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Table of Content

    15 October 2020, Volume 31 Issue 10
    Special Features of Plant Protection
    Field control efficacy of 12 insecticides and five species of natural enemies to Thysanogyna limbata
    CHEN Qi, WANG Rui, WEI Ya-juan, LIU Jian-jun
    2020, 31(10):  3241-3247.  doi:10.13287/j.1001-9332.202010.039
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    Thysanogyna limbata is a pest on the landscape plant Firmiana platanifolia. In this study, we evaluated the control efficacy of twelve insecticides and five common natural enemies to T. limbata. The results showed that the control efficacy of thiamethoxam and imidacloprid to T. limbata was much better than other insecticides. For the three application methods evaluated (spraying, injection, and root-irrigation), the spraying method should be avoided and the injection performed better. If conditions permitted, root-irrigation method could be used as a supplementary method. Among the five natural enemies, Chrysoperla sinica and Lemnia saucia had the best control effect on T. limbata, which could replace insecticide in the long-term control effect. Therefore, C. sinica and L. saucia could be used as safe and environment-friendly pattern to prevent T. limbata in the medium- and long-term in the garden, whereas injection of thiamethoxam and imidacloprid could be used as a short-term and rapid treatment.
    Investigation on the resistance of wheat germplasm resources to aphid based on fuzzy recognition and electrical penetration graph (EPG)techniques
    JIANG Ya-xiu, CHANG Wen-jing, ZHAN Yi-di, LIU Zhen, LIU Yong
    2020, 31(10):  3248-3254.  doi:10.13287/j.1001-9332.202010.033
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    We analyzed the resistance of wheat germplasm resources with different genetic backgrounds to aphids by fuzzy recognition technique in field and electrical penetration graph (EPG) in laboratory, with the aim to find new aphid-resistance resource. Results from a two-year field experiment showed that most trititrigia had medium and low resistance, while most triticale were medium and low susceptible. The trititrigia 21 (medium resistance), trititrigia 22 (low resistance), triticale 31 (medium susceptable) and triticale 32 (low susceptable) with stable resistance traits and diffe-rent resistance levels were selected for feeding behavior analysis of Sitobion avenae. We analyzed the basic waveforms, including non-feeding wave (Np), probing wave (P), potential drop (Pd), secretion of water saliva wave (E1), phloem feeding wave (E2), cellular mechanical hindrance wave (F), and xylem feeding wave (G). The time for initial probe of S. avenae on trititrigia was significantly longer than that of triticale, while the duration of E1 wave on trititrigia was significantly longer than that of triticale. The duration of F wave on trititrigia 21 and the Np wave on the trititrigia 22 were the longest, while that of P wave on triticale 31 and the G wave on triticale 32 were the longest. Taking the durations of E1, F and Np waves as indices, the field identification on the resis-tance of wheat germplasm resources to aphid based on fuzzy recognition technique was basically consistent with that using EPG. Our results suggest that E1, F and Np waves could be used to evaluate the resistance levels of wheat to aphid. Tititrigia 21 and 22 were more resistant to aphid, which could be used as the germplasm for breeding aphid-resistance wheat varieties.
    Biocontrol potential of Talaromyces purpurogenus and its regulation on soil microbial community
    TIAN Ye-han, PENG Hai-ying, WANG De-hao, LI Xiao-fang, HE Bang-ling, GAO Ke-xiang
    2020, 31(10):  3255-3266.  doi:10.13287/j.1001-9332.202010.037
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    Talaromyces purpurogenus strain Q2 is a kind of beneficial microbe originally separated from the rhizosphere of healthy cucumber. In this study, we evaluated the biocontrol potential of strain Q2 against four soil-borne diseases by plate confrontation culture, potting in the greenhouse. We further estimated the control efficacy of strain Q2 combined metam-sodium fumigation against Fusarium wilt of bitter gourd in the field. The mechanism of strain Q2 controlling bitter gourd wilt and regulating soil microbial community was examined by plate dilution culture, high throughput sequencing and quantitative PCR. The results showed that strain Q2 could efficiently reduce disease incidence of Fusarium wilt of bitter gourd, potato stem canker, black shank of tobacco and black root rot of tobacco in the green house. Its biocontrol efficacy on black shank of tobacco and bitter gourd wilt was 75.3% and 63.4%, respectively. Biocontrol efficacy of strain Q2 on bitter gourd wilt was 51.0% in the artificial disease nursery inoculated pathogen of bitter gourd wilt, while the control efficacy of strain Q2 combined with soil fumigation technology was more than 80% in the same experiment condition. Strain Q2 application and soil fumigation altered soil microbial community composition and recovery trend. Metam-sodium fumigation significantly reduced the abundances of Fusarium oxysporum and causal agent of bitter gourd wilt. Strain Q2 further suppressed the efficient recovery trend of the pathogen. After application of strain Q2, Penicillium was enriched in soil, as well as the beneficial microbes involved in the suppression of F. oxysporum, such as Bacillus and Gaiella. Overall, after soil fumigation, biocontrol efficacy of strain Q2 on soil-borne diseases such as Fusarium wilt could attribute to the formation of beneficial microbial communities in soil and inhibition of strain Q2 on growth and development of F. oxysporum.
    Chemical composition of body extracts from Apriona germari and its function in sexual communication
    XU Zhao-huan, LIAO Wei-cai, LIU Wei, WANG Guang-li
    2020, 31(10):  3267-3272.  doi:10.13287/j.1001-9332.202010.031
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    To elucidate the composition of semiochemicals of Apriona germari and its function in sexual communication, GC-MS was used to detect the composition of semiochemicals of the overall body and the end abdominal tissue extracts in A. germari. Y-tube olfactometer was used to determine the olfactory response of adult female and male to the standard compounds of the five main extracts. The contact reaction test with male and female adults was performed to the eluted adults that smeared tandard compounds. The results showed that the main ingredients of semiochemicals were alkanes and alkenes with more than 10 carbons. Concentration of (Z)-9-Tricosene was the highest, followed by heptacosane, nonacosane, nonadecene, octacosane, 9-Hexylheptadecane, aldehyde, and ester. Results of the olfactory reaction showed that nonacosane had a significant attractivity to both male and female adults, and that heptacosane had a significant attractivity only to female adults. Nonadecene had a extremely significant repellent activity to female adults. 1-docosene and (Z)-9-Tricosene had no evident role to the male and female adults. Results of the contact test showed that male adults had the strongest courtship responses to the eluted adults with 1-docosene, heptacosane and nonacosane. Female adults had the strongest courtship responses to the eluted adults with nonacosane. Our results indicated that 1-docosene, heptacosane, and nonacosane were important component of the sex pheromone of A. germari, which played an important role in the sexual communication.
    Effects of different corn varieties on development and reproduction of Spodoptera frugiperda
    DAI Qian-xuan, LI Zi-yuan, TIAN Yao-jia, ZHANG Zhen-fei, WANG Lei, LU Yong-yue, LI You-zhi, CHEN Ke-wei
    2020, 31(10):  3273-3281.  doi:10.13287/j.1001-9332.202010.020
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    To understand the damage capability of the invasive pest Spodoptera frugiperda on diffe-rent corn varieties in China, we evaluated survival fitness of S. frugiperda on three varieties of sweet corn (i.e., Suitian No.1, Zhengtian 68, and Huajintian No.1) and three varieties of waxy corn (i.e., Jingkenuo 2000, Guangheitiannuo, and Guangnuo No.1) by constructing life table for all populations. The correlation of biological parameters of S. frugiperda to the main nutrients and crude fiber content in corn leaves were analyzed. Results showed that the larva survival rate, pupal weight, and production of S. frugiperda on sweet corns were significantly higher than those on waxy corns. The intrinsic rate of increase (rm) of S. frugiperda on the sweet corns ranged from 0.1566 to 0.1843, and the net reproductive rate (R0) ranged from 187.97 to 353.35, being higher than those reared on the waxy corns (rm was from 0.0998 to 0.1465, and R0 was from 25.89 to 95.34). S. frugiperda reared on the sweet corns had higher population growth ability than those reared on the waxy corns. The content of main nutrients such as vitamin C, starch, soluble sugar, protein, fat, total amino acids, and crude fiber in the sweet corn leaves were higher than those in the waxy corn leaves. There were positive correlations between R0 of S. frugiperda to the contenst of vitamin C, starch, soluble sugar, protein, and crude fiber in corn leaves. The results indicated that S. frugiperda reared on the sweet corn leaves had higher survival fitness than those reared on the waxy corn leaves.
    Cross-resistance and the underlying mechanisms of clothianidin resistant population of Frankliniella occidentalis to insecticides
    YAN Gai-lan, WANG Sheng-yin
    2020, 31(10):  3282-3288.  doi:10.13287/j.1001-9332.202010.034
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    Clothianidin, belonging to neonicotinoid insecticide with systemic and contact mechanisms, is used to control the invasive pest Frankliniella occidentalis. To identify the resistance risk, we examined the cross-resistance to multiple insecticides and mechanisms of clothianidin resistant population of F. occidentalis. The results showed that F. occidentalis developed a high level of resis-tance to clothianidin (56.8-fold) after selecting for 45 generations. The resistant population of F. occidentalis had medium level of cross-resistance to thiamethoxam, imidacloprid, chlorpyrifos, cyhalothrin and emamectin benzoate (18.6>RR50>11.3), and the low level of cross-resistance to phoxim and methomyl, but no cross-resistance to chlorfenapyr and spinosad. The synergists piperonyl butoxide (PBO) and triphenyl phosphate (TPP) had significant synergistic effects on clothianidin in killing the resistant population (CL), Yunnan wild population (YN) and susceptible population (S). Compared with the sensitive population, the CL populations had significantly increased activities of mixed-functional oxidases P450(3.6-fold), b5(2.9-fold) and O-demethylase (4.9-fold), and carboxylesterase (2.5-fold), with no significant difference in the activities of glutathione S-transferases among CL and S populations. The results highlight the role of increasing mixed-functional oxidases and carboxylesterase in the resistance of F. occidentalis to clothianidin.
    Resistance risk and resistance stability of Frankliniella occidentalis to nitenpyram, clothianidin and thiamethoxam
    YAN Gai-lan, WANG Sheng-yin
    2020, 31(10):  3289-3295.  doi:10.13287/j.1001-9332.202010.035
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    To effectively control the damage of Frankliniella occidentalis (Pergande), we evalutated the resistance risk and resistance stability of F. occidentalis to nitenpyram, clothianidin and thiamethoxam. With the method of dipping Phaseolus vuglaris, we selected the resistance populations from the susceptible population with nitenpyram, clothianidin and thiamethoxam, respectively. Both the resistance inheritance and resistance risk were analyzed with the resistance reality hereditary. After 30 generations' selections, the selected-populations showed high level of insecticide resistance to nitenpyram, clothianidin and thiamethoxam, with a resistance ratio of 44.7-fold, 45.5-fold, and 32.7-fold, respectively. The development rate of resistance to clothianidin, nitenpyram, and thiamethoxam reduced in turn, with a resistance reality heritability of 0.1503, 0.1336 and 0.1258, respectively. Stopping selection for 10 continuously generations, the resistance levels of selection resis-tance populations declined slowly, but could not regain the original susceptibility to nitenpyram, clothianidin and thiamethoxam. After resistance selection, the sensitivity of F. occidentalis nymphs to clothianidin, nitenpyram, and thiamethoxam was significantly higher than that of adults. F. occidentalis had the great potential to gain high level resistance to nitenpyram, clothianidin and thiamethoxam. Compared with other two insecticides, the resistance of F. occidentalis to thiamethoxam increased slower and decreased faster. Therefore, using thiamethoxam in nymph stage might be beneficial to effectively control F. occidentalis.
    Original Articles
    Effects of selective cutting on the distribution pattern and inter-specific association of arbor seedlings in Tilia amurensis secondary forest
    LIU Yue, ZHANG De-peng, JI Li, XU Li-ying, DONG Ling-bo, YANG Li-xue
    2020, 31(10):  3296-3304.  doi:10.13287/j.1001-9332.202010.004
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    The distribution pattern and interspecific associations of arbor seedlings were examined in two Tilia amurensis forest stands in Zhangguangcailing, with one without man-made interference (natural recovery secondary forest) and the other one being 20-year-old after selective cutting (selective cutting secondary forest). The results showed that the importance value of the seedlings of the soft broad-leaved (heliophile) and tolerant tree species was 7.9 and 64.5 in natural recovery secondary forest, and was 3.9 and 68.9 in selective cutting secondary forest, respectively. The spatial distribution pattern of arbor seedlings in natural recovery and selective cutting secondary forests showed clustered distribution at the scale of 0-18 m and 0-15 m, respectively. Most of tree species pairs were negatively correlated at large scale (14-45 m) in the natural recovery secondary forest, whereas tree species pairs at all the scales were mostly uncorrelated in the selective cutting secon-dary forest. Most of the tree pairs of T. amurensis seedlings (57%) with other tree species showed negatively correlation at large scale (31-45 m). In the natural recovery secondary forest, the proportion of negatively correlated tree pairs was higher than 60%. In selective cutting secondary forest, Acer mono seedlings were negatively correlated with other tree species at more scales (6-45 m). In the natural recovery secondary forest, the pairs of A. mono and other arbor seedlings were positively correlated at small scale (0-5 m), but not at large scale (31-45 m). Therefore, selective cutting accelerated the succession of the secondary forest of T. amurensis, which induced random distribution of the arbor seedlings at the large scale (31-45 m), promoted a more coordinated inter-specific relationship, and adjusted the spatial competition between T. amurensis seedlings. Both stands were under succession, and thus suitable artificial management should be carried out to promote tree regeneration and community restoration.
    Species composition and community structure of coniferous-broadleaved mixed forest in Xiaolong Mountain, Gansu Province, Northwest China
    SU Qiao-ling, LI An-min, YUAN Shi-yun, LIU Wen-zhen, MI Xiang-cheng, DING Yi, ZANG Run-guo
    2020, 31(10):  3305-3312.  doi:10.13287/j.1001-9332.202010.002
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    Xiaolong Mountain, located in warm temperate subtropical transition zone, is one of the important biodiversity conservation areas in China. We analyzed species composition, community structure, and habitat preferences of all woody plant species with DBH (diameter at breast height)≥1 cm in a 6 hm2 plot in Xiaolong Mountain, Gansu Province, Northwest China. A total of 29251 individuals (41735 stems) belonging to 33 families, 65 genera, and 124 species were recorded. The 28 species with importance value ≥1 contributed 82.9% to the total abundance. The top four species with the highest importance value were Quercus aliena var. acuteserrata, Betula platyphylla, Lindera aggregata var. playfairii and Corylus heterophylla. The structure of DBH size class of all stems showed an inverse ‘J' type, indicating a successful regeneration tendency in the understory. Results from the indicator species analysis showed that 11 species had significant habitat prefe-rences, an two species (Ostrya japonica and Acer stachyophyllum subsp. betulifolium) had the most obvious preferences. Results from the redundancy analysis and partial methods showed that topographic factors played a dominant role in determining species distribution.
    Variation of stem radius of Larix principis-rupprechtii and its influencing factors in the semi-humid Liupan Mountains, China
    WANG Ya-rui, LIU Ze-bin, WANG Yan-hui, XIONG Wei, YU Peng-tao, XU Li-hong, MA Jing
    2020, 31(10):  3313-3321.  doi:10.13287/j.1001-9332.202010.005
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    We measured stem radius of Larix principis-rupprechtii at the semi-humid Liupan Mountains using the automatic band dendrometer over the growing season in 2016. We examined the diurnal and seasonal variations of stem radius, determined the main stem growth period, and analyzed the response of stem radius to environmental factors during the main stem growth period. The aim was to accurately understand the effects of short-term environmental variation on tree growth. The results showed that stem radius had a clear diurnal variation, with the phases of daytime shrin-kage, nighttime recovery, and increment. The seasonal variation of stem radius could be divided into three distinct stages, including stem relatively stable, stem continuous increasing, and stem swell-shrinking fluctuation. Under the meteorological, soil moisture and topographic conditions of 2016, main stem growth period of L. principis-rupprechtii started from 14th May and ended on the 31th July, with the maximum radius growth rate occurred on 8th June. The environmental factors influencing the daily radius shrinkage at different phases (shrinkage phase, daily, cycle) were gene-rally the same, including temperature (including the air and soil temperature), solar radiation intensity, saturation vapor pressure deficit and soil water content. Temperature had the highest contribution (50.3%-71.0%). However, the influencing factors of daily radius increment varied at different phases. Precipitation (with a contribution of 86.9%) and maximum air temperature (13.1%) were the influencing factors at the radius increment phase. Precipitation (50.3%), saturation vapor pressure deficit (29.9%), relative humidity (12.7%) and solar radiation intensity (7.1%) were the factors at stem cycle. Precipitation and solar radiation intensity were the factors at diurnal scale. Radius increment was more sensitive to environmental variation at the time of stem cycle than that at diurnal scale.
    Stand biomass model for Pinus koraiensis plantation based on different additive methods in Heilongjiang Province, China
    XIN Shi-dong, YAN Yun-xian, JIANG Li-chun
    2020, 31(10):  3322-3330.  doi:10.13287/j.1001-9332.202010.003
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    Large-scale estimation of forest biomass has received much attention. Constructing a stand-level biomass model is a method for estimating tree layer biomass. In this study, we constructed stand biomass models of Korean pine plantations based on aggregation method 1, aggregation method 2, adjustment method, and disaggregation method. The prediction precision of four additive methods was compared and analyzed to provide theoretical basis for biomass prediction of Korean pine plantations in Heilongjiang Province. Weighted functions were used to eliminate the heteroscedasticity of each model, with the leave-one-out cross validation (LOOCV) as the validation method. The results showed that the overall prediction ability of the adjustment method was slightly better than other methods. The specific prediction precision was ranked as adjustment method > aggregation method 1 > aggregation method 2 > disaggregation method. The prediction precision of four additive methods was not consistent when considering their prediction ability of different stand basal areas. When the stand basal area of Korean pine plantations was distributed in the interval of 0-10 or 50-60 m2·hm-2, the parameter estimation values of disaggregation method performed better. When the stand basal area was distributed in other intervals, the parameter estimation values of adjustment method was better.
    Effects of seed size and drought stress on the growth and physiological characteristics of Quercus wutaishanica seedlings
    YAN Xing-fu, DENG Xiao-juan, WANG Jing, ZHOU Li-biao, ZHANG Jin-feng, LUO Yong-hong
    2020, 31(10):  3331-3339.  doi:10.13287/j.1001-9332.202010.006
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    The effects of seed size and drought stress on the growth and physiological characteristics of Quercus wutaishanica seedlings were investigated under shading conditions of a pot experiment in greenhouse. There were four treatments, including 80% field water content (FWC), 60% FWC, 40% FWC, and 20% FWC [CK, light drought stress (LDS), medium drought stress (MDS), and high drought stress (HDS), respectively]. The results showed that leaf area per plant, total dry mass, and root-shoot ratio of Q. wutaishanica seedlings regenerated from large seeds (3.05±0.38 g) were significantly higher than those from small seeds (1.46±0.27 g) in all four treatments. Shoot height, basal stem diameter, leaf number, specific leaf area, relative growth rate, and net assimilation rate of the seedlings from large seeds were higher than those of seedlings from small seeds under the treatments of LDS, MDS and HDS. Activities of peroxidase (POD), catalase (CAT), and superoxide dismutase (SOD) in large-seeded seedlings were higher than those of small-seeded seedlings under all treatments, while the contents of MDA, soluble protein, free proline, and total chlorophyll of large-seeded seedlings were higher than those of small-seeded seedlings only under some drought stress treatments. All growth parameters except the root-shoot ratio decreased with the increases of drought stress. The HDS treatment resulted in 19.4% and 20.0% decline in total dry mass of large- and small-seeded seedlings respectively, compared with those of CK. With increasing drought stress, the activities of POD, CAT, and SOD decreased after an initial increase. POD activity of large- and small-seeded seedling under MDS treatment was 126.7% and 142.1% higher than CK, while CAT was 170.0% and 151.9% higher than CK, respectively. However, the MDA content of seedlings from large and small seeds under HDS treatment was 86.5% and 68.9% higher than that of CK, respectively. The contents of soluble protein, free proline, and total chlorophyll rose at first and then fell with increasing drought stress, and soluble protein content in large- and small-seeded seedlings experienced MDS enhanced 320.7% and 352.7%, respectively. Those results indicated that large-seeded seedlings of Q. wutaishanica had stronger drought tolerance than small-seeded seedlings due to their growth and physiology advantages. Large-seeded seedlings with stronger resistance to drought stress should be applied to artificial regeneration of the degraded secondary Q. wutaishanica plantations.
    Stem hydraulic architecture of Malus sieversii in degraded wild fruit forest in Ili valley, China
    SUN Yi-xiang, ZHANG Jing, ZHOU Xiao-bing, TAO Ye, ZHANG Yuan-ming
    2020, 31(10):  3340-3348.  doi:10.13287/j.1001-9332.202010.008
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    To reveal mechanisms underlying the dieback of Malus sieversii in degraded wild fruit forest in Ili valley of China, we compared the differences in stem hydraulic architecture, water transport effectiveness and safety, as well as their influencing factors among three growth classes of dead branches ratios, including Class Ⅰ (<20%), Class Ⅱ (40%-60%) and Class Ⅲ (>80%), respectively. With the increases in degradation degree of Xinjiang wild fruit forest, sapwood-specific hydraulic conductivity and leaf-specific hydraulic conductivity decreased, without significant differences among the three growth classes. Branch embolism at dusk and hydraulic safety significantly increased. The xylem water potential at 50% loss of hydraulic conductivity was -1.87, -1.35 and -0.53 MPa for Class Ⅰ, Ⅱ and Ⅲ, respectively. Predawn and midday leaf water potential and the hydraulic safety margin exhibited an order of Ⅰ>Ⅱ>Ⅲ. Xylem anatomical cha-racteristics and branch and leaf traits related to hydraulics were significantly different among the three growth classes. Results from correlation analysis revealed a weak tradeoff between xylem-specific hydraulic efficiency and xylem safety of M. sieversii. Stem hydraulic architecture of M. sieversii altered with the decline of Xinjiang wild apple forest. With increasing degrees of degradation, the severity of xylem embolisms aggravated, resistance to cavitation embolisms reduced, and the risk of water imbalance increased.
    Altitudinal changes of soil organic carbon fractions of evergreen broadleaved forests in Guanshan Mountain, Jiangxi, China
    XI Dan, YU Ze-ping, XIONG Yong, LIU Xiao-yu, LIU Jun
    2020, 31(10):  3349-3356.  doi:10.13287/j.1001-9332.202010.009
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    We investigated soil total organic carbon (TOC), recalcitrant organic carbon (ROC), and labile organic carbon (LOC) of evergreen broadleaved forests at different altitudes (400, 600, 800, 1000 and 1200 m) in Guanshan National Nature Reserve, Jiangxi Province, with the aim to understand their altitudinal distribution. The results showed that soil TOC, ROC and LOC contents were the highest in the surface layer and decreased with soil depth. With the increases of altitude, contents of soil TOC, ROC, readily oxidizable organic carbon (ROOC), microbial biomass carbon (MBC), and particulate organic carbon (POC, 0-20 cm depth) increased with a peak at 1000 m and then decreased, whereas soil water-soluble organic carbon (WSOC) contents and POC contents in 20-40 cm layer did not change. In 0-10 cm soil layer, the proportions of ROC to TOC at 800 and 1200 m were significantly higher than those at 400 and 1000 m, while the proportions of LOC to TOC were the highest at 400 m. The proportions of ROC and LOC to TOC in 10-40 cm layer showed a low-high-low tendency along the altitude, with peaks at 1000 and 600 m, respectively. Soil organic carbon fractions were positively correlated with soil moisture, microbial biomass nitrogen, and soluble organic nitrogen. A positive correlation was observed between LOC and ammonium concentration. Our results suggested that altitude significantly affected the distribution of soil organic fractions, with soil ROC, ROOC and MBC being more sensitive to altitudinal changes. Soil ROC and LOC at high altitude were prone to decomposition and transformation under conditions with sufficient water and nitrogen, which reduced soil carbon stability. It was essential to study the dyna-mics of soil organic carbon in high altitude forests under global warming scenarios.
    Leaf nutrient resorption characteristics of Robinia pseudoacacia at different ages and their response to soil nutrient availability
    XU Miao-ping, ZHANG Xin-yi, LI Wen-jie, REN Cheng-jie, YANG Gai-he, HAN Xin-hui
    2020, 31(10):  3357-3364.  doi:10.13287/j.1001-9332.202010.001
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    To reveal nutrient resorption characteristics of Robinia pseudoacacia and their driving factors in hilly and gully regions, we measured the concentration of total nitrogen and total phosphorus in leaves and the concentrations and stoichiometry of organic carbon, total nitrogen, total phospho-rus, ammonium, nitrate and available phosphorus in soils of R. pseudoacacia plantations with different stand ages. We analyzed the relationship between leaf nitrogen and phosphorus resorption efficiencies and soil nutrient characteristics. The nutrients in plants and soil changed significantly with stand ages. The total and available phosphorus concentrations were low in the soil. Nitrogen resorption efficiency first increased and then decreased with the increases of stand age, with a range of 48.2%-54.0% and a mean value of 48.5%. Phosphorus resorption efficiency increased significantly with stand age, with a range of 45.2%-49.4% and a mean value of 46.9%. Nitrogen resorption efficiency showed negative response to soil nitrogen and N:P. Phosphorus resorption efficiency was significantly positively correlated to soil N:P and negatively correlated to soil available phosphorus. Our results indicated that soil nutrient availability negatively drove nutrient resorption efficiency. The strategies of leaf nutrient resorption responded strongly to soil N:P due to the N2-fixing effect and P-limitation of R. pseudoacacia.
    Physiochemical properties and microbial community characteristics of rhizosphere soil in Parashorea chinensis plantation
    HAN Xiao-mei, HUANG Ze-yue, CHENG Fei, YANG Mei
    2020, 31(10):  3365-3375.  doi:10.13287/j.1001-9332.202010.019
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    We explored the impacts of different mixed trees on the improvement of soil microecological environment in rhizosphere of Parashorea chinensis, including pure P. chinensis plantation (WC), mixed P. chinensis and Dalbergia odorifera plantation (WJ), mixed P. chinensis and Eucalyptus urophylla × E. grandis plantation (WA). Soil physical and chemical properties were analyzed. The characteristics and distribution of soil microbes in the rhizosphere were measured by the methods of Biolog-Eco micro plate and phospholipid fatty acid methyl ester (PLFA). Soil water content, soil pH, organic matter, total nitrogen, total potassium content and the activities of sucrase, urease and acid phosphatase in rhizosphere soil of WA were significantly higher than those of WC and WJ, without difference between WC and WJ. There were no significant differences in the contents of nitrate nitrogen, ammonium nitrogen, and available potassium between WA and WJ, which were obviously higher than those in WC. There were significant differences in total phosphorus and available phosphorus contents among the three stands, with an order of WJ>WA>WC. The average color change rate (AWCD), Shannon index, Simpson index, McIntosh index and the utilization of six types of carbon source substrates in microorganisms were the highest in the rhizosphere soil of WA, followed by WJ and WC. Results of principal component analysis showed that carbohydrates, amino acids and phenolic acids were the main carbon sources for microbial utilization. In WA, the PLFA content of rhizosphere soil microorganism, bacteria, fungi and actinomycetes was the highest, followed by WJ and WC. There were significant positive correlation between soil physical and che-mical properties and the microbial characteristics. Combining the physical and chemical properties of soil and the functional and structural characteristics of microbial communities, the mixed P. chinensis and E. urophylla × E.grandis plantation may be most conductive to the improvement of the rhizosphere microecological environment and increase soil available nutrients at the young tree phase of P. chinensis.
    Responses of transpiration to variation in evaporative demands and soil water in a larch plantation at the south side of Liupan Mountains, China
    CAO Gong-xiang, WANG Yun-ni, GUO Zhong, JI Meng, WANG Yan-hui, XU Li-hong
    2020, 31(10):  3376-3384.  doi:10.13287/j.1001-9332.202010.015
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    Quantifying the response of tree transpiration (T) to the variation of soil water supply capability and atmospheric evaporative demand is beneficial for a better prediction of water use and hydrological cycles in forests and deepen the understanding of the relationship between forest and water. Larix principis-rupprechtii in the Xiangshuihe watershed at the south side of Liupan Mountains was used as the research object. We simultaneously monitored sap flow density by thermal diffusion probe and the environmental factors. The response of the T to the soil volumetric water content (VWC) and potential evapotranspiration (PET) was analyzed. The results showed the response curve of T to VWC was quite similar under any different PET levels. With increasing VWC, T increased rapidly and then slowly, and began to be stable when VWC reached a threshold. This process could be well fitted by the saturated exponential function. However, the VWC threshold was different, and its value increased with rising PET. The relationship of daily T to PET was a quadra-tic equation, and PET also had a threshold effect. A stand transpiration model considering the effect of soil water supply capacity and atmospheric evaporative potential was founded which coupled the response relationship of T to PET and VWC in the rapid growth season. This model could well estimate the diurnal variation of transpiration, and provide guidance for the management of plantation water control.
    C:N:P stoichiometry of leaves and fine roots in typical forest swamps of the Greater Hinggan Mountains, China
    LIU Xu-yan, HU Yu-kun
    2020, 31(10):  3385-3394.  doi:10.13287/j.1001-9332.202010.007
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    Investigating ecological stoichiometry of leaves and fine roots of forest swamps in the Greater Hinggan Mountains will improve our understanding of plant nutrient use and material cycling in ecosystems at high latitudes with high sensitivity to climate change. In this study, we collected leaf and fine root samples from 19 dominant and subordinate vascular plant species and measured their C, N and P concentrations in three typical forest swamps (Larix gmelinii-Carex schmidtii, L. gmelinii-Vaccinium uliginosum-moss and L. gmelinii-Ledum palustre-Sphagnum) of the Greater Hinggan Mountains, China. We compared C:N:P stoichiometry in leaves and fine roots among different forest swamp types, plant growth forms, and mycorrhizal types. Standardized major axis regression was performed to examine the relationships between leaf and fine root stoichiometry. The results showed that interspecific variation accounted for the largest proportion of total variation in C:N:P stoichiometry of leaves (42.5%-84.6%). N:P had the highest, C:N had the intermediate, and C:P had the lowest interspecific variation in both leaves and fine roots. L. gmelinii-C. schmidtii forest swamps, which had higher soil nutrient and water availability, had lower C:N and C:P in leaves and fine roots. N:P of all three forest swamps were lower than 10, indicating N limitation in this ecosystem. Herbaceous plants had significantly lower leaf C:P, fine root C:N, and fine root C:P than woody species. Both ectomycorrhizal and ericoid mycorrhizal plants had higher leaf and fine root C:N and C:P than arbuscular mycorrhizal and non-mycorrhizal species, while the C:P of ericoid mycorrhizal plants was significantly higher than that of ectomycorrhizal species. Forest swamp type, plant growth form, and mycorrhizal type all had greater influences on leaf and fine root C:N and C:P rather than N:P. Leaf and fine root C:N, C:P, and N:P were positively correlated, indicating strong coordination between plant above- and below-ground C:N:P stoichiometry.
    Composition and spatial distribution of main species in grassland community of Baiyinhua mining area, China
    CHUN Feng, BAO Gang, ZHANG Wei-qing, SAI Xiyalatu
    2020, 31(10):  3395-3403.  doi:10.13287/j.1001-9332.202010.010
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    We analyzed composition and spatial distribution of main species in the surrounding grassland of Baiyinhua mining area in Inner Mongolia. The results showed that there were 55 plant species in the grassland, with dominant species being Stipa grandis, Carex korshinskyi, and Cleistogenes squarrosa, and common species being Leymus chinensis, Agropyron cristatum, and Anemarrhena asphodeloides. The accumulative relative importance value of those six species was 79.6%, with their densities being 26.6, 204.7, 105.4, 107.1, 68.2 and 55.1 individuals·m-2, respectively. The population density of those six species was modeled by the semi-variance function. The population distribution was in accordance with the exponential model, exponential model, exponential model, spherical model, linear model and Gaussian model, respectively. Through analyzing the spatial distribution pattern, structure ratios were 59.2%, 97.2%, 89.1%, 94.5%, 62.6% and 72.1%, respectively. The spatial autocorrelation of C. korshinskyi, C. squarrosa and L. chinensis populations was mainly affected by structural factors, whereas S. grandis, A. cristatum and A. asphodeloides were mainly affected by random factors. According to results from the fractal dimension analysis, population distribution patterns of S. grandis, C. korshinskyi, C. squarrosa and A. cristatum were simple, and the spatial dependence was strong. Both L. chinensis and A. asphodeloides showed contrasting patterns with those four species. From 2D and 3D images, S. grandis and A. asphodeloides showed gradient diffusion, while C. korshinskyi, C. squarrosa, L. chinensis and A. cristatum showed patch distribution. The results showed that the spatial distribution of the main species in this grassland community did not correlate with mining.
    Effects of biological soil crusts on solute transport characteristics of sandy and loessal soils on the Loess Plateau, China
    WANG Fang-fang, XIAO Bo, SUN Fu-hai, LI Sheng-long
    2020, 31(10):  3404-3412.  doi:10.13287/j.1001-9332.202010.025
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    Biological soil crusts (BSCs) greatly change surface soil structure and nutrient enrichment processes in arid and semiarid regions. However, their impacts on solute transport characteristics and nutrient loss are still not clear. In this study, the solute (Cl- and Ca2+) transport experiments were conducted on soils covered by moss-dominated BSCs and uncrusted soil on sandy and loessal soils on the Loess Plateau, respectively. We analyzed the solute transport characteristics of the BSCs covered soil and uncrusted soil in different soil depths (0-5 cm and 5-10 cm). The BSCs mulching generated delay effects on the solute breakthrough process of 0-5 cm soils. The breakthrough time of Cl- in the BSCs covered soil was 3.83 (sandy soil) and 2.09 times (loessal soil) longer than that in the uncrusted soil. The breakthrough time of Ca2+ in the BSCs covered soil was 2.50 and 2.73 times longer than that in the uncrusted soil. Due to the strong influence of BSCs mulching, the pore volume number of the complete solute breakthrough at 0-5 cm depth was higher than that at 5-10 cm depth in the BSCs covered soils. The breakthrough time of Cl- at 0-5 cm depth was increased by 67.3% (sandy soil) and 51.8% (loessal soil) by the BSCs as compared with that at 5-10 cm depth. The breakthrough time of Ca2+ at 0-5 cm depth was increased by 8.0% and 33.7% by the BSCs. The BSCs reduced soil pore water flow velocity by 37.5%-70.2% compared with the uncrusted soil. Except for the sandy soil at 5-10 cm depth, the BSCs increased the solute dispersion coefficient by 1.73-6.29 times and the degree of dispersion by 2.77-20.95 times compared with the uncrusted soils. After the complete breakthrough of solute, the content of Ca2+ in the BSCs layer (0-2 cm) was 4.14 and 2.58 times higher than that in the uncrusted sandy and loessal soils, respectively. In conclusion, our results indicated that BSCs could reduce the deep percolation and loss of nutrients accumulated in surface soil through improving their solute adsorption and retention abilities, which is of great significance for the improvement of soil fertility and vegetation restoration on degraded land in arid and semiarid regions.
    Synergistic effects of organic fertilizer coupled with phosphate-solubilizing and nitrogen-fixing bacteria on nutrient characteristics of yellow-brown soil under carbon deficiency
    WANG Zhi-kang, XU Zi-heng, CHEN Zi-yun, FU Xiang-xiang
    2020, 31(10):  3413-3423.  doi:10.13287/j.1001-9332.202010.023
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    Understanding the dynamics of phosphate-solubilizing and N2-fixing bacteria on soil nutrient and related enzyme activity under different organic fertilizer proportions (OFP) could provide references for screening appropriate inoculant type, OFP, and fertilization period. Here, we set four OFP levels (mass ratio: 0%, 4%, 8%, 12%) and inoculated two phosphate-solubilizing bacteria (Bacillus megaterium, Pseudomonas fluorescens) and two N2-fixing bacteria (Azotobacter chroococcum, Azospirillum brasilence) in the subtropical yellow-brown barren soil. After a 60-day soil incubation under controlled conditions (28 ℃, darkness), we examined the impacts of single/mixed applications of beneficial bacteria on soil available nutrients and related enzyme activities at different OFP levels and different sampling times (3rd, 8th, 16th, 30th, 45th, 60th day). The results showed that soil available nutrient contents increased with the elevated OFP levels, and exhibited as 12%>8%>4%>0%. With the extension of culture time, soil nutrient contents in all treatments first increased and then decreased. Compared with the single application of organic fertilizer, combined application of organic fertilizer and bacterial inoculants resulted in higher and longer improvement of soil nutrient contents and enzyme activities. The effects of inoculants on soil nutrient properties varied across four OFP levels. When the OFP was low (0-4%), inoculation significantly increased soil available nutrient contents, with no the differences between inoculants at the initial stage. However, with the extension of the culture time and the elevation of OFP, phosphate-solubilizing bacteria (especially for B. megaterium) significantly increased available phosphorus content while N2-fixing bacteria (especially for A. brasilence) significantly increased available nitrogen content. The mixed inoculant with four strains showed phosphate-solubilizing effect on soil and performed better than the single application of phosphate-solubilizing bacteria, but without prominent effect on nitrogen fixation. Soil nutrient contents were positively correlated with enzyme activity, which was affected by both cultural time and carbon-nitrogen ratio. Bacterial inoculations could significantly increase nutrient contents in the short term, but the specific functions of beneficial bacteria on soil were highly dependent on organic carbon input and carbon-nitrogen ratio. Coupled application of inoculants and organic fertilizer at an appropriate OFP level (8%-12%) could increase and extend the soil-remediating effects, while the inoculation should be conducted with an interval of 45-60 days to ensure the survival rate and the consecutive effect on soil.
    Effects of biochar application combined with nitrogen fertilizer on soil physicochemical pro-perties and winter wheat yield in the typical ancient region of Yellow River, China
    LI Chuan-zhe, ZHANG Huan, YAO Wen-jing, XU Cong, WU Di, WANG Ji-dong, AI Yu-chun, ZHANG Yong-chun
    2020, 31(10):  3424-3432.  doi:10.13287/j.1001-9332.202010.028
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    The aims of this study were to reveal the effects of biochar application combined with nitrogen fertilizer on soil physicochemical properties and crop yield in the typical ancient region of Yellow River, and to clarify the dynamics of carbon and nitrogen content and soil physicochemical properties with different treatments of biochar and nitrogen, which could provide scientific basis for reasonable fertilization of soil, quality improvement of cultivated land, and yield increase of winter wheat. A two-year field experiment was conducted with different biochar applications (0, 15, 30 t·hm-2) combined with different nitrogen levels (N 270, 330 kg·hm-2) to investigate their effects on soil physicochemical property in the typical ancient of Yellow River. After 2-yr biochar application, the generalized soil structure index (GSSI) was increased and three-phase structure distance index of soil (STPSD) was decreased, and three-phase ratio was significantly improved. The most ideal state of three-phase ratio was in the condition of 30 t·hm-2 biochar application. Soil compactness and bulk density was decreased, total porosity and capillary porosity was increased, water holding capacity was improved, water and gas permeability was enhanced, and soil hardening was relieved. The composition of soil aggregate was also changed. Soil aggregate >0.25 mm particle size was increased by 70.6%-94.4%, and mean weight diameter (MWD) was improved by 24.0%-48.0%. Biochar application significantly increased organic carbon content by 15.8%-67.0%, adjusted soil C/N, reduced nitrogen release intensity, improved utilization rate of nitrogen fertili-zer, and enhanced soil fertility. However, it didn't increase soil pH. Soil pH showed a significant downward in 10-20 cm layer. With the same amount of nitrogen application, biochar application significantly increased average yield of winter wheat by 9.6%-25.6% in two years. With the same amount of biochar application, average yield of winter wheat with high nitrogen application was 2.5%-4.4% higher than that with conventional nitrogen application. In summary, combined biochar and nitrogen application could improve soil micro-environment, soil fertility and crop yield. Comprehensively considering soil modification, crop yield improvement and input cost, the optimum amount of fertilization was biochar application (30 t·hm-2) combined with nitrogen fertilizer (330 kg·hm-2).
    Effects of phytase Q9 on the yield and senescence characteristics of summer maize shaded in the field
    HUANG Xin-hui, REN Bai-zhao, ZHAO Bin, LIU Peng, ZHANG Ji-wang
    2020, 31(10):  3433-3444.  doi:10.13287/j.1001-9332.202010.024
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    Light shortage in the canopy of summer maize resulted from the decrease of solar radiation and the increase of planting density in Huanghuaihai region could reduce maize yield. In order to explore the effects of phytase Q9 on leaf senescence characteristics of summer maize, three sha-ding treatments with summer maize hybrid ‘Denghai 605' (DH605) were conducted, including shading at flowering to maturity stage (S1), shading at ear stage (S2), and shading at whole growth stage (S3) with natural lighting in the field as control (CK). Chemical control reagent phytase Q9 was used to regulate the shading treatments (the original solution was diluted by 100 times) and the CK exogenously, namely shading at flowering to maturity stage-phytase Q9 (S1Q), shading at ear stage-phytase Q9 (S2Q), and shading at whole growth stage-phytase Q9 (S3Q), and natural lighting-phytase Q9 (CKQ), with spraying water at the same stage as the control. The results showed that leaf area index (LAI), soil-plant analysis development (SPAD) value and net photosynthetic rate of summer maize was significantly reduced by shading, which led to decreases of yield. The activities of superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) in ear-leaf decreased. The content of malondialdehyde (MDA) and free proline increased, and that of soluble protein decreased. The spraying phytase Q9 significantly increased LAI, SPAD and net photosynthetic rate in S3Q and S2Q. MDA and free proline content in S3Q, S2Q, and S1Q were significantly decreased, and soluble protein content and POD activity was significantly increased. SOD and CAT activities in S2Q and S3Q were significantly increased. The yield of S3Q, S2Q and S1Q were 19%, 8% and 7% higher than that of S3, S2 and S1 respectively. There was no significant difference between CKQ and CK. In conclusion, phytase Q9 could effectively alleviate the negative impact of low light on yield formation of summer maize, and increase grain yield by improving photosynthetic capacity of leaves and delaying leaf senescence.
    Effects of straw returning and fertilization on soil fertility and yield and quality of edible sweetpotato
    LIU Ming, ZHANG Ai-jun, CHEN Xiao-guang, JIN Rong, ZHAO Peng, JIANG Wei, TANG Zhong-hou
    2020, 31(10):  3445-3452.  doi:10.13287/j.1001-9332.202010.022
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    Two-year field experiments were conducted in 2017-2018 to examine the effects of wheat straw returning and fertilization on soil fertility and enzyme activities, as well as the yield and qua-lity of edible sweetpoato. There were five treatments, including conventional fertilization+zero straw (CK), conventional fertilization+50% straw returning (50%S), zero fertilization+100% straw returning (100%S-F), conventional fertilization+100% straw returning (100%S), conventional fertilization+100% straw retuning+150 kg N·hm-2 (100%S+N). The treatments of straw returning and fertilization significantly increased the contents of available phosphorus (P), hydroly-zable nitrogen (N), total N, and organic matter in soils, and increased the activities of soil catalase, alkaline phosphorylase, urease, and invertase. The storage root yield, single root fresh weight and commodity potato rate were significantly increased under the treatments of straw returning and fertilization. The storage root yield was the lowest under the treatment of 50%S. After two years of straw returning, storage root yield and commodity potato rate were the highest under the treatment of 100%S. In general, the contents of starch and protein in sweetpotato were increased after two years of straw returning and fertilization, but the contents of reducing sugar and soluble sugar were decreased under 100%S and 100%S+N treatments. Our results suggested that straw returning in full quantity was better than straw returning in half quantity. The storage root yield and commodity potato rate was the highest under the combination of full quantity straw returning and conventional fertilization, with the taste of sweetpotato being changed. Thus, the amount of nitrogen fertilizer should be appropriately reduced in actual practice.
    Responses of root physiological characteristics of different drought-tolerant cotton varieties to drought
    LI Jun-hong, WANG Yuan-yuan, XIA Jun, GAO Hong-yun, SHI Xiao-juan, HAO Xian-zhe, LUO Hong-hai
    2020, 31(10):  3453-3460.  doi:10.13287/j.1001-9332.202010.021
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    In order to explore the physiological responses of root system of different drought-resistant cotton varieties to drought and their relationships with biomass, we examined the effects of drought stress on root vigor, antioxidant enzyme activities and anatomic structure (duct diameter, number) and biomass of different drought-tolerant varieties, including the drought-inolerant variety ‘Xinluzao 17' (L17) and the drought-tolerant variety ‘Xinluzao 22' (L22). Both varieties were grown under soil column cultivation conditions, with conventional irrigation (CK), mild drought (W1) and moderate drought (W2) treatments. The results showed that drought stress caused significant reductions in soluble protein (SP) content, root vigor (RV), the number of cork layers, the number of rhizome ducts, the diameter of the ducts in both varieties. The higher root MDA content, CAT, POD and SOD activities in response to drought led to reduction of aboveground dry mass. Compared with that of L17, SP content, 0-40 cm and 80-120 cm soil layer RV, the number of cork layers, the number of rhizome ducts, the diameter of ducts, and the aboveground dry mass of L22 all signi-ficantly increased. Under the W2 treatment, the RV decrease of L22 was 26.2% lower than that of L17, and CAT, POD, SOD activities and the thickness of cortex were 43.6%, 6.9%, 25.4%, 19.9% higher than that of L17. There were positive correlations between dry mass and RV, SOD, POD, the number of cork layers, the diameter and number of rhizome ducts. Therefore, cotton variety with strong drought tolerance could maintain higher root activity, cork layer number, the diameter of rhizome ducts, and number under drought conditions, and thus promote the accumulation of aboveground biomass, which was the physiological mechanism for their stronger drought tolerance.
    Responses of soil moisture and photosynthetic characteristics to mulching materials and ridge-to-furrow ratios in rapeseed fields in southwest dryland of China
    XING Yi, ZHANG Kang-ping, WANG Zhi-yuan, ZHANG Xiao-duan, WU Hai-yan, RAN Tai-lin, XIANG Xin-hua, WANG Long-chang
    2020, 31(10):  3461-3472.  doi:10.13287/j.1001-9332.202010.027
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    In order to deal with the frequent seasonal drought and improve water use efficiency and crop photosynthetic efficiency in drylands of southwest China, a field experiment was conducted to investigate the effects of different mulching materials (common white film, common black film, biodegradable film and no film) and ridge-to-furrow ratios (40 cm:40 cm and 40 cm:80 cm) on soil water storage, as well as photosynthetic characteristics, fluorescence parameters and chlorophyll relative content (SPAD) of rapeseed, with the flat planting as the control. The results showed that the average soil water storage under different mulching materials followed the order: ridge with common black film (BR) ≈ ridge with common white film (WR) ≈ ridge with biodegradable film (BDR) > ridge with no film (NR) > flat planting (FP). Meanwhile, ridge-to-furrow ratios did not affect soil water storage. The net photosynthetic rate, stomatal conductance and fluorescence para-meters (Fm, Fv, Fv/Fm, Fv/Fo, qP and qN) of rapeseed under ridge-furrow with film mulching was higher than those under flat planting. Compared with control, SPAD value was improved by 6.1%, 8.6%, 8.5% and 3.6% under WR, BR, BDR and NR, while instantaneous water use efficiency (IWUE) was increased by 18.3%, 11.4%, 16.3% and 10.4% under those treatments, respectively. Rapeseed yield under BR, WR and BDR was significantly higher than that in control, while NR did not increase yield. The treatment of ridge with common black film + 40 cm:40 cm as ridge-to-furrow ratio could gain the highest economic benefit. Ridge-furrow planting of rainfall harvesting could improve soil moisture, increase crop photosynthetic capacity, and raise yield and economic income in rapeseed fields in drylands of southwest China.
    Impacts of shading on seedling growth and mineral accumulation in Paeonia lactiflora
    ZHAN Li-jie, ZHANG Hong-bao, LI Zong-tai, MENG Wei, XU Wei, LI Ling-hao
    2020, 31(10):  3473-3479.  doi:10.13287/j.1001-9332.202010.029
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    Shading is one of the important strategies to protect seedlings of Paeonia lactiflora. The effects of shading treatments on seedling growth and mineral accumulation of Duolun P. lactiflora were investigated in a greenhouse experiment to provide guidance for P. lactiflora cultivation. One week after emergence, seedlings were treated with 20%, 40%, 60% or 80% shading for two months, with no-shading as the control (CK). The results showed that shading treatments significantly increased plant height by 19.9%, 31.1%, 52.9%, and 63.7%, respectively. However, shading significantly reduced the root mass ratio and root to shoot ratio by 21.5%, 23.6%, 29.2%, 41.8% and 40.6%, 44.0%, 50.9%, 63.2%, respectively. Moreover, 40%, 60% and 80% shading significantly increased specific leaf area by 77.0%, 84.1% and 65.2%, and significantly increased chlorophyll content by 92.3%, 128.7%, 98.1%, and increased carotenoid content by 86.9%, 113.1% and 90.5%, respectively. The treatments of 40%, 60%, and 80% shading significantly decreased root biomass by 61.4%, 74.3% and 78.6%, respectively. Compared with CK, 20%, 40% and 80% shading, the 60% shading treatment increased root phosphorus content by 245.7%, 65.9%, 40.5% and 10.3%, increased potassium content by 102.9%, 131.7%, 57.0%, 63.3% and magnesium content by 131.3%, 55.1%, 40.4%, 7.7%, respectively. 60% shading was an appropriate shading intensity for P. lactiflora seedling cultivation based on local conditions in Duolun.
    Application of evaporative demand drought index (EDDI) in drought identification of Liaoning Province, China
    LIU Dong-ming, JI Rui-peng, CHEN Peng-shi, ZHANG Wei-wei, LI Jing
    2020, 31(10):  3480-3488.  doi:10.13287/j.1001-9332.202010.011
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    The evaporative demand drought index (EDDI) is a multi-scale drought index developed from the atmospheric evaporation demand (E0). EDDI is independent of precipitation and suitable to different underlying surfaces, which can well capture water stress signals at different time scales. Based on the meteorological observation data at 52 stations in Liaoning Province from 1961 to 2018, we estimated daily E0, calculated EDDI at six time scales (annual, growing season, spring, summer, autumn and winter), and further identified the interannual variability of drought occurrence in Liaoning Province for the past 58 years. The results showed that EDDI had obvious interannual variation, with two high concentration periods in multiple time scales. In the 1960s, when there were many years and serious drought in Liaoning Province, high EDDI values were concentrated at the five time scales (annual, growing season, spring, autumn and winter). 2014-2018 was another relatively concentrated period of EDDI high value at all time scales except winter. In 1981-1982, the values of EDDI were high at the time scales of the annual, growth season, summer and autumn. The periods of 1963-1965 (except summer), 1972-1973 (growth season, summer), 1989-1990 (annual, growth season, spring and winter), 1997-1998 (annual, growth season and summer), 2004-2005 (spring and winter) and 2013-2014 (annual, growth season and autumn) occurred abrupt alternation from dry to wet or from wet to dry. In 1985-1987, 1993-1995 and 2005-2013, Liaoning Province had obvious dry gaps.
    Spatiotemporal variation of reference evapotranspiration in Shanxi Province, China
    LI Na, HUO Zhi-guo, ZHOU Xiao-yu, BAI Qin-feng, PEI Xiu-miao, QIAN Jin-xia
    2020, 31(10):  3489-3498.  doi:10.13287/j.1001-9332.202010.012
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    Based on data of daily precipitation, temperature, sunshine hours, relative humidity, wind speed and vapor pressure of 70 meteorological stations from 1960 to 2019 in Shanxi Province, the Penman-Monteith model was applied to calculate the reference evapotranspiration (ET0). The spatiotemporal variations of ET0 as well as the ET0 in different climatic zones and at different altitudes were quantitatively analyzed. The results showed that the mean annual ET0 decreased from west to east in 1960-2019. A jumping point was detected in 1982, with the mean annual ET0 increased both in 1960-1982 and 1983-2019. The monthly and ten-day changes of ET0 showed single peak curves. The variation of ET0 in different climatic zones was as follows: ET0 in temperate and semi-arid areas was higher than that in warm temperate and semi-humid areas and warm temperate and semi-arid areas in spring, summer, autumn and the whole year, while in winter, the highest ET0 was in warm temperate and semi-humid areas. ET0 varied with altitudes, with ET0 in <660 m altitude areas being higher than that in other altitudes in summer, autumn, winter and the whole year.
    Characteristics and driving forces of wetland landscape pattern evolution of the city belt along the Yellow River in Ningxia, China
    GAO Zu-qiao, BAI Yong-ping, ZHOU Liang, QIAO Fu-wei, SONG Long-jun, CHEN Xiao-ning
    2020, 31(10):  3499-3508.  doi:10.13287/j.1001-9332.202010.013
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    Wetlands are one of the most productive ecosystems in the world, with functions of water purification, climate regulation, and carbon sinks. Due to the stresses caused by human social development and changes of natural conditions, wetlands have been seriously damaged. We examined the evolutionary law of landscape pattern of wetland along the Yellow River, and acquainted the current situation of wetland resources and dynamic change. Based on satellite images of year 2000, 2009, and 2018 from Landsat, we used landscape indices and geographic detectors to quantitatively analyze the characteristics and driving forces of wetland landscape pattern evolution of the city belt along the Yellow River in Ningxia from 2000 to 2018. The results showed that the wetland area of the city belt along the Yellow River in Ningxia enlarged first and then decreased from 2000 to 2018. The wetland area increased by 52.2 km2 in the early stage of the study with an increasing rate of 8.2%, and decreased by 26.8 km2 with a reduction rate of 3.9% in the later stage. The wetland was mainly transformed to construction land and unused land, with transfer out area being 166.7 and 158.4 km2 respectively. New wetland was mainly transformed from unused land, forest, and grassland, with an area of 543.1 km2. The fragmentation degree of wetland landscape in city belt was increasing, the balanced distribution of all kinds of wetlands was gradually strengthened, the landscape diversity was increasing, and the dominant landscape types were gradually weakening. Natural factors and socio-economic factors jointly affected the evolution of wetland landscape pattern in city belt. Among all socio-economic factors population was the most important one. Among natural factors, precipitation and temperature were important. Other driving factors were relatively weak, but could not be ignored.
    Assessing soil pH in Anhui Province based on different features mining methods combined with generalized boosted regression models
    WANG Shi-hang, LU Hong-liang, ZHAO Ming-song, ZHOU Ling-mei
    2020, 31(10):  3509-3517.  doi:10.13287/j.1001-9332.202010.018
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    We explored the application of different feature mining methods combined with genera-lized boosted regression models in digital soil mapping. Environmental covariates were selected by two feature selection methods i.e., recursive feature elimination and selection by filtering. Using the original environmental covariates and the selected optimal variable combination as independent varia-bles, soil pH prediction model of Anhui Province was established and mapped based on the genera-lized boosted regression model and random forest model. The results showed that both kinds of feature mining methods could effectively improve the accuracy of soil pH prediction by generalized boosted regression models and random forest model, and could reduce dimensionality. Compared with the random forest model, the prediction accuracy of the validation set of the generalized boosted regression model was slightly lower. In the training set, the accuracy of the generalized boosted regression models was much higher than that of the random forest model, with higher interpretation and better overall effect. The main parameters of the random forest model, ntree and mtry, had limi-ted effect on the model. Different parameters and their combination could affect the prediction accuracy of the generalized boosted regression models, and thus should be tuned before modeling. The results of spatial mapping showed that soil pH in Anhui Province showed a pattern of “south acid and north alkali”.
    Zonation on non-point source pollution risk in the lower reaches of Zijiang River based on the “source-sink” theory
    JIA Yu-xue, SHUAI Hong, HAN Long-fei
    2020, 31(10):  3518-3528.  doi:10.13287/j.1001-9332.202010.017
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    Non-point source pollution risk assessment and zonation research are of great significance for the eco-environmental protection and optimization of land use structure. We identified the “source” and “sink” landscape using the “source-sink” landscape pattern theory based on the two phases of land use data in the lower reaches of Zijiang River in 2010 and 2018. We comprehensively considered the non-point source pollution occurrence and migration factors, and used location-weighted landscape contrast index (LCI) and non-point source pollution load index (NPPRI) to analyze non-point source pollution risk spatio-temporal characteristics in the study area. Zonation on non-point source pollution in the lower reaches of Zijiang River was studied by identifying the key factors of non-point source pollution risk. The results showed that the overall risk of non-point source pollution was relatively low. The sub-basin with “sink” landscape was the main type, accounting for 61.2%. Non-point source pollution risk was low in the southwest and was high along the banks of Zhixi River, Taohua River and main stream of Zijiang River, as well as plain in the northeast of the lower Zijiang River. The risk of non-point source pollution from 2010 to 2018 showed an increasing trend. The changes in landscape pattern, especially the expansion of rural settlement, arable land and the shrinkage of forest land had positive and negative responses to the risk of non-point source pollution, respectively. LCI, slope, and distance were the key factors affecting the change of the risk index of non-point source pollution. The lower reaches of the Zijiang River could be divided into four control regions: pollution treatment area near river, low slope pollution control area, ecological restoration-risk prevention and control area, and ecological priority protection area.
    Decomposition of driving factors of industry-related CO2 emissions and its decoupling with economic growth in Fujian Province, China
    LAI Wen-ting, WANG Yuan, HUANG Lin-lin, HUANG Yi-min, LUO Jin, CHEN Hua-yang
    2020, 31(10):  3529-3538.  doi:10.13287/j.1001-9332.202010.016
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    The emission of CO2 from major sectors and key industries are the predominant sources of regional CO2 emissions. It is the prerequisite to promote sectoral carbon emissions reduction, to cla-rify their influencing factors and investigate their relationship with regional economic growth. It is also of great significance for the implementation of regional total carbon emissions control. Using the Logarithmic mean Divisia index method (LMDI) and the Tapio decoupling model, we analyzed the driving factors, and decoupling status with economic growth of 13 major carbon emissions industries in Fujian Province from 1997 to 2017. The results showed that the electricity and heat production and supply industry was the major source of CO2 emissions in Fujian Province, with an increase of 101.74 Mt (from 18.89 Mt to 120.63 Mt) during the period 1997 to 2017. The top three industries with the fastest annual growth rate in CO2 emissions were non-ferrous metal smelting and rolling processing industry (18.1%), textile industry (12.1%), and ferrous metal smelting and rolling processing industry (12.1%). Among the influence factors for the changes in carbon emissions in 13 major industries, economic growth effect and population scale effect were the main positive driving factors, while the restraining effects of energy structure, energy intensity, and industrial structure were continuously increasing. In terms of decoupling relationship, the decoupling index between economic growth and industry-related CO2 emissions showed a downward trend on the whole. Since the 11th Five-Year-Plan period, some industries had begun to show strong decoupling to some extent. The farming, forestry, animal husbandry, fishery and water conservancy industry exhibited expansive negative decoupling, whereas the electricity and heat production and supply industry exhibited weak negative decoupling during 13th Five-Year Plan period. The effects of energy structure and energy intensity had substantial impacts on the decoupling with economic growth for various industries. The industrial structure effect had a smaller impact on the decoupling with economic growth, while the population scale effect had almost no impact.
    Differences in the tolerance and accumulation of arsenate in the consortia with various proportions of Chlorella salina and Bacillus subtilis
    YU Qing-nan, CHEN Shuang-shuang, ZHENG Chao, ZHANG Chun-hua, GE Ying
    2020, 31(10):  3539-3546.  doi:10.13287/j.1001-9332.202010.032
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    We constructed consortia of Chlorella salina and Bacillus subtilis with various alga-bacterium ratios (1:0, 1:1, 1:2, 1:3, 1:4). After being treated with arsenate [As(Ⅴ)] for 7 d, we measured the growth, As accumulation, adsorption and absorption, and As speciation transformation of consortia. Results showed that the chlorophyll content, dry weight, and specific growth rate of the symbiont increased significantly with increasing B. subtilis ratio after the As(Ⅴ) treatment, being 1.81 mg·L-1, 125.0 mg, and 0.28 mg·L-1·d-1 under the condition of the alga-bacterium ratio being 1∶4 and As(Ⅴ) being 750 μg·L-1, respectively. The accumulation and absorption of As by the consortia decreased with the bacterial proportion increasing from 1:0 to 1:4. As accumulation changed with the As concentration, with a dominance of absorption under 75-150 μg·L-1 As(Ⅴ) and a dominance of adsorption under 300-750 μg·L-1As(V). There were As(Ⅴ) and As(Ⅲ) in the consortia. When the proportion of bacteria increased, the rate of As(Ⅴ) reduction enhanced (up to 12.6%). Our results indicated that the increases of B. subtilis improved As(Ⅴ) tolerance and reduction, but decreased the As(Ⅴ) accumulation by the symbiont.
    Effects of sawdust dosage on the diversity and community structure of bacteria associated with the hyphae of Pleurotus eryngii
    XU Xin, LIU Ting, KONG Xu-qiang, CHEN Jian-qiu, CHEN Li-ding, HUANG Sheng, SUN Shu-jing
    2020, 31(10):  3547-3553.  doi:10.13287/j.1001-9332.202010.036
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    Some fungi engage symbiosis with bacteria, which can effectively promote the metabolism and growth of fungi. The diversity and community structure of bacteria can reflect the growth and substrate utilization of fungi. In this study, we analyzed the effects of different sawdust dosages on the community structure and diversity of bacteria associated with the hyphae of Pleurotus eryngii using high-throughput sequencing technology (HST) based on PCR-amplified 16S rRNA V3-V4 fragments. The results showed that the high-quality sequences from five groups of mycelia samples were clustered into 25 phyla, 52 classes, 114 orders, 199 families, and 406 genera. Proteobacteria (35.0%-85.9%) and Firmicutes (6.5%-38.4%) were the most abundant bacterial phyla, while Acinetobacter (14.8%-71.6%) and Pseudomonas (1.7%-22.3%) were the dominant symbiotic genera. Compared with the mycelia grown on the complete culture medium, sawdust addition could increase the diversity of bacteria coexisting with P. eryngii mycelia, and change the community structure of 10 dominant phyla and 9 dominant genera. P. eryngii cultivated in substrate containing 5 g sawdust had the fastest mycelium growth rate, thick mycelia, and neatly edges. Furthermore, judging from the abundance and diversity, Pseudomonas and Lactobacillus became the dominant genera, which were positively correlated with the mycelia growth vigour. Sawdust, as an important carbon source, could affect the growth and development of P. eryngii and the community structure and diversity of bacteria coexisting with mycelia. This study would lay a theoretical foundation for exploring the molecular mechanism of sawdust and mycelium symbiosis affecting the growth and development of P. eryngii.
    Effects of four aphid species on development and reproduction of Harmonia axyridis
    SUN Li-juan, YU Hai-xia, ZHENG Chang-ying
    2020, 31(10):  3554-3558.  doi:10.13287/j.1001-9332.202010.030
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    To examine the suitability of Myzus persicae, Lipaphis erysimi, Semiaphis heraclei and Aphis gossypii to propagation of Harmonia axyridis population, we studied the development and reproduction of this ladybird by constructing two-sex life table in the laboratory with those four aphid species as diet. The results showed that the immature duration of H. axyridis decreased in an order of L. erysimi (18.18 d), A. gossypii (17.48 d), S. heraclei (16.23 d), and M. persicae (15.77 d). The survival rates of preadult period were S. heraclei (88.3%), M. persicae (86.7%), L. ery-simi (55.0%), and A. gossypii (55.0%). The fecundity of those species were S. heraclei (1750.5), M. persicae (1441.5), A. gossypii (1006.3), and L. erysimi (965.2). The longevity of adult ladybird were S. heraclei (78.8 d), M. persicae (63.1 d), A. gossypii (54.3 d), and L. erysimi (48.4 d). The intrinsic rate of increase (rm) of H. axyridis population decreased in an order of M. persicae (0.19), S. heraclei (0.18), L. erysimi (0.14), and A. gossypii (0.14). The net reproduction rates (R0) were S. heraclei (895.83), M. persicae (600.62), L. erysimi (273.47), and A. gossypii (268.33). Among those four aphid species, S. heraclei and M. persicae were more suitable for the propagation of H. axyridis population.
    Trophic structure of pelagic fishery organism assemblage in the central and western South China Sea in spring revealed by carbon and nitrogen stable isotope analysis
    KONG Ye-fu, WU Zhong-xin, YAN Yun-rong, TIAN Tao, GAO Dong-kui, YANG Jun, WU Ying-chao
    2020, 31(10):  3559-3567.  doi:10.13287/j.1001-9332.202010.038
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    Carbon and nitrogen stable isotope analysis was carried out on pelagic fishery organisms caught in light traps and falling nets in the central and western South China Sea in the spring of 2018. The stable isotope values of the sampled individuals were used to elucidate the isotopic variations for the pelagic fishery organisms, to classify species into trophic functional groups, and to compare the differences of trophic structure among the classified trophic functional groups. The results showed that among 23 fishery species the mean δ13C value of Coryphaena hippurus was the lowest (-17.58‰±0.21‰), and that of Grammistes sexlineatus was the highest (-19.86‰±0.33‰). The mean δ15N values ranged from 8.31‰ in Psenes cyanophrys to (12.46±0.74)‰ in Chirocentrus dorab. The continuous trophic spectrum indicated that the trophic level (TL) for the sampled pela-gic fishery organisms ranged from 3.01 to 4.23, of which 19 species (83% of the total) fell between TL 3.0 and 4.0. The 23 species of fishery organisms were classified into three trophic functional groups, i.e., plankton feeding functional group (PFFG), nekton feeding functional group (NFFG), and mixed feeding functional group (MFFG). The analysis of standard ellipse area (SEA) showed that the PFFG occupied the largest trophic niche width (SEA=1.56‰2), followed by the MFFG (SEA=0.99‰2) and NFFG (SEA=0.31‰2). The MFFG overlapped with PFFG and NFFG in the trophic niche, with a relative percentage of 17% and 26%, respectively. There was no overlap between PFFG and NFFG.
    Reviews
    Carbon and nitrogen stable isotopes technology in the researches on alpine meadow ecosystem in Qinghai-Tibet Plateau: Progress and prospect
    ZHOU Chun-li, LI Yi-kang, CAO Guang-min, PENG Cuo-ji, SONG Ming-hua, XU Xing-liang, ZHOU Hua-kun, LIN Li
    2020, 31(10):  3568-3578.  doi:10.13287/j.1001-9332.202010.026
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    Carbon and nitrogen stable isotopic technique has been widely used in research of glassland ecosystems. Here, we summarized studies using carbon and nitrogen stable isotopes in the alpine meadow ecosystem on the Qinghai-Tibet Plateau. Firstly, we reviewed the environmental factors which influenced carbon and nitrogen isotope composition (δ13C and δ15N) of plants and soils in alpine meadow, such as altitude, moisture, fertilization, grassland degradation, and temperature. The values of plant δ13C were positively correlated with altitude, and negatively correlated with atmospheric pressure, grassland degradation and temperature. The relationship between plant δ13C and precipitation was non-linear. The values of soil δ13C were positively correlated with altitude and grassland degradation. The values of plant δ15N were positively correlated with soil moisture and fertilization, and negatively correlated with grassland degradation. Secondly, we reviewed the current application and progresses of 13C and 15N in the identification of plant photosynthetic type, water use, nutrient transport along food chain and carbon and nitrogen cycle in the alpine meadow. Finally, we prospected the 13C and 15N isotopes application in researches on soil organic carbon and soil respiration in the alpine meadow, transitions of vegetation type, and climate change, soil N2O trace, exploration of vegetation degradation, identification of the origin of Tibetan medicine and animal food, etc. 13C and 15N isotopes could be widely used and play important roles in researches on the alpine ecosystems.
    Representation, analysis and application of landscape graph based on graph theory
    SONG Li-li, QIN Ming-zhou, ZHANG Peng-yan, XIA Yi-fei, MA Jie, CAO Wei
    2020, 31(10):  3579-3588.  doi:10.13287/j.1001-9332.202010.014
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    Landscape structure and spatial pattern are the core issues in landscape ecology. The application of graph theory provides a research framework for landscape pattern analysis. Landscape graph based on graph theory is gradually applied to the connectivity modeling of biodiversity conservation and decision support of landscape planning. The representation, analysis and application of landscape graph have become a hot topic in conservation biology and landscape ecology. In this review, we first introduced the graph theory basis of landscape map. Based on the Scopus database, 257 published journal papers with the words “landscape graph”, “connectivity” and “network” in titles, abstracts, and keywords from 1993 to 2019 were retrieved. We analyzed the research progress and development trend of this field from the aspects of annual published papers, journal sources, research areas, research institutions and landscape types involved. The results showed that before 2017, the number of journal papers published showed an overall increasing trend, and after 2017, the annual number of published papers decreased year by year. The main research forces were concentrated in United States, France, Canada, and China, contributing to 86.8% of the total published papers. Most of the research results were published in “Landscape Ecology”, “Landscape and Urban Planning”, and “Biological Conservation”. In the research content, the representation of landscape graph mainly included the definition of nodes, the measurement of edges and the simulation of landscape. The analysis of landscape graph involved analysis index and landscape graph partitioning. This study mainly focused on the application of landscape graph in science and practice, including biodiversity conservation, landscape (ecological network) planning and management, the assessment of landscape impacts. Landscape graph based on graph theory influences conservation science and planning practitioners by helping understand landscape connectivity changes, animal behavior and habitat conservation. The impact of graph theory on conservation science and planning comes from the rich theoretical basis and mature research methods. Landscape graph based on graph theory provides a springboard for ecological understanding of landscape structure and pattern, and is an important tool for global researchers and practitioners.
    Mechanism of arbuscular mycorrhizal fungi improve the oxidative stress to the host plants under salt stress: A review
    SUN Si-miao, CHANG Wei, SONG Fu-qiang
    2020, 31(10):  3589-3596.  doi:10.13287/j.1001-9332.202010.040
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    Soil salinization induced by the dual effects of natural environment and human activities is a serious ecological problem globally. Salinization caused osmotic imbalance, ion stress, oxidative damage, and other hazards to plants, leading to retard, reduce biomass and even total crop failure. Arbuscular mycorrhizal fungi (AMF) is a group of beneficial microorganism with wide distribution. AMF can form symbiotic relationship with most plant roots, with ecological significance in various stressed ecosystems. Because of the highly effective antioxidative system in symbionts, AMF could improve plant anti-oxidative response under salt stress and enhance their tolerance to salt stress. Here, we reviewed the research progress of arbuscular mycorrhizal symbiosis in improing plant antioxidative mechanism, including oxidative damage, osmotic regulation, antio-xidant mechanism and bioactive molecules. Finally, research prospects were proposed to provide theoritical support for improving plant salt tolerance by mycorrhizal biotechnology.