qinling Mountain (Jiwozi)and southern (Chenjiashan), central (Huaishuzhuang), and northern site (Xiasiwan) of Loess Plateau, with the gas exchange, chlorophyll fluorescence parameters, stomatal density, and stomatal size of Q. wutaishanica leaves measured. From the south to the north along the precipitation and thermal gradient, weather varied from cool and humid to warm and semi-arid, and the maximum net photosynthetic rate (P_{n max}) and light saturation point (L_sp) of Q. wutaishanica leaves reduced obviously from 13.34 to 6.99 μmol CO₂·m^-2·s^-1 and from 1489.9 to 1055.6 μmol·m^-2·s^-1, dark respiration rate (R_d) and light compensation point (L_cp) increased evidently from 0.313 to 1.080 μmol CO₂·m^-2·s^-1 and from 7.49 to 31.96 μmol·m^-2·s^-1, the minimum fluorescence (F_o) and coefficient of non-photochemical quenching (NPQ) displayed an increasing trend, and actual photochemical quantum yield of PSⅡ (Φ_PSⅡ), apparent electron transport rates (ETR), and coefficient of photochemical quenching (q_P) reduced obviously. These results demonstrated that the photosynthetic capacity of Q. wutaishanica declined gradually with decreasing precipitation, but the stomatal density and stomatal size showed no obvious difference among the study sites except for the southern site of Loess Plateau. It was speculated that the depressed net photosynthetic rate of Q. wutaishanica leaves induced by the declined Φ_PSⅡ and ETR could be one of the main causes for the formation of northern boundary of Q. wutaishanica forest.

Soil quality assessment of alpine meadow in Haibei State of Qinghai Province.

2011, 22(06):  1416-1422. 

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Taking the typical alpine meadows Potentilla froticosa shrub meadow, Kobresia humilis meadow, and K. pygmaea meadow in the Haibei State of Qinghai Province as the research objects, a comprehensive assessment of soil quality was conducted by principal component analysis (PCA), with seven indices of soil microbial activities and ten indices of soil chemical properties. The soil quality of the alpine meadow could be characterized by three principal components (PC). In the first component (PC₁), 13 indices had high factorial loads; in the second component (PC₂), 3 indices had high factorial loads; in the third component (PC₃), only one index, total phosphors, had high factorial load. In combining with Norm values, eleven indices including microbial biomass carbon (MBC), urease, alkaline phosphatase, protease, organic matter, total N, available N, available P, available K, bulk density, and CEC were selected to establish minimum data set (MDS) for the comprehensive assessment of soil quality of alpine meadow in Haibei. The PCA and corresponding weight coefficient analysis showed that the soil quality (0-10 cm and 10-20 cm layers) of the three kind meadows was in the order of K. humilis meadow > P. froticosa shrub meadow > K. pygmaea meadow, and P. froticosa shrub meadow > K. pygmaea meadow > K. humilis meadow, respectively.

Salinization-alkalization of Leymus chinensis grassland in Songnen Plain of Northeast China.

2011, 22(06):  1423-1430. 

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Field survey and site study were conducted to approach the process and causes of salinization-alkalization of Leymus chinensis grassland in Songnen Plain, and to examine the hypothesis of soil disturbance-bareness. In the grassland, surface soil (0-30 cm) had a lower salt content, while deeper soil (>30 cm) was in adverse. Thereby, the grassland was defined as soil-salted grassland. There was an increasing salt content in surface soil. This process was called as soil salinization-alkalization, and the grassland under the salinization-alkalization was named as alkali-salinized grassland. The leading reason for the surface soil salinization-alkalization was that the surface soil originally with low salt content was disturbed and lost away, subsurface soil rich in salt emerged as new surface soil, and the salt in deeper soil layers accumulated in the new surface soil and other soil layers. Secondary halophyte communities formed on the surface-soil-disturbed new bare land, but the communities had no succession sequence. The degradation process of the grassland was soil degradation first, followed by vegetation degradation, halophyte invasion, and successive evolution from nearly primitive condition.

Characteristics of CO₂ emission from Carex-dominated wetland in Poyang Lake  in non-flooded period.

2011, 22(06):  1431-1436. 

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By using static chamber/gas chromatography, the CO₂ fluxes in a Carex cinerascen-dominated wetland in the Poyang Lake Nanji Wetland National Nature Reserve were measured in non-flooded period (from September 2009 to April 2010). Two treatments were installed, i.e., soil-plant system (TC) and aboveground plant removal (TJ), representing ecosystem respiration and soil respiration, respectively. There was an obvious seasonal variation in the ecosystem respiration and soil respiration. The respiration rate in treatment TC ranged from 89.57 to 1243.99 mg CO₂·m^-2·h^-1, and that in TJ was from 75.30 to 960.94 mg CO₂·m^-2·h^-1. Soil respiration  accounted for 39%-84% of ecosystem respiration, with an average of 64%. Soil temperature was the main factor controlling the ecosystem respiration and soil respiration, explaining more than 80% of the respiration variance. The temperature coefficient (Q₁₀), an index of temperature sensitivity for respiration, was 3.31 for ecosystem respiration and 2.75 for soil respiration. The Q₁₀ value was higher in winter than in autumn and spring. No significant correlation was observed between soil moisture and CO₂ fluxes. In non-flooded period, the C. cinerascens-dominated wetland acted as a carbon sink of atmospheric CO₂, with a carbon uptake of 1717.72 g C·m^-2.

Effects of growth regulators and growth media on root-hair development of Poncirus trifoliate.

2011, 22(06):  1437-1442. 

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By using river sand and mixed soil as growth media, and treating with different concentration IBA, ETH, and NAA, this paper studied the root-hair development of Poncirus trifoliate seedlings, and the development cycle and distribution pattern of the root-hairs under phosphorus deficiency in sand culture. The root-hairs had a development cycle of about 4 days, and formed block-shaped and clumped, mainly around root, and with uneven distribution. Sand culture gave rise to the production of more root hairs, with an average of 486.3 per tap root, and treating with 1.0 μmol·L^-1 of IBA and ETH notably promoted root-hair development. The phosphorous deficiency in sand culture induced more root hair formation (636.3 per tap root). Mixed soil culture produced lesser root-hairs (212.3 per tap root), and all the test growth regulators had no obvious effects on the root-hair development.

Effects of inoculating arbuscular mycorrhizal fungi on Artemisia annua growth and its officinal components.

2011, 22(06):  1443-1449. 

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A pot experiment was conducted to study the effects of inoculating arbuscular mycorrhizal (AM) fungi on the growth, nutrient uptake, and officinal components of Artemisia annua. Inoculation with AM fungi Glomus mosseae and G. versiforme improved the uptake of nitrogen, phosphorus, and potassium by A. annua, and increased the leaf chlorophyll content, net photosynthetic rate, stomatal conductance, and transpiration rate as well as the stem diameter and aboveground biomass of A. annua, with greater effects of inoculating G. mosseae than G. versiforme. After the colonization of G. mosseae and G.versiforme, the artemisinin content in A. annua stem, branch, and leaf was increased by 32.8%, 15.2%, and 19.6%, and 26.5%, 10.1%, and 14.9%, and the volatile oil content in leaf was increased by 45.0% and 25.0%, respectively, compared with the control. Furthermore, mycorrhizal colonization led to changes in volatile components.

Nitrogen uptake and allocation characteristics of flue-cured tobacco in Nanxiong tobacco-planting area of Guangdong Province.

2011, 22(06):  1450-1456. 

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By the method of field in situ culture and ¹⁵N isotopic tracer technique, and taking flue-cured tobacco (Nicotiana tobacum) cultivar K326 as test material, a field experiment was conducted in the Nanxiong tobacco-planting area of Guangdong Province to study the characteristics of soil nitrogen (N) mineralization, the patterns of N accumulation and allocation in tobacco plants, and the allocation of plant-absorbed fertilizer N applied in current growth season. In the study area, the amount of soil mineralized N increased with tobacco growth, peaked at 75 days after transplanting, and decreased thereafter. The soil  mineralized N at each tobacco growth stage was significantly higher in the control than in the N fertilization treatment. The N accumulation in tobacco plant organs was in the order of leaf > stalk > root. Tobacco plants mainly absorbed fertilizer N at rosette stage and topping stage, and mainly absorbed soil N at mature stage. The absorbed N in tobacco whole growth period was mainly derived from soil N, and the absorbed soil N and its proportion to the total absorbed N increased evidently with extending growth stage and ascending leaf position. The fertilizer N use efficiency per plant and the residual rate and loss rate of applied fertilizer N were 30.8%, 32.3%, and 36.9%, respectively. In the study area, soil N mineralization rate was relatively high, and soil N had greater effects on the quality of upper tobacco leaves. Under the application rate of 150 kg N·hm^-2, the residual amount and loss amount of applied fertilizer N were relatively high.

Effects of reduced solar radiation on winter wheat flag leaf net photosynthetic rate.

2011, 22(06):  1457-1464. 

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Taking winter wheat Triticum aestivum L. (cv.Yangmai 13) as test material, a field experiment was conducted in Nanjing City to study the effects of simulated reduced solar radiation on the diurnal variation of winter wheat flag leaf photosynthetic rate and the main affecting factors. Five treatments were installed, i.e., 15% (T₁₅), 20% (T₂₀), 40% (T₄₀), 60% (T₆₀), and 100% (CK) of total incident solar radiation. Reduced solar irradiance increased the chlorophyll and lutein contents significantly, but decreased the net photosynthetic rate (P_n). Under different solar irradiance, the diurnal variation of P_n had greater difference, and the daily maximum P_n was in the order of CK＞T₆₀＞T₄₀＞T₂₀＞T₁₅. In CK, the P_n exhibited a double peak diurnal curve; while in the other four treatments, the P_n showed a single peak curve, and the peak was lagged behind that of CK. Correlation analysis showed that reduced solar irradiance was the main factor affecting the diurnal variation of P_n, but the physiological parameters also played important roles in determining the diurnal variation of P_n. In treatments T₆₀ and T₄₀, the photosynthesis active radiation (PAR), leaf temperature (T_l), stomatal conductance (G_s),and transpiration rate (T_r) were significantly positively correlated with P_n, suggesting their positive effects on P_n. The intercellular CO₂ concentration (C_i) and stomatal limitation (L_s) had significant negative correlations with P_n in treatments T₆₀ and T₄₀ but significant positive correlations with P_n in treatments T₂₀ and T₁₅, implying that the C_i and L_s had negative (or positive) effects on P_n when the solar irradiance was higher (or lower) than 40% of incident solar irradiance.

Effects of planting density and spraying PP333 on winter wheat lodging-resistance and grain yield.

2011, 22(06):  1465-1470. 

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Taking two winter wheat varieties Gaocheng 8901 and Yannong 21 with different end-use qualities as test objects, a field experiment was conducted in the experimental farm of Shandong Agricultural University from 2008 to 2010, aimed to study the effects of different planting density and spraying PP333 on the basal stem morphological characteristics, snapping-resistance, lodging-resistant index, and grain yield. Gaocheng 8901 had higher lodging-resistance but lower grain yield than Yannong 21. Comparing with low planting density (180×10⁴ basic seedlings per hm²), high planting density (240×10⁴ basic seedlings per hm²) decreased the culm snapping-resistance and lodging-resistant index of the two varieties, especially Yannong 21. Spraying PP333 decreased the plant height and the basal internodes length, increased the snapping-resistance and lodging-resistant index, strengthened the lodging-resistance, and improved the spike number and grain yield. Correlation analysis showed that the second internode length, percentage of basal internodes (1+2) length to total internode length, and apparent lodging ratio were significantly negatively correlated with culm lodging resistant index. Therefore, to adopt an appropriate planting density combined with spraying PP333 could improve the lodging-resistance of winter wheat and its grain yield, being an important high-yielding cultivation technique for wheat production in sub-humid zone.

Effects of different mulching measures on winter wheat field soil respiration in Loess Plateau dry land region.

2011, 22(06):  1471-1476. 

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A field experiment was conducted to study the effects of different mulching measures on the diurnal and seasonal variations of winter wheat field soil respiration in dry land region of Loess Plateau. Four treatments were installed, i.e., 300 kg·hm^-2 straw mulching (M₃₀₀), 600 kg·hm^-2 straw mulching (M₆₀₀), plastic film mulching (PM), and no mulching (CK). In all treatments, the soil respiration rate had a decreasing trend from autumn to winter, but increased rapidly after winter and peaked at jointing stage. Comparing with CK, treatments mulching promoted the soil respiration obviously from wintering to maturing stage, with significant differences between treatment PM and the others. The average soil respiration rate in treatments M₃₀₀ and M₆₀₀ in whole growth period was 1.52 μmol CO₂·m^-2·s^-1 and 1.47 μmol CO₂·m^-2·s^-1, being 10.2% and 6.6% higher than the CK (138 μmol CO₂·m^-2·s^-1), respectively, and that in treatment PM was 3.63 μmol CO₂·m^-2·s^-1, 163% higher than CK. The diurnal variation of soil respiration rate in CK and in M₃₀₀ and M₆₀₀ presented a single peak curve and peaked at 12:00 and 14:00, respectively, but for PM treatment, the diurnal variation of soil respiration rate was similar with that in CK at jointing stage while presented a bimodal curve at maturing stage, with the peaks at 12:00 and 16:00, respectively. Soil respiration rate had an exponential correlation with soil temperature, and a parabolic correlation with soil moisture.

Freeze resistance analysis of different wheat cultivars based on the relationships between physiological indices and grain yield.

2011, 22(06):  1477-1484. 

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A pot experiment with twenty wheat cultivars was conducted to investigate the superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT) activities and the MDA, soluble protein and soluble sugar contents of functional leaves as well as the grain yield, 1000-grain weight, and grain morphological characters under low temperature stress. Low temperature (-4 ℃) stress at stem elongation stage resulted in the changes of grain morphology and yield characters. For most of test cultivars, their grain length-width ratio, grain roundness, and sterile spikelets increased, and their grain equivalent diameter, grain area, 1000-grain weight, and grain yield decreased. Path analysis indicated that after treated with low temperature at stem elongation stage, the SOD activity and soluble sugar content of functional leaves, especially the SOD activity (direct path coefficient -0.578), were the dominant factors affecting grain yield. Taking the percentage of decreased grain yield due to low temperature stress as the assessment criterion, the test twenty winter wheat cultivars were divided into three groups. Cultivars Jimai 19, Jimai 20, Liangxing 99, Shannong 1135, Shannong 8355, Taishan 23, Taishan 9818, Wennong 6, and Yannong 21 belonged to high freeze resistance group, cultivars Linmai 2, Weimai 8, Yannong 19, and Zimai 12 were of low freeze resistance group, and the other seven cultivars belonged to medium freeze resistance group. The seedling stage comprehensive assessment index (D value) had a significant negative correlation with the percentage of decreased grain yield (r=-0.512*), suggesting that the stronger freeze resistance of wheat at seedling stage was beneficial to the higher wheat grain yield, and seedling stage was the critical period to be selected to identify the freeze resistance of wheat.

Effects of light quality on rice seedlings growth and physiological characteristics.

2011, 22(06):  1485-1492. 

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By using light emitting diode (LED) to accurately modulate spectral energy distribution, and with fluorescent light as the control, this paper studied the effects of light quality on the seedlings growth and physiological characteristics of rice cultivars ‘Wuyunjing 7’ and ‘Kangyou 63’. Light quality had significant effects on the seedlings growth, and there existed differences at different growth stages. Blue LED inhibited the height growth significantly, and increased the leaf soluble protein content of ‘Wuyunjing 7’ and the healthy index of the two rice cultivars at five-leaf stage. Red LED increased the stem diameter and healthy index at three-leaf stage and the leaf soluble sugar and starch contents at five-leaf stage significantly. Red-blue LED increased the root number, stem diameter, healthy index, root activity, and root soluble sugar content at three-leaf stage and the fresh mass, dry mass, healthy index, and leaf soluble sugar and sucrose contents at five-leaf stage significantly. Yellow LED increased the plant height and leaf pigment content at initial growth stage. Overall, red-blue LED was more beneficial to the culture of strong rice seedlings.

Distribution of Bt protein in transgenic cotton soils.

2011, 22(06):  1493-1498. 

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A pot experiment with red soil, yellow brown soil, and yellow cinnamon soil was conducted to detect the Bt protein content in rhizosphere and non-rhizosphere soils at different growth stages of transgenic Bt cotton and common cotton by using enzyme linked immunosorbent assay (ELISA). With the planting of transgenic Bt cotton, the Bt protein content in rhizosphere soil was significantly higher than that in non-rhizosphere soil; while in common cotton soils, there was no significant difference in the Bt protein content between rhizosphere soil and non-rhizosphere soil. At bud stage of transgenic Bt cotton, the Bt protein content in rhizosphere soil was in the order of yellow cinnamon soil > yellow brown soil > red soil, being 144%, 121%, and 238% of that incommon cotton rhizosphere soil; at florescence stage of transgenic Bt cotton, the Bt protein content in rhizosphere soil was in the order of yellow brown soil > yellow cinnamon soil > red soil, being 156%, 116%, and 197% of that in common cotton rhizosphere soil, respectively. Regardless of planting Bt cotton or common cotton, the Bt protein content in rhizosphere and non-rhizosphere soils had an initial increase with the growth of cotton, peaked at florescence stage, and then decreased. Throughout the whole cotton growth period, the Bt protein content in transgenic Bt cotton rhizosphere soil was higher than that in Bt cotton non-rhizosphere soil, and also, higher than that in common cotton rhizosphere soil, indicating that transgenic Bt cotton could release its Bt protein to rhizosphere soil.

Effects of inoculating earthworm on the seed yield and its oil content of winter oilseed rape.

2011, 22(06):  1499-1503. 

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A field experiment was conducted to study the effects of inoculating earthworm (Metaphire guillelmi) on the yield components, seed yield, and seed oil content of winter oilseed rape (Brassica napus L. cv. Zhongshuang 9). Inoculating earthworm increased the primary branch numbers per plant, main raceme pod numbers per plant, seed numbers per pod, and 1000-seeds weight, but the effect wasnot significant. However, comparing with the control, inoculating earthworm increased the pod number per plant, seed yield per plant, and seed yield of whole plot significantly, with the increment being 36.7%, 46.5%, and 29.7%, respectively, which could be related to the promotion effect of earthworm on the plant growth and its nitrogen uptake at vegetative growth stage. After the inoculation with earthworm, the seed oil content somewhat decreased, but, owing to the significant increase of seed yield under the effect of earthworm, both the oil production per plant and the oil production of whole plot increased significantly by 37.4% and 21.0%, respectively, compared with the control.

Present situation of maize straw resource utilization and its effect in main maize production regions of China.

2011, 22(06):  1504-1510. 

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A survey was carried out in three main maize production regions in Northeast, North, and Southwest China, including 720 villages of 125 counties, with the purpose of investigating the present situation of maize straw resource utilization and its effect. Among the present utilization ways of maize straw resource, the main ones were returning to soil, feeding livestock, and using as fuel, their proportions being 30.8%, 26.2%, and 24.6%, respectively. In Northeast China, the top three utilization ways were fuel, livestock feed, and returning to soil, with the proportions being 35.4%, 30.8% and 19.8%; in North China, the top three were returning to soil, livestock feed, and fuel, with the proportions being 43.6%, 19.9%, and 17.9%; and in Southwest China, they were returning to soil, livestock feed, and fuel, with the proportions being 29.0%, 27.9%, and 20.5%, respectively. In the survey areas, the proportion of using maize straw as fuel was smaller (128%), and that of using as industrial raw material was only 0.7%. Returning maize straw to soil increased maize yield (the increment in Northeast, North, and Southwest China was 632.0, 371.6, and 290.4 kg·hm^-2, respectively), improved soil condition, and decreased the application rates of manure, nitrogen, phosphorus, and potassium fertilizers by 20%-30%, 16%-30%, 24%-34%, and 33%-38%, respectively. The maize yield increased with increasing straw mass and its returning amount and proportion. However, because of wanting complete sets of available machines, straw returning was low in quality, which increased the difficulty in weed controlling and promoted the occurrence of some diseases and insect pests, giving impacts on maize seedlings growth. It would be necessary to strengthen the researches on the related complete set maize straw returning techniques.

Changes of China agricultural climate resources under the background of global climate change. Ⅵ. Change characteristics of precipitation resource and its possible effect on maize production in Sanjiang Plain of Heilongjinag Province.

2011, 22(06):  1511-1522. 

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Based on the 1959-2007 daily precipitation data and 1983-2007 spring maize phenologyical data, the thresholds of extreme precipitation at different places in Sanjiang Plain of Heilongjiang Province were calculated by percentile method, and, in combining with the indices involving the frequency and intensity of extreme precipitation, longest consecutive wet (dry) days, and contribution rate of extreme precipitation, the annual change characteristics of extreme precipitation, quantitative change of different grade precipitation, and distribution characteristics of extreme precipitation at each growth stage of spring maize were analyzed. In 1959-2007, the annual precipitation in Sanjiang Plain showed a slight decreasing trend, and the decreasing amplitude of precipitation days was much larger than that of precipitation. Accordingly, the annual distribution of precipitation tended to be more concentrated. The frequency and intensity of extreme precipitation declined, and the annual fluctuation of the frequency was bigger than that of the intensity. There was a slight decrease in the proportion of annual extreme precipitation to annual precipitation, but the decreasing tendency was not significant. The annual light rain days had a significant decreasing trend, but the annual moderate and heavy rain days didn’t have. During spring maize growth season, the distribution ratio of extreme precipitation from high to low was reproductive growth stage, coexistence stage of vegetative growth and reproductive growth, vegetative growth stage, and pre-mergence stage. There was a significant decrease in the proportion of the precipitation during spring maize growth season to annual precipitation, resulting in an increasing risk of precipitation scarcity during the growth season. The longest consecutive dry days during spring maize growth season showed a significant increasing trend, with the increment averaged 1.1 d·(10 a)^-1, while the longest consecutive wet days showed a significant decreasing trend, with the decrement averaged 0.5 d·(10 a)^-1. Under natural precipitation, the spring maize drought risk in the study region increased.

Changes of agroecosystem service value during urbanization of Guangzhou City, South China.

2011, 22(06):  1523-1530. 

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Based on the 1996, 2000, 2004, and 2008 statistical data of Guangzhou City, and by the methods of marketing valuation, shadow price, afforestation cost, carbon tax, and industrial oxygen-producing, this paper calculated the related service values of various agroecosystems in Guangzhou, and assessed the changes of agroecosystem service value during the rapid urbanization of the City. In 1996-2008, though the service values of farmland, grassland, and water ecosystems had somewhat increase, the overall agroecosystem service value of Guangzhou decreased, mainly due to the more decrease of forest ecosystem service value which occupied more than 90% of the total service value each year. Over the studied period, the proportion of each individual functional service value to the total service value changed little, and the contribution of each individual functional service value was in the order of climate regulation > gases regulation > product service > waste treatment > soil conservation > biodiversity conservation > recreation and culture > water source retention and storage. The sum of climate regulation and gases regulation service values took over 91% of the total agroecosystem service value. There was a significant negative correlation（R=-0.905，P<0.01）between urbanization rate and total agroecosystem service value, suggesting that the increase of urbanization rate would lead to a decrease of agroecosystem service value. Therefore, it requires an appropriate reservation of various agroecosystems to maintain the regional sustainable development during urbanization.

Coupling coordinated development of ecological-economic system in Loess Plateau.

2011, 22(06):  1531-1536. 

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Based on system theory, a coupling coordinated development model of ecological-economic system in Loess Plateau was established, and the evaluation criteria and basic types of the coordinated development of the ecological-economic system were proposed. The county-level coupling coordinated development of the ecological-economic system was also discussed, based on the local characteristics. The interactions between the ecological and economic systems in Loess Plateau could be divided into four stages, i.e., seriously disordered development stage, mild-disordered development stage, low-level coordinated development stage, and high level well-coordinated development stage. At each stage, there existed a cyclic process of profit and loss-antagonist-running-dominant-synchronous development. The coupling development degree of the ecological-economic system in Loess Plateau was overall at a lower level, being about 62.7% of the counties at serious disorder, 30.1% of the counties at mild disorder, and 7.1% of the counties at low but coordinated level. The coupling development degree based on the model established in this study could better reflect the current social-economic and ecological environment situations, especially the status of coordination. To fully understand the coupling of ecological-economic system and to adopt appropriate development mode would be of significance to promote the county-level coordinated development in Loess Plateau.

Atmospheric correction of visible-infrared band FY-3A/MERSI data based on 6S model.

2011, 22(06):  1537-1542. 

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Based on the observation data from the meteorological stations in Taiyuan City and its surrounding areas of Shanxi Province, the atmosphere parameters for 6S model were supplied, and the atmospheric correction of visible-infrared band (precision 250 meters) FY-3A/MERSI data was conducted. After atmospheric correction, the range of visible-infrared band FY-3A/MERSI data was widened, reflectivity increased, high peak was higher, and distribution histogram was smoother. In the meantime, the threshold value of NDVI data reflecting vegetation condition increased, and its high peak was higher, more close to the real data. Moreover, the color synthesis image of correction data showed more abundant information, its brightness increased, contrast enhanced, and the information reflected was more close to real.

Calculation of regional carbon emission: A case of Guangdong Province.

2011, 22(06):  1543-1551. 

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By using IPCC carbon emission calculation formula (2006 edition), economy-carbon emission dynamic model, and cement carbon emission model, a regional carbon emission calculation framework was established, and, taking Guangdong Province as a case, its energy consumption carbon emission, cement production CO₂ emission, and forest carbon sink values in 2008-2050 were predicted, based on the socio-economic statistical data, energy consumption data, cement production data, and forest carbon sink data of the Province. In 2008-2050, the cement production CO₂ emission in the Province would be basically stable, with an annual carbon emission being 10-15 Mt C, the energy consumption carbon emission and the total carbon emission would be in inverse U-shape, with the peaks occurred in 2035 and 2036, respectively, and the carbon emission intensity would be decreased constantly while the forest carbon sink would have a fluctuated decline. It was feasible and reasonable to use the regional carbon emission calculation framework established in this paper to calculate the carbon emission in Guangdong Province.

Application of small remote sensing satellite constellations for environmental hazards in wetland landscape mapping: Taking Liaohe Delta, Liaoning Province of Northeast China as a case.

2011, 22(06):  1552-1558. 

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To timely and accurately acquire the spatial distribution pattern of wetlands is of significance for the dynamic monitoring, conservation, and sustainable utilization of wetlands. The small remote sensing satellite constellations A/B stars (HJ-1A/1B stars) for environmental hazards were launched by China for monitoring terrestrial resources, which could provide a new data source of remote sensing image acquisition for retrieving wetland types. Taking Liaohe Delta as a case, this paper compared the accuracy of wetland classification map and the area of each wetland type retrieved from CCD data (HJ CCD data) and TM5 data, and validated and explored the applicability and the applied potential of HJ CCD data in wetland resources dynamic monitoring. The results showed that HJ CCD data could completely replace Landsat TM5 data in feature extraction and remote sensing classification. In real-time monitoring, due to its 2 days of data acquisition cycle, HJ CCD data had the priority to Landsat TM5 data (16 days of data acquisition cycle).

Variation characteristics of runoff coefficient of Taizi River basin in 1967-2006.

2011, 22(06):  1559-1565. 

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Based on the daily precipitation and runoff data of six main embranchments (Haicheng River, Nansha River, Beisha River, Lanhe River, Xihe River, and Taizi River south embranchment) of Taizi River basin in 1967-2006, this paper analyzed the variation trend of runoff coefficient of the embranchments as well as the relationship between this variation trend and precipitation. In 1967-2006, the Taizi River south embranchment located in alpine hilly area had the largest mean annual runoff coefficient, while the Haicheng River located in plain area had the relatively small one. The annual runoff coefficient of the embranchments except Nansha River showed a decreasing trend, being more apparent for Taizi River south embranchment and Lanhe River. All the embranchments except Xihe River had an obvious abrupt change in the annual runoff coefficient, and the beginning year of the abrupt change differed with embranchment. Annual precipitation had significant effects on the annual runoff coefficient.

Isolation and identification of a highly efficient pyrene-degrading Mycobacterium sp. strain N12.

2011, 22(06):  1566-1572. 

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By using selective enrichment method, a highly efficient pyrene-degrading bacterium strain N12 was isolated from an oil-contaminated soil collected from Shenfu irrigation area of Shenyang. Based on the physiological and biochemical characteristics and the phylogenetic similarity of 16S rDNA gene sequence, the strain N12 was identified as Mycobacterium sp., which could utilize phenanthrene, acenaphthene, fluorine, and pyrene, but not anthracene, naphthalene, and benzo(a)pyrene as the sole carbon and energy source. However, when the strain N12 was cultured with pyrene and phenanthrene, 79.0% of benzo(a)pyrene could be co-metabolized within 9 days. The degradation rate of 100 mg·L^-1 of pyrene by the strain N12 was 94.4% within 7 days and 100% after 14 days, and that of 600 mg·L^-1 of pyrene was 56.1% within 7 days and 95.5% within 14 days. The addition of glucose promoted the degradation of pyrene. It was suggested that the strain N12 was an efficient PAHs-degrading bacterium, being a potential candidate for the bioremediation of PAHs-contaminated soils.

Main bacterial groups in banana soil under rotated and continuous cropping.

2011, 22(06):  1573-1578. 

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Banana wilt is the main disease in banana production, while banana-leek rotation can effectively control the occurrence of the disease. In order to understand the variations of soil bacterial groups under banana-leek rotation and banana continuous cropping, soil samples under these two cropping systems were collected to extract crude DNA, and the bacterial 16S rDNA in V3 region was amplified by PCR. The PCR products were then separated by DGGE, and the main different bands were sequenced and compared with the records of NCBI to identify the germs. Under banana-leek rotation, soil bacterial diversity was richer, and the main bacterial groups were Bacteroidetes, Proteobacteria, Actinobacteria, Chloroflexi, and Acidobacteria; while under banana continuous cropping, the soil bacterial diversity was somewhat decreased, and the main bacterial groups were Firmicutes, Proteobacteria, Actinobacteria, and Chloroflexi.

Comparison of two plant-bird mutualistic systems in Asian tropical rainforests.

2011, 22(06):  1579-1584. 

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To deeply understand how the morphological features of plants affect the visiting of pollen- and seed dispersal birds is beneficial to elucidate the ecological and evolutionary consequences of plant-bird interactions. In this paper, a comparative study was conducted on the avian pollen- and seed dispersal networks across four tropical rainforest habitats having experienced different levels of anthropological disturbance in Southwest China. It was observed that the inter-active network of plant-frugivorous bird was highly asymmetrical, while that of plant-seed dispersal bird was not asymmetrical. The differences between the two networks mainly manifested in the bird abundance, bird movable capability, and plant features attracting bird visiting. The understanding of these differences allowed us to reveal the mutualistic relationship between plant and bird.

Butterfly species diversity and its conservation in Wuyunjie National Nature Reserve, Hunan Province of China.

2011, 22(06):  1585-1591. 

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By using line-transect method, an investigation was conducted on the species diversity of butterfly in Wuyunjie National Nature Reserve, Changde City of Hunan Province from June 2008 to September 2010. Aiming at the main factors including plant species richness (D), mean elevation ( E), average distance from stream/river (F), and human interference level (K) that affecting the species richness of butterfly in 31 segment-level transects in 4 line-transects, multiple regression analysis was made, and the diversity and similarity of the butterfly communities in the experimental zone, buffer zone, and core zone of the Reserve were compared. A total of 147 butterfly species were collected, belonging to 94 genera and 10 families, among which, 4 species was nationally conserved species. Multiple regression analysis showed that D, E, and K were the three most major factors affecting the distribution of butterfly. The species richness of butterfly had significant positive correlation with D (P<0.01), and negative correlations with E and K (P<0.05). The species diversity and evenness index of butterfly were higher in core zone than in experimental zone and buffer zone, dominance index was the highest in experimental zone, and a higher similarity index (0.526) was observed between buffer zone and core zone. To conserve the species diversity of butterfly in the Reserve, efforts should be made to protect the plant species richness, keep the natural forest succession, decrease the human interference properly, and tighten up the management of butterfly habitat.

Bioactivity and action modes of bisdemethoxycurcumin against Tetranychus cinna
barinus Bois. (Acari:Tetranychidae).

2011, 22(06):  1592-1598. 

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This paper determined the contact-killing and fumigant activities of natural plant product bisdemethoxycurcumin (BDMC) on the important phytophagous mite Tetranychus cinnabarinus (Acari: Tetranychidae) at its different life stages, and studied the repellency effects of BDMC on the mite larvae, nymphs, and adults, and the inhibition efficiency of BDMC on the female mite oviposition under the conditions of 26 ℃±1 ℃, 60%-80% RH, and light cycle 14L∶10D h. The median lethal concentration (LC₅₀) of BDMC at 48 h against female adults determined by slide-dip method was 0.433 mg·mL^-1. At concentration 0.883 mg·mL^-1 (LC₇₀), the contact-killing activity of BDMC against different life stage T. cinnabarinus was in the order of larva > nymph > adult > egg, and the corrected mortality of larvae at 24 h and 48 h was 60.0% and 83.3%, respectively. BDMC had no obvious fumigant activity against different life stage T. cinnabarinus, and the corrected mortality was all less than 3% after treatment 24 h and 48 h. BDMC had stronger repellency activity against the mite, with the repellency rate against larvae at different treatment times all above 85%, followed by against nymphs, and that against adults after 72 h being only 47.8%. BDMC had obvious oviposition inhibition activity against female adults, with the inhibition rate after 120 h reached 89.3%. All the results suggested that the main action modes of BDMC against T. cinnabarinus were contact-killing, repellency, and oviposition inhibition.

Phytoplankton community structure in Mingzhu Lake of Chongming Island, Shanghai.

2011, 22(06):  1599-1605. 

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A preliminary study was conducted on the phytoplankton community structure and the annual variation of species diversity in Mingzhu Lake of Chongming Island from January to December 2007. A total of 120 phytoplankton species belonging to 8 phyla and 63 genera were collected, among which, Phormidium tenue, Meismopedia tenuissima, M. convoluta, Microcystis incerta and Synedra ulna were the dominant species. The mean annual density and biomass of the phytoplankton were 5361.57×10⁴ cell·L^-1 and 7.68 mg·L^-1, respectively. There was a significant difference in the monthly phytoplankton standing crop (P<0.01), being the highest in July, but no significant difference was observed among different observation stations. The Shannon index and Margalef index of the phytoplankton community were higher in spring and winter than in the summer and autumn. Biological evaluation indicated that the water quality of Mingzhu Lake was better in spring and winter than in the other two seasons, and canonical correlation analysis (CCA) suggested that the main factors affecting the phytoplankton community were water temperature, followed by total phosphorus, and total nitrogen.

Genetic structure of wild Macrobrachium nipponense populations in Taihu Lake based on microsatellite analysis.

2011, 22(06):  1606-1614. 

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By using eight highly polymorphic microsatellite DNA loci, this paper analyzed the genetic structure of wild Macrobrachium nipponense populations
in Taihu Lake. For the 15 M. nipponense populations in the Lake, there were at least three of the loci presenting heterozygosity deficiency and obvious deviation from Hardy-Weinberg equilibrium after Bonferroni correction. The observed heterozygosity values of the 15 populations were all above 0.683, displaying a high genetic diversity, but the diversity varied obviously with site. For example, the genetic diversity of the eastern and southern populations at Dukou and Luxiang was higher than that of the western and northern populations at Huazhuang and Yangzhu. For the 15 populations, parts of the loci showed heterozygote excess and departure from mutation-drift equilibrium, suggesting that the population structure had experienced bottleneck effect and the population amount had declined. The AMOVA analysis across all the populations and loci showed that the genetic divergence among the 15 populations was at a lower level (F_ST=0.011). 98.9% of the genetic variation came from intra-population, and 1.1% came from inter-population, suggesting that all the M. nipponense populations in the Lake could be protected and managed as a single unit in genetic resource. However, the genetic distance between Huazhuang and Wutangmen populations reached 0.206, being close to the delimitation of species identification. Further studies would be needed for the sustainable utilization of the genetic resource of M. nipponense in Taihu Lake.

Thirty years of US Long-Term Ecological Research: Characteristics, results, and lessons learned of——Taking the Virginia Coast Reserve as an example.

2011, 22(06):  1615-1622. 

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In order to observe and understand long-term and large-scale ecological changes, the US National Science Foundation initiated a Long-Term Ecological Research (LTER) program in 1980. Over the past 30 years, the US LTER program has achieved advances in ecological and social science research, and in the development of site-based research infrastructure. This paper attributed the success of the program to five characteristics, i.e., 1) consistency of research topics and data across the network, 2) long-term time scale of both the research and the program, 3) flexibility in research content and funding procedures, 4) growth of LTER to include international partners, new disciplines such as social science, advanced research methods, and cooperation among sites, and 5) sharing of data and educational resources. The Virginia Coast Reserve LTER site was taken as an example to illustrate how the US LTER works at site level. Some suggestions were made on the China long-term ecological research, including strengthening institution construction, improving network and inter-site cooperation, emphasizing data quality, management, and sharing, reinforcing multidisciplinary cooperation, and expanding public influence.

Management modes of different ownership forests and their ecological effects: A review.

2011, 22(06):  1623-1631. 

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China is in a critical period for the ownership reform of state-owned and collectively owned forests, which desiderates theoretical support and practical experience. However, the researches on the management modes of these forests and their ecological effects are scarce. In Europe and America, manifold ownership forest management has a long history, and relevant experts have made many researches on the ownership management contents and modes, as well as their effects on forest timber productivity, biodiversity, and landscape feature. To summarize and refer to these research harvests is definitely necessary and imminence for our forest ownership reform. This paper reviewed the management aims, modes, and ecological effects of state-owned and privately owned (industrial private and non-industrial private) forests, the parcelization and divestiture of forest ownership, and the associated protection policies of different ownership forests in the representative countries and regions in Europe and North America. The research prospect was also put forward.

Landscape classification: Research progress and development trend.

2011, 22(06):  1632-1638. 

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Landscape classification is the basis of the researches on landscape structure, process, and function, and also, the prerequisite for landscape evaluation, planning, protection, and management, directly affecting the precision and practicability of landscape research. This paper reviewed the research progress on the landscape classification system, theory, and methodology, and summarized the key problems and deficiencies of current researches. Some major landscape classification systems, e.g., LANMAP and MUFIC, were introduced and discussed. It was suggested that a qualitative and quantitative comprehensive classification based on the ideology of functional structure shape and on the integral consideration of landscape classification utility, landscape function, landscape structure, physiogeographical factors, and human disturbance intensity should be the major research directions in the future. The integration of mapping, 3S technology, quantitative mathematics modeling, computer artificial intelligence, and professional knowledge to enhance the precision of landscape classification would be the key issues and the development trend in the researches of landscape classification.

Effects of agricultural practices on community structure of arbuscular mycorrhizal fungi in agricultural ecosystem: A review.

2011, 22(06):  1639-1645. 

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Arbuscular mycorrhizal (AM) fungi are rich in diversity in agricultural ecosystem, playing a vital role based on their unique community structure. Host plants and environmental factors have important effects on AM fungal community structure, so do the agricultural practices which deserve to pay attention to. This paper summarized the research advances in the effects of agricultural practices such as irrigation, fertilization, crop rotation, intercropping, tillage, and pesticide application on AM fungal community structure, analyzed the related possible mechanisms, discussed the possible ways in improving AM fungal community structure in agricultural ecosystem, and put forward a set of countermeasures, i.e., improving fertilization system and related integrated techniques, increasing plant diversity in agricultural ecosystem, and inoculating AM fungi, to enhance the AM fungal diversity in agricultural ecosystem. The existing problems in current agricultural practices and further research directions were also proposed.

Microbial degradation of microcystins in water environment: A review.

2011, 22(06):  1646-1652. 

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Lake and reservoir’s eutrophication and its produced microcystins (MCs) have enormous threats to ecological environment and human health. Because the conventional water pollution control techniques have definite limitations, it’s quite urgent to develop new technique to remove the MCs from water environment. MCs can be effectively degraded by specific microbes, and its intermediate and terminal products are non-toxic or low-toxic. This paper summarized the MCs-degrading microbial strains, biodegradation processes, mechanisms, and affecting factors, degraded products and their structural characteristics, and the applications of MCs-degrading microbial strains in water environment restoration. The further research directions were also proposed. It was hoped that this review could provide technical ideas for restoring MCs-polluted lakes and reservoirs and ensuring drinking water safety in China.

Effects of elevated atmospheric CO₂ concentration and nitrogen addition on the growth of Calamagrostis angustifolia in Sanjiang Plain freshwater marsh.

2011, 22(06):  1653-1658. 

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By using open top chamber, an experiment with two levels of atmospheric CO₂ concentration (350 and 700 μmol·mol^-1) and three levels of nitrogen supply (0, 5, and 15 g N·m^-2) was conducted to investigate the effects of elevated atmospheric CO₂ and nitrogen supply on the growth of Calamagrostis angustifolia in the freshwater marsh of Sanjiang Plain. Under elevated atmospheric CO₂ concentration, the phenophase of C. angustifolia advanced. Jointing stage was advanced by 1-2 d, and maturity stage was advanced by 3 d. Elevated atmospheric CO₂ promoted the tillering of C. angustifolia, with the increment of tiller number under 0, 5, and 15 g·m^-2 of nitrogen supply being 8.2% (P<0.05), 8.4% (P<0.05), and 5.5% (P>0.05), respectively. Elevated atmospheric CO₂ also promoted the aboveground biomass at jointing and heading stages, the increment being 12.4% and 20.9% (P<0.05), respectively, and increased the belowground biomass at later growth stages, with the increment at dough stage and maturity stage being 20.5% and 20.9% (P<0.05), respectively. The responses of C. angustifolia biomass to elevated atmospheric CO₂ concentration depended on nitrogen supply level. Under sufficient nitrogen supply, the promotion effect of elevated atmospheric CO₂ concentration on the biomass of C. angustifolia was higher.