Table of Content

18 September 2017, Volume 28 Issue 9

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Response of decomposition and nutrient release in different diameter fine roots of Pinus tabuliformis plantation to N addition.

GU Li-cha, WANG Guo-liang, JING Hang, YAO Xu

2017, 28(9):  2771-2777.  doi:10.13287/j.1001-9332.201709.018

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We examined the effects of four nitrogen (N) addition treatments, i.e., N₀(0 g N·m^-2 a^-1), N₃(3 g N·m^-2 a^-1), N₆(6 g N·m^-2 a^-1) and N₉(9 g N·m^-2 a^-1) on the decomposition and nutrient release processes of fine roots with different diameters in Pinus tabuliformis plantation using litterbag method. The results showed that the decomposition process of fine roots could be divided into rapid (0-60 d) and slow (60-300 d) decomposition stages. The decomposition mass percentages of fine roots with 0-0.4 mm, 0.4-1 mm and 1-2 mm were7.6%, 10.4% and 11.4% on the 60th day and 19.8%, 23.5% and 30.5% on the 300th day, respectively, indicating that finer root had lower decomposition rates. N addition reduced significantly the decomposition rates of fine roots with 0-0.4 mm diameter, but had no significant influence on those of root with 0.4-1 mm and 1-2 mm diameters. Compared with the control, N₃, N₆ and N₉ treatments reduced the decomposition rates by 2.1%, 4.5% and 5.8%, respectively. N addition increased both the C and N remaining percentages of fine roots with 0-0.4 mm and 0.4-1 mm diameters, but had no significant influence on those with 1-2 mm diameters. Additionally, P remaining percentages of fine roots had no response to the N addition. Compared with the control, N₃, N₆ and N₉ treatments increased the root C remaining percentages by 8.1%, 9.4% and 4.5% in 0-0.4 mm diameter roots, and 2.5%, 2.5% and 0.9% in 0.4-1 mm diameter roots, respectively. Similarly, N₃, N₆ and N₉ treatments also increased the root N remaining percentages by 5.3%, 16.3% and 16.7% in 0-0.4 mm diameter roots and 0.9%, 2.3% and 3.9% in 0.4-1 mm diameter roots, respectively. The transfer models for C, N and P in 0-0.4 mm and 0.4-1 mm diameters were direct releasing, and the transfer models for N showed an enriching-releasing model. N deposition may decrease the fine root decomposition rates mainly by affecting the decomposition process of fine roots with 0-0.4 mm diameters (mainly the first two order roots).

Temporal and spatial dynamics of soil nitrogen, phosphorus, potassium, organic matter and pH in the water level fluctuation zone of canyon landform area of the Three Gorges Reservoir, China.

JIAN Zun-ji, PEI Shun-xiang, GUO Quan-shui, QIN Ai-li, MA Fan-qiang, ZHAO Yu-juan, XIAO Wen-fa, KANG Yi

2017, 28(9):  2778-2786.  doi:10.13287/j.1001-9332.201709.016

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Based on the long-term monitoring data of soil chemical properties before never experiencing water level fluctuation (2008) and after experiencing 1 time (2009), 4 times (2012), 7 times (2015) of water level fluctuation in the water level fluctuation zone with the altitude of 155-172 m, located at the Wushan and Zigui section of the Three Gorges Reservoir (TGR), the temporal and spatial dynamics of soil nitrogen (N), phosphorus (P), potassium (K), organic matter (OM) and pH value were studied and their nutrient status were evaluated. The contents of soil total nitrogen (TN), available nitrogen (AN), available potassium (AK) and OM gradually decreased with the increasing times of experiencing water level fluctuation, while the contents of total phosphorus (TP), total potassium (TK) and available phosphorus (AP), and pH value exhibited the opposite trend. The contents of TN, TK and AP in different soil layers displayed as Wushan > Zigui before never experiencing water level fluctuation and after experiencing 1 time of water level fluctuation. However, after experiencing 4 times and 7 times of water level fluctuation, they changed as Zigui > Wushan. Differences of soil chemical indicators in different soil layers gradually decreased with the increasing times of experiencing water level fluctuation. Compared with the nutrient classification standard of the national second soil census, the contents of TP and AP were extremely high grade in Zigui plot and the content of AP was high grade in Wushan plot after experiencing 7 times of water level fluctuation, and other soil indicators were in the middle or below grade. The hydrolo-gical regime characteristics of the TGR and the interference of human activities, as well as the diffe-rences of soil chemical indicators in nature were the major driving factors that caused the temporal and spatial dynamics of soil N, P, K, OM and pH in the water level fluctuation zone of canyon landform area of the TGR.

C, N and P stoichiometry characteristics of different-aged Robinia pseudoacacia plantations on the Loess Plateau, China

MA Ren-tian, AN Shao-shan, HUANG Yi-mei

2017, 28(9):  2787-2793.  doi:10.13287/j.1001-9332.201709.020

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Three different stand ages of Robinia pseudoacacia plantations, including young plantation (5-10 years old), middle-age plantation (11-15 years old), and mature plantation (21-30 years old), were selected as the objects, to explore the contents of C, N and P and their ecological stoichiometry characteristics in roots, stems, leaves and litter. The results showed that carbon, nitrogen and phosphorus contents varied in the range of 376.74-486.67, 8.66-29.70 and 0.79-1.95 g·kg^-1, respectively in different components of R. pseudoacacia plantations with different ages. There was a low variability of C content, a high variability of P content. The high C content was found in middle-age plantation, and the high N and P contents were found in mature plantation. The high C, N and P contents were found in leaves, and the low N content was found in stems for diffe-rent-aged R. pseudoacacia plantations. C/N, C/P and N/P in different components of R. pseudoacacia plantation were 15.74-53.40, 242.47-606.39 and 8.10-20.57, respectively. C/N, C/P and N/P of stems in mid-mature plantation and young plantation were significantly higher than those in mature plantation. C/N and C/P were high in stems, and C/N and C/P was low in leaves in diffe-rent-aged R. pseudoacacia plantations. There was no correlation among carbon, nitrogen and phosphorus contents in leaves and roots of R. pseudoacacia plantations, but significant positive correlation between the nitrogen content and phosphorus content in litter and stems. It indicated that the litter and stems were built on the proportional input of nitrogen and phosphorus elements. Compared with the global scale, R. pseudoacacia plantation in the Loess Plateau had the high carbon storage capacity, abundant nitrogen content and relative lack of phosphorus, which became the major limi-ting factor for growth of R. pseudoacacia plantation.

Effects of change in precipitation amount on soil respiration and photosynthetic characteristics of Phragmites australis in a coastal wetland in the Yellow River Delta, China.

CHEN Liang, SUN Bao-yu, HAN Guang-xuan, LIU Zi-ting, HE Wen-jun, WANG An-dong, WU Li-xin

2017, 28(9):  2794-2804.  doi:10.13287/j.1001-9332.201709.039

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The coastal wetland has shallow underground water level and is affected by the fresh water and salt water in vertical direction. The changes in precipitation amount can alter the conditions of soil water and salt, thus affecting soil respiration and plant photosynthesis. In order to clarify the effect of the change in precipitation amount on soil respiration and photosynthetic characteristics, we used rainout shelters and rainwater pipes to manipulate precipitation amount in the coastal wetland in the Yellow River Delta. Soil respiration and photosynthetic light response curve of Phragmites australis were measured during the growing season in 2015. Moreover, environmental factors including soil temperature, soil water content and soil salt content were measured simultaneously. The results showed that the whole growing season could be divided into three periods, drought period, wet period and flooding period, according to soil moisture condition. The effect of precipitation change on soil respiration and photosynthetic characteristics of P. australis was controlled by soil moisture condition. During the drought period, increased precipitation increased soil respiration significantly by 31.8% compared to the control. In addition, increased precipitation also increased stomatal conduc-tance (g_s) and photosynthetic capacity of plant leaf compared with those in the control, while decreased precipitation decreased soil respiration significantly by 41.1% compared with that in control. Meanwhile, decreased precipitation decreased the stomata obstruction and photosynthetic capacity of P. australis. During the wet period, soil respiration and the temperature sensitive of soil respiration (Q₁₀) decreased in both increased and decreased precipitation treatments. Increase and decrease in precipitation amount both had no significant effect on the light response curve of P. australis. During the flooding period, increase and decrease in precipitation amount both had no significant effect on soil respiration, however, they aggravated and reduced the flood damage in reed plants, respectively. The net photosynthetic rate of P. australis was from high to low as the decreased precipitation > CK > increased precipitation.

Response of radial growth of Larix potaninii var. macrocarpa to climate change at upper distributional limits on Northwestern Yunnan Plateau, China.

ZHANG Yun, YIN Ding-cai, TIAN Kun, XIAO De-rong, SUN Mei, WANG Hang, ZHANG Wei-guo

2017, 28(9):  2805-2812.  doi:10.13287/j.1001-9332.201709.011

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Based on dendrochronological methods, we established residual chronologies of Larix potaninii var. macrocarpa by using its radial growth records at upper distributional limits of three mountains (Yulong, Haba and Potatso), in order to study the growth response variation to climate change among three sites and to identity the key climatic factors that affected the radial growth of L. potaninii var. macrocarpa in Northwestern Yunnan Plateau, China. The results showed that the temperature during current early growing season (May and June) was the main factor influencing the radial growth of L. potaninii var. macrocarpa, as indicated by a significant positive correlation between them at the three sampling sites. The radial growth of L. potaninii var. macrocarpa at Potatso National Park was also affected by temperature before growing season, presenting a significant negative correlation with temperature in previous July, and a significantly positive correlation with temperature in previous November, respectively. The radial growth responses of L. potaninii var. macrocarpa to precipitation varied among the three sites, showing a pattern from a negative correlation to a positive correlation with the increase of latitude. The radial growth showed a significant negative correlation with precipitation in current early growing season in Yulong Snow Mountain (the most southern part), a significant negative correlation with precipitation in current September in Haba Snow Mountain (the middle of the latitudinal gradient), and a significant positive correlation with precipitation in current March in Potatso National Park (the most northern part), respectively. Additionally, the radial growth of L. potaninii var. macrocarpa in Yulong Snow Mountain was also positively affected by precipitation in current July. According to the prediction of climate models, the changing pattern and the degree of response of radial growth to temperature and precipitation, the future climate change would probably benefit the growth of L. potaninii var. macrocarpa in Northwestern Yunnan Plateau.

Spatial distribution pattern of seedlings and saplings of three forest types by natural regene-ration in Daxin’an Mountains Xinlin Forestry Bureau, China.

JIA Wei-wei, XIE Xi-tao, JIANG Sheng-wei, LI Feng-ri

2017, 28(9):  2813-2822.  doi:10.13287/j.1001-9332.201709.014

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Based on the survey data of 16 sampling plots in three main forest types (including Larix gmelinii forest, Betula platyphylla forest, and mixed coniferous and broad-leaved forest) in Daxing’an Mountains, the seedlings and saplings were divided into 3 grades according to plant height, i.e., Grade I, height ≤ 60 cm; Grade II, 60 cm < height ≤ 200 cm; Grade III, height ≥ 200 cm and diameter at breast height <5 cm. With four different sampling scales, distribution pattern and pattern intensity of seedlings and saplings were determined, and the pattern change and size were analyzed using seven clumping indices. The results showed that the seedlings and saplings of L. gmelinii were dominated by grade II, and the density increased first and then decreased with the increase of grade. However, L. gmelinii in the other two forest types (i.e., B. platyphylla forest and mixed fore-st) and B. platyphylla seedlings and saplings in all three forest types were dominated by grade III, with the smallest number in grade I, and the seedling density increased with the increase of grade level. L. gmelinii seedlings and saplings in the three forest types all had a clumping pattern on four different sampling scales. B. platyphylla seedlings and saplings in B. platyphylla forest also had a clumping pattern on four scales except the random distribution on 10 m × 20 m scale. L. gmelinii seedlings and saplings in mixed forest had the largest clumped intensity on 5 m × 10 m sampling scale, while L. gmelinii in the other two forest types and B. platyphylla seedlings and saplings in the three forest types had the largest clumped intensity with the sampling scale of 5 m×5 m. The clumped intensities of L. gmelinii and B. platyphylla seedlings and saplings in L. gmelinii forest decreased with the increase of grade level, in which the distribution of B. platyphylla changed from clumping to random or uniform pattern. The clumped intensities of L. gmelinii and B. platyphylla seedlings and saplings in B. platyphylla forest and mixed forest increased with the increasing grade, changed from uniform to clumping pattern. The L. gmelinii and B. platyphylla seedlings and saplings with different regeneration grades in all three forest types had the same population pattern size of 25 m². The population pattern intensities of L. gmelinii and B. platyphylla seedlings and saplings were significantly different in different forest types and regeneration grades.

Cooling effects of urban forest community structure.

TANG Ze, REN Zhi-bin, ZHENG Hai-feng, HE Xing-yuan

2017, 28(9):  2823-2830.  doi:10.13287/j.1001-9332.201709.012

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In this study, the influence of community structure on the cooling effect of urban forest was studied in Changchun by field sampling. The results showed that the temperatures of urban fore-sts with different canopy densities showed the same fluctuation trend with time. The temperature in urban forest was lower with higher canopy density. Community structure characteristics of urban fore-st affected the urban thermal environment. Among the structural indices used in this study, canopy density (CD), leaf area index (LAI) and tree height (H) had the most significant relationships with the cooling effect of urban forest, while stem density (SD), diameter at breast height (DBH) and base area (BA) had no significant influence on the thermal environment. CD and H were linearly correlated with the cooling intensity of urban forest, and cooling intensity increased by 0.5 ℃ for each 10% increase of canopy density and 0.05 ℃ for each 10 cm increase of tree height. There was a positive nonlinear correlation between the LAI and the cooling intensity. Further, a reasonable threshold of LAI for the cooling function was found in the range of 0.23-2.3. When the LAI was in the range of threshold value, the cooling intensity increased rapidly with the increase of LAI.

Comparisons of height-diameter models of Chinese fir based on mixed effect in Dabie Mountain area, China.

FAN Wei, XU Chong-hua, CUI Jun, WANG Jing-jing, LIU Xi-jun, XU Xiao-niu

2017, 28(9):  2831-2839.  doi:10.13287/j.1001-9332.201709.036

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A total of 1087 sets of data from 30 plots of Chinese fir (Cunninghamia lanceolata) plantations were collected from Mazongling forestry farm in Dabie Mountains of Anhui Province. Seven commonly used height-diameter (H-D) models (i.e. linear, Chapman-Richards, Logistic models, etc.) were selected and fitted by the least square method to obtain the optimal basic model (equation 11, a Chapman-Richards model with variable D only). Based on this optimal basic mo-del, we built up the H-D model (equation 12) with two stand variables [mean height of dominant trees (DH) and density). Meanwhile, with the consideration of plot random effect, the mixed mo-del, called equation 13 and 14, which based on equation 11 and 12 were constructed, using the power and exponent functions to eliminate heteroscedasticity. Then coefficient of determination (R²), root-mean-square error (RMSE), mean absolute error (MAE) and mean absolute percen-tage error (MAPE) were used to evaluate their abilities of model fitting and prediction for determining the best model. The results showed that the fit accuracy of the model with stand variables(equation 12) (R²=0.863, RMSE=1.381, MAPE=0.971) was better than the basic model (equation 11) (R²=0.827, RMSE=1.554, MAPE=0.101). For error variance, the power function and the exponent function could eliminate the heteroscedasticity, but the former was better than the latter. The mixed models (equation 13, 14) had better fitting and prediction precision than equation 11, 12. There was no significant difference between the two mixed models (equation 13, 14) in fitting and prediction precision. In application, due to a better description of H-D relationship between different stands, the mixed-effect model (equation 13) could be used to predict tree height for Chinese fir plantations with higher precision.

Responses of soil microbial community structure to simulated warming in alpine timberline in western Sichuan, China.

ZHENG Hai-feng, CHEN Ya-mei, YANG Lin, LI Hong-jie, WANG Li-feng, SHEN Xian, LIU Yang

2017, 28(9):  2840-2848.  doi:10.13287/j.1001-9332.201709.032

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Studying the response of soil microbial community structure to simulate warming is of great significance for predicting soil carbon, nitrogen and phosphorus cycles in the context of global climate change. Therefore, the effect of simulated warming on the soil microbial community structure was studied with the open-top chamber (OTC), as determined by phospholipid fatty acids (PLFAs) in the alpine timberline ecosystem in western Sichuan. The results showed that simulated warming enhanced the daily mean air temperature by 0.87 ℃, the daily mean temperature of soil organic layer (OL) and mineral soil layer (ML) increased 0.5 ℃ and 0.23 ℃, respectively. The microbial community composition of soil organic layer was more sensitive to the simulated warming than that of the mineral soil layer. Bacteria (TB) were more sensitive to the simulated warming than fungi (TF). Simulated warming also significantly affected the ratios of fungi to bacteria (F/B) and gram-negative bacteria to Gram-positive bacteria (G^-/G⁺) of the soil organic layer, whereas it had no significant effect on the microbial PLFAs content of mineral soil layer. In all treatments, the content of microbial PLFAs and the ratios of F/B and G^-/G⁺ were in order of non-growing season (NGS) < early growing season (EGS) < late growing season (LGS). The redundancy analysis suggested that the soil carbon contents (DOC 12.1%, DC 9.5% and TC 3%) were the determination factors affecting microbial community structure, and the dissolved nutrient (DOC and DC) had a greater effect on microbial community structure than the total nutrient (TC and TN).

Environmental response of intrinsic water use efficiency of Pinus thunbergii in Dalian City, China.

RUAN Ya-nan, XIAO Ying-nan, YANG Li-xin, ZHOU Yong-bin, CHEN Zhen-ju

2017, 28(9):  2849-2855.  doi:10.13287/j.1001-9332.201709.022

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Based on Pinus thunbergii growing in Dalian City, we developed the time series of tree radial growth, tree-ring stable carbon isotope ratio (δ¹³C) and intrinsic water use efficiency (WUE_i) in the period of 1951-2010, and studied their variation and the climate related significance. Radial growth of the pines showed a decrease trend, tree-ring δ¹³C decreased slightly, but WUE_i increased significantly (P<0.05) after 1980. Climate factors affected tree-ring width, δ¹³C and WUE_i of the pines, and the effects showed seasonal variation. Temperatures respectively showed positive and negative correlations with radial growth of the pines in summer and winter, while monthly precipitation and relative humidity in June had positive correlations with tree-ring width in general. Monthly temperature had weakly positive correlations with δ¹³C and WUE_i in March-September, and slightly negative correlation during the rest months of a year. Precipitation and relative humidity respectively had negative correlations with δ¹³C and WUE_i in general. The rapid warming environment in the city contributed to the WUE_i increase of urban trees.

Influence of topography on leaf area index in a typical mixed broadleaved-Korean pine forest in Xiaoxing’an Mountains, China.

LIU Zhi-li, BI Lian-zhu, SONG Guo-hua, WANG Quan-bo, LIU Qi, JIN Guang-ze

2017, 28(9):  2856-2862.  doi:10.13287/j.1001-9332.201709.024

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Based on a 30 hm² mixed broadleaved-Korean pine (Pinus koraiensis) forest monitoring plot at Fenglin National Nature Reserve in Xiaoxing’an Mountains, China, we estimated leaf area index (LAI) for major tree species and total LAI for all species using empirical models between LAI and basal area. We explored the influence of four kinds of terrain factors (including altitude, slope degree, slope aspect and curvature) and the combination influence on the spatial distribution of LAI. Results showed that the four terrain factors all had a significant effect on spatial distribution of LAI for five major tree species, including P. koraiensis, Abies nephrolepis, Tilia amurensis, Ulmus laciniata and Acer mono. But the slope aspect had a significant effect on the spatial distribution of LAI for Betula costata. The four kinds of terrain factors all significantly affected the spatial distribution of total LAI for all species. The plot could be divided into five habitat types, including the ridge, sunny, valley sunny side, shady and valley shady side. The habitat types had significant effects on the spatial distribution of total LAI, and the LAI in the ridge with a mean value of 8.85 was significantly higher than that in the other habitat types, followed by LAI in sunny with a mean value of 7.62. The LAI in the valley sunny and shady sides did not differ significantly, and the valley shady side had the lowest LAI, with a mean value of 4.42.

Responses of physiological parameters in plants on sub-alpine meadow to slope aspects.

LIU Min-xia, ZHAO Rui-dong, ZHANG Can, LI Rui, SHAO Peng

2017, 28(9):  2863-2869.  doi:10.13287/j.1001-9332.201709.030

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Variations of chlorophyll, free proline, soluble sugar content and stable carbon isotope composition (δ¹³C) of Kobresia humilis, Stelleracha maejasme and Oxytropis ochrocephala were studied on different slope aspects of sub-alpine meadow in Gannan, and the physiological mechanism of plant adaptation to drought stress was discussed as well. The results showed that soil water content (north slope 0.36 g·g^-1, south slope 0.15 g·g^-1) decreased, and soil temperature (north slope 14.76 ℃, south slope 24.85 ℃), light intensity (north slope 540.34 lx, south slope 744.12 lx) increased from north, west north slope, west slope, west south slope and south slope. Plant species composition also changed accordingly. Main species were shrub (Potentilla fruticosa) and forbs on north slope, and grass on south slope. The contents of proline, soluble sugar, chlorophyll and stable carbon isotope of three plant species changed from north to south slope, and the amplitude of variation of physiological parameters also differed among species. The contents of proline, soluble sugar and stable carbon isotope showed a significant negative correlation with soil water content, and correlated significantly positively with soil temperature and light intensity. The chlorophyll content was correlated significantly positively with soil water content, and significantly negatively with soil temperature and light intensity, and soil water content was the key factor influencing plant survival growth at aspect gradient. The results showed that the physiological parameters of plant leaf could be used as an index of plant stress resistance, and the resistance of 3 species was in order of Kobresia humilis > Stellera chamaejasme > Oxytropis ochrocephala.

Mechanism of rainfall infiltration in apple orchards on Loess Tableland, China.

ZHENG Shuang-ke, SI Bing-cheng, ZHANG Zhi-qiang, LI Min, WU Qi-fan

2017, 28(9):  2870-2878.  doi:10.13287/j.1001-9332.201709.031

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Dye tracing experiments were carried out in apple orchards of 20 years old in Changwu tableland using Brilliant Blue FCF solution of 4 g·L^-1. Three water application methods (sprinkler, flood, stemflow simulation) were used to simulate regular 50 mm rainfall infiltration, intense 50 mm rainfall infiltration and stem flow infiltration (18 L of stemflow amount), respectively. The results showed that for sprinkler water application, the average dye-stained depth was 0.28 m and shallow. The average and median values of uniform infiltration fractions were larger than 0.65 and 0.7, respectively, indicating that the proportion of the uniform part was larger in the infiltration process, and piston flow was the main mechanism of rainfall infiltration in apple orchards on Loess Tableland. For flood water application, the average and maximum dye-stained depths were 0.53 m and 0.59 m, respectively. The depths were also shallow, indicating that it was difficult to recharge deep soil water for a short time under the conditions of intense rainfall and activation of macropores. For stemflow simulation water application, the maximum dye-stained depth was 0.46 m and also shallow, indicating that it was difficult for rainfall to recharge deep soil along the roots by stem flow.By comparing the dying of live and decayed roots, it was found that live roots (≥2 mm) had minor water conductivity, while the infiltration channels formed by degraded roots (≥2 mm) had better water conductivity. Most of the apple tree roots were horizontally distributed near the soil surface, and the lateral preferential flow was more likely to occur when these surface roots decomposed, thus preventing rainfall from infiltrating into the deep soil. In conclusion, piston flow was the main recharge mechanism of deep soil water recharge in apple orchards on Loess Tableland of China, and the channels such as soil macropores and degraded vertical roots might also be an approach to deep soil water recharge.

Response of pollinator diversity to geomorphic types and seasons in mountainous region of western Henan Province, China.

WANG Mei-na, DING Sheng-yan, LU Xun-ling, CUI Yang

2017, 28(9):  2879-2887.  doi:10.13287/j.1001-9332.201709.040

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A field experiment was set to catch pollinating insects by deploying traps, to investigate the abundance and richness of pollinating insects under different intensities of land use by humans in mountainous areas of western Henan Province both in spring and autumn. Combining with the characteristics of the vegetation community, the diversity of pollinating insects, community similarity and species importance (importance value) were studied in this paper. A total of 23275 pollinating insects were captured in spring and autumn, and the dominant groups were mostly Hyme-noptea and Diptera. The amount of pollinators captured in spring was 1.8 times as much as that in autumn, and the individual abundance of the pollinators between these two seasons were significantly diffe-rent. The relative abundance of Hymenoptea and Diptera captured in spring and autumn was relatively high, with unapparent seasonal variation. The amounts of Lepidoptera and Coleoptera were relatively small, and the amount of Lepidoptera captured in spring was extremely rare, and the same for Coleoptera captured in autumn. Shannon index, Pielou evenness index and Margalef richness index in hilly areas were the highest of all geomorphic types, while the dominance index and species individual amounts in mountainous areas were the highest. Significant differences of the diversity and dominance of pollinating insects existed among different geomorphic types, such as, the diversity of pollinators in hilly areas was significantly different from that in mountainous and plain areas, and the dominance in mountainous areas was significantly different from that in hilly areas. There was a little effect of seasonal variation on the community of pollinating insects, but the species compositions within the community were still different. According to similarity coefficient of Morisita-Horn and Sørensen, only Hymenoptea community had significant difference between mountainous and hilly areas. The species importance was also different in spring and autumn, such as in spring, Vespidae had the highest importance value, and followed by Tachinidae and Drosophilidae; while in autumn, Anthomyiidae had the highest importance value, and followed by Vespidae. Pollinating insects are very important to crops. They can affect crop growth and grain production. In the process of crops planting, it is important to make sure that they suit the local conditions. Combining the rational planning of land use with the vegetation types of different geomorphic types, the species composition should be adjusted properly. The protection of the diversity of pollinating insects is meaningful to maintain the sustainable development of agriculture and improve ecosystem services.

Characteristics of soil organic carbon and related exo-enzyme activities at different altitudes in temperate forests.

GUO Zhi-ming, ZHANG Xin-yu, LI Dan-dan, DONG Wen-ting, LI Mei-ling

2017, 28(9):  2888-2896.  doi:10.13287/j.1001-9332.201709.027

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We measured soil organic carbon contents, hydrolase and oxidoreductase activities relating to carbon cycling at 7 different altitudes of Laotudingzi Mountain in temperate forest ecosystem, and studied the affecting factors of soil organic carbon contents and the related soil extracellular enzyme activities along the altitude. The results showed that soil organic carbon (SOC), particulate organic carbon (POC) and dissolved organic carbon (DOC) contents increased significantly with altitude except between 825-1233 m, and DOC/SOC decreased significantly with altitude. The activities of α-glucosidase, β-glucosidase, β-xylosidase and cellobiohydrolase increased significantly with altitude, and the hydrolase activities were significantly and positively correlated with SOC, POC, DOC, total nitrogen (TN) and soil moisture contents (SMC). Peroxidase (POD) activity was significantly lower at 675 m in Larix gmelinii plantation than at the other altitudes, and was positively correlated with soil nutrient contents (SOC, TN, POC, DOC) and soil moisture. Polyphenol oxidase (PPO) activity was higher in Korean pine plantation at 825 m and in deciduous broad-leaved forest at 947 m than at the other altitudes, and PPO activity was only positively correlated with soil pH, suggesting that soil acidity was a major factor influencing PPO activity. Soil nutrient and water contents were important factors that influenced the distribution of soil hydrolase along altitude in temperate forest ecosystem.

Diversity of arbuscular mycorrhizal fungi in the rhizosphere of tea plant from Anhui tea area, China.

LIU Hui, CHEN Meng, HUANG Yin-di, REN Jia-hong, FAN Dong-fang, ZHAO Juan

2017, 28(9):  2897-2906.  doi:10.13287/j.1001-9332.201709.037

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In order to provide potentially valuable resource for applying mycorrhizal biotechnology in tea industry, the distribution of AMF resources from Anhui tea area was studied. AMF infection rate, the series of infection, the intensity of infection and the type of mycorrhizae of tea plant were measured using an improved acetic acid ink staining method. AMF spores were isolated by wet screening technique and identified based on morphological characteristics. The results indicated that AMF could invade the root of tea plant and form AMF-plant symbioses, AMF infection rate ranged from 36% to 95%, and the series of infection was above 3 and the intensity of infection was strong. A total of 36 species of AMF belonging to 8 genera in the rhizosphere of tea plant were identified from Anhui tea area. Among them, Funneliformis constrictum was the dominant species; Glomus reticulatum, Acaulospora spinosa, Acaulospora foveata, Acaulospora gerdemannii, Acaulospora bireti-culata and Acaulospora excavata were the common species; F. badium, F. verruculosum, Acaulospora morrowae, F. claroideum, Acaulospora rehmii, Acaulospora cavernata, G. halonatum, Acaulospora denticulata, F. geosporum, G. etunicatum, Acaulospora mellea and Entrophospor infrequens were the rare species, and the other species were the uncommon species. The communities of AMF shared relatively low similarity (0.14-0.55) at different sampling sites which belonged to the low and medium level. Correlation analysis showed that spore density had a positive correlation with the infection rate, and species richness had a positive correlation with the infection rate and T-GRSP. There was typical AM structure in root of tea plant in Anhui tea area and the diversity of AMF was rich. All of these could provide rich resources for the development of special AMF fertilizer for tea plant.

Characteristics of heavy metal enrichment efficiency in different organs of urban green tree Cinnamomum camphora.

CHE Ji-lu, YU Shu-quan, LIU Hui, QIU Wen-xin, WEN Ya-ting

2017, 28(9):  2907-2916.  doi:10.13287/j.1001-9332.201709.010

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The objective of this study was to explore the enrichment efficiency of heavy metals in Cinnamomum camphora organs under soil heavy metal concentration and pollution gradients. The compartments of the organs were leaf, branch, trunk, and rhizosphere soils, while the heavy metals under investigation were Cu, Zn, Pb, Cr, Mn and Ni. The results showed that the concentration of heavy metals was significantly different by organs, types of heavy metals, and concentration of rhizosphere soil heavy metals. Heavy metal concentration in leaf and branch followed the order of Mn ＞ Zn ＞ Cu ＞ Cr ＞ Pb ＞ Ni, while in trunks it followed the order of Mn ＞ Zn ＞ Cr ＞ Pb ＞ Ni ＞ Cu. The enrichment coefficient of Mn in leaf had the maximum of 2.409, and that of Ni in trunk was 7.6 and 16 times higher than that in leaf and branch, respectively. In addition, the enrichment coefficients of Cu, Zn, Pb, Cr and Ni in the truck were much higher than the other organs under diffe-rent soil heavy metal concentration gradients. The heavy metal enrichment capacities of Cu, Zn, Pb, Cr, Mn and Ni followed the order of leaf ＞ trunk ＞ branch. As the pollution gradient increased, the heavy metal enrichment coefficient decreased gradually. The heavy metal enrichment efficiency of C. camphora (DBH=22 cm) followed the order of leaf ＞ trunk ＞ branch, and the enrichment of Cu, Zn, Pb, Cr and Ni in trunk was significantly higher than in the other organs. The study showed that the C. camphora had a certain enrichment capacity to absorb heavy metals of Cu, Zn, Pb, Cr, Mn and Ni in soils. The enrichment efficiency of Pb and Ni in trunk was significantly higher than the other organs, which accounted for 82.7% and 91.9% of the total accumulation. Thus, C. camphora has the potential to be an alternative option in phytoremediation of heavy metal contaminated soils.

Effects of parent rock and bamboo age on silicon and phytolith-occluded carbon in the leaves of Moso bamboo.

LIU Jun-xia, HUANG Zhang-ting, JIANG Pei-kun, HUANG Cheng-peng, FENG Sheng-fei, CHEN Chen, YIN Shuai

2017, 28(9):  2917-2922.  doi:10.13287/j.1001-9332.201709.023

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In order to study effect of parent rocks and bamboo ages on the contents of silicon and phytolith occluded organic carbon (PhytOC) in fresh leaves of Moso bamboo plants as well as the interrelations between silicon and phytolith contents, the fresh leaf samples of Moso bamboo plants with different ages (1- and 3-year old) and different parent rocks (grantie, sandshale and tuff) were collected from the main production area in Zhejiang Province. The results showed that parent rock and bamboo age had a significant impact on the contents of Si and phytolith in fresh leaves of Moso bamboo plants. The contents of Si and phytolith in fresh leaves of Moso bamboo plants on the soils derived from the three parent rocks were in the order of grantie (33.19 g·kg^-1) > sandshale (32.64 g·kg^-1) > tuff (24.51 g·kg^-1), and grantie (105.81 g·kg^-1) > sandshale (93.50 g·kg^-1) > tuff (59.40 g·kg^-1). The contents of Si and phytolith in fresh leaves of 3-year old Moso bamboo plants were significantly higher than those of 1-year old plants. The parent rock and bamboo age did not affect the contents of organic carbon in the phytolith, but affected the PhytOC content in the dry matter. There was significant positive correlation between the Si and phytolith in the leaves from 3-year old Moso bamboo plants on the soils derived from the different parent rocks, but not for the leaves from 1-year old bamboo plants. Both parent rock and bamboo age were important factors affecting the contents of Si and phytolith in the Moso bamboo leaves. Therefore, the accurate estimation of the contents of phytolith in the plants distributed in different regions and diffe-rent soil types in China should consider the influence of parent rock and plant age.

Response of seed germination and seedling physiological characteristics of Medicago sativa to the simulated osmotic potential of PEG6000.

CHEN Shi-chao, WANG Meng, WANG Ji, GAO Yong, LIU Zong-qi, WANG Xiang

2017, 28(9):  2923-2931.  doi:10.13287/j.1001-9332.201709.025

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The responses of seed germination and seedling physiological characteristics of alfalfa to different osmotic potentials were studied with the varied concentrations of PEG6000 (0%, 5%, 10%, 15%, 20%, 25% and 30% corresponding to osmotic potential of 0, -0.06, -0.17, -0.32, -0.53, -0.79 and -1.10 MPa, respectively) in this study. Five indexes of seed germination increased firstly and then decreased with a decrease of osmotic potential. Indexes of germination and vigor were the highest when osmotic potential was -0.06 MPa. Rate, potential and index germination reached the maximum when osmotic potential was -0.17 MPa. Seedling POD, SOD, CAT activities and chlorophyll content increased firstly and then decreased with a decrease of osmotic potential, and indexes reached the maximum when osmotic potential was -0.17 MPa. The ratio of chlorophyll a to chlorophyll b decreased firstly and then increased with a decrease of osmotic potential, and it reached the minimum when osmotic potential was -0.06 MPa. Pro, MDA and REC increased with a decrease of osmotic potential. Seed germination and the comprehensive indexes of seedling physiology were optimal for seed germination when osmotic potential was -0.06--0.17 MPa. Seed germination was restrained when the osmotic potential was lower than -0.79 MPa.

Mechanical properties of black soil after straw incorporation: Effect of straw mixing amount.

LIN Lin, ZHANG Cheng-cheng, WANG En-heng

2017, 28(9):  2932-2938.  doi:10.13287/j.1001-9332.201709.019

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Aiming to explore how mixing amount of chopped straw affects mechanical properties of black soil, in our study, two typical black soils with no tillage (high organic matter and low clay content) and with tillage for 40 years (low organic matter and high clay content) were chosen as subject samples. With the length of the chopped straw being 15 mm according to the pretrial results, compression-rebound and shearing behavior of black soil with different proportions of straw returning (0%, 25%, 50%, 75%, 100%) were determined by calculating and analyzing the compression index, rebound index, cohesion and internal friction with the methods of indoor oedometer test and triaxial test. Results showed that the mechanical properties of black soil improved after incorporation with straw, and soil with low organic matter content significantly responded to the change of straw mixing amount. The black soil showed the strongest resistance to compression and the strongest recovery capacity after compaction when the proportion of straw returning was 100%. However, shear strength of the black soil was greatest when the proportion of straw returning was 50%. In conclusion, black soil has a better potential to resist compression and erosion especially when the ratio of straw returning was 50%-100%.

Effects of biochar and nitrogen fertilizer application on nitrogen nutrition in leaves and seed quality of tree peony.

JIANG Tian-hua, WEN Li-zhu, GUO Yun-hui, YU Yuan-yuan, SUN Cui-hui, SUN Xia, ZHENG Cheng-shu

2017, 28(9):  2939-2946.  doi:10.13287/j.1001-9332.201709.026

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The objective of this experiment was to explore the effects of biochar and nitrogen application on nitrogen accumulation and translocation of leaves, seed yield and quality of tree peony. The field experiment was conducted with three biochar levels, 0 (B₀), 1 kg·m^-2(B₁), 2 kg·m^-2(B₂) applied, and three nitrogen application rates, no nitrogen application (N₀), 40 g·m^-2(N₁), 60 g·m^-2(N₂) employed. There are in total 9 treatments, including B₀N₀, B₀N₁, B₀N₂, B₁N₀, B₁N₁, B₁N₂, B₂N₀, B₂N₁ and B₂N₂. The results showed that the biochar and nitrogen fertilizer application increased the contents of protein N and non-protein N in leaves at different stages, as well as the N translocation from leaves to seeds and the N accumulation in seeds. N translocation from leaves to seeds and the N accumulation in seeds under B₁N₁ increased by 27.6% and 27.1%, respectively, compared with B₀N₀. Greater 100-seed mass and seed yield were obtained under B₁N₁ and B₂N₁, respectively, and increased by 13.6% and 16.4% compared with the B₀N₀. No significant difference was found among B₁N₁, B₁N₂, B₂N₁ and B₂N₂ when it came to yield per plant. The higher contents of protein N and total amino acid in seeds were obtained under B₂N₁ and B₁N₂ respectively, increased by 29.3% and 36.2% compared with B₀N₀. The biochar and nitrogen application increased the contents of total fatty acid and unsaturated fatty acid in seeds, and the higher content of total fatty acid was obtained under B₂N₁, increased by 17.4% compared with B₀N₀. The biochar and nitrogen application could increase the N accumulation in leaves and the N translocation from leaves to seeds, the seed yield and the contents of protein N, amino acid and fatty acid. The biochar input of 1 kg·m^-2 and the nitrogen fertilizer input of 40 g·m^-2 could lead to better results.

Changes in antioxidant capacity, main bioactive compounds and volatile constituents of Rhodiola kirilowii after introduction and acclimatization.

LI Meng-fei, YAO Yuan-yuan, YANG Lin-gui, GE Li, WANG Ke-peng, YANG De-long, XING Hua

2017, 28(9):  2947-2954.  doi:10.13287/j.1001-9332.201709.017

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An experiment was conducted on the antioxidant capacity, contents of soluble sugar, flavonoids, phenolics and salidroside, and volatile constituents in rhizome (taproot and lateral root) of cultivated and wild Rhodiola kirilowii selected from Luqu County, Gannan Tibetan Autonomous, Gansu Province, China. The results showed that the inhibition rate (I) and ferric reducing/antioxidant power (FRAP) value, the contents of soluble sugar, total flavonoids, phenolics and salidroside in the rhizome of cultivated R. kirilowii were significantly higher than that of wild plant, respectively. Both of the rhizomes of cultivated and wild R. kirilowii contained 21 volatile constituents, with acetophenone, 2-furaldehyde and hexadecanoic acid occupying high relative contents. The relative changes of 15 volatile constituents in cultivated rhizome were higher compared with that of wild rhizome, such as 3-hydroxydodecanoic acid, 2,4-di-tert-butylphenol and linoleoyl choride in taproot, and 2-acetyl furan, p-hydroxyphenyl ethanol and eugenol in lateral root. I and FRAP value, the contents of total flavonoids, phenolics and salidroside in lateral root of cultivated and wild R. kiri-lowii were significantly higher than that of taproot. There were 12 volatile constituents increased in lateral root compared with taproot, such as 3-hydroxydodecanoic acid, 10,13-octadecadiynoic acid methyl ester, p-hydroxyphenylethanol. After introduction and acclimatization, the antioxidant capa-city, contents of main bioactive compounds and volatile constituents in the rhizome of R. kirilowii were superior to that of wild species, and the quality of lateral root was better than taproot.

Multiple resistance selection with insecticides and change of detoxification enzyme activities in Tetranychus turkestani Ugarov et Nikolski (Acari: Tetranychidae).

WANG Xiao-jun, ZHAO Yi-ying, ZHAO Qian, BAO Jian-hong, ZHANG Yan-na

2017, 28(9):  2955-2960.  doi:10.13287/j.1001-9332.201709.003

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In order to explore the multi-pesticide resistance and biochemical mechanism of Tetranychus turkestani, the related susceptible strains (SS) of T. turkestani were treated by mixture of spirodiclofen, fenpropathrin and abamectin to breed multiple resistance strains (Mp-R) in the laboratory. The results showed that the multiple resistance of T. turkestani had reached 35.74 folds after 15 generations. The analysis on the detoxification enzyme activity of different strains showed, compared with the susceptible strains, the carboxyl esterase (CarE), glutathione-s-transferase (GSTs) and the mixed function oxidase (MFO) of the multiple resistance strains had reached 1.21, 1.53 and 9.18 folds, respectively, suggesting the increased activities of CarE, GSTs and MFO could induce the formation of multiple resistance to three insecticides among which MFO might be the main one. By comparing the pesticide sensitivity and detoxification enzyme activity of Mp-R and Ip-R, it was showed that continuous mixing use of the three pesticides might slow the resistance of T. turkestani to fenpropathrin, but accelerate its resistance to abamectin.

Effects of Trichoderma hazianum and T. viride on seed germination and seedling growth of Chinese fir.

LI Yan-juan, LIU Bo, ZHUANG Zheng, SHANG Tian-she, LIU Qing-qing, ZHU Chen-xi, WANG Zheng-ning

2017, 28(9):  2961-2966.  doi:10.13287/j.1001-9332.201709.028

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Various concentrations of Trichoderma hazianum and T. viride treatments (0.003, 0.03, 0.3, 3, 30, 300 mg·L^-1) were designed to investigate their effects on seed germination and seedling growth of Chinese fir. The results showed that seed germination and seedling growth were signifi-cantly affected by all concentrations of both Trichoderma, and they presented to increase and then fall with the increasing treatment concentrations. The seed germination rate, germination energy, germination index, vigor index, seedling root length, shoot height and fresh mass reached their maxima at the 0.03 mg·L^-1 treatment. Compared with the control, the increments were 57.6%, 125.0%, 51.0%, 209.2%, 114.3%, 16.1% and 24.6% for T. hazianum, and 42.7%, 76.7%, 43.9%, 185.4%, 113.8%, 8.6% and 22.6% for T. viride, respectively. SOD and POD activities of Chinese fir seedlings reached their maxima, while MDA content reached the minimum at 0.3 mg·L^-1 treatment. Compared with the control, SOD and POD increased by 157.6% and 179.9%, while MAD decreased by 86.1% for T. hazianum, and SOD and POD increased by 127.5% and 116.2%, while MAD decreased by 72.4% for T. viride. This study indicated that 0.03-0.3 mg·L^-1 T. harzianum and T. viride could not only promote seed germination and seedling growth, but also improve the activities of antioxidant enzymes and the resistance of Chinese fir seedlings.

Effects of Odontothrips loti (Thysanoptera: Thripidae)damage on clone root, stem, leaf and assimilation product distribution of alfalfa.

HU Gui-xin, PENG Ran, JING Kang-kang, FANG Qiang-en, ZHANG Xiao-yan

2017, 28(9):  2967-2974.  doi:10.13287/j.1001-9332.201709.008

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In order to find the correlation between assimilation product distribution in alfalfa organs and its tolerance to Odontothrips loti, the resistance, growth characters and soluble sugar in roots, stems and leaves were evaluated under different O. loti densities, using resistant clone (R-1) and susceptible clone (I-1) as indicating materials. The results showed that the damage index of R-1 and I-1 increased with increasing thrips density, and the damage index of R-1 was significantly (P<0.05) lower than that of I-1 under the same thrips density. For both R-1 and I-1, the plant height, leaf area, stem diameter and internode length decreased after O. loti damaged, meanwhile the internode number, the diameter of collar root and main root and lateral root number increased. Under the low pest density, the aboveground biomass of R-1 and I-1 clones increased with the increasing pest density, but the root to shoot ratio decreased. Under the high pest density, the aboveground biomass decreased with the increasing pest density, but the root to shoot ratio increased. The curve inflection points between the root to shoot ratio and pest density, and between the stem biomass and pest density were 5 thrips adult per branch for R-1 clone, and 3 thrips adult per branch for I-1 clone. For R-1, under the low pest density, the soluble sugar content in stems and leaves increased with the increasing pest density. Under high pest density, the soluble sugar content in stems and leaves decreased with the increasing pest density. The soluble sugar content in roots of R-1, and in stems, leaves and roots of I-1 decreased with the increasing pest density. In conclusion, the agronomic traits, resistance and utilization of assimilation distribution of R-1 alfalfa were higher than those of I-1 alfalfa.

Resistance of bean leaves induced by exogenous jasmonic acid and its effects on activities of protective and detoxification enzymes in Frankliniella occidentalis.

LI Shun-xin, ZHI Jun-rui, YANG Guang-ming, YUE Wen-bo, YE Mao

2017, 28(9):  2975-2983.  doi:10.13287/j.1001-9332.201709.038

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To make clear whether the exogenous jasmonic acid (JA) could induce resistance of bean (Phaseolus vulgaris) plant and its effect on the enzyme activities in 2nd instar nymph of wes-tern flower thrips (Frankliniella occidentalis), the contents of nutrients and secondary metabolites were measured at 1, 5 and 10 days after spray of JA solution at the concentration of 1, 0.1, 0.01 or 0.001 mmol·L^-1 on bean leaves with healthy plants as control. Changes in enzyme activities were analyzed from 2nd instar nymphs of F. occidentalis that were inoculated on bean leaves treated as mentioned above. The results showed that there were not significant differences in protein contents of leaves at 1 day after treatment by different concentrations of JA with that of healthy bean plants, but the protein contents at 5 and 10 days after treatment were significantly lower than that of the control. The content of free amino acids in leaves at 1 day post treatment was significantly higher than that of the control and gradually decreased. After treatment of JA, the soluble sugar content was significantly lower than that of the control and decreased with the elevation of JA concentration and the prolongation of treatment time. The chlorophyll content in leaves at 1 day post JA treatment significantly decreased, but gradually rose with the increase of treatment time. The contents of tannins, flavones and phenols in leaves under different treatment time with various concentrations of JA were significantly higher than that of the control. The changes of biochemical substances of leaves damaged by thrips were similar to that of JA induction. After F. occidentalis feeding on the JA-treated bean lea-ves for 24 h, the activities of protective enzymes [i.e., superoxide dismutase (SOD), catalase (CAT) and peroxidase (POD)] and detoxification enzymes [i.e., glutathione S-transferase (GST), carboxylesterase (CarE) and acetylcholine esterase (AchE)] in this insect were significantly higher than those feeding on healthy plants, but these enzymes’ activities changed to diffe-rent extent under different treatment time with various concentrations of JA. The changes of activities of enzymes in F. occidentalis feeding on leaves damaged by thrips were similar to that of feeding on the JA-treated leaves. These findings indicated that exogenous jasmonic acid could induce the resis-tance of bean plant, and F. occidentalis that had fed on bean leaves treated by JA generated anti-defended strategy to adapt to the change of host plants.

Effects of endophytic bacteria 252 and 254 on peroxidase (POD)and catalase (CAT)activities of wheat seedlings under salt stress.

ZHAO Long-fei, XU Ya-jun, LAI Xin-he, CHANG Jia-li, OU Qi-fan, MENG Jia-qi, PENG Ding-hua

2017, 28(9):  2984-2992.  doi:10.13287/j.1001-9332.201709.034

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Taking wheat variety Zhou18 as test material, salt stress, salt stress plus inoculation of endophytic bacteria, and no treatment (control) were set, and the effects of inoculation of endophytic bacteria on the growth of wheat seedlings under salt stress were investigated through pot experiment. The results showed that endophytic bacterial strains 252 and 254 shared the highest similarity with Bacillus vallismortis and Agrobacterium tumefaciens, respectively. On the 14th day, treatment of endophytic bacterium 252 plus salt stress increased POD activity in wheat seedlings with increasing the salt concentration, and showed the highest POD activity (13370 U·g·min^-1) at salt concentration of 100 mmol·L^-1. On the 21th day, POD and CAT activities in the treated wheat seedlings were significantly higher than those of controlled group, and reached the maximum on the 28th day under salt concentrations of 150 mmol·L^-1 and 250 mmol·L^-1, respectively. By contrast, wheat seedlings inoculated with strain 254 showed the highest CAT activity under salt concentration 250 mmol·L^-1 on the 14th day. Seedlings treated with strain 254 had significantly higher POD and CAT activities at salt concentration 100-250 mmol·L^-1 on the 21th day, and CAT activity was the highest at salt concentration of 150 mmol·L^-1. On the other hand, CAT activity peaked at salt concentration of 200 mmol·L^-1 on the 28th day. Therefore, the repairing effects of inoculated endophytic bacteria on wheat seedlings varied along with its culture stage and salt concentration. Endophytic bacterial strains 252 and 254 could enhance POD and CAT activities in wheat seedlings under salt stress, and exert significant repairing effects on the growth of wheat seedlings.

Effect of corn-soybean intercropping and nitrogen application on characteristics of soil meso- and micro-invertebrate community in red soil.

YANG Wen-ting, WANG Xiao-wei, XU Jian-cheng, MIAO Jian-qun, WANG Shu-bin, YANG Bin-juan, HUANG Guo-qin

2017, 28(9):  2993-3002.  doi:10.13287/j.1001-9332.201709.004

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A two-year (2013-2014) field experiment was conducted to explore the effect of cropping systems (corn monoculture, soybean monoculture and corn-soybean intercropping) and nitrogen application rate (0, 150 kg·hm^-2) on soil meso- and micro-invertebrate community composition and structure by using Tullgren in red soil. The results showed that a total of 7860 individuals were found during the two years, which belonged to 29 orders, 10 classes and 3 phyla. The dominant groups were Acarina and Collembola. Intercropping and nitrogen application both increased the average density of soil fauna at jointing stage of corn in 2013. The number of groups of soil fauna was obvious higher in 2014 than that in 2013. Meanwhile, nitrogen application could increase the average density of soil fauna in 2014. From the results of two-year multi-variance analyses on soil fauna, cropping pattern and corn growth stage had no significant impact on soil meso- and micro-invertebrate community. But in 2014, nitrogen application significantly affected the soil fauna group, indexes of Simpson and density-group (DG); the interaction between cropping pattern and corn growth stage obviously affected soil fauna average density, group number, DG and abundance; the interaction between nitrogen application rate and corn growth stage obviously affected indexes of Simpson, DG and Shannon. From the results of detrended correspondence analysis (DCA), cropping pattern and nitrogen application rate had no obvious impact on soil meso- and micro-invertebrate community in red soil. The dynamic of community structure was related with corn growth stages. In conclusion, corn-soybean intercropping with reasonable nitrogen application could improve soil meso- and micro-invertebrate average density and group, and sustain a good diversity of soil fauna in red soil.

Influence of Fe₃O₄ nanoparticles on lettuce (Lactuca sativa L.)growth and soil bacterial community structure.

XU Jiang-bing, WANG Yan-ling, LUO Xiao-san, FENG You-zhi

2017, 28(9):  3003-3010.  doi:10.13287/j.1001-9332.201709.033

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With extensive application of Fe₃O₄ nanoparticles in a variety of fields, the possibility of their exposure to agricultural environment is growing. This raises the concerns on their effects on environment. In this investigation, we carried out a pot experiment to investigate the impacts of diffe-rent concentrations of Fe₃O₄ nanoparticles (1, 10, 100 mg·kg^-1), as well as their counterparts, bulk Fe₃O₄ particles, on the lettuce growth and the soil bacterial community. We not only measured the net photosynthetic rate of plant leaves, the Fe content in plant, but also determined the soil bacterial community structure and components using the high throughput technique. Results showed that responses of the plant and bacterial community varied with the increase of Fe₃O₄ nanoparticles concentration. At the low concentration, Fe₃O₄ nanoparticles stimulated plant growth, accompanied by the increased abundance of Xanthomonadales and the decreased abundance of Cyanobacteria and Sphingobacteria, but no significant changes were observed for the bacterial alpha diversity indices. At the high concentration, Fe₃O₄ nanoparticles could not only suppress plant growth, increase Fe content in plant tissue and soil electronic conductivity, but also decrease the phylogenetic diversity of bacterial community, reduce the abundances of Xanthomonadales and Sphingobacteria, and increase the proportion of Cyanobacteria. Moreover, the responses of some functional guilds in soil bacterial community varied between the Fe₃O₄ nanoparticle treatment and the bulk counterpart. This indicated that the size and the concentration of Fe₃O₄ were the factors influencing soil bacterial community, which would potentially impact the plant development. Therefore, more attention should be focused on soil microbes when evaluating the biological effects of nanoparticles.

Slow-release system of dimethyl disulfide, a repellent of Apolygus lucorum adults, and its repellent effect under field conditions.

PAN Hong-sheng, XIU Chun-li, LU Yan-hui

2017, 28(9):  3011-3015.  doi:10.13287/j.1001-9332.201709.005

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Previous trials found that dimethyl disulfide (DMDS) showed obvious repellency to Apolygus lucorum adults under laboratory and field conditions. However, this effect only lasted 6 days after spray under field condition. In this study, we screened the slow-release materials, controlled release formulations, diluted concentration of DMDS, and eventually examined the lasting effect of slow-release system in the open field. The results showed that it could keep the slow-release effect of DMDS at least 15 d in the field when we used vial of PE and mineral oil under the dilution of 1: 10. In addition, applying this slow-release system into jujube orchard after 30 d, it reduced 48.0% of the overwintering eggs of A. lucorum within 10 m from the repellent stripe. Our study provided the groundwork for the application of DMDS to control this mirid bug in the field.

The antimicrobial activity and mechanism of Cymbopogon citratus essential oil against Alternaria solani.

LIU Yao-hua, MA Xin-yao, CHENG Zuo-hui, ZHAO Rui, LI Rui, LI Sheng-cai

2017, 28(9):  3016-3022.  doi:10.13287/j.1001-9332.201709.001

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To explore the antifungal function and application potential of Cymbopogon citratus essential oil in the biological control of plant diseases, the disk-diffusion and fumigation methods were used to measure the inhibitory effect of C. citratus essential oil against Alternaria solani and its effect on cell membrane permeability, soluble protein and malondialdehyde (MDA) content, nutrient absorption, and superoxide dismutase (SOD) activity of mycelium. The results showed that C. citratus essential oil had a strong time and dose-dependent inhibitory effect, however showed no sterilization effect on A. solani. Overall, fumigation was a more effective method than disk-diffusion. After 48 hours of C. citratus essential oil treatment, the half maximal inhibitory concentration (IC₅₀) values were 13.40 μL·L^-1 and 103.23 mg·L^-1 for fumigation and disk-diffusion, respectively. After 144 hours, they were 33.81 μL·L^-1 and 145.16 mg·L^-1, respectively. The conductivity and MDA content of mycelium were 2.7 and 2.2 folds as that of the control 12 hours after C. citratus essential oil treatment of 125 mg·L^-1, the SOD activity and soluble protein content were increased by 88.5% and 21.9%, and the absorption of reducing sugar was decreased by 11.3%. These results indicated that C. citratus essential oil could inhibit the growth of A. solani mycelium by destroying cell membrane integrity and reducing nutrient absorption, which should be taken as a potential biological agent for controlling plant diseases.

Relationship of river microhabitat heterogeneity and macroinvertebrate spatial distribution.

ZHANG Hai-ping, ZHANG Yu-hang, MA Kai, YU Yang, QU Xiao-dong

2017, 28(9):  3023-3031.  doi:10.13287/j.1001-9332.201709.007

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As a good indicator, macroinvertebrates are widely adopted in the assessment of river ecological status. Macroinvertebrate distribution is affected by factors of macro-, meso- or micro-scale. The previous research on relationship of macroinvertebrate and habitat factors mainly focused on the meso-scale. Based on surveys of macroinvertebrates and microhabitat factors at a 10 m reach, the spatial distribution characteristics of macroinvertebrates and its relationship with microhabitat heterogeneity were analyzed here to obtain the following results. 1) Macroinvertebrate density, biomass, richness and Shannon index varied with habitat types. The Shannon index values of riffle, pool and run were 2, 1.9, and 1.78, respectively. 2) Spatial autocorrelation existed among the density, biomass, richness index and Shannon index of macroinvertebrate. 3) There were differences in the relationships between microhabitat factors and macroinvertebrate spatial distribution. The fitting degree of flow depth, as well as velocity, and the macrobenthos was weak, while the fitting relationship between composition of sediment and macrobenthos was relatively good. Results demonstrated a positive correlation between macroinvertebrate density and the volume percen-tage of substrate with particle size <4 mm. The biomass, richness index and Shannon index showed a positive spatial correlation with the volume percentage of substrate with particle size >32 mm. The results of this study could provide references for diffusion mechanism research on macroinvertebrates, sample settings and physical habitat restorations.

Relationship between macroinvertebrate composition and environmental factors in habitats of Chinese giant salamander in Zhangjiajie, Hunan Province, China.

WANG Chong-rui, LIANG Zhi-qiang, SUO Wen-wen, WU Yuan-an, HE Ping, WU Ji, WEI Qi-wei, LIU Xun-hua

2017, 28(9):  3032-3040.  doi:10.13287/j.1001-9332.201709.035

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In January 2013 and 2014, field investigations were conducted at 5 sampling sites located in the Hunan Zhangjiajie Chinese Giant Salamander National Nature Reserve. The results showed that: 1) A total of 73 and 78 taxa were identified in two surveys, respectively, belonging to 16 orders, 8 classes, and 5 phyla. Aquatic insects dominated the macroinvertebrate assemblages, accounting for 90.4% and 89.7% of the total number of taxa in the two surveys, respectively; 2) The average density of macroinvertebrates was 1610.4 ind·m^-2 and 1671.4 ind·m^-2, and the average biomass of macroinvertebrates was 11.22 g·m^-2and 12.34 g·m^-2 in the two surveys, respectively; 3) The two surveys had, respectively, an average Shannon diversity index (H) of 2.45 and 2.33, an average Margalef diversity index (d_M) of 4.01 and 3.76, and an average Pielou evenness index (J) of 0.72 and 0.69. By comparing the average biodiversity indices between January 2013 and 2014, the habitat quality of Chinese giant salamander appeared to have declined; 4) The comparison curves of abundance and biomass at each sampling site in the two surveys indicated that the quality of river habitat experienced moderate disturbance at sampling sites S₁ and S₅, and that only sampling site S₄ was undisturbed; 5) Non-metric multidimensional scaling (NMDS) ordination, based on macroinvertebrate abundance, showed the convergence between all sampling sites was better in 2013 than in 2014 under a similarity of 40%; 6) The association between the NMDS ordination scores (axis 1 and axis 2) and environmental variables were tested by Spearman rank correlation. The results showed that the following environmental variables had explanatory power on macroinvertebrate assemblage: River width, NH₄⁺-N, altitude, COD_Mn, and BOD₅. In summary, the relationship between macroinvertebrate composition and environmental factors showed that some streams in the Reserve still supported a relatively favorable habitat, which could meet the habitat requirements for the Chinese giant salamander. However, some regions in this Reserve had been experiencing increased human impacts that made the habitat fragile. Therefore, we are calling for a strict management and protection strategy to be put in place in this region.

Optimization and simulation on purification of petroleum pollutants in wetland water of Liaohe River estuary, China.

MA Yu, WU Bo, LI Feng-mei, GUO Shu-hai

2017, 28(9):  3041-3049.  doi:10.13287/j.1001-9332.201709.029

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The level of oil pollution and purification efficiency of wetland water in Shuguang area of Liaohe oilfield were analyzed comprehensively by plot investigation and system simulation. The estimation model of petroleum pollutants purification capacity was built correspondingly based on Monte Carlo method. Furthermore, according to its natural features, water flow andnutritional factors such as nitrogen and phosphorus were regulated to obtain an optimal design of purification ability in different wetland units. The results indicated that the ability to purify petroleum pollutants was different in each research unit, which mainly resulted from the differences in structure of the wetland and in its internal features. Under natural conditions, the purification efficiency of petroleum pollutants was 5.4%, and the average residual concentration was about 1.05 mg·L^-1. After optimization, the removal rate of petroleum pollutants increased to approximately 20%. The constructed optimization and simulation methods of wetland purification could provide an important technical tool for the removal of petroleum pollutants in the Liaohe River estuary wetland water.

Temporal and spatial differences in carbon footprint in farmland ecosystem: A case study of Henan Province, China.

ZHANG Peng-yan, HE Jian-jian, PANG Bo, LU Cheng-peng, QIN Ming-zhou, LU Qian-cheng

2017, 28(9):  3050-3060.  doi:10.13287/j.1001-9332.201709.015

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Farmland ecosystem is an important part of terrestrial ecosystem, which plays a dual role of carbon source and carbon sink. It has important significance for the maintenance of carbon ba-lance of the whole ecosystem. In this paper, the farmland ecosystem was taken as the research object, ArcGIS 10.1, SPSS 20, Sigmaplot 12.5 were adopted to construct farmland ecosystem carbon footprint model, and to calculate and analyze the relationships among carbon emissions, carbon absorption and carbon footprint in farmland ecosystem in Henan Province. The results showed that, from 2005 to 2014, the average annual growth rate of carbon emission was 2.7% in the researcharea. The carbon emission caused by the fertilizer application in the area accounted for 66.2% of the total carbon emission, which was the highest among all sources. The application intensity of fertilizer was 890.38 kg·hm^-2, which was far higher than the recognized security warning line in developed countries (225 kg·hm^-2). Overall, the total carbon storage showed an upward trend in farmland ecosystem in Henan Province. Wheat had the highest proportion of carbon uptake, accounting for 60% of the total carbon absorption, and the rice had the fastest growth rate of carbon absorption at 7.9%. The farmland ecosystem in Henan Province had a carbon surplus and farmland ecosystem carbon footprint showed an overall increasing trend. Farmland ecosystem carbon footprint accounted for 5.7% of productive land area over the same period. Carbon emission, carbon sequestration and carbon footprint had similar spatial distributions, which appeared more in the southeast and less in the northwest, and large regional differences and variation range were their most important external features.

Ecological risks identification of ecological resettlement area based on cognitive analysis of different stakeholders.

HAN Xiao-jia, WANG Ya-juan, LIU Xiao-peng, YE Jun-yan, WEN Sheng-qiang

2017, 28(9):  3061-3070.  doi:10.13287/j.1001-9332.201709.021

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In ecological resettlement area, there are complex conflicts of interest among different groups in terms of ecological environment protection. It is an important task of ecological risk mana-gement to construct a decision-making model accordingly, taking into considerations of the stakeholders’ knowledge of category and interference intensity in ecological resettlement area. This paper categorized migrants in ecological resettlement into four different interest groups in accordance with stakeholder theory, and adopted participatory semi-structured interview and qualitative polymerization to build an ecological risk factor system with 3 primary variables and 13 secondary variables. Besides, the ecological risk identification was further carried out by utilizing Fuzzy Cognitive Map (FCM) and Artificial Neural Network (ANN) model. The cognitive results of stakeholder groups revealed that the garbage pollution risk variable was most widely mentioned by different interest groups. In the meanwhile, obvious differences existed among stakeholder groups on ecological risk variables. The managers paid attention to the formulation of environmental protection and the implementation of the policy; the residents were concerned about the improvement of the living standard, which was directly related to the environmental consciousness and behaviors; most of the operators pursued economic interests and environmentalists focused on the eco-environmental problems. The graph theory index of stakeholder groups showed that the managers and environmentalists were more comprehensive and clear with regard to the understanding of ecological risks in resettlement areas. The overall risk cognition results of all the stakeholders in the resettlement area revealed that the ecological environmental risk factors significantly affected the safety and satisfaction of residents, and the public policy played a major role in the risk management of resettlement areas. The centrality of risk variables further showed that improving the living standards was the key to prevent ecological risks. The results of ecological risk perception and management scenarios showed that solving the problem of garbage pollution could improve the ecological environment, and the key was to ameliorate and implement the relevant public policies; establishing and improving the social security system was directly related to the living standards of residents and environmental protection behaviors; and strengthening infrastructure construction would affect the landscape ecological pattern, biological habitat and biodiversity, and improve residents’ satisfaction and public participation.

Analysis of the typical radionuclides for neon flying squid of the high seas fisheries in North Pacific Ocean and risk assessment in 2013.

TANG Feng-hua, ZHANG Sheng-mao, CUI Xue-sen, WANG Jing-long, DU Jin-zhou

2017, 28(9):  3071-3077.  doi:10.13287/j.1001-9332.201709.006

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To understand the pollution effect of radionuclides emitted from Fukushima nuclear accident on marine organisms, we collected flying squid samples in the North Pacific Ocean (40°-44°N, 145°-160° E) from August to November in 2013. Radionuclides’ concentrations at different localities were analyzed by the ultra-low background high purity germanium (HPGe) γ spectrometer. The result showed that nuclide specific activities of ¹³⁴Cs and ^110mAg were not higher than the background values, while those of ²¹⁰Pb, ¹³⁷ Cs and ⁴⁰ K were detected in all samples. Specific activity ranges of ²¹⁰Pb, ¹³⁷ Cs and ⁴⁰ K for neon flying squid were 0.99-7.60 Bq · ^-1, the mininum detection limit to 0.37 Bq · ^-1and 46.00-107.00 Bq · ^-1, respectively. The 250-300 mm mantle length group of neon flying squid had the highest nuclide concentration of ²¹⁰Pb, and the minimum concentration of ²¹⁰Pb was found in the 200-250 mm and >400 mm groups. The 200-250 mm mantle length group had the highest nuclide concentration of ¹³⁷Cs, and the 250-300 mm and 350-400 mm groups had the minimum. The 250-300 mm mantle length group had the highest nuclide concentration of ⁴⁰K, and the 150-200 mm group had the minimum, and the overall distribution was much more uniform. Nuclide concentration distributions were different in different organs of neon flying squid, but all highest values were detected in innards. Risk assessment showed that the entropy values of all tested marine life value and basic value of radionuclide content in the fishing grounds of North Pacific high seas were not higher than 1, indicating there was no high risk of the radiation on fishery resources temporarily in North Pacific Ocean. The study provided the theory basis for assessment of the marine ecological environment and public health hazard resulted from Fukushima nuclear accident.

Otolith morphological diversity of Electrona carlsbergi based on elliptical Fourier analysis.

WEI Lian, ZHU Guo-ping

2017, 28(9):  3078-3086.  doi:10.13287/j.1001-9332.201709.002

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The otolith of Electrona carlsbergi has diverse morphological characteristics. In order to further study the morphological diversity, a total of 456 sagittal otoliths of E. carlsbergi (standard length 6.0-8.8 cm), which were collected off the South Shetland Islands, were observed and discriminated. The otoliths of E. carlsbergi were classified into four types based on the morphological characteri-stics, and 77 Fourier feature coefficients of four types were analyzed by elliptical Fourier analysis. Based on the pairwise comparison on Fourier feature coefficients of four types, the proportions of pairs of coefficients with significant differences accounted for 61.0% (highest) and 28.6% (lowest) of the total, respectively. Based on the principal component analysis (PCA) of 77 Fourier coefficients, the cumulative contribution rate of first 22 principal components was 76.5%. 17 Fourier feature coefficients were selected to conduct the stepwise discriminant analysis (SDA), and the total discriminated rate was 87.2%. The contours reconstructed by the elliptical Fourier analysis distinctly reflected the differences among the four types of otolith. Four types for E. carlsbergi’s otoliths which appeared on various fish sizes and body masses indicated that the appearance of otolith types was stochastic. The types of otolith were not consistent in the left and right otoliths, indicating different types occurred between both sides of the otoliths. Types I and II were the main forms of E. carlsbergi otoliths, accounting for 72.6% of the total, while types III and IV were the secondary forms, accounting for 27.4% of the total.

Source apportionment of heavy metals in solid and its application in coastal sediment of China.

LIANG Xian-meng, SONG Jin-ming, YUAN Hua-mao, LI Xue-gang, LI Ning, DUAN Li-qin

2017, 28(9):  3087-3098.  doi:10.13287/j.1001-9332.201709.009

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Source apportionment of heavy metals in sediments is significant to distinguish the influence of human activities from nature changes on offshore eco-environment evolution. This overview focused on three widely used source apportionment methods: Multivariate statistical technique, geochemical method and geostatistical analysis and highlighted that the positive matrix factorization and lead isotopic trace were two relatively preferable methods to quantitatively assess the anthropogenic source of heavy metals. Based on the heavy metal concentrations in coastal sediments of China, heavy metals were primarily of anthropogenic origin with their contribution close to or higher than 50% in coastal sediment of China evaluated by combination of different source identification me-thods (multivariate analysis, estimation based on background value and lead isotopic trace), and estuaries and bays were typical polluted regions. The current researches on source apportionment had the problems that the source endmembers were still vague and the interpretation of data lacks corresponding reliability evaluation. The future research should be focused on the integration and optimization of multi-methods to improve the accuracy of source apportionment, extracting informative indicators to represent specific anthropogenic activities or natural source and recognizing the geoche-mical process and mechanism of anthropogenic emissions of heavy metals when entering into coastal environment to provide referential fingerprints for source interpretation.

Microbe-assisted drought resistance for tobacco plants: Mechanisms and applications.

HUANG Hua-gang, LYU Li-xin, ZHANG Yan-ming, JIANG Zhuang, SHEN Yan, AN Qian-li

2017, 28(9):  3099-3110.  doi:10.13287/j.1001-9332.201709.013

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Drought is one of the most destructive abiotic stresses to tobacco farming in China. Many microbes in symbiosis or association with plant roots are able to help plant to avoid and tolerate drought stress. Microbes absorb water via mycelia and transport water to plant hosts; microbes produce plant hormones or change plant endogenous hormones to promote root development and elongation or leaf stomatal closure, leading to drought avoidance via increase of water absorption and decrease of water loss. Microbes modulate plant signal transduction pathways mediated by different plant hormones to induce plant systemic tolerance to abiotic stresses via accumulation of osmoprotectants, antioxidants, and scavengers of reactive oxygen species. Microbes also help plant hosts to absorb nutrients and thus support plant metabolism and growth under drought stress. This paper reviewed the mechanisms of microbe-assisted plant resistance to drought stress based mainly on the studies on tobacco and tomato plants inoculated with arbuscular mycorrhizal fungi, the model endophytic fungus Piriformospora indica, and plant growth-promoting rhizobacteria. This paper also discussed the use of these beneficial microbes to promote tobacco resistance to drought stress for tobacco farming.