Table of Content

20 August 2018, Volume 29 Issue 8

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Effects of fire severity and recovery time on organic carbon content of forest soil in Great Xing’an Mountains, China.

ZHANG Yu-jing, WU Zhi-wei, GU Xian-li, FU Jing-jing, YAN Sai-jia

2018, 29(8):  2455-2462.  doi:10.13287/j.1001-9332.201808.016

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Fire is one of the major factors that alter structure and function of forest in the Great Xing’an Mountains, with consequences on soil carbon cycling in forests. In this study, we collected soil samples (layers O, A, AB, BC, and C) under different fire-severity levels (low, moderate, and high) and post-fire recovery times (1987-2012) in the forests of Great Xing’an Mountains. Analysis of variance and multiple comparison were used to analyze effects of fire severity and reco-very time on content of soil organic carbon. The results showed that soil organic carbon (SOC) content in layer O presented a rising trend under both moderate- and high-severity fire disturbances. The content of SOC in layers A and B decreased year by year under low- and moderate-severity fires, which ranked in the order: 3 years > 5 years > 10 years > over 10 years since fire. The content of SOC under high-severity fire presented an increasing trend within 10 years since fire distur-bance and then decreased rapidly over 10 years. The content of SOC in layer BC presented no obvious changes.

Monitoring and evaluation of the effects of Grain for Green Project in the upper and middle reaches of China’s Yangtze River.

LIU Zu-ying, WANG Bing, ZHAO Yu-sen, NIU Xiang

2018, 29(8):  2463-2469.  doi:10.13287/j.1001-9332.201808.011

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Based on the comprehensive interpretation of GIS, we analyzed the normalized vegetation index (NDVI), land use types and digital elevation model (DEM), and revealed the results achieved by the Grain for Green Project in 84 prefecture-level regions in the middle and upper reaches of the Yangtze River. The results showed that the NDVI was growing in this area from 2000 to 2015. Compared with 2000, 2.1% of the farmland was no longer cultivated. 25% of the farmland with slope more than 35°, and 2.7% of the farmland with the slope of 25° to 35°, and the most part of moderate slope farmland had been converted. Arable land was mainly converted to woodland and grassland. The coverage of forest and grassland significantly increased, with an enhancement of 21.9%. The land area of low vegetation coverage was greatly reduced. The area with vegetation coverage less than 10% decreased by 95.3%, while the land area of high vegetation coverage significantly increased. The soil erosion intensity generally reduced. The land area with mild, strong, extremely strong soil erosion grade were all reduced by more than 10%, whereas severe soil erosion had not been alleviated. The proportion of forest coverage was 60% in this area. The magnitude of vegetation coverage changes varied in different periods. The spatial distribution was uneven, with higher coverage in the east than in the west. More works are needed to strenthen the management of Grain for Green Project in this area.

Effects of carbon and nitrogen additions on soil organic C, N, P contents and their catalyzed enzyme activities in a grassland.

LI Huan-ru, ZHU Ying, TIAN Ji-hui, WEI Kai, CHEN Zhen-hua, CHEN Li-jun

2018, 29(8):  2470-2476.  doi:10.13287/j.1001-9332.201808.031

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Soil organic C, N, P contents and their catalyzed enzyme activities play an important role in maintaining and supplying energy and nutrient in grasslands. There is no consensus on the effects of N deposition on soil organic nutrients and enzyme activities in grassland ecosystems. It remains unclear whether C addition will retard the negative effects of N deposition. We carried out an experiment in Hulun Buir grassland of Inner Mongolia to examine the effects of C and N additions on soil organic C, N, P and relative enzyme activities after three years treatments. The experiment was conducted with N treatments at five levels (0, 25, 50, 100 and 200 kg·hm^-2·a^-1) and with C treatments at three levels (0, 250 and 500 kg·hm^-2·a^-1). The results showed that higher levels of N addition significantly decreased dehydrogenase (DHA) and β-1,4-N-acetylglucosaminidase (NAG) activities by 22.3% and 12.5%, respectively. Nitrogen addition had no significant effect on soil organic N and decreased the organic C and P contents by 6.6% and 14.5%, respectively. High C addition significantly increased DHA, β-glucosidase (BG) activities and increased soil organic N and organic P by 15.1%, 12.2%, 1.9%, 2.6%, respectively. The results suggested that continuous N inputs inhibited microbial activities and caused losses of soil organic C and organic P. Carbon addition could enhance microbial activities and promote the secretion of enzymes and increase soil organic N and P. The combined C and N addition could play an important role in maintaining the balance and supply of soil C, N, and P in grassland ecosystem.

Effects of balanced fertilization on growth and fruit quality of ‘Huang-guan’ pear on desert area.

CAO Gang, ZHAO Ming-xin, BI Shu-hai, CAO Su-fang, WANG Wei, LI Hong-xu

2018, 29(8):  2477-2484.  doi:10.13287/j.1001-9332.201808.010

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A field experiment was carried out to study the effects of balanced fertilization on growth and development, yield, fruit quality and mineral content in ‘Huang-guan’ pear to provide a theoretical basis for the reasonable level of fertilization in pear orchards. Four treatments were arranged with 12-year old ‘Huang-guan’ pear trees from the same orchard: conventional fertilization (CK), low levels of N, P₂O₅ and high level of S (T₁), medium levels of N, P₂O₅ and S (T₂), high levels of N, P₂O₅ and low level of S (T₃). The results showed that different treatments had little effect on the growth and development of current-year branch and leaves in the first year. However, in the se-cond year, T₁ treatment promoted the length and diameter of current-year branch by 16.2% and 11.4%, respectively. Continuous fertilization could increase the leaf mineral contents in different degrees. The contents of Cu, Fe, and Zn in leaves under T₁ treatment, Mg and B in leaves under T₂ treatment, and P and Mn in leaves under T₃ treatment were highest. Different fertilization levels had no significant effect on yield but on fruit quality. The contents of soluble sugars and vitamin C (Vc) were significantly increased by T₂ treatment, which was 4.2% and 7.1% higher than those in CK. However, T₁ significantly decreased contents of total soluble solid, soluble sugars and Vc, while highest organic acid content presented in T₃. Fruit Fe content was positively correlated with soluble sugar content and fruit shape index, but was negatively correlated with single fruit mass, organic acids and Vc. Fruit P content was positively correlated with fruit shape index and firmness, but was negatively correlated with contents of soluble sugars, organic acids and Vc. Accordingly, T₂ could improve fruit quality and maintain the productivity, and thus should be the suitable fertilization strategy for the ‘Huang-guan’ pear management in desert area.

Effects of drought and rewatering on leaf photosynthesis, chlorophyll fluorescence, and root architecture of citrus seedlings.

WEI Qing-jiang, FENG Fang-fang, MA Zhang-zheng, SU Shou-ting, NING Shao-jun, GU Qing-qing

2018, 29(8):  2485-2492.  doi:10.13287/j.1001-9332.201808.028

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Drought severely affects citrus growth and development. In order to explore the mechanism of drought response of citrus, two cultivars (Sanhuhongju and Sanhuhuahong) that differing in drought tolerance were used as materials. The drought and rewatering treatment was conducted in pot experiments, with leaf photosynthesis, chlorophyll fluorescence, and root architecture being measured. The results showed that drought significantly decreased net photosynthetic rate (P_n), stomatal conductance (g_s), transportation rate (T_r), and intercellular CO₂ concentration (C_i) of both cultivars, but Sanhuhongju generally showed less reduction. After rewatering, photosynthetic parameters were partly recovered but still lower than that in control. The water use efficiency (WUE) of Sanhuhongju was significantly increased after drought stress for 15 d, but the WUE of Sanhuhuahong was decreased except at the 15 day of drought stress. In addition, the maximum photosynthesis efficiency of PS II (F_v/F_m) was increased in both cultivars, but the photochemical quantum yield of PS II [Y(II)] was increased in Sanhuhuahong under drought. Both the apparent electron transport rate (ETR) and photochemical quenching (q_P) were inhibited in the treated seedlings. The non-photochemical quenching (NPQ) was decreased in Sanhuhongju while increased in Sanhuhuahong under drought and rewatering conditions. Drought stress resulted in the decrease of root surface area and volume of both cultivars, and it inhibited root elongation of Sanhuhuahong while improved the root length and root tip number of Sanhuhongju. The length of first lateral roots of Sanhuhongju was increased after drought stress 10 d, but did not change at the drought stress prophase of Sanhuhuahong, and then significantly decreased after 20 d. Furthermore, drought stress inhibited all lateral roots development except the tertiary lateral root of Sanhuhongju, and root growth could not be recovered by rewatering except root tip number. In conclusion, Sanhuhongju showed less reduction in leaf photosynthesis than Sanhuhuahong, with higher WUE and light use efficiency under drought stress. The increases of root tip number and lateral root length would help improve water uptake ability in Sanhuhongju.

Effects of nitrogen fertilizer application on carbon dioxide emissions from soils with different inorganic carbon contents.

YU Wei-jia, LI Xue-song, CHEN Zhu-jun, ZHOU Jian-bin

2018, 29(8):  2493-2500.  doi:10.13287/j.1001-9332.201808.009

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The application of nitrogen (N) fertilizer results in decreases of soil pH, but its effects on CO₂ emission from soils with different inorganic carbon contents remain unclear. An closed-jar incubation experiment was conducted to examine the effects of N fertilizer and nitrification inhibitor (DCD) on soil pH and CO₂ emissions from three soil types with different contents of soil inorganic carbon (SIC), including paddy soil (PS), lime concretion black soil (CS), and eum-orthic anthrosols (AS). There were three treatments for each soil type, including control (N₀), 0.2 g·kg^-1 N fertilizer (N_0.2), and its combination with DCD (N_0.2+DCD). Soil pH, contents of mineral N (NH₄⁺, NO₃^-), and CO₂ emissions were measured. The results showed that N fertilizer addition significantly reduced soil pH and increased soil CO₂ cumulative emissions in each type of soil. Compared to control, the CO₂ cumulative emissions after 49 days incubation from the three soil types were enhanced by 39.4%, 23.4%, and 71.8% for PS, CS, AS soils, respectively. The soil pH of N_0.2+DCD for three soil types were significantly higher than N_0.2 after 49 days incubation, indicating that DCD application inhibited soil nitrification process. There were no significant differences in the mean CO₂ cumulative emissions of PS and CS soils between N_0.2 and N_0.2+DCD treatments; however, N_0.2+DCD treatment significantly reduced cumulative CO₂ emissions from AS soil by 12.5%. Soil inorganic carbon can effectively buffer soil acidification caused by N fertilizer addition. The CO₂ emission in calcareous soil following N addition is not only derived from the mineralization of soil organic carbon, but also from the dissolution of inorganic carbon. Given the large differences in soil inorganic carbon content in different regions of China, the problem of soil acidification and soil inorganic carbon pool consumption caused by long-term large amount of N fertilizer inputs deserve more attention.

Effects of conservation tillage on soil water condition and winter wheat yield in farmland

DING Jin-li, WEI Hong-yi, YANG Yong-hui, ZHANG Jie-mei, WU Ji-cheng

2018, 29(8):  2501-2508.  doi:10.13287/j.1001-9332.201808.005

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Conservation tillage is one of the most important agricultural management measures on soil water conservation and crop yield increments. Based on long-term experiment during 2011 to 2016, effects of different tillage treatments, including conventional tillage, no-tillage and subsoiling treatments, on soil water condition, crop yield and water use efficiency were analyzed. The results showed that the average and relative soil water conservation rate was 7.3% and -0.68% at jointing stage of winter wheat under no tillage and subsoiling treatments, respectively. Compared with conventional tillage, soil water storage significantly increased in 0-60 cm soil layer at jointing stage of winter wheat under no-tillage. Besides, the mean values of soil water content significantly increased in 0-100 cm soil layer at jointing, flowering, filling, and harvesting stages under no tillage treatment while that was not significantly increased at jointing stage under subsoiling treatment. Furthmore, no-tillage treatment significantly increased the yield and water use efficiency of winter wheat, especially in the dry years. Therefore, soil moisture conservation ability and yield increment of no tillage was better than that of the subsoiling treatment in dry years.

Optimum nitrogen application rate to maximum yield and environment protection for winter wheat in Weibei dryland, China.

LIU Yan-ni, MA Chen, YU Xin-yang, ZHAI Bing-nian, LI Zi-yan, WANG Zhao-hui

2018, 29(8):  2509-2516.  doi:10.13287/j.1001-9332.201808.024

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To get the optimum nitrogen (N) fertilization rate which could guarantee wheat yield and protect environment, we examined wheat yield, N use efficiency, apparent N loss and soil N balance in Weibei dryland with a 3-year field experiment. The results showed that annual wheat yield increased and then decreased as N application rate increased in all the years with different annual rainfall, but the cumulative apparent N use efficiency significantly decreased. Higher yield and N use efficiency were obtained at the fertilization rate of 150 kg·hm^-2. Residual nitrate-N concentrations significantly increased with the increases of N application rate. When the N application rate was between 75 and 150 kg·hm^-2, the apparent N loss and loss rate were nearly the same, but if N application rate was higher than 150 kg·hm^-2, the apparent loss and loss rate significantly increased. In conclusion, N application rate at 150 kg·hm^-2 in Weibei dryland could guarantee high yield and N use efficiency, and simultaneously maintain residual nitrate-N concentration and reduce apparent N loss.

Effects of wide-range planting on the yield and nitrogen use efficiency of winter wheat cultivar Tainong 18.

CHU Jin-peng, ZHU Wen-mei, YIN Li-jun, SHI Yu-hua, DENG Shu-zhen, ZHANG Liang, HE Ming-rong, DAI Xing-long

2018, 29(8):  2517-2524.  doi:10.13287/j.1001-9332.201808.027

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The effects of wide-range planting (WR) versus drilling-planting (DP) on grain yield, nitrogen use efficiency (NUE), and nitrogen uptake efficiency (UPE) were investigated using winter wheat cultivar Tainong 18 at experimental fields in Tai’an and Yanzhou during the growing seasons of 2015 and 2016. The results showed that planting pattern, experimental field location, and their interaction significantly affected the grain yield, NUE, and related indices of cultivar Tainong 18. Compared to DP, the WR pattern significantly increased grain yield by 22.5% and 15.4% at Tai’an and Yanzhou, respectively, by raising the number of spikes per unit area at maturity (originating from the greater numbers of tillers per plant and per unit area) and the number of spikes per plant. Compared to DP, the WR pattern significantly increased UPE by 27.7% and 17.5% at Tai’an and Yanzhou, respectively. NUE with the WR pattern at Tai’an and Yanzhou was also increased, respectively, by 22.5% and 15.4% by enhancing nitrogen accumulation and increasing the UPE. A stonger positive effect on yield was observed at Tai’an than at Yanzhou. Thus, the popularization and application of a WR pattern would synergistically improve grain yields and NUE in winter wheat.

Effects of dark induced senescence on the function of photosystem II in flag leaves of winter wheat released in different years.

YANG Cheng, ZHANG De-qi, DU Si-meng, SHAO Yun-hui, FANG Bao-ting, LI Xiang-dong, YUE Jun-qin, ZHANG Su-yu

2018, 29(8):  2525-2531.  doi:10.13287/j.1001-9332.201808.021

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Cultivar renewing is important for the increases of wheat yield. Studying changes of different physiological characteristics in the succession process of wheat varieties has great implications for future breeding. The senescence rate of flag leaf is a key factor affecting winter wheat yield. The variation of photosystem II function during senescence of flag leaves of wheat from different ages is still not clear. 31 wheat varieties planted in Henan Province from different ages since 1941 were examined in this experiment. The variation of photosystem II function was analyzed through measu-ring the relative chlorophyll content, and chlorophyll fluorescence induction dynamics during the senescence of flag leaves which were induced by continued dark. The results showed that the chlorophyll content of flag leaves was gradually increased in the succession of winter wheat. The chlorophyll degradation rate in the leaves of modern varieties was lower than the earlier varieties during the senescnece of flag leaves. Meanwhile, J point of the fluorescence induction kinetics curves in flag leaves of modern varieties increased less than I point. The photosystem II maximum photochemical efficiency and the amount of active reaction centers per unit area gradually increased during succession of wheat varieties, but the reduced extent in leaves of modern varieties was lower than that in the earlier ones. There was no significant correlation between the change of chlorophyll content and F_v/F_m in senescent leaves. There was significant positive correlation when the leaves aging degree increased, with the slope of trend line gradually increased. The photosystem II unit area and the amount of active reaction center was positively related with the aging degree, and both the correlation degree and slope of trend line increased with the increases of senescence extent of the leaves. The results suggested that chlorophyll content of flag leaf increased and the degradation rate slowed down gradually during the succession of wheat varieties. The anti-aging ability of photosynthetic electron transfered from Q_A to Q_B was improved, which contributed to the slowing down of the decline of F_v/F_m and the amount of active reaction center. The increased chlorophyll content and anti-aging ability of photosystem II also contributed to the increases of yield in the succession of winter wheat.

Effects of microbial fertilizer on soil improvement and fruit quality of kiwifruit in old orchard.

KU Yong-li, XU Guo-yi, ZHAO Hua, DONG Tian-wang, CAO Cui-ling

2018, 29(8):  2532-2540.  doi:10.13287/j.1001-9332.201808.025

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The continuous cropping obstacles caused by the increase of kiwifruit planting period resulted in imbalance of soil microbial community structure, and decrease of soil enzyme activity and physicochemical indicators, which substantially reduced both the quality and yield of kiwifruit. Under the field conditions, the traditional fertilization of fruit farmers was used as a control (CK) to study the effects of two different microbial fertilizers, JF and KF, which had been verified the growth promotion of kiwifruit aseptic seedlings test, on soil microbial community structure, soil enzyme activities, soil physicochemical characters during different growth periods of kiwifruit (germination period, florescence period, fruit enlargement period, fruit ripening period and next year germination period), as well as fruit quality. The results showed that both fertilizers significantly increased the ratio of bacteria with fungi and the ratio of actinomycetes with fungi in the kiwifruit orchard soil, indicating that they could improve and balance the soil microbial community structure. The enzymes activity in kiwifruit orchard soil with the addition of both fertilizers were significantly higher than that in CK, and among which sucrose, urease, phosphatase and polyphenol oxidase were increased by 17.9%-83.5%, 7.9%-83.0%, 7.3%-45.4% and 8.1%-140.3%, respectively. JF and KF increased soil fertility (the concentrations of available nitrogen, phosphorus, potassium, total nitrogen, total phosphorus, total potassium, and organic matter content significantly increased) and decreased soil pH (a decrease of 0.29 to 0.34). After application of microbial ferti-lizer, the content of vitamin C, soluble sugar, soluble protein and other contents of kiwifruit increased, and the titratable acid content decreased. Therefore, the application of both fertilizers could balance soil microbial community structure, enhance soil fertility, and improve the fruit quality of kiwifruit. Our results provide robust theoretical basis for the application of microbial fertilizers in the old-aged kiwifruit orchards.

Effects of ditch-buried organic matter and irrigation amount after anthesis on the photosynthetic characteristics and yield of maize.

MENG Yan, SUN Xiao-han, ZHENG Bin, WANG Liang, LI Zeng-jia, LI Geng, NING Tang-yuan

2018, 29(8):  2541-2550.  doi:10.13287/j.1001-9332.201808.007

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Managements of organic matter and irrigation after anthesis will increase the capacities of water conservation and supply in maize field, with consequences on photosynthetic performance and yield under water-saving condition. We analyzed the gas exchange parameters and the performance of the photosystem Ⅱ of ear leaves, and yield of maize cultivars Zhengdan 958, under three modes of ditch-buried organic matter (no straw returned: M₀, wheat straw returned: M₁, mixtures of cow manure and wheat straw returned: M₂) before seeding with two irrigation levels after anthesis (normal irrigation: W₁, water-saving irrigation: W₂). The results showed that M₂ treatment significantly increased photosynthetic capacity and dry matter accumulation after anthesis compared with M₁ treatment. Compared with water-saving irrigation, normal irrigation enhanced the photosynthesis of ear leaves. M₂W₁ treatment significantly increased net photosynthetic rate (P_n), stomatal conduc-tance (g_s), transpiration rate (T_r), and performance of photosystem Ⅱ (φ_po and Ψ_o) of ear leaves after anthesis, while reduced intercellular CO₂ concentration (C_i). In addition, M₂W₁ treatment significantly increased light utilization efficiency and maintained higher photosynthetic properties in ear leaves, and significantly increased dry matter accumulation and grain yield. Water-saving irrigation reduced photosynthetic performance of ear leaves, which declined the yield. But compared M₂ with M₀, water use efficiency, grain growth rate and yield increment under water-saving irrigation were higher than those under normal irrigation. Thus, mixtures of cow manure and wheat straw returned combined with normal irrigation could significantly increase photosynthetic properties of ear leaves and dry matter accumulation, which were the major reasons for yield enhancement. Importantly, the mixture of cow manure and wheat straw returned combined with water-saving irrigation could decrease the loss of crop yield resulted from lower irrigation.

Characteristics of soil nitrate accumulation and leaching under different long-term nitrogen application rates in winter wheat and summer maize rotation system.

WENG Ling-yun, YANG Xiao-qia, LYU Min-juan, XIN Si-ying, CHEN Shuai, MA Wen-qi, WEI Jing

2018, 29(8):  2551-2558.  doi:10.13287/j.1001-9332.201808.026

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Winter wheat and summer maize were the main crops in the North China Plain. While intensive farming system could generally achieve high yield, the perennial large amounts of nitrogen (N) fertilization application cause environmental problems including NO₃^--N accumulation and leaching at deep soil layer. Here, the effects of different N application rates on soil NO₃^--N accumulation and leaching in winter wheat-summer maize cropping system were investigated from 2010 to 2016 at Qingyuan County, Hebei Province, China. There were five treatments with N application rates at 0 (N₀), 100 (N₁₀₀), 180 (N₁₈₀), 255 (N₂₅₅) and 330 (N₃₃₀) kg·hm^-2. Results showed that crop yield and soil N status significantly varied among treatments for both wheat and maize after each harvest, respectively. Soil NO₃^--N were accumulated during winter wheat growing season and leached to deeper soil during summer maize growing season. Moreover, the soil NO₃^--N accumulation amount in the 90 to 180 cm soil profile decreased with the decreases of N inputs (N₃₃₀ > N₂₅₅ > N₁₈₀ > N₁₀₀ > N₀). Soil NO₃^--N could be leached to 990 cm soil depth. There were six NO₃^--N accumulation peaks in the soil profile, with the peaks presenting at deeper soil profile with higher N fertilization rate. The deepest peak appeared at 840 cm soil depth with the N application rate of 330 kg·hm^-2. From the distribution of NO₃^--N accumulation in the soil profile, only around 10% of total NO₃^--N was accumulated between 0-90 cm soil depth, while the rest accumulated below 90 cm, which could not be largely absorbed by plants. Therefore, NO₃^--N leaching during summer maize growing season was serious and it was greater with higher N fertilization rate which might lead to increased risk of underground water contamination. In terms of balanced crop yield and soil NO₃^--N accumulation, the rate of 180 kg·hm^-2 would be the optimum one in areas with similar cultivation and environmental conditions to the present study.

Effects of elevated atmospheric CO₂ concentration on the stability of soil organic carbon in different layers of a paddy soil.

CHEN Dong, YU Hong-yan, ZOU Lu-yi, TENG Yue, ZHU Chun-wu

2018, 29(8):  2559-2565.  doi:10.13287/j.1001-9332.201808.008

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It is vital to study the effects of elevated atmospheric CO₂ concentration on the soil orga-nic carbon (SOC) stability in different soil layers for better understanding the mechanism of SOC transformation under the elevated atmospheric CO₂ concentration. The paddy soil in a long-term FACE (Free Air Carbon-dioxide Enrichment) experiment was selected as the research object. Through the SOC physical fractionation and soil mineralization incubation, the effects of elevated atmospheric CO₂ concentration on the soil organic carbon (SOC) content, particle organic matter (POM) content, SOC mineralization intensity, and enzyme activities were measured. Then, the effects of elevated atmospheric CO₂ concentration on the SOC stability in different layers were exa-mined. The results showed that the elevated atmospheric CO₂ concentration had no significant effect on SOC content, but significantly increased the POM-C content by 93.7% and the invertase and polyphenol oxidase activities by 61.1% and 83.7% in the topsoil layer, respectively. These results indicated that SOC stability of topsoil was reduced under the elevated atmospheric CO₂ concentration. However, the elevated atmospheric CO₂ concentration had no significant effect on the SOC stability of deep soil layer. Our results would help assess the capacity of soil sequestrated and accumulated organic carbon and provide basis for scientific management of farmland under greenhouse effect in the future.

Effects of different nitrogen application rates on low temperature resistance of late rice at heading and flowering stage.

CAO Na, XIONG Qiang-qiang, CHEN Xiao-rong, HE Hao-hua, ZHU Chang-lan, FU Jun-ru, CAI Shuo, XU Tao

2018, 29(8):  2566-2574.  doi:10.13287/j.1001-9332.201808.022

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Four levels of nitrogen application (N₁, low nitrogen, 90 kg N·hm^-2; N₂, normal nitrogen, 180 kg N·hm^-2; N₃, high nitrogen, 250 kg N·hm^-2; N₄, ultra high nitrogen, 330 kg N·hm^-2) were set to examine the effects of nitrogen application on the growth and development, yield formation and related physiological characteristics of late rice under low temperature condition during heading and flowering stage, with super hybrid late rice variety Wufengyou T025 as test material. The results showed that yield of all treatments decreased in different degrees under the low temperature conditions, with the yield of N₂ being the highest, and N₁ the lowest. The effective panicles per plant and total grains per panicle in N₃ and N₄ were higher than those of the other treatments, but their seed setting rate and harvest index were significantly decreased. With the increases of nitrogen application rates, pocketed panicle rate, the total dry mass and chlorophyll contents (SPAD value) increased to different extent, while the panicle dry mass of N₂ was the highest. After low temperature, chlorophyll content, net photosynthetic rate and transpiration rate of the total treatments decreased to varying degrees, and the declined range of the net photosynthetic rate and trans-piration rate in N₃ and N₄ were higher than other treatments. The contents of free proline, malondialdehyde and peroxidase activity of all treatments increased to varying extent, while superoxide dismutase, catalyes activities and the soluble protein contents decreased, with the magnitude of variation in N₃ and N₄ being the greatest. It demonstrated that high amounts of nitrogen application were unfavorable to late rice to resist low temperature at heading and flowering stage and thus misuse of nitrogen fertilizer application should be avoided in production. The suitable amount of nitrogen application in double cropping late rice was not more than 180 kg·hm^-2.

Effects of purified humic acid on the growth and nitrogen metabolism of cucumber seedlings under nitrogen stress.

GU Duan-yin, WANG Xiu-feng, GAO Jun-jie, JIAO Juan, LIU Zhong-liang, ZHANG Yan-yan

2018, 29(8):  2575-2582.  doi:10.13287/j.1001-9332.201808.029

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To investigate the effects of purified humic acid (PHA) on the growth and nitrogen metabolism of cucumber under different levels of nitrogen stress and to explore the mechanism of PHA’s alleviation on abiotic stress, we examined the effects of PHA on ‘Xintaimici’ cucumber growth and nitrogen metabolism under low nitrogen (1.0 mmol·L^-1 NO₃^-) stress and high nitrogen (101 mmol·L^-1 NO₃^-) stress in hydroponics compared with normal level (11 mmol·L^-1 NO₃^-). The results showed that the growth of cucumber seedlings was inhibited under nitrogen stress treatments. Plant height, stem diameter, leaf area and dry matter accumulation under nitrogen stress were lower than that at normal nitrogen level. Dry matter accumulation under the normal nitrogen level and low nitrogen stress were significantly increased by PHA, but there was no significant difference under high nitrogen stress. The absorption of NO₃^- in cucumber seedlings was affected by PHA, showing increased nitrate content in cucumber seedlings under low nitrogen stress and decreased under high nitrogen stress. PHA significantly decreased ammonium content in roots and leaves under low and high nitrogen stress. Compared with normal level of nitrogen (CK), NR, GS, GOGAT, GDH activity in roots and leaves and NiR activity in roots significantly decreased under low and high nitrogen stress. PHA increased the activities of NR, NiR, GS, GOGAT, and GDH to different extents. PHA increased amino acid and soluble protein content in cucumber seedling roots and leaves. In summary, PHA addition alleviated the inhibitory effect of nitrogen stress on the growth of cucumber seedlings.

Effects of soil salinity on Bt protein content and nitrogen metabolic physiology in boll shell of Bt cotton

WANG Yong-hui, CHEN Jian-ping, SUN Yan-ru, ZHANG Xiang, CHEN De-hua

2018, 29(8):  2583-2589.  doi:10.13287/j.1001-9332.201808.030

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In order to clarify the effects of soil salinity on the insect-resistance of boll in transgenic Bt cotton, potted plants of two Bt cotton cultivars Xinmian 33B (salt-sensitive) and Zhong 07 (salt-tolerant) were exposed to five levels of soil salinity (0, 0.15%, 0.30%, 0.45% and 0.60%). The results showed that Bt protein content of boll shell decreased with increasing soil salinity. Compared with the control (0% soil salinity level), the Bt protein content of boll shell decreased significantly when the soil salinity level was above 0.15% for Xinmian 33B and above 0.30% for Zhong 07. The reduction extent of Bt protein content of boll shell at 30 days post anthesis (DPA) was greater than that at 10 DPA under the same soil salinity level. Significant reductions of soluble protein contents, nitrate reductase (NR), and glutamate pyruvate transaminase (GPT) activities were observed when the boll shell Bt protein content was significantly reduced. The content of free amino acid, protease, and peptidase activity of boll shell significantly increased when the soil salinity level was above 0.30%. In conclusion, soil salinity affected boll shell nitrogen metabolism and reduced Bt protein synthesis. Middle and high soil salinity levels could enhance decomposition of Bt protein, which further decreases the expression level of insecticidal protein.

Mechanism of reduced insecticidal protein expression in Bt cotton under high temperature and drought based on proteomics.

ZHANG Xiang, LIANG Pan-pan, WEI Chen-hua, DENG Guo-qiang, WANG Jian, PENG Sheng,CHEN Yuan, CHEN De-hua

2018, 29(8):  2590-2600.  doi:10.13287/j.1001-9332.201808.006

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To provide theoretical basis for the safety of insecticidal efficiency in Bt cotton, the effects of high temperature and drought stress on insecticidal protein expression and protein diffe-rently expression profile was studied. In this study, the Bt cotton cultivar Sikang 3 was used as expe-rimental material, with two treatments (40% field capacity and 38 ℃, HD, and 60% field capacity and 32 ℃, CK). Differences in proteomics of Bt cotton between HD and CK were compared using label-free quantitative proteomics technology. The results showed that high temperature and drought caused a significant reduction of insecticidal protein content in bolls, with a decrease of 38.2 ng·g^-1 FM. The analysis of differential protein expression by label-free quantitative proteomic approach showed that 83 proteins were significantly up-regulated, but 104 proteins were significantly down-regulated in HD stressed cotton plants compared with CK. 122 new proteins were detected and 167 proteins expression was not observed under stressed conditions. Results from the enrichment analysis of differently expressed protein between two treatments showed that 14 KEGG (Kyoto Encyclopedia of Genes and Genomes) pathways were affected under stress. Three KEGG pathways were related to the Bt protein synthesis and degradation: carbohydrate digestion and absorption pathway, protein export pathway, and protein processing in endoplasmic reticulum pathway. In the carbohydrate digestion and absorption pathway, the starch hydrolysis ability of HD treated cotton plants increased, while the ability to phosphorylate the hexoses, fructose and glucose decreased. In protein export pathway, the peptide synthesis in HD treatment was not significantly affected, while the process of transferring peptides into the endoplasmic reticulum was prohibited. In the protein processing in endoplasmic reticulum pathway, the ability of ubiquitin mediated proteolysis was increased in HD treatment.

Spatial point patterns and their association dynamics of forest landscapes in Maoershan region, Northeast China between 1983 and 2016.

SUN Yun-xia, LIU Zhao-gang, DONG Ling-bo

2018, 29(8):  2601-2614.  doi:10.13287/j.1001-9332.201808.012

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Researches on the dynamics of spatial point patterns and their associations of forest landscape has important implications for maintaining forest stability and making forest management decisions. Based on the four period datasets of forest resource inventory in Maoershan region in 1983, 1993, 2004, and 2016, the O-ring statistics within Programita software (version 2010) was used to quantitatively analyze the dynamics of spatial point patterns and associations. The results showed that the cover percentage of soft-wood broadleaved mixed forest (SBM) significantly decreased, the percentage of natural Quercus mongolica (NMO) increased in the beginning, and then became lower. The percentage of hard broadleaved mixed forest (HBM), Larix gmelinii (RLG) and Pinus sylvestris var. mongolica (RPS) plantations increased dramatically from 1983 to 2016. During the study period, the scale of clumped distribution for the SBM, HBM, NMO all significantly decreased with the increasing spatial scale. The clumped distribution ranging from 0-7 km decreased to 0-3 km, and then tended to be random or uniform distribution with the further increases of spatial scale. The patterns of RLG showed aggregated distribution within the small scale and tended to be random or uniform distribution with the increasing scale. However, the range of scale of uniform distribution increased and random distribution decreased. The patterns of RPS showed clumped distribution within small scale (0-4 km) and the range of scale tended to be larger. On the whole, the spatial association between most of the landscape types within the small scale showed negative association. With the increases of scale, these landscape types gradually become non-association or positive association. However, only a few landscape types (e.g. RLG and RPS in 1983) showed positive association in a small scale. With the increases of scale, all the relationship tended to be non-association. The dynamics of the association of forest landscapes showed different regularity. The dynamics of spatial point patterns and associations of Maoershan region were the comprehensive results of the forest management during 1983 and 2016.

Spatial heterogeneity of soil hydrolase activities and their influencing factors in a typical Karst catchment of Guizhou Province, China.

LIU Shuo, WANG Qiu-bing, SHI Wen-jiao, ZHANG Xin-yu

2018, 29(8):  2615-2623.  doi:10.13287/j.1001-9332.201808.023

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Soil enzyme activities are sensitive indicators of soil quality. However, their spatial hetero-geneity and the influencing factors are not well known. In this study, geostatistics, Kriging method, one-way ANOVA and correlation analyses were used to examine the spatial variability and influencing factors of activities of six soil hydrolases: β-1,4-glucosidase (βG), β-1,4-xylosidase (βX), cellobiohydrolase (CBH), β-1,4-N-acetylglucosaminidase (NAG), leucine amino peptidase (LAP), and acid phosphatase (AP) in 0-10 cm soil layers in a karst catchment in Guizhou Pro-vince, China. The results showed that the activities of those soil hydrolase had different spatial hete-rogeneity. The optimal models were the spherical models for βX, CBH and AP, the Gaussian model for βG and NAG, and the exponential model for LAP, respectively. The spatial structure ratios C/(C₀ +C) of βG, βX, CBH, NAG and LAP activities were 99.9%, 99.9%, 99.9%, 76.3% and 96.6%, respectively, implying strong spatial autocorrelation and weak influence from topographic factors. The spatial structure ratio of AP activity was 50.0%, suggesting moderate spatial autocorrelation and vulnerable to the influences of random factors. The variation ranges of the hydrolase acti-vities were greater than the sampling distance, indicating that the sampling methods could mirror spatial variability of the soil enzyme activities at a small watershed scale. Land use type significantly affected the activities of NAG and AP. Slope position significantly affected AP activity. The activity of AP was negatively correlated with soil pH, while the activities of other enzymes except NAG were positively correlated with soil pH. Our results provided useful information on the spatial distribution mechanism of soil hydrolase.

Applicability of five drought indices for agricultural drought evaluation in Jilin Province, China.

MU Jia, QIU Mei-juan, GU Yu, REN Jing-quan, LIU Yang

2018, 29(8):  2624-2632.  doi:10.13287/j.1001-9332.201808.014

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Drought is a severe meteorological disaster on agriculture in Jilin Province. Agricultural drought can be represented by drought indices, but there is no universal applicable index. It is of great significance to examine the applicability of drought indices for agricultural drought evaluation. Based on daily meteorological data, soil moisture data, and drought statistical information from 1961 to 2014, we selected typical drought years and typical drought zones. The applicability of five drought indices was evaluated, including precipitation anomaly percentage (PA), relative moisture index (MI), crop water deficit anomaly index (CWDIa), Palmer drought severity index (PDSI) and meteorological drought comprehensive index (MCI). The results showed that agricultural drought evaluation of MI was consistent best with drought information for two typical drought years of 1997 and 2007, followed by PA and MCI. For typical drought zones (Tongyu in the west, Lishu in the center and Helong in the east), MI and PDSI performed much better than other ones. During growing season, PA was more applicable in April, July and August, MI was applicable to April, May and September, CWDIa only performed well in May, PDSI could be an indicator to agricultural drought in June, July, August and September, MCI was useful in May, June, July and August. For different regions with agricultural drought, MI, PDSI and MCI were applicable in western region, PDSI in central region, and PA, PDSI and MCI were suitable for eastern region.

Landscape preference of different stakeholders in highly intensive farming agricultural landscape.

TANG Qian, FENG Shu, LIANG Guo-fu, DING Sheng-yan

2018, 29(8):  2633-2640.  doi:10.13287/j.1001-9332.201808.015

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Intensive agriculture is the way for production and management in modern agriculture, which increases the yield per unit area of farmland, brings a series of environmental and ecological problems, and limits the sustainability of agriculture. Landscape preference focuses on different stakeholders’ preferences for landscape, reflects the influences of human’s subjective feelings and behaviors on landscape. Based on the agricultural landscape of Fengqiu County in Henan Province, we investigated the characteristics of the landscape elements which stakeholders preferred and analyzed the reasons using the questionnaire survey and other related methods. We proposed several suggestions for future development of the agricultural landscape in study area. The results showed that stakeholders preferred the landscape element which is simple and easy to manage, and emphasized the production and economic functions of agricultural landscape. Experts and local environmentalists preferred the landscape elements with multiple functions and benefits, as well as complex landscape configurations with high heterogeneity, with the aim to develop the multifunctional agricultural landscape. Factors such as education level, professional background and types of intervie-wees had obvious influences on the landscape preference of stakeholders. The decision-making beha-vior of government, the degree of economic compensation, and the technological support of eco-agriculture would be the important factors determining the possible development of landscape structure and function in the future.

Emergy analysis of four typical planting modes in Karst faulted basins of Yunnan Province, China.

ZOU Zhi-gang, ZHANG Hao, ZENG Zhao-xia, ZHANG Jian-yun, ZHAO Jie-jun, BAO Song-lian, ZENG Fu-ping

2018, 29(8):  2641-2650.  doi:10.13287/j.1001-9332.201808.020

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Accurate evaluation of typical cropping patterns in faulted basins can provide scientific guidance for planting in the area. The planting modes of marigold, pomegranate, pomegranate+grass+sheep in Mengzi City of Yunnan Province were compared with the traditional corn planting mode. The ecological benefits and economy benefits of these rocky desertification control modes were analyzed by the method of emergy analysis. The environmental loading ratio (ELR) and emergy restoration ratio (ERR) were 13.80 and 0.41 in pomegranate planting mode, respectively, while 0.30 and -2.87 in marigold planting mode. The ecological benefits in pomegranate planting mode and marigold planting mode were lower than that of corn, and ELR and ERR were 1.30 and 4.64, respectively. However, the economic pure benefit per unit (EPBU) in pomegranate planting mode and marigold planting mode were 3.05 and 59.98 times of that in corn mode, respectively, indicating that pomegranate planting mode and marigold panting mode had higher economic benefits than that of corn. Pomegranate+pasture+sheep mode had the highest ecological and economic benefits among the four modes. The plus of forage+livestock subsystem to pomegranate planting mode had high eco-efficiency (ELR of 4.95, ERR of 0.63) and economic benefit (EPBU of 71.38 times than that of corn). Thus, we recommend that the local government should increase technical support for marigold planting mode and pomegranate+pasture+sheep mode, which including optimizing structures of fertilizer input, and crop cultivation and livestock breeding processes. Meanwhile, government could establish short-term labor markets for picking of fruits and flowers.

Influence of climate change on the suitable ranges for planting pickled mustard tuber in Chongqing.

LI Hong-qun, LIU Xiao-li, WANG Jian-hua, FU Yong-yao, DING Shi-min, XIE Wang-yang, ZHANG Jing

2018, 29(8):  2651-2657.  doi:10.13287/j.1001-9332.201808.018

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Pickled mustard tuber (Brassica juncea var. tumida) belonging to Cruciferae, is a unique economic crop in China. Climate is an important factor affecting the distribution of pickled mustard tuber. Based on species presence data at 279 locations and 22 high-resolution environmental factor layers, we analyzed the potential planting area of pickled mustard tuber in Chongqing by MaxEnt model under the current conditions and the future distributions for the periods 2050s and 2070s under the climate change scenarios of RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5 described in the Special Report on Emissions Scenarios (SRES) of IPCC (Intergovernmental Panel on Climate Change). The results showed that MaxEnt model was excellent in predicting its potential plan-ting area. The cumulative contributions of dominant factors reached as high as 81.7%, including precipitation of wettest month, temperature annual range, minimum temperature of coldest month, isothermality, mean diurnal range and average maximum temperature. The threshold of those factors was 173-183 mm, 27.2-28.3 ℃, 1.8-3.8 ℃, 22.5-24 ℃, 6.2-6.8 ℃ and 14.8-18.0 ℃, respectively. Under current condition, the optimum suitable areas of pickled mustard tuber, which amounted to 4.2%, were in the northeast, west and east of Fuling, the east and south of Changshou, the south and southeast of Dianjiang, the northwest and north of Fengdu, the southeast of Zhongxian, and a small part of Wulong and Nanchuan, while the proportion of moderately suitable areas was 6.3%. Under four climate change scenarios, the optimum suitable areas would drop to 2.7%, 3.8％, 3.1％, 3.2％ and 3.1%, 3.7％, 3.5％, 2.9％ for the periods 2050s and 2070s, respectively, while moderately suitable areas would rise gradually.

Evaluation and change of Danjiangkou Reservoir dynamic capacity.

LIU Hai, WU Jing, YIN Jie, WANG Min, CHEN Xiao-ling

2018, 29(8):  2658-2666.  doi:10.13287/j.1001-9332.201808.013

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Dynamics of storage capacity of the Danjiangkou Reservoir have important significance to guarantee water diversion middle route project. Aiming at the problems of complexity in measurement and short-term fluctuation in capacity in Danjiangkou Reservoir, we chose remote sensing data of Landsat series and HJ-1A/B, and DEM data, constructing a new method for extraction of dynamic storage capacity, extracting the monthly dynamic information of reservoir capacity in 2000-2016. We analyzed the factors that caused the dynamic change of storage capacity and its impacts on water diversion. The results showed that, in the past 17 years, the largest reservoir capacity of Danjiangkou was 19.216 billion m³ and the minimum was 7.974 billion m³, with an average of 11.204 billion m³. After the first phase of the middle route of south-to-north water transfer, the storage capacity of Danjiangkou Reservoir had been gradually increased. In terms of the monthly averages, the capacity from May to October increased gradually, from October through December showed fluctuate change, and decreased gradually from December to next May. The cyclical artificial storage and climate change were the driving forces for the changes of the storage capacity. The Danjiangkou Reservoir could meet the need for water transfer under the reasonable dispatching of the reservoir water.

Application of extreme value distribution theory in the forecast of chilling return periods of Guangdong Province, China.

TANG Li-sheng, WANG Hua, LIU Wei-qin, LIU Ye

2018, 29(8):  2667-2674.  doi:10.13287/j.1001-9332.201808.019

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Chilling is the third weather disaster following flood and typhoon in Guangdong Province. Prediction of chilling return period is of practical significance for scientific reduction and protection of disaster. Four models, including Gumbel distribution, Weibull distribution, log-normal distribution and Peasron-III distribution, were applied, based on the chilling index, to fit the probability distribution of chilling extreme calculated by chilling accumulation for 86 weather stations of Guangdong Province from 1961 to 2015 (December to the following February). The optimal models were selected to calculate the chilling extreme value of return periods. Results showed that Pearson-III distribution was the optimal model for 77 out of the 86 weather stations. The log-normal distribution was optimal for eight weather stations and Gumbel distribution was optimal for only one station. Weibull distribution was not suitable for modeling extreme value of Guangdong Province. Different return periods of 10-, 25-, 50- and 100-year were predicted by optimal distribution models respectively, with a relative error less than 6%. Chilling extreme for years presented obviously latitude distribution feature, with more in north side and less in south side, which matched the distributions of the lowest temperature, average temperature and temperature dipping scale during chilling period. Our results are useful for guiding the chilling defense for relevant industries in Guangdong Province.

Construction of ecological corridors in Changli County based on ecological sensitivity and ecosystem service values.

TANG Feng, ZHANG Peng-tao, ZHANG Gui-jun, ZHAO Li, ZHENG Yu, WEI Ming-huan, JIAN Qing

2018, 29(8):  2675-2684.  doi:10.13287/j.1001-9332.201808.017

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Ecological corridors provide essential routes for biological migration, which would promote species exchange among different habitats. The construction of corridors is beneficial to alle-viate the damages caused by the fragmentation of landscapes due to the acceleration of urbanization, with significance to biodiversity conservation. In this study, we located the ecological sources with the results of ecological sensitivity evaluation and ecosystem service value analysis in Changli County based on its land use status in 2015. Then, we produced the potential corridors with the minimal cumulative resistance model (MCR) and the minimum cost path method, and identified the key corridors with the gravity model. We put forward the ecological corridor system including four important corridors and two general corridors to underpin the scientific knowledge for the ecological corridor construction project and biodiversity conservation. The results showed that the ecological sensitivity of this area was relatively moderate and ecosystem services value was relatively low. Both the ecological sensitivity and ecosystem services were lower in the middle area but higher in around areas. The ecological sources were mainly distributed in the northern Jieshi Mountain Scenic Area, the eastern coastal state-owned forest farm and the western water source conservation area, which were highly coincident with the nature reserves determined by Ecological Environment Construction and Protection Planning (2011-2030) in the study area. The total length of the corridors was 112.66 km, within which the length of important ones was 47.61 km and that of general ones was 65.05 km. The best width of the corridors was around 30 to 60 m. The ecological corridors and ecological sources constituted an annular closed area, which would effectively promote species migration and the exchange of material and energy.

Assessment of aquatic ecological security for mountainous rivers: A case study in the Taizi River Basin, Northeast China.

LI Meng-di, FAN Jun-tao, KONG Wei-jing, ZHANG Yuan, CHI Ming-hui

2018, 29(8):  2685-2694.  doi:10.13287/j.1001-9332.201808.033

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Watershed ecological security is strongly associated with the aquatic ecological status of the upper mountainous area. The present study aimed to assess the watershed ecological security status of the mountainous area under the PSFR (Pressure-State-Function-Response) assessment framework. An evaluation index system was established according to the watershed characteristics, which included four project hierarchical layers, i.e., aquatic ecological pressure, aquatic ecological state, ecological function, and social response, 11 component layers and 23 evaluation indexes. This index system was applied to evaluate the watershed ecological security status of the mountainous area (35 sub-watersheds) in the Taizi River Basin, Liaoning Province. Our results showed that the aquatic ecological status of the study area could be classified into three groups: insecure, general secure and secure, no very insecure and very secure status. Nine sub-watersheds were at the insecure ecological status, accounting for 25.7% of the total sub-watersheds, whereas 22 sub-watersheds were at the general secure state, representing 62.9% of the study area. In contrast, only four sub-watersheds were grouped at the secure status. Furthermore, agricultural activity was identified as the most significant factor responsible for the aquatic ecological security of mountainous area in the Taizi River Basin. Habitat degradation, including water quality deterioration and habitat loss, significantly reduced the ecological functions of the Taizi River Basin, and decreases in rare and peculiar species and biodiversity also posed a threat to the ecological integrity of the study region. Our results could be applied to diagnose the major factors affecting aquatic ecological security, and provide information for effective ecological restoration.

oil microbial biomass and enzyme activities among different artificial forests in Ziwuling, Northwest China.

BAI Xue-juan, ZENG Quan-chao, AN Shao-shan, ZHANG Hai-xin, WANG Bao-rong

2018, 29(8):  2695-2704.  doi:10.13287/j.1001-9332.201808.001

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Decades of ecological restoration on the Loess Plateau has achieved significant on-site benefits to reduce soil erosion and improve soil quality, with remarkable off-site effects of reducing sediment delivery to Yellow River. However, regional forest community succession is still far from being adequately developed. The Ziwuling forest region and its highly developed forest community, as an advanced eco-zone, can lend practical experience to other regions on the Loess Plateau and help to identify the most suitable tree species for a better regional restoration in the future. With the aim to systematically understand the potential effects of typical local tree species to soil properties, three typical and well-established artificial forests in the Ziwuling region, Robinia pseudoacacia, Pinus tabuliformis and Platycladus orientalis were investigated in this study, with the climax community Quercus wutaishanica as a reference. All the four forest type had comparable stand age (25 years). Soil samples from 0-20 cm layers were collected from those four plantations. The soil microbial biomass (carbon and nitrogen), soil enzyme (invertase, urease and alkaline phosphatase) activities and their correlations were measured and analyzed. The results showed that: 1) soil invertase activity ranged from 16.94 to 64.49 mg·g^-1·24 h^-1, the soil urease activity from 0.15 to 0.26 mg·g^-1·24 h^-1, and the alkaline phosphatase activity from 0.65 to 1.23 mg·g^-1·24 h^-1. The activities of those three enzymes were significantly higher in the P. orientalis soil that in the R. pseudoacacia and P. tabuliformis soils. The geometric average values in the P. orientalis soil were even greater than that in the Q. wutaishanica soil. 2) The soil microbial biomass carbon and nitrogen varied from 247.37 to 529.84 mg·kg^-1 and 41.48 to 77.91 mg·kg^-1, respectively. Both of them were significantly greater in the P. orientalis soil than that in the R. pseudoacacia and P. tabu-liformis soils. Even though the soil microbial biomass carbon in the P. orientalis soil remained lower than that in the Q. wutaishanica soil, its soil microbial biomass nitrogen was greater than in the Q. wutaishanica soil. 3) The dissolved organic carbon and nitrogen in the P. tabuliformis soil were much greater than that in other species, even greater than their own soil microbial biomass carbon and nitrogen. Such a result indicated that dissolved organic matter might play a more important role in providing plant available nutrients than microbial biomass in the P. tabuliformis soil. 4) The microbial biomass carbon and nitrogen were significantly positively correlated with the total organic carbon and the total nitrogen, particularly for the R. pseudoacacia and P. tabuliformis soils. There were significantly positive relationships between the soil invertase activity, urease activity and alkaline phosphatase activity, and their soil organic carbon, total nitrogen and total phosphorus contents. 5) Based on the results of principal component analysis, we concluded that the artificial forests types had obvious effects on soil microbial carbon and nitrogen, soil organic carbon, total nitrogen, the ratio of carbon to phosphorus, the ratio of nitrogen to phosphorus and urease activity. Overall, our findings suggested that P. orientalis is better than R. pseudoacacia and P. tabuliformis in term of improving soil properties in the south forest zone on the Chinese Loess Plateau.

Influence of long-term enclosure and free grazing on soil microbial community structure and carbon metabolic diversity of alpine meadow.

XUE Ya-fang, ZONG Ning, HE Nian-peng, TIAN Jing, ZHANG Yong-qing

2018, 29(8):  2705-2712.  doi:10.13287/j.1001-9332.201808.004

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Soil microbial community structure and functional diversity have great implications for the maintenance of the function and stability of grassland ecosystem. We studied the variation of soil microbial community structure, community diversity of carbon metabolism and their driving factors between the long-term enclosure and the free grazing grasslands in Qinghai-Tibet Plateau by using phospholipid fatty acid and Biolog techniques. The results showed that: 1) there were significant differences in soil microbial community structure and the utilization of carbon source between the long-term enclosed and free grazed grasslands. 2) Long-term enclosure significantly increased the content of total PLFA, bacteria, fungi and actinomycetes. 3) Soil carbon metabolic activity, diversity and richness in free-grazing grassland was significantly higher than the enclosed grassland, but evenness showed an opposite pattern. 4) Compared with the free grazed grassland, long-term enclosure significantly increased the utilization of polymers, carbohydrates, carboxylic acids, and amines by soil microorganisms. 5) Results from the redundancy analysis showed that vegetation coverage significantly affected soil microbial community structure and carbon metabolism. The soil microbial content, carbon metabolism diversity and richness in the long-term enclosed grassland were higher than those of the free grazing grassland, indicating that long-term enclosure was more conducive to improve the diversity and carbon metabolism of soil microbial community.

Effects of different low limits of irrigation on nutrients, enzyme activity and glomalin-rela-ted soil protein in soil aggregates of drip irrigation under plastic film.

MA Jian-hui, YE Xu-hong, HAN Chang-dong, WANG Dan-lei, ZHANG Yu-ling, YU Na, ZOU Hong-tao, ZHANG Yu-long

2018, 29(8):  2713-2720.  doi:10.13287/j.1001-9332.201808.039

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Irrigation is the main source of soil water in greenhouse. There is a lack of understanding on the effects of drip irrigation under the plastic film on the distribution characteristics of soil nutrients, enzyme activity and glomalin-related soil protein (GRSP) in soil aggregates. The effects of different irrigation low limits (20 kPa, D₂₀; 30 kPa, D₃₀; 40 kPa, D₄₀) on soil organic carbon (SOC), total nitrogen (TN), total phosphorus (TP), urease activity, invertase activity and GRSP in soil aggregates were investigated under the greenhouse with the continuously six years’ irrigation. The results showed that compared with D₂₀ and D₄₀ treatments, D₃₀ treatment significantly decreased the proportion of micro-aggregate (<0.25 mm), increased the proportion of macro-aggregate (>0.25 mm), and improved the mean mass diameter (MWD) by 26.4% and 13.4%, respectively. The concentrations of SOC, TN, TP and GRSP were relatively higher in 2-1 mm, 1-0.25 mm, and <0.053 mm aggregates. About 46.5% of SOC, 53.3% of TN and 37.7% of TP were distributed in the 1-0.25 mm aggregates. The urease and invertase activities were increased with the decreases in the size of aggregates, which were significantly increased in D₃₀ and D₄₀ treatments. The 1-0.25 mm aggregates had highest contributions to enzyme activities, with 38.7% of urease and 41.2% of invertase in bulk soil. Results from the correlation analysis showed that MWD was highly positively correlated with GRSP, SOC and urease activity, and the concentration of GRSP was highly positively correlated with SOC and urease activity. Therefore, the irrigation low limits of 30 kPa promoted soil aggregate stability and protection of soil aggregates to nutrients, enzyme activities and GRSP in greenhouse.

Responses of fungal community structure and functional group to fertilization in yellow clayey soil.

NIE San-an, WANG Yi, LEI Xiu-mei, ZHAO Li-xia, LIN Rui-yu, WANG Fei, XING Shi-he

2018, 29(8):  2721-2729.  doi:10.13287/j.1001-9332.201808.003

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We investigated the responses and underlying mechanisms of community composition, and function group of fungi in yellow clayey paddy soil to different long-term fertilization, which may provide scientific basis for rational fertilization and sustainable development in agriculture ecosystems. There were four treatments, including control (CK), inorganic fertilizer (NPK), inorganic fertilizer combined with manure (NPKM), and inorganic fertilizer combined with straw (NPKS). Illumina high-throughput sequencing and FUNGuild were performed to investigate the fungal community structure and functional group, respectively. Ascomycota, Basidiomycota, and Zygomycota were identified as the three dominant ones. The proportion of Ascomycota in NPKM and NPKS were significantly lower (49% and 47%, respectively) compared with CK (71%) and NPK (74%) treatments, with the main reduced orders of Hypocreales, Pleosporales and Eurotiales. While there was higher relative abundance of Basidiomycota in NPKM and NPKS (18% and 28%) compared to CK (14%) and NPK (10%), the orders with enhancement were Tremellales, Trechisporales, and Agaricales. The ratio of Basidiomycota was decreased with sole inorganic fertilizer. Moreover, the relative abundance of Zygomycota was increased after 33 years of fertilization, which was dominated by Mortierellales and Basidiobolales at order level. Diversity indices including Shannon, Simpson, Chao1 and ACE were all significantly declined in NPK compared with CK, NPKM and NPKS treatments, whereas Chao1 index and ACE index in NPKM and NPKS were higher than that in CK and NPK. Saprotroph was the main fungal functional group across all the four treatments (48%-57%). Higher proportion of symbiotroph fungi was identified in soils with NPKS and NPKM (17%) in comparison to CK and NPK. The main guilds with the increasing proportion were arbuscular mycorrhizal fungi and ectomycorrhizal fungi. However, significantly higher proportion of animal pathogen fungi were detected in NPK (10%) than other treatments. Redundancy analysis (RDA) showed that moisture, salinity and porosity in soil were more strongly related with fungal community composition and fungal functional composition than soil organic matter and total nitrogen. Our results suggest that sole application of inorganic fertilizer results in great changes in fungal community compositions and the hazard of over production of pathogen fungi, whereas combined organic-inorganic fertilization would be beneficial to maintain the healthy environment through increasing fungal diversity and the ratio of symbiotrophic fungi in yellow clayey paddy soil.

Sources and pollution characteristics of antibiotic resistance genes and conditional pathogenic bacteria in concentrated swine feeding operation.

LIU Chang-li, ZHENG Guo-di, WANG Lei, CHEN Tong-bin, SHAO Zhu-ze, CHEN Lin

2018, 29(8):  2730-2738.  doi:10.13287/j.1001-9332.201808.037

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Air in concentrated animal feeding operations contains antibiotic resistance genes and airborne pathogens, with potential threat to human and animal health. In this study, air was sampled in the living area, outside, and inside of a fattening pig house in a pig farm for 24 and 48 hours. Feedstuffs, drinking water additives, and feces in the pig house were collected. Three kinds of antibiotic resistance genes (macrolide, β-lactam, and tetracycline) and seven pathogenic microorganisms (Campylobacter, Clostridium perfringens, Enterococcus, Escherichia coli, Yersinia enterocolitica, Staphylococcus spp., and Streptococcus suis) were detected by polymerase chain reaction (PCR). Six genes with high detection rates were selected, with their concentrations being determined by real-time quantitative PCR (qPCR). Results showed that three macrolide and two tetracycline resistance genes were detected in all air samples. Enterococcus, Escherichia coli, Yersinia enterocolitica, and Staphylococcus spp. were detected in air samples and drinking water additive. The concentrations of most target genes were above 10⁴ copies·m^-3. The gene concentrations near the pig house were much higher than those in the living area. Main sources of antibiotic resistance genes and pathogens in the air were pig manure and drinking water additive. Sampling time of 24 h in the pig farm met the requirements for PCR detection. Sampling time of 48 h had a higher sampling efficiency than that of 24 h in the living area of the pig farm, whereas sampling time of 24 h was more appropriate than that of 48 h in high bioaerosol concentration area such as the pig house.

Effects of sewage irrigation on growth of rice seedlings and soil environment with straw incorporation.

LIU Ya-wen, XUE Li-hong, YANG Lin-zhang, WANG Yue-man

2018, 29(8):  2739-2745.  doi:10.13287/j.1001-9332.201808.034

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The effects of sewage irrigation on the growth of rice seedlings and soil environment under wheat straw returning were examined with a pot experiment. Root morphology, root activity, tiller number, plant height, dry matter accumulation of rice seedling, soil ferrous ions content, organic acid content and enzyme activity were measured. The results showed that sewage irrigation significantly increased the number of tillers and root activity at 41 days after transplanting under no N fertilizer application. Under the same N input level, sewage irrigation combined with N fertilizer promoted the growth of rice seedlings and root, and increased the root length, root surface area, root volume, root activity, tiller number and dry matter accumulation. Sewage irrigation significantly reduced the contents of soil ferrous ions and organic acid, while significantly increased the activities of soil urease and catalase. These results indicated that the combination of sewage irrigation and N fertilizer could effectively reduce the negative effect of straw returning on rice seedling and thus enhance soil fertility and quality.

Concentrations and pollution assessment of mercury in farmland soil of Xinqiao Mining Area of Tongling, Anhui, China.

KUANG Ying, FANG Feng-man, LI Yang-bing, LIN Yue-sheng, YAO You-ru, WU Ming-hong, WU Hui-jun, WANG Yue

2018, 29(8):  2746-2752.  doi:10.13287/j.1001-9332.201808.038

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To investigate the effects of mining activities on mercury (Hg) enrichment in farmland soil, soil samples were collected from four villages (Xinjian Village, Yehu Village, Xinhu Village and Hucheng Village) in the vicinity of Xinqiao Mining Area, Tongling. Hg concentration was measured by atomic fluorescence spectrophotometer. The geo-accumulation index was used to evaluate the Hg pollution level of the soils. The results showed that average concentration of total Hg in farmland soil was (0.137±0.078) mg·kg^-1, which exceeded the background value of soil Hg in Tongling area. The average concentration of Hg in four villages followed the order of Xinjian Village (0.221 mg·kg^-1)>Xinhu Village (0.118 mg·kg^-1)>Yehu Village(0.115 mg·kg^-1)>Hucheng Village (0.096 mg·kg^-1). Moreover, the average Hg concentration of different forms in Xinjian Village followed the order of residue (0.036 mg·kg^-1) > alkali soluble (0.031 mg·kg^-1) > hydrogen peroxide soluble (0.022 mg·kg^-1)> acid soluble (0.020 mg·kg^-1)> water soluble (0.012 mg·kg^-1). The distance from the mining area was the main factor affecting the distribution of soil Hg concentration in farmlands. The contaminated Xinqiao River, to some degree, had exa-cerbated soil Hg pollution. Soil organic matter affected the accumulation and transformation of total Hg and hydrogen peroxide Hg in the farmlands. The order of the geo-accumulation index followed as Xinjian Village(1.559) >Xinhu Village(0.654) >Yehu Village(0.616) >Hucheng Village(0.356). The pollution level of farmland soil in Xinjian Village belonged to middle level of Hg pollution,which deserved more attention.

Effects of carbon supplementary modes on phosphorus bioaccumulation/phosphorus harvesting process in a tidal flow constructed wetland.

QIAO Zi-han, QI Ran, WANG Zhen, DING Ya-nan, YAO Jie, ZHANG Yun

2018, 29(8):  2753-2762.  doi:10.13287/j.1001-9332.201808.032

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We explored the effects of carbon supplementary modes on operational performance in a tidal flow constructed wetland (TFCW) utilizing phosphorus bioaccumulation/phosphorus harvesting (PB-PH) process. Three different carbon supplementary modes were adopted during the periodical phosphorus harvesting process. The results showed that the carbon supplementary mode significantly affected the performances of phosphorus bioaccumulation and phosphorus harvesting throughout the experiment. The optimization of carbon supplementary mode would facilitate the maintenance of abundance and activities of polyphosphate-accumulating organisms (PAOs). Subsequently, the amounts of phosphorus release and PHB synthesis in PAOs, as well as the utilization rate of supplementary carbon, could be effectively enhanced during the phosphorus harvesting process. The efficient and stable phosphorus removal effects of the TFCW could be ensured during the phosphorus bioaccumulation process. When the PB-PH cycle length was 30 d and using the continuous circulation carbon supplementary mode, the amount of phosphorus retained in the bed and the mean phosphorus harvesting efficiency of the TFCW were 26994.88 mg and 70.8%, respectively. Regarding a typical PB-PH cycle, the mean phosphorus removal efficiency of the TFCW could achieve (91.4±2.1)% during the phosphorus bioaccumulation process. The amounts of phosphorus release and PHB synthesis in PAOs, and the utilization rate of supplementary carbon in the system could reach up to (1563.72±127.84) mg, (4.52±0.39) mmol C·g^-1 VSS, and (97.3±1.6)%, respectively.

Spatial-temporal variation in population structure of Antarctic krill (Euphausia superba)in the Scotia Sea, Antarctic in 2016.

DING Bo, ZHU Guo-ping, ZHANG Hai-ting

2018, 29(8):  2763-2770.  doi:10.13287/j.1001-9332.201808.040

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The Scotia Sea occupies the highest density of Antarctic krill (Euphausia superba), which is the traditional fishing ground of krill fishery. However, the population structure of krill differed significantly inter-annually, seasonally and regionally. In order to understand the population dynamics of krill in this region, we analyzed the spatial-temporal variation on population structure of krill using samples collected randomly from fishery survey during January to September 2016. The results showed that sex ratio presented remarkably difference among different months. Females dominated in the population from January to May, but the opposite result occurred from June to September. During the survey period (January to September), juveniles only presented in the January popu-lation, and the percentage of adult females was over 40% and similar to that in February. The proportion of sub-adult females were over 50%, but the proportion of female adults were decreased gradually from March to May. The sub-adult males predominated in the population from June to August. The proportion of sub-adult females increased significantly but the number of male adults decreased in September. Sub-adult females occupied half of population in the Bransfield Strait from February to May. The proportion of spent females (25.6%) was higher than those of individuals with other sexual maturity stages and the gravid females occupied higher percentage of population off northeastern waters of the King George Island in January. From June to September, about half of the population was mature males, but the proportion of mature females was very low off northeastern waters of the South Georgia Island. Maturity stage composition indicated that peak spawning occurred in January and February and that spawning grounds occurred off northeastern waters of the King George Island and in the Bransfield Strait.

Construction technology of amphibian habitat and the evaluation of its effectiveness.

XIE Han-bin, ZHANG Wei, LI Ben, LI Bi-cheng, ZHANG Yun-fei, WANG Tian-hou

2018, 29(8):  2771-2777.  doi:10.13287/j.1001-9332.201808.002

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Drastic decline and extinction of amphibian species occurred around the world. Human-induced habitat loss and degradation are major threats to amphibians. Repairing or rebuilding amphibian habitat is an important way for amphibian restoration. During the process of urbanization, the construction of appropriate habitats is the key measure for amphibian conservation. In this study, construction technique and assessment of the reform amphibian habitat was carried out. To match the habitat requirements of five common amphibian species in Shanghai, Luhui seedling base in Pujiang Town (Minhang District, Shanghai, China) was selected as an experimental site from May 2014 to September 2016. We used ecological engineering measures that could provide amphibian habitat, such as changing topographic, adjusting water systems, vegetation restoration, and so on. To explore how these new technologies benefited amphibians’ biodiversity, five sampling lines (100 m × 5 m) were selected and amphibians were monitored during the breeding period (May-June) and non-breeding period (August-September), once in each period in 2014 and 2016. A total of four species were recorded with a density of (164.0±63.7) ind·hm^-2 in the breeding period in 2014, and four species with a density of (160.0±29.7) ind·hm^-2 in the non-breeding period in 2014, whereas five species with a density of (560.0±159.3) ind·hm^-2 in the breeding period in 2016, and five species with a density of (628.0±186.2) ind·hm^-2 in the non-breeding period in 2016. Our results suggested that this technology could significantly increase amphibians’ biodiversity in the degraded amphibian habitat, which might be applied in other similar habitats in China.

Stock assessment methods on marine crustacean species: A review.

WANG Rui, ZHU Guo-ping

2018, 29(8):  2778-2786.  doi:10.13287/j.1001-9332.201808.035

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Crustaceans, such as crab, lobster, prawn, and Antarctic krill, have formed a vast and commercially valuable fishery globally. Although the importance and scale of these crustacean fishe-ries are increasing, the suitable and effective methods for stock assessment and management of crustacean fisheries are urgent to be improved compared to other fisheries. We reviewed and evaluated four kinds of stock assessment methods for assessing crustacean fishery, including the surplus production model, delay-difference model, the depletion model, and size-structured model. We described the application of those models in stock assessment of crustacean fishery, and briefly summarized the assumptions and data needed in these models. We further compared the advantages and disadvantages of those models. In addition, the assumptions of the models, the estimation method of the parameters, and the general solution of uncertainty were analyzed. Finally, the future direction and prospect of crustacean stock assessment were discussed.

Construction of healthy wetland ecosphere in estuarine delta: Theory and method.

HAN Guang-xuan, NIU Zhen-guo, LUAN Zhao-qing, WANG Guang-mei, ZHANG Li-wen, GUAN Bo

2018, 29(8):  2787-2796.  doi:10.13287/j.1001-9332.201808.036

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The health of wetland ecosphere in an estuarine delta is determined by many factors, such as continuity of natural processes, ecosystem connectivity, habitat heterogeneity, and food web diversity. The contradiction between ecological and environmental protection and regional development in the estuarine delta is becoming more and more prominent. A series of man-made and natural processes directly and indirectly resulted in habitat fragmentation of wetlands, which has direct and strong impacts on the ecosphere health and the habitat function of wetlands. In this paper, we provided a perspective on researches on the basic theory of healthy wetland ecosphere, landscape ecological network system, hydrologic network construction, key food webs, and habitat heterogeneity. At the regional and landscape scales, with the linkages between land use and ecosystem integrity as the main line, we clarified the influences of habitat fragmentation on wetland ecological functions, especially the effects of landscape integrity and river connectivity on wetland habitat. At the community and ecosystem scales, emphasis should be given on the relationship between food web and ecosystem stability, especially the supporting role of food web diversity and habitat heterogeneity on the construction of wetland biosphere. Further efforts should focuse on the wetland habitats construction based on landscape integrity, hydrologic connectivity, habitat heterogeneity and food web diversity. These efforts could help to develop and optimize the theory and method of constructing wetland ecosphere and enhancing its ecological function, and promote the sound development of regional ecological environment and resource utilization in estuarine deltas.