Table of Content

18 October 2010, Volume 21 Issue 10

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Articles

Carbon exchange of Chinese boreal forest during its growth season and related regulation mechanisms.

2010, 21(10):  2449-2456. 

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Based on the two-year continuous observation on the carbon exchange of Chinese boreal forest during its growth seasons in 2007 and 2008 by the method of open path eddy covariance, this paper analyzed the seasonal dynamics of the gross ecosystem productivity (GEP), ecosystem respiration (R_e), and net ecosystem carbon exchange (NEE) of the forest, with related regulation mechanisms approached. The GEP, R_e, and NEEof the forest reached to their maximum in the vigorous growth period from late June to mid August, but the dates of the maximum appeared differed. The mean daily GEP, R_e, and NEE were 19.45, 15.15, and -1.45 g CO₂·m^-2·d^-1 in 2007, and 17.67, 14.11, and -1.37 g CO₂·m^-2·d^-1in 2008, respectively. The intensity of the carbon exchange during growth season was obviously stronger in 2007 than in 2008, possibly due to the higher mean air temperature (12.46 ℃ in 2007 vs. 11.04 ℃ in 2008) and the higher mean photosynthetically active radiation (PAR) (697 μmol·m^-2·s^-1 in 2007 vs. 639 μmol·m^-2·s^-1 in 2008). The GEP had close linear relationships with air temperature and PAR, and the correlation coefficient of GEP and air temperature was around 0.55(P<0.01). The R_e was mainly controlled by air temperature, with the correlation coefficient being 0.66-0.72 (P<0.01), and the NEE was mainly controlled by PAR, with the correlation coefficient being 0.59-0.63 (P<0.01).

Effects of tree diameter at breast height and soil moisture on transpiration of Schima superba based on sap flow pattern and normalization.

2010, 21(10):  2457-2464. 

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The eigenvalues of continuous sap flow pattern, i.e., skewness and kurtosis, were used to investigate the water usage of Schima superba with different diameter at breast height (DBH), and the method of normalization was firstly applied to eliminate the effects of strong affecting factor （photosynthetic active radiation，PAR) to explore the possible relationship between weak affecting factor (soil moisture) and sap flow. Generally, the trees with larger DBH had smaller skewness of sap flux density and later-appeared but larger peak values, suggesting that much more water was transpired, and the larger trees showed smaller skewness and later-appeared larger peak values in wet season than in dry season, suggesting that more water was transpired in wet season. On the other hand, smaller trees had lesser differences in the skewness between dry and wet seasons, suggesting that there was no significant difference in the transpiration between the two seasons. The relationship between individual tree’s transpiration and soil moisture was significant and positive after the two parameters being normalized with PAR peak values. When the soil moisture content was higher, the transpiration of the trees with larger DBH was steadily increasing with soil moisture, while that of the trees with moderate or smaller DBH had opposite trend, presumably due to their transpiration and water absorption were approached to the limit.

Seasonal variations of fine root production and mortality in Larix gmelinii plantation in 2004-2008.

2010, 21(10):  2465-2471. 

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Minirhizotron approach was employed to investigate the seasonal variations of fine root production and mortality in Larix gmelinii plantation in 2004-2008. At the same time, air temperature, precipitation, and soil temperature and moisture at 10 cm depth were recorded. The overall aim of this study was to determine the seasonal patterns of fine root production and mortality in the plantation, and their relationships with the four environmental factors. On an annual basis, the fine root length production ranged from 0.20 to 0.78 mm·cm^-2, while the mortality varied from 0.26 to 0.72 mm·cm^-2. The mean fine root production and mortality in 2004-2006 were 0.67 mm·cm^-2 and 0.59 mm·cm^-2, respectively, being greater than the corresponding values (0.37 mm·cm^-2 and 0.39mm·cm^-2) in 2007-2008. During growth season (from May to October), the fine root production in late spring and early summer (June and July) occupied 51%-68% of total, while that in late autumn (October) only occupied 1%-4%. The root mortality in late summer (August) and autumn (September and October) ranged from 59% to 70%, but that in early spring (May) only ranged from 1% to 5%. Correlation analysis indicated that 66% of the variation in fine root production could be explained by air temperature, and only 24% and 27% could be explained by the soil temperature at 10 cm depth and precipitation, respectively. Fine root mortality only showed an exponential positive correlation with the soil temperature at 10 cm depth.

Effects of simulated nitrogen deposition on the fine root characteristics and soil respiration in a Pleioblastus amarus plantation in Rainy Area of West China.

2010, 21(10):  2472-2478. 

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Fine root is critical in the belowground carbon (C) cycling in forest ecosystem. Aimed to understand the effects of nitrogen (N) deposition on the fine root characteristics and soil respiration in Pleioblastus amarus plantation, a two-year field experiment was conducted in the Rainy Area of West China. Four treatments with different levels of N deposition were installed, i.e., CK (0 g N·m^-2·a^-1), low N (5 g N·m^-2·a^-1), medium N (15 g N·m^-2·a^-1), and high N (30 g N·m^-2·a^-1). There were great differences in the biomass and element contents of <1  mm and 1-2 mm fine roots among the treatments. Comparing with < 1 mm fine roots, 1-2 mm fine roots had higher contents of lignin, P, and Mg, but lower contents of cellulose and Ca. Nitrogen deposition increased the biomass of < 2mm fine roots significantly, with the values being (533±89) g·m^-2 in CK, and (630±140), (632±168), and (820±161) g·m^-2 in treatments low N, medium-N, and high N, respectively. The N, K, and Mg contents of <2 mm fine roots also had an obvious increase under N deposition. The annual soil respiration rate in treatments CK, low N, medium N, and high N was (5.85±0.43), (6.48±0.71),(6.84±0.57), and (7.62±0.55) t C·hm^-2·a^-1, respectively, indicating that N deposition had obvious promotion effects on soil respiration. There were significant linear relationships between the annual soil respiration rate and the biomass and N content of <2 mm fine roots. N deposition increased the fine root biomass and promoted the root metabolism, and stimulated the rhizospheric soil respiration rate via promoting microbial activities.

Soil physical and chemical characteristics under different vegetation restoration patterns in China south subtropical area.

2010, 21(10):  2479-2486. 

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This paper studied the change  of soil physical and chemical properties under eleven vegetation restoration patterns (1 kind of secondary forest, 2 kinds of pure coniferous plantations, 5 kinds of evergreen broad-leaved plantations, 2 kinds of conifer and broad-leaved mixed plantations, and 1 kind of  shrub) typical in Daqingshan of Guangxi. Obvious differences were observed in the soil physical and chemical properties under different vegetation restoration patterns. The soil physical properties were better in secondary forest but poorer in pure conifer plantations. Conifer and broad-leaved mixed plantations had lower soil bulk density, and their soil total porosity and water-holding capacity were higher than those in pure plantations. There were no significant differences in the soil porosity among the 5 evergreen broad-leaved plantations. Except that of soil total K, the contents of soil nutrients in secondary forest were higher than those in plantations, and the soil C/N ratio and pH value were relatively lower. Comparing with shrub, the 9 plantations had an obvious change in their soil nutrient contents, e.g., the increase ofsoil total N and available K. The 2 pure coniferous plantations had lower soil nutrient contents, but after mixed planted with evergreen broad-leaved trees, their soil nutrient contents increased markedly, and the soil C/N ratio decreased.

Canopy interception characteristics of main vegetation types in Liupan Mountains of China.

2010, 21(10):  2487-2493. 

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Based on field observation and modeling analysis, this paper studied the canopy interception, interception capacity, and some parameters for interception modeling of main forest types in Liupan Mountains of China. For the test main forest types, the ratio of their canopy interception to precipitation ranged from 8.59% to 17.94%, throughfall was more than 80%, and stemflow ranged from 0.23% to 3.10%. The canopy interception capacity was 0.78-1.88 mm, among which, leaf interception capacity was 0.62-1.63 mm, and stem interception capacity was 0.13-0.29 mm. Conifer forest had a higher canopy interception capacity than broad-leaved forest. The modified model considering the change of leaf area index, which was used in this paper, had a higher simulating precision than the interception model used before. The simulation results for Betula albo-sinensis  forest, Pinus armandii  forest, Prunus shrub, and Quercus liaotungensis-Tilia paucicostata forest were good, but those for Quercus liaotungensis forest, Pinus tabulaeformis forest, and Acer tetramerum and Euonymus sanguineus shrub were bad, which might be related to the differences in  canopy structure, leaf area index, and precipitation characteristics.

Effects of forest gap on herbaceous plant diversity in mixed birch-fir forest of Taibai Mountain.

2010, 21(10):  2494-2500. 

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To better understand the effects of forest gap on the herbaceous species community in a mixed birch-fir forest of Taibai Mountain in Qinling, CCA ordination and random permutation test were employed to analyze the distribution pattern of the species composition across a gradient of gap size, and the relationships between the distribution of 55 herbaceous species with ≥5 individuals and the habitat variables (convexity, slope, and soil total N, total P, available N, available P, pH, and organic matter). In this forest, gap area occupied 19.8% of the total land area, gap density was 20.7 per hm², and gap size varied from 25.6 to 279.1 m², with a mean of 93.7 m². The species richness in herbaceous layer in gaps was significantly positively correlated with gap size, but of the 69 herbaceous species identified in the gaps, most species were found across all gap sizes, and only eight species were found in larger gaps (>120 m²). No successional change was observed in the herbaceous species distribution with gap size. The CCA ordination and random permutation test also showed that 27.3% of the 55 species with abundance ≥5 had significant association with the eight habitat variables. It was concluded that gap size contributed to the species richness, but determined the diversity constitution in random.

Larix gmelinii tree-ring width chronology and its responses to climate change in Kuduer, Great Xing’an Mountains.

2010, 21(10):  2501-2507. 

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Based on the established tree-ring width chronology of Larix gmelinii in Kuduer, Great Xing’an Mountains, this paper analyzed the relationships between L. gmelinii tree-ring width chronology and related climatic variables, including air temperature, precipitation, and PDSI. In the study area, the L. gmelinii tree-ring width chronology was significantly negatively correlated with the air temperature in May and July (P<0.01), had no significant correlation with precipitation, but significantly positively correlated with the PDSI in June-August (P<0.05), suggesting that hydro-thermal variables had significant coupling effects to the radial growth of L. gmelinii in its growth season, particularly in May and July. The L. gmelinii  tree-ring width chronology had significant correlations with large scale climatic regimes such as the Pacific Decadal Oscillation (PDO) in both low and high frequency variations, illustrating the significant effects of the remote oceanic climatic regimes to the local tree growth.

Selection of distance thresholds of urban forest landscape connectivity in Shenyang City.

2010, 21(10):  2508-2516. 

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By using the QuickBird remote sensing image interpretation data of urban forests in Shenyang City in 2006, and with the help of geographical information system, this paper analyzed the landscape patches of the urban forests in the area inside the third ring-road of Shenyang. Based on the habitat availability and the dispersal potential of animal and plant species, 8 distance thresholds (50, 100, 200, 400, 600, 800, 1000, and 1200 m) were selected to compute the integral index of connectivity, probability of connectivity, and important value of the landscape patches, and the computed values were used for analyzing and screening the distance thresholds of urban forest landscape connectivity in the City. The results showed that the appropriate distance thresholds of the urban forest landscape connectivity in Shenyang City in 2006 ranged from 100 to 400 m, with 200 m being most appropriate. It was suggested that the distance thresholds should be increased or decreased according to the performability of urban forest landscape connectivity and the different demands for landscape levels.

Total flavonoids and icariin contents of Epimedium pubescens in different types of communities and their relationships with soil factors.

2010, 21(10):  2517-2522. 

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Epimedium pubescens and soil samples were collected from the Betula albosinensis community (communityⅠ), Cyclobalanopsis glauca var. gracilis community (community Ⅱ), and Cinnamomum longepaniculatum community (community Ⅲ) in Tangjiahe Nature Reserve in August 2009, with the total flavonoids and icariin contents in E. pubescens samples measured by high performance liquid chromatography and UVspectrophotometer, and the relationships between these contents and soil parameters analyzed. Among the plant organs of E. pubescens, leaf had the highest contents of total flavonoids and icariin, while stem had the lowest one. The total flavonoids and icariin contents of E. pubescens were significantly higher in community Ⅰ［(5.32±0.23)%, (0.47±0.05)%］than in communities Ⅱ［(4.06±0.03)%, (0.32±0.01)%］and Ⅲ［(4.15±0.07)%, (0.28±0.09)%］(P<0.05), and negatively correlated with soil total nitrogen and alkali-hydrolyzable nitrogen (P<0.05) but positively correlated with soil pH (P<0.01), suggesting that the soil with lower level of nitrogen and higher level of acidity in communityⅠcould enhance the total flavonoids and icariin contents of E. pubescens.

Effects of water stress on photosynthesis, biomass, and medicinal material quality of Tribulus terrestri.

2010, 21(10):  2523-2528. 

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A pot experiment was conducted to study the effects of water stress on the photosynthetic characteristics, biomass accumulation, and principal medicinal compositions of Tribulus terrestri. Water stress changed the diurnal variation of T. terrestri photosynthesis, decreased the net photosynthetic rate and transpiration rate significantly, weakened the plant photosynthetic and assimilative capability, and accordingly, hindered the dry matter accumulation and decreased the biomass. However, water stress promoted the accumulation of gross saponins in T. terrestri. In the treatments with irrigation amounts 150 and 450 mm, the gross saponins content was 13.26 and 12.47 mg·g^-1, respectively, being significantly different from that in the treatments with irrigation amounts 250 and 350 mm. The dynamic accumulation of gross flavonoids and gross saponins had an opposite tendency with that of biomass, namely, the contents of these principal medicinal compositions were the lowest when the biomass was the maximal. Correlation analysis showed that the biomass accumulation of T. terrestri was significantly correlated with outside environmental factors, while the contents of secondary metabolism products were affected not only by the outside environmental factors, but also by the inside factors such as biomass accumulation.

Effects of exogenous nitric oxide on highbush blueberry PSⅡ photochemical activity and antioxidant system under high temperature stress.

2010, 21(10):  2529-2535. 

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Taking the test tube ‘Duke’ highbush blueberry (Vaccinium corymbosum) seedlings having been transplanted to the field for 6 months as test materials, this paper studied the effects of exogenous nitric oxide (NO) on their growth, PSⅡ photochemical activity, and antioxidant system under high temperature stress. Applying 0,2, 0,5, and 1,0 mmol·L^-1 of exogenous sodium nitroprusside (SNP) could alleviate the decrease of maximum photochemical efficiency (F_v/F_m), actual photochemical efficiency under light(Φ_PSⅡ), photochemical quench (q_P), and nonphotochemical quench (NPQ) caused by high temperature, and prevented the damage of high temperature on photosynthetic apparatus. Comparing with the control, treatments NO decreased the leaf membrane permeability and MDA content, increased the SOD and CAT activities significantly, and promoted proline accumulation. Appropriate concentration SNP could significantly alleviate the damage of high temperature stress on highbush blueberry seedlings, and 0.5 mmol·L^-1 of SNP had the most satisfactory effect.

Sorbus pohuashanensis seed dispersal and germination and their relationships with population natural regeneration.

2010, 21(10):  2536-2544. 

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Sorbus pohuashanensis is an important non-timber tree species in Northeast China, but poor in natural regeneration via seed dispersal. In this paper, a field observation was made on the seed dispersal of S. pohuashanensis, its seedling emergence, and soil seed bank, aimed to study the factors affecting the natural regeneration of this tree species. There were 96.1% of naturally dispersed S. pohuashanensis seeds distributed within the range of 2 m around the stock tree, and 97.0% of the seeds in soil seed bank distributed in litter layer and 0-2 cm surface soil. The seed quantity in soil seed bank differed greatly with seasons, being the maximum ［(257.7±69.2) seeds per square meter］in early November in the year of seed dispersal, and the minimum［only (2.9±2.9) seeds per square meter］in next July. Temperature was not the limiting factor affecting the seedling emergence of S. pohuashanensis ［at 0 ℃-5 ℃, the seedling emergence percentage could reach (67.5±6.6)%］,but strongly affected the seedling emergence rate. The most proper soil moisture content for the seedling emergence was 50%, under which, the seedling emergence percentage could reach (74.7±4.2)%. When the soil moisture content was up to 60%, the seedling mortality was the lowest (32.6%±0.6%). All the results suggested that the seed dispersal pattern of S. pohuashanensis and the spatiotemporal dynamics of soil seed bank could affect the seedling emergence of the tree species, and further, affect the population natural regeneration of S. pohuashanensis via seed dispersal.

Effects of combined application of nitrogen and phosphorus on diurnal variation of photosynthesis at grain-filling stage and grain yield of super high-yielding wheat.

2010, 21(10):  2545-2550. 

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Taking super high-yielding wheat cultivar Jimai 22 as test material, a field experiment was conducted to study the effects of combined application of nitrogen (N) and phosphorus (P) on the diurnal variation of photosynthesis at grain-filling stage and the grain yield of the cultivar. In treatments CK (without N and P application) and low N/P application (225 kg N ·hm^-2 and 75 kg P ·hm^-2), the diurnal variation of net photosynthetic rate (P_n) was presented as double-peak curve, and there existed obvious midday depression of photosynthesis. Under reasonable application of N/P (300 kg N·hm^-2and 150 kg P ·hm^-2, treatment N₂P₂), the midday depression of photosynthesis weakened or even disappeared. Stomatal and non-stomatal limitations could be the causes of the midday depression. Increasing N and P supply increased the P_n, stomatal conductance (G_s), stomatal limitation value (L_s), and transpiration rate (T_r). Fertilizer P had less effects on the photosynthesis, compared with fertilizer N. When the P supply was over 150 kg·hm^-2, the increment of P_n was alleviated and even decreased. Among the fertilization treatments, treatment N₂P₂ had the highest P_n, G_s, and water use efficiency, being significantly different from CK. It appeared that fertilizer N had greater regulatory effect on the diurnal variation of photosynthesis, compared with fertilizer P, while the combined application of N and P had significant co-effecton the P_n, G_s, and T_r. A combined application of 300 kg N ·hm^-2 and 150 kg P ·hm^-2 benefited the enhancement of P_n and grain yield.

Effects of elevated ozone concentration on wheat grain protein components with FACE system.

2010, 21(10):  2551-2557. 

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In 2006-2009, a Free-Air Controlled Enrichment (FACE) system was applied to study the effects of elevated ozone concentration (［O₃］) on the grain protein components and their dynamics of four winter wheat varieties Yannong 19, Yangmai 16, Yangmai 15, and Yangfumai 2. Two levels of ［O₃］were installed, i.e., ambient level (CK-O₃) and 50% higher than the ambient level (E-O₃). With the increase of ［O₃］, the grain protein content of the varieties increased, with the increment being 7.55%-16.37% (2006-2007), 4.93%-22.63% (2007-2008), and 2.29%-17.65% (2008-2009) in the three years, respectively, and the differences between treatments, varieties, and years being all significant. Adversely, the grain protein yield was decreased significantly by 1.83%-11.64% (2006-2007), -0.41%-24.22% (2007-2008), and -1.90% -15.81% (2008-2009), respectively in the three years. The contents of four grain protein components (albumin, globulin, gliadin, and glutenin) were significantly higher under E-O₃ than under CK-O₃, and the differences between treatments, varieties, and years were significant, except the albumin and glutenin contents between treatments.

Effects of DA-6 on leaf photosynthetic carboxylase and protective enzyme activities and grain yield of high-yielding summer maize.

2010, 21(10):  2558-2564. 

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A field plot experiment was conducted to study the effects of foliar spraying DA-6 at the rates of 10, 20, and 40 mg·L^-1at jointing stage on the leaf photosynthetic carboxylase and protective enzyme activities and grain yield of high-yielding summer maize cultivar Denghai 661. Comparing with the control (foliar spraying surfactant and water), spraying 10, 20, and 40 mg·L^-1 of DA-6 increased the grain yield of Denghai 661 significantly, with the increment being 10.0%, 8.9%, and 9.4%, respectively, but no significant differences were observed among the DA-6 treatments. Different concentration DA-6 increased the leaf area index, net photosynthetic rate, and RuBPCase and PEPCase activities significantly, and the promotion effects on the net photosynthetic rate and RuBPCase and PEPCase activities increased with increasing concentration of DA-6. After treated with DA-6, the leaf superoxide dismutase, catalase, peroxidase, and gultathione S-transferase activities and the leaf soluble protein content at the stages of silking, grain-filling, milky, and wax maturity all increased significantly, and the leaf malondialdehyde decreased significantly, compared with the control. The catalase activity increased with increasing DA-6 concentration, but the other indices had no significant differences among the DA-6 treatments.

Effects of nitrogen fertilization rate and harvest time on summer maize grain yield and its quality.

2010, 21(10):  2565-2572. 

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In order to approach the optimal nitrogen fertilization rate and suitable harvest time for the high grain yield and quality of summer maize in HuangheHaihe Area, a field experiment with five nitrogen fertilization rates (0, 113,181, 249, and 375 kg N·hm^-2) and two harvest time (S₁: September 23, conventional harvest time for local farmers, and S₂: September 29, 6 days delayed) was conducted. The results showed that the kernel number, grain yield, and 1000-grain mass increased with nitrogen fertilization rate, but the differences were not significant. With increasing nitrogen fertilization rate, the protein and lysine contents of the grains increased, while the starch content decreased. After 6 days delayed for harvest, the grain yield, 1000-grain mass, and the starch and lysine contents of the grains increased, but the protein and crude fat contents decreased. Based on the yield level, the optimal nitrogen fertilization rate for the summer maize in Huanghe-Haihe Area was 113-180 kg N·hm^-2, and the suitable harvest time was from September 29 to October 5.

Proteomics of rice leaf and grain at late growth stage under different nitrogen fertilization levels.

2010, 21(10):  2573-2579. 

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Taking super-rice Liangyoupeijiu as test material, and by the method of two-dimensional gel electrophoresis (2-DE), this paper studied the changes in the leaf and grain proteomics of the variety at its late growth stage under different levels of nitrogen fertilization (1/2 times of normal nitrogen level, 20 mg·L^-1; normal nitrogen level, 40 mg·L^-1; 2 times of normal nitrogen level, 80 mg·L^-1), with the biological functions of 16 leaf proteins, 9 inferior grain proteins, and 4 superior grain proteins identified and analyzed. Nitrogen fertilization could affect and regulate the plant photosynthesis via affecting the activation of photosynthesis-related enzymes and of CO₂, the light system unit, and the constitution of electron transfer chain at the late growth stage of the variety. It could also promote the expression of the enzymes related to the energy synthesis and growth in inferior grains. High nitrogen fertilization level was not beneficial to the synthesis of starch in superior grain, but sufficient nitrogen supply was still important for the substance accumulation and metabolism. Therefore, rational nitrogen fertilization could increase the photosynthesis rate of flag leaves, enhance the source function, delay the functional early ageing, and promote the grain-filling at late growth stage.

Effects of exogenous melatonin on ascorbate metabolism system in cucumber seedlings under high temperature stress.

2010, 21(10):  2580-2586. 

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Taking cucumber cultivar ‘Jinchun 4’ as test material, and by the method of foliar spraying, this paper studied the effects of exogenous melatonin (MT) on the ascorbic acid (AsA) metabolism system in cucumber seedlings under high temperature stress. Under the stress of high temperature, the leaf hydrogen peroxide (H₂O₂) and malondialdehyde (MDA) contents of the cucumber seedlings increased obviously, ascorbic acid (AsA) and glutathione (GSH) contents had a persistent decrease while dehydroascorbate (DHA) and oxidized-glutathione (GSSG) contents had a gradual increase, and AsA/DHA and GSH/GSSG decreased greatly. The activities of ascorbate peroxidase (APx), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), and glutathione reductase (GR) in the seedling leaves under high temperature stress increased markedly, with the maximum after 12 h stress. Foliar spraying MT could effectively restrain the accumulation of H₂O₂ and MDA in seedling leaves, increase the leaf AsA and GSH contents and the activities of ascorbic acid metabolizing enzymes APx, MDHAR, GR and DHAR, and accordingly, enhance the H₂O₂-scavenging ability, inhibit the production of active O₂, maintain the stability of cell membrane, reduce the damage of high temperature to the plants, and improve the ability of cucumber seedlings against high temperature stress.

Effects of bio-fertilizer on organically cultured cucumber growth and soil biological characteristics.

2010, 21(10):  2587-2592. 

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Field trials of organic farming were conducted to examine the effects of different bio-fertilizers on the organically cultured cucumber growth, soil enzyme activities, and soil microbial biomass. Four treatments were installed, i.e., organic fertilizer only (CK), bio-fertilizer “Zhonghe” combined with organic fertilizer (ZHH), biofertilizer “NST” combined with organic fertilizer (NST), and bio-fertilizer “Bio” combined with organic fertilizer (BIO). Bio-fertilizers combined with organic fertilizer increased the cucumber yield significantly, and improved the root growth and leaf chlorophyll content. Comparing with that in CK, the cucumber yield in treatments ZHH, NST, and BIO was increased by 10.4%, 12.4%, and 29.2%, respectively. At the seedling stage, early flowering stage, and picking time of cucumber, the soil microbial biomass C and N in treatments ZHH, NST, and BIO were significantly higher than that in CK, and the activities of soil urease, acid phosphatase, and catalase were also higher.

Amino sugars mineralization and its responses to exogenous substances in black soil of Northeast China.

2010, 21(10):  2593-2598. 

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By the method of intermittent leaching aerobic incubation, this paper studied the mineralization of three kinds of microbes-derived amino sugar (glucosamine, muramic acid, and galactosamine) in black soil of Northeast China, and the responses to glucose addition and glucose plus nitrogen amendment. The mineralization of the amino sugars was compound-specific. During incubation period, the content of muramic acid decreased by 25.4%, while that of glucosamine decreased by 7.1%, suggesting that bacteria-derived muramic acid was more inclined to be mineralized, compared with fungi-originated glucosamine. However, the mineralized amount of glucosamine (68.4 mg·kg^-1) was greater than that of muramic acid (15.4 mg·kg^-1). Both glucose addition and glucose plus nitrogen amendment improved the contents of glucosamine and muramicacid significantly, but the effect varied. The mineralization of galactosamine was much slower, and less affected by exogenous substances addition, indicating that galactosamine was more stable in test soil.

Ecological reasons for the difference in nicotine content of flue-cured tobacco planted in different regions of Hunan Province.

2010, 21(10):  2599-2604. 

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Aimed to explore the ecological reasons for the difference in nicotine content of flue-cured tobacco planted in different regions of Hunan Province, field experiments were conducted in Sangzhi, Liuyang, and Yongzhou counties, the three typical tobacco regions of Hunan Province, taking tobacco variety K326 as the test object. Simultaneously, pot experiments with local soils and guest soils were carried out. The nicotine content of mid position tobacco leaves was analyzed at harvest time. Field experiments showed that the average nicotine content of tobacco leaves differed significantly among test sites, with that in Sangzhi being the highest, followed by Liuyang, and Yongzhou. Pot experiments showed that climate had significant effects on the average nicotine content of tobacco leaves, while soil and its interaction with climate had less effects. The contribution rate of climate, soil, and their interaction on the variance of the average nicotine content was 60.0%, 12.8% and 27.2%, respectively. The main sub-ecological factors closely related to the average nicotine content of flue-cured tobacco planted in different regions of Hunan Province were in turn the cloud cover at maturing stage, the relative humidity, sunshine hours, diurnal temperature variance, and rainfall at root-extending stage, and the average air temperature at vigorous growth stage. Generally, climate was the main ecological factor that led to the nicotine content difference of flue-cured tobacco planted in different regions of Hunan Province.

Changes of China agricultural climate resources under the background of climate change. Ⅰ. Spatiotemporal change characteristics of agricultural climate resources in South China. 

2010, 21(10):  2605-2614. 

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By using the 1961-2007 daily weather data from 66 meteorological stations all over South China, this paper studied the spatiotemporal change characteristics of agricultural climate resources, including heat, light, and precipitation, in this region on the scales of whole year and temperaturedefined growth season. In 1961-2007, the mean annual air temperature in this region tended to be increased by 0.20 ℃·（10 a）^-1, and the climatic trend of ≥10 ℃ accumulated temperature in temperaturedefined growth season increased gradually from north to south, with an average of 98 ℃·d·（10 a）^-1. Comparied with those in 1961-1980, the areas of the accumulated temperature zone of 6200-7500 ℃·d and  7500-8000 ℃·d  in 1981-2007  increased by 1.5×10⁴ and 4.7×10.4km², respectively. In 1961-2007, the sunshine hours on the scales of whole year and temperature-defined growth season decreased by -57 h·（10 a）^-1 and -38 h·（10 a）^-1, respectively, and the areas with sunshine hour ≥1800 h on the two scales tended to be decreased, compared with those in 1961-1980. The precipitation on the two scales increased slightly, and the increment varied obviously in different parts of the region. There were 62% and 52% of the stations where the reference crop evapotranspiration on the scales of whole year and temperature-defined growth season was in negative, respectively. In 1981-2007, the high-value area of reference crop evapotranspiration decreased, while the low-value area increased, compared with those in 1961-1980. The mean climatic trend of annual humidity index  was 0.01·(10 a)^-1, and 70% of the stations showed an increasing trend. Comparing with that in 1961-1980, the humidity index on the scale of temperature-defined growth season in 1981-2007 was increased by 0.02, with 53% of the stations showed positive. On the whole, the change characteristics of climate in South China in 1961-2007 showed a tendency of warming and wetting, which would impact the cropping system, yield, and agricultural structure in the region.

Evaluation of sustainable development of Dalian Economic and Technological Development Zone based on MuSIASEM theory.

2010, 21(10):  2615-2620. 

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Based on the theory of multiple-scale integrated assessment of societal and ecosystem metabolism (MuSIASEM), a comprehensive evaluation was made on the human activity time, exosomatic energy input, and added value of Dalian Economic and Technological Development Zone in 2000-2007. During the study period, the life quality of local citizens increased year after year, while the agricultural industry dwindled. Manufacturing industry was still the main pillar industry, but its energy consumption was greater. Service industry was at its early stage, falling behind manufacturing industry. The exosomatic metabolic level of the whole zone and its various industries had an obvious increase, and the energy intensity decreased continuously. With the fact that both the human activity time and the exosomatic energy input had a ceaseless decrease, the economic added value increased steadily, and the zone was under its way towards sustainable development.

Characteristics and changes of landscape pattern in Wuhan City based on Ripley’s K function.

2010, 21(10):  2621-2626. 

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By using Ripley’s K function, an important method of point pattern analysis, and taking the TM remote sensing images of 1987, 1996 and 2007 as data source, this paper studied the characteristics and changes of landscape pattern in Wuhan City. The results showed that in 1987-2007, farmland was the landscape matrix in Wuhan, while water body, forestland, grassland, urban and rural built up land, and unutilized land types were the patches or corridors, which spatially clumped significantly in all scales. The landscape aggregation of water bodies was inferior to that of forestland, grassland, and urban and rural built-up land. The farmland clumped spatially in fine scales, but became random or uniform in coarse scales. Meantime, the areas of forestland and urban and rural built-up land increased largely, while water body, grassland, and farmland decreased greatly. In addition, the landscape spatial characteristics of all landscape types changed variously. On the whole, the landscape aggregation of forestland and urban and rural built-up land decreased, and became more uniform. Meanwhile, the water body, grassland, and farmland took on a more uneven and clumped landscape pattern. To analyze the landscape pattern through sample points had the advantages of conciseness, accuracy, and easiness-to-use, in comparison with the methods of  quadrat and sample line (or transect).  Ripley’s K function was proved to be an efficient means for analyzing landscape pattern in different scales, and fit for the supplement and support of landscape metrics.

Genetic heterogeneity of Beauveria bassiana population in pure Masson’s pine plantation.

2010, 21(10):  2627-2634. 

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By the method of ISSR, the genetic heterogeneity of 111 Beauveria bassiana isolates in a pure Masson’s pine plantation in Magu Mountains of Anhui Province was analyzed. A total of 58 loci were obtained with 7 ISSR primers, 54 of which (93.10%) were polymorphic. For the isolates sampled at different time, their Nei’s gene diversity （H_e）was 0.2552, Shannon’s diversity index （I） was 0.3825, coefficient of gene differentiation （G_st） was 0.2269, and gene flow N_m was 0.8518. The genetic distance between the isolates sampled in May and July was the shortest (0.0408). For the isolates grouped based on host orders, their H_e was 0.2623, I was 0.3884,  G_stwas 0.1964, andN_mwas 1.0223. The genetic distance between the isolates from Coleopteran and Hymenoteran was the shortest (0.0163). All the results suggested that the genetic heterogeneity of B. bassiana population in the test plantation was rich, and the genetic variation between B. bassiana sub-populations was relatively low but that within the sub-populations was high, and none of the isolates were identical or highly similar with each other.

Ecological distribution of arbuscular mycorrhizal fungi in alpine grasslands of Tibet Plateau.

2010, 21(10):  2635-2644. 

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Seventy soil samples with the roots of 37 dominant or common plant species on the grasslands in south and north Tibet Plateau were collected to study the ecological distribution of arbuscular mycorrhizal （AM） fungi  in the investigation area. A total of 35 AM fungi species belonging to 5 genera were isolated, among which, 18 species belonged to Glomus, 9 species belonged to Acaulospora, 6 species belonged to Scutellospora, 1 species belonged to Entrophospora, and 1 species belonged to Paraglomus. There were 23 AM fungi species belonging to 4 genera isolated from south Tibet, and 22 species belonging to 4 genera from north Tibet. The Shannon diversity index of AM fungi in south and north Tibet Plateau was 2.31 and 2.75, respectively, and the spore density and species richness were significantly higher in north Tibet than in south Tibet. In different ecological zones, lesser AM fungi common species were found, species distribution was more site-specific, and different dominant species were observed. In alpine grassland, mountain meadow, and alpine meadow, the Shannon index of AM fungi was 1.91, 1.83, and 1.80, respectively; while in severely degraded temperate grassland, this index was only 1.64. The highest species richness of AM fungi occurred at the altitude of 4000-4600 m, but the highest Shannon index and species evenness occurred at the altitude of 4600-5220 m, with the values being 2.42 and 0.79, respectively. At all altitudes, Glomus was the dominant genus, and its relative abundance was higher when the altitude was  below 4000 m. Acaulospora was mainly observed at the altitudes higher than 4000 m, Scutellospora was  mainly distributed at the altitude 3500-5220 m, Paraglomus  mainly occurred in the north alpine meadow with an altitude of 4000-5220 m and occasionally in the alpine steppe, whereas Entrophospora was only found in the south temperate grassland with an altitude of 3500-3700 m.

Evolvement of soil bacterial community in intensively managed Phyllostachys praecox stand and related affecting factors.

2010, 21(10):  2645-2651. 

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By using PCR-DGGE and redundancy analysis (RDA), this paper studied the variations of soil bacterial community structure during the intensive management of Phyllostachys praecox stand, and analyzed the soil factors affecting the diversity of the bacterial community. The results showed that after the transformation of paddy field into P. praecox stand, the Shannon and richness indices of soil bacterial community increased significantly. Long-term intensive management of P. praecox stand altered the community structure of soil bacteria, reflecting in the changes of main bacterial populations and the great decrease after an initial increase of the diversity indices of soil bacterial community. Soil pH, soil total nitrogen, and soil available nitrogen and potassium could explain  76.1% of the total variation of soil bacterial community, and soil pH showed the greatest effect though it was not significant, indicating that the evolvement of soil bacterial community under the long-term intensive management of P. praecox stand was the result of the synergistic effects of several soil factors.

Screening, identification, and biocontrol effect of antagonistic bacteria against Phytophthora capsici.

2010, 21(10):  2652-2658. 

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A total of 98 isolates with antagonistic activity against Phytophthora capsici were isolated from the rhizosphere soil of healthy pepper plants in the fields seriously infected by pepper Phytophthora capsicit, and two strains named as HL-3 and LZ-8 were screened, which had the characteristics of wide-spectrum antagonism and good growth under poor soil condition. The HL-3 and LZ-8 were identified as Paenibacillus polymyxa and Bacillus pumilus, respectively, based on their morphological and biochemical characteristics and 16S rDNA sequences. The two strains could inhibit the mycelium growth of P. capsici, and the inhibitory effect of HL-3 and LZ-8 was 72% and 68%, respectively. The two strains also had antifungal activities toward other plant pathogens such as Verticillium dahliae, Fusarium oxysporum  f. sp. cucumerinum, F. oxysporum f. sp. vasinfectum,  Rhizoctonia solani, Phtophthora parasitica var. nicotiana, and Ralstonia solanacearum. Pot experiment showed that the biocontrol effects of HL-3 and LZ-8 against P. capsici at the seedling stage of pepper were 72% and 83 %, respectively, and both of the strains had significant growth-promoting effect on pepper plants.

Changes of heavy metals form during aerobic high temperature composting of pig manure and the effects of passivators.

2010, 21(10):  2659-2665. 

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Sequential extraction method was employed to study the heavy metals concentration and form change during aerobic high temperature compositing of pig manure, and the effects of amendment with different proportion of passivators on the concentration and form change. During the composting process, the concentrations of total As, Cu, and Zn in the manure all increased to some extent. As for the form change of the heavy metals, the exchangeable As and Zn decreased while the residual As and Zn increased, indicating that the availability of As and Zn declined through the composting process. On the other hand, the exchangeable and residual Cu decreased while the carbonate, Fe/Mn, and organic bound Cu increased, suggesting the potential environmental risk of the future application of the compost. Among the passivators amended, 5.0% of sepiolite and 2.5% of bentonite had the best effect in reducing the availability of As and Zn, with the residual form of As and Zn after composting increased by 79.8% and 158.6%, respectively, and 7.5% of sepiolite induced the least decrement (39.3%) of residual Cu, compared with the control. Therefore, amendment with appropriate proportion of passivator during pig manure composting could decrease the availability of heavy metals in the manure, and reduce the environmental risk of applying the compost to farmland.

Endogenous NO and ROS generation in grape roots and leaves under CdCl₂ stress.

2010, 21(10):  2666-2670. 

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Taking the cutting seedlings of grape variety ‘Ze-xiang’ as test materials, a hydroponic experiment was conducted to study the generation patterns of
endogenous nitric oxide (NO) and reactive oxygen species (ROS) in their roots and leaves, and the changes of root MDA content and root activity under the stress of cadmium chloride (CdCl₂). In the treatments 0-1 mmol·L^-1 of CdCl₂, the NO content and NOS activity in roots and leaves and the root activity all presented a tendency of increasing first and decreasing afterwards with increasing CdCl₂. At 0.01 mmol·L^-1 of CdCl₂, the NO content and NOS activity in roots increased by 51% and 63%, respectively; but at >0.1 mmol·L^-1 of CdCl₂, they decreased significantly. At 0.01 and 0.05 mmol·L^-1 of CdCl₂, the leaf NO content and NOS activity had the greatest increase; at 0.5 and 1.0 mmol·L^-1 of CdCl₂, the root O₂^-· generation rate and H₂O₂ and MDA contents increased significantly. At the same concentrations of CdCl₂, the O₂^-·  generation rate in leaves was much lower while the H₂O₂ content was much higher, compared with those in roots.

Leaf cell damage and changes in photosynthetic pigment contents of three moss species under cadmium stress.

2010, 21(10):  2671-2676. 

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A hydroponic experiment was conducted to study the leaf cell damage and the changes in photosynthetic pigment contents of three moss species under Cd stress, aimed to reveal the Cd sensibility and tolerance of the species. Even though the Cd stress was relatively low (1 mg Cd·L^-1), the leaf cells of Dolichomitriopsis diversiformis and Plagiomnium acutum were damaged. With the increasing level of Cd stress, the leaf cell damage of the three moss species aggravated significantly, and the resulted damage under high level (100 mg·L^-1) Cd stress was in the order Brachythecium procumbens > P. acutum >D. diversiformis. Relatively low (1 mg·L^-1) Cd stress had no significant effects on the total chlorophyll content of the three species. However, with the increase of Cd stress (≥ 10 mg·L^-1), the total chlorophyll content decreased significantly, with the order of B. procumbens > P. acutum > D. diversiformis. The Cd stress at 1 and 10 mg·L^-1 had no significant effects on the chlorophyll a/b, but the Cd stress at 100 mg·L^-1 led to a significant decrease of chlorophyll a/b in P. acutum and B. procumbens. The maximal decline of carotenoid content in B. procumbens was observed at 1 mg·L^-1 of Cd. The three moss species could significantly enrich Cd, and the Cd enrichment was D. diversiformis > P. acutum > B. procumbens. The leaf cell damage rate and the changes of chlorophyll and carotenoid contents could be used to indicate the differences in the sensitivity of D. diversiformis, P. acutum, and B. procumbens to Cd stress. D. diversiformis had the strongest tolerance to Cd stress, while P. acutum and B. procumbens had weaker tolerance. The tolerance of the three moss species to Cd stress was positively correlated to the capability of their Cd enrichment.

Animal predation and dispersal of Sorbus pohuashanensis fruits and seeds.

2010, 21(10):  2677-2683. 

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Sorbus pohuashanensis is an important non-timber tree species in Northeast China. There are two approaches for its fruit- and seed dispersal, i.e., natural dispersal and animal dispersal. In this paper, a field observation was conducted to study the characteristics of animal predation and dispersal of S. pohuashanensis fruits and seeds, and the effects of the predation and dispersal on the natural regeneration of the tree species. During the fruit-ripening stage of S. pohuashanensis in 2008 and 2009, there were 8 species of birds visiting S. pohuashanensis fruits, among which, three pulp-eating species Turdus naumanni, Cyanopica cyana, and Dendrocopos leucotos could disperse S. pohuashanensis seeds. The visiting frequency of the three species to S. pohuashanensis fruits was 54%, 12%, and 7%, respectively, and the first stop spot after predation was mainly within 5-10 m away from the visited trees (with a proportion of 68.2%), secondly within 5 m (27.3%), and only 4.5% was out of 10 m. The retention time of S. pohuashanensis fruits in the digestive tract of the bird dispersers was up to 20 min, implying a long potential dispersal distance. Fruit- and seed placement tests showed that the fruits artificially placed in different habitats were disappeared within 6-7 days, and the fruit predators on the ground were mainly rodents and ground-feeding birds, with the predation rates being 50%-70%, while the seed predators on the ground were rodents, ground
-feeding birds, and ants, with the predation rates only 1%-5%. S. pohuashanensis could provide food for a variety of frugivorous animals, and in return, the animals could disperse S. pohuashanensis seeds, which might have profound effects on the natural regeneration of S. pohuashanensis.

Coexistence mechanism of ant community in lac plantation under habitat heterogeneity.

2010, 21(10):  2684-2690. 

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In order to reveal the coexistence mechanism of ant community in lac plantation, an investigation was made on the ant community composition and the ability of ant species in discovering and holding food resources in a lac plantation in Yayi Town of Mojiang County, Yunnan Province, with the relationships between ant body size and its ability of finding food under habitat heterogeneity probed. There were six dominant ant species in the plantation, i.e., Tetraponera allaborans (Walker), Crematogaster macaoensis Wheeler, Crematogaster ferrarii Emery, Dolichoderus thoracicus (Smith), Polyrhachis proxima Roger, and Camponotus parius Emery. The hind leg length (y) of the six ant species increased allometrically with their head width (x), and the regression equation was y=0.56+1.02x+5.97x²-10.85x³. Different ant species had significant differences in their actual and relative frequency in discovering food resources in different habitats, but habitat type had no significant effects on the actual frequency in holding food resources by the ant species. The ant species with bigger head width and bigger body size index could discover more food resources in simple habitat. In contrast, the ant species with smaller head width, shorter hind leg length, and smaller body size index could discover more food resources in complex habitat. The heterogeneity of habitat caused the coexistence of ants: the smaller ant species lived in complex habitat, while the larger ones lived in simple habitat. In addition, numerically dominant ant species were unable to possess all  resources, and thereby, could provide the opportunity to other ant species for resources acquisition, making the species coexistence come true.

Spatial structure and distribution simulation of Aphis gossipii Glover population based on GIS.

2010, 21(10):  2691-2696. 

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Based on geographic information system (GIS) and geostatistical analysis, this paper studied the spatial structure of Aphis gossipii Glover population
 in Xiangshan District of Zhongwei City, Ningxia Province, with the spatial distribution of the population simulated by ordinary Kriging interpretation. The spatial structure of A. gossipii population varied with its occurrence stage (initial, blossom, and final stage). The semivariograms of A. gossipii could be described by exponential or Gaussian model, indicating that A. gossipii had an aggregated spatial arrangement. The aggregation degrees at different occurrence stages were all beyond 45%, and the spatial correlation ranged from 10.37 km to 29.11 km. The spatial variance was greatly affected by
spatial autocorrelation. The population dynamics of A. gossipii at its different occurrence stages could be easily analyzed and intuitively simulated from the two aspects of time and space by spatial distribution simulation, and thus, the occurrence position and degree of A. gossipii could be easily determined.

Impact of climatic change on soybean production: A review.

2010, 21(10):  2697-2706. 

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Since the industrial revolution, the rapid increase of global atmospheric concentration of CO₂ and other greenhouse gases has induced the global warming and the change of global precipitation pattern. The growth, development, yield, and quality of soybean are subject to all these changes of climatic conditions. Soybean is one of the major grain and oil crops in the world and in China, and any change in the soybean production under future climate scenario will affect the grain- and edible oil security nationally and internationally. This paper reviewed the effects of elevated atmospheric CO₂, global warming, and water stress on soybean growth, and discussed the future research needs, which could provide scientific basis for realizing soybean production in the future and for implementing in advance proper policies in the context of climatic change impact on soybean production.

Persisters and their effects on microbial biofilm tolerance: A review.

2010, 21(10):  2707-2714. 

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Persisters are a group of special subpopulation of bacteria, only occupying <0.1% of the whole population but having the characteristics different from the ordinary bacteria and resistant mutants. They have complex formation mechanism, and are difficult to isolate and culture. The persisters can adapt to the adverse environment via “dormancy-growth-proliferation” to maintain their survival and cell structure stability, and play a vital role in the multi-drug and multi-metal tolerance of microbial biofilm, being of great significance in maintaining the stability of microbial community structure. This paper reviewed the research progress on the characteristics of persisters, their gene regulation mechanisms, and their effects on the multi-drug and multi-metal tolerance of microbial biofilm. The related research directions in the future were also prospected.

Effects of elevated ultraviolet-B radiation on the chemical composition of wheat straw and the N₂O emission from soil amended with the straw.

2010, 21(10):  2715-2720. 

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An outdoor experiment was carried out to investigate the effects of elevated ultraviolet-B radiation on the chemical composition of wheat straw, and an indoor incubation test was conducted to study the effects of the amendment of the straw on soil N₂O emission.Outdoor experiment showed that the enhanced UV-B decreased the aboveground biomass of wheat, increased the lignin and total N contents of wheat straw by 94.2% and 12.3%, respectively, and decreased the C/N ratio of the straw. Incubation test showed that comparing with the amendment of conventional wheat straw, the amendment of  wheat straw received enhanced UV-B radiation during plant growth increased  soil N₂O emission under the dry-land and flooded conditions significantly. When nitrate was applied, the soil N₂O emission in the treatment with straw received enhanced UV-B radiation during plant growth was 3.2 times higher than that with the conventional straw under dry-land condition, but did not differ significantly under flooded condition. The amendment of wheat straw which received UV-B radiation during plant growth had no significant effects on soil respiration.

Climatope change and its relations with city development of Haikou City in 1961-2007.

2010, 21(10):  2721-2726. 

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Based on the 1961-2007 meteorological data of Haikou City and its urbanization level in 1989-2007, this paper studied the climatope change and its relations with city development of the City. In 1995-2007, the mean annual air temperature in Haikou had an obvious increase, with an increment of 093 ℃·a^-1,while the mean annual relative humidity decreased obviously, with a decrement of 3% per year, compared with those in 1961-1990. Both the mean annual air temperature and the mean annual relative humidity had significant correlations with the urbanization level of Haikou, suggesting that urbanization could better explain the recent 20 years variation of climate elements in Haikou. The city development of Haikou not only changed the climatope elements, but also affected the air quality, making the frequency of acid rain increased, and the mean annual acid rain pH value decreased.