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Table of Content

    18 January 2018, Volume 29 Issue 1
    CONTENTS
    Simulation on photosynthetic-CO2 response of Quercus variabilis and Robinia pseudoacacia in the southern foot of the Taihang Mountain, China.
    REN Bo, LI Jun, TONG Xiao-juan, MU Yan-mei, MENG Ping, ZHANG Jin-song
    2018, 29(1):  1-10.  doi:10.13287/j.1001-9332.201801.003
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    In this study, leaf photosynthetic CO2-response curves of Quercus variabilis and Robinia pseudoacacia were measured using a Li-6400XT photosynthetic measurement system in the southern foot of the Taihang Mountain, China. The rectangular hyperbola model (RH), nonrectangular hyperbola model (NRH) andYe model (YZP) were used to fit photosynthetic-CO2 response curves and compare photosynthetic parameters, including the maximum net photosynthetic rate (Amax), the initial carboxylation rate (η), light respiration rate (Rp), CO2 compensation point (CCP) and CO2 saturation point (CSP). Compared with the NRH and YZP models, Amax, η, Rp and CCP obtained by the RH model were higher, and were 59.8%, 128.6%, 133.4% and 19.8% higher than the measured values. The accuracy of the RH model was lower and its relative error was higher than that of the NRH and YZP models.Compared with the RH and YZP models, Amax fitted by the NRH model was higher, and was 11.1% higher than the measured value. η, Rp and CCP fitted by the NRH model were closer to the measured values. CO2 saturation phenomenon of photosynthesis could be simulated by the YZP model, and Amax and CSP were fitted well. Amax, Rp and CCP in the shaded leaves of Q. variabilis were 31.3%, 5.2% and 14.3% lower than those in the sunlit leaves. Amax, Rp and CCP in shaded leaves of R. pseudoacacia were 23.5%, 11.0% and 5.4% more than those in the sunlit leaves. η in the shaded leaves of Q. variabilis and R. pseudoacacia were 6.9% and 7.0% higher than those in the sunlit leaves, respectively. Rp and CCP of R. pseudoacacia leaves had linear relationships with temperature (T) and photosynthetic active radiation (PAR), and η had a significant relationship with stomatal conductance (gs). η of Q. variabilis leaves was linearly correlated with PAR and gs, and CCP was affected by T and relative humidity. Amax of Q. variabilis leaves had significant positive linear relationships with RH and gs.
    Effects of selective cutting disturbance on soil phosphorus adsorption and desorption in a Korean pine and broad-leaved mixed forest in the Xiaoxing’an Mountains, China.
    ZHANG Xin, GU Hui-yan, CHEN Xiang-wei
    2018, 29(1):  11-17.  doi:10.13287/j.1001-9332.201801.004
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    This study examined the characteristics of phosphorus (P) adsorption and desorption in surface soil (0-10 cm) of a secondary forest after selective cutting disturbance at three levels of intensity (low, medium, high) in order to reveal the effects of different disturbance intensities on soil P adsorption and desorption. Maximum adsorption amount (Qm), adsorption intensity factor, maximum buffer capacity, maximum desorption amount, average desorption rate and readily desorptable phosphorus were measured. Qm in the focal forests was 1383.93-1833.34 mg·kg-1, and Qm in forests with middle and high disturbance intensities was significantly higher than that in forests with low disturbance intensity and in primary forests. P adsorption intensity was 0.024-0.059 L·mg-1, and forests with high and low disturbance intensities increased the P adsorption intensity significantly. The maximum buffer capacity varied from 35.68 to 97.97 L·kg-1, with the highest value found in the forest with the highest disturbance intensity. Selective cutting significantly reduced the potential for phosphorus supply in the forest soils. The maximum desorption amount, average desorption rate and readily desorptable phosphorus content in the focal forests were 526.32-797.54 mg·kg-1, 14.7%-25.5% and 1.79-5.41 mg·kg-1, respectively, indicating that the ability of soil to release phosphorus significantly decreased with increasing disturbance intensity. Selective cutting changed the phosphorus adsorption and desorption characteristics by reducing the supply and release of soil phosphorus.
    Spatial pattern and interspecific spatial association of tree seedlings in a secondary forest in montane region of eastern Liaoning Province, China.
    ZONG Guo, BAI Xue-jiao, ZHANG Shu-yuan, CAI Jun-qi
    2018, 29(1):  18-24.  doi:10.13287/j.1001-9332.201801.002
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    We established a 4 hm2(200 m×200 m) temperate secondary forest plot in the montane region of eastern Liaoning Province, China, and analyzed the spatial patterns and interspecific spatial associations of tree seedlings at scales of 0-50 m. The results showed that under complete spatial randomness null model, 95% of the species at the scale of 0-20 m showed a significant aggregation pattern, and 19 species at the scale of 0-16 m showed an aggregation pattern. The proportion of species exhibiting aggregated patterns decreased with the spatial scale. At the scale of 50 m, the random distribution pattern became the main form of tree species distribution. Underheterogeneous Poisson process null model, 5% of the species at the scale of 0-24 m showed a significant aggregation pattern, and 42% and 58% of the species at the scale of 26-50 m showed a random distribution and regularity patterns, respectively. Under complete spatial randomness null model, the proportion of species pairs of positive correlation was the highest, and at the scale of 50 m, the proportion of species pairs showed positive correlation, uncorrelated and negative correlation tended to be equal. Under heterogeneous Poisson process null model, species pairs mainly showed negative correlation, and the proportion of species pairs exhibiting negative correlation increased with spatial scale. The results implied that seed dispersal limitation and habitat heterogeneity could explain the aggregation pattern of tree seedlings. The strong aggregation of tree seedlings also contributed to close interspecific spatial associations and poor stability of the regeneration community.
    Storage of carbon and nitrogen in Quercus and Platycladus orientalis plantations at different ages in the hilly area of western Henan Province, China.
    WANG Yan-fang, LIU Ling, LI Zhi-chao, SHI Xiao-feng, YANG Xiao-yan, SHANGGUAN Zhou-ping
    2018, 29(1):  25-32.  doi:10.13287/j.1001-9332.201801.009
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    In the study, the method of space substituting time was used to investigate the distribution pattern of carbon and nitrogen storages in Quercus and Platycladus orientalis plantation ecosystems at different ages in hilly area of western Henan Province, China. We also analyzed the dynamic changes of soil carbon and nitrogen storages in different soil layers in the two plantation ecosystems. The results showed that the carbon storage in the arbor and litter layers increased with the increasing tree age. The storage of carbon and nitrogen in soil aggregated mainly in the surface layer and showed a trend of decrease-increase-decrease with the increasing tree age in all soil layers. The ranges of carbon and nitrogen storage in the surface soil were 20.31-50.07 and 1.68-2.12 t·hm-2 in Quercus plantation, and 23.99-48.76 and 1.59-2.34 t·hm-2 in P. orientalis plantation, respectively. Carbon storage ranges in Quercus and P. orientalis plantation ecosystems at different ages were 52.04-275.82 and 62.18-279.81 t·hm-2, respectively. The carbon sequestration capacity in P. orientalis plantation was a little higher than that in Quercus plantation. Soil C/N increased with the increase of afforestation age.
    Knot attributes of Korean pine plantation based on mixed effect model.
    JIA Wei-wei, CUI Can, LI Feng-ri
    2018, 29(1):  33-43.  doi:10.13287/j.1001-9332.201801.020
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    Based on 1534 knot data from 60 sample trees in a Korean pine plantation in Mengjiagang Forest Farm, Heilongjiang Province, China, mixed effect model of knot attributefactors (knot diameter, sound knot length, year of death of knot and knot angle) of Korean pine plantation was established using NLMIXED and GLIMMIX procedures of SAS software. The prediction accuracy of models was compared using evaluation statistics, such as Akaike information criterion (AIC), Bayesian information criterion (BIC), -2Log likelihood(-2LL), and likelihood ratio test (LRT). Results showed that all of the mixed effect models that considered tree effect performed better than conventional fixed-effect models. For knot diameter models, the model with random parameter combination of b1, b2 had the best performance. For sound knot length models, the model with random parameter combination of b1, b3 had the best performance. For the models of year of death of knot, the model with random variables of knot diameter was proved to be the optimal generalized linear mixed model. For the models of knot angle, the model with randomvariables of intercept, knot diameter, sound knot length was proved to be the optimal generalized linear mixed model. Mixed effect model was more effective than conventional fixed-effect model for describing knot attributes. The combination of knot attributes models and reasonable prunning schemes could improve timber quality of Korean pine which is one of the main commercial tree species in Northeast China.
    Object-oriented segmentation and classification of forest gap based on QuickBird remote sensing image.
    MAO Xue-gang, DU Zi-han, LIU Jia-qian, CHEN Shu-xin, HOU Ji-yu
    2018, 29(1):  44-52.  doi:10.13287/j.1001-9332.201801.011
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    Traditional field investigation and artificial interpretation could not satisfy the need of forest gaps extraction at regional scale. High spatial resolution remote sensing image provides the possibility for regional forest gaps extraction. In this study, we used object-oriented classification method to segment and classify forest gaps based on QuickBird high resolution optical remote sensing image in Jiangle National Forestry Farm of Fujian Province. In the process of object-oriented classification, 10 scales (10-100, with a step length of 10) were adopted to segment QuickBird remote sensing image; and the intersection area of reference object (RAor) and intersection area of segmented object (RAos) were adopted to evaluate the segmentation result at each scale. For segmentation result at each scale, 16 spectral characteristics and support vector machine classifier (SVM) were further used to classify forest gaps, non-forest gaps and others. The results showed that the optimal segmentation scale was 40 when RAor was equal to RAos. The accuracy difference between the maximum and minimum at different segmentation scales was 22%. At optimal scale, the overall classification accuracy was 88% (Kappa=0.82) based on SVM classifier. Combining high resolution remote sensing image data with object-oriented classification method could replace the traditional field investigation and artificial interpretation method to identify and classify forest gaps at regional scale.
    Effects of nitrogen deposition on diversity and composition of soil bacterial community in a subtropical Cunninghamia lanceolata plantation.
    HAO Ya-qun, XIE Lin, CHEN Yueh-min, TANG Cai-di, LIU Xiao-fei, LIN Wei-sheng, XIONG De-cheng, YANG Yu-sheng
    2018, 29(1):  53-58.  doi:10.13287/j.1001-9332.201801.034
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    The increasing rate of atmospheric nitrogen (N) deposition has become the focus of research attention. Soil bacterial community plays an important role in soil nutrient cycling. We stimulated N deposition at the Forest Ecosystem of Fujian Normal University and Global Change Research Station in Chenda Town, Sanming City in the Fujian Province of China. We examined the effect of N deposition on the structure and composition of soil bacterial community using 16S rDNA amplification sequencing. The results showed that short-term addition of N had no significant effect on the soil bacterial diversity and composition, but high N treatment significantly affected therelative abundance of individual bacterial species, which increased the abundance of Copiotrophic group and decreased that of the corresponding Oligotrophic group, indicating that changes in soil bacterial nutrient strategies were driven by the availability of nutrients. Enhanced understanding of the responses of soil bacterial community and nutrient distribution pattern to rapid N deposition could improve the prediction ability about the future environment.
    Effects of warming and nitrogen addition on community production and biomass allocation in an alpine meadow.
    ZONG Ning, DUAN Cheng, GENG Shou-bao, CHAI Xi, SHI Pei-li, HE Yong-tao
    2018, 29(1):  59-67.  doi:10.13287/j.1001-9332.201801.006
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    A long-term experiment, involving exogenous N addition and simulated warming, was conducted in an alpine meadow in Damxung, northern Tibet, to study how warming and N addition influence community production and biomass allocation. The results showed that warming resulted in a warm but dry microsite, that was, air temperature increased by 1.6 ℃ and soil surface temperature increased by 1.4 ℃, and soil water content decreased by 4.7%. Under no N addition treatments, warming significantly decreased plant aboveground biomass by 61.5%, 108.8% and 77.1% in 2012, 2013 and 2014, respectively. Under high N treatments (40 and 80 kg N·hm-2·a-1), warming had no significant effect on aboveground biomass. These findings indicated that the effect of warming might be dependent on N addition level, and N addition could compensate for soil N loss caused by warming. Warming led to an increase in root/shoot by 98.6%, 60.7% and 97.8% in 2012, 2013 and 2014 under no N addition treatments, respectively. Under the ambient condition, the change percentages of aboveground and belowground biomass of plant communities first increased and then decreased along an N gradient, with the saturation thresholds of above- and below-ground biomass for N addition 56.0 and 55.5 kg N·hm-2·a-1, respectively. Under the warming condition, above- and belowground biomass increased linearly with increasing N addition. These findings suggested that warming modulated the response patterns of alpine meadows to exogenous N input, which was mainly caused by decreased soil inorganic N under warming. The estimation of N thresholds highlights that alpine meadows are more sensitive to future N deposition than other types of grasslands.
    Effects of altitude on the reproductive characteristics of Saussurea przewalskii at the eastern margin of the Tibetan Plateau, China.
    WANG Yi-feng, QI Ru-lin, YANG Ya-jun, YANG Yang, SONG Wei-dong, MAO Wan-yi
    2018, 29(1):  68-74.  doi:10.13287/j.1001-9332.201801.007
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    The paper studied the effects of altitude on reproductive characteristics in 12 populations of Saussurea przewalskii at the eastern Qinhai-Tibetan Plateau, China. The results showed that the size, reproductive organ biomass, vegetative organ biomass, capitulum number, and seed number of individual plant decreased with the increasing altitude, and the capitulum mass and hundred-grain mass increased continuously. S. przewalskii could ensure its reproduction by reducing plant body size to decrease resource consumption, and increasing the allocation of limit resources to flower biomass. In order to ensure sexual reproduction, the reproductive allocation of the plants increased with increasing the altitude. There was a trade-off between capitulum number and capitulum mass, and between seed number and hundred-grain mass, which allowed the plants to maximize their fitness under stressful conditions.
    Responses of normalized difference vegetation index (NDVI) to precipitation changes on the grassland of Tibetan Plateau from 2000 to 2015.
    WANG Zhi-peng, ZHANG Xian-zhou, HE Yong-tao, LI Meng, SHI Pei-li, ZU Jia-xing, NIU Ben
    2018, 29(1):  75-83.  doi:10.13287/j.1001-9332.201801.014
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    Precipitation change is an important factor in the inter-annual variation of grassland growth on the Tibetan Plateau. The total amount, distribution pattern and concentration time are three basic characteristics of precipitation change. The temporal and spatial characteristics of precipitation change were analyzed based on climate data of 145 meteorological stations on the Tibetan Plateau and nearby areas from 2000 to 2015. The total precipitation amount was characterized by annual precipitation, distribution pattern of precipitation during the year was characterized by improved precipitation concentration index (PCI), and precipitation centroid (PC) was defined to indicate the change in precipitation concentrated time. To better illustrate the response of grassland to precipitation change, vegetation growth status was characterized by the maximum value of normalized difference vegetation index (NDVImax). Results indicated that the annual precipitation and PCI had an apparent gradient across the whole plateau and the latest PC occurred in the southern plateau. NDVImax of alpine shrub grassland was significantly correlated with the change of PCI,increased with even distribution of precipitation during growth period, and limited by the total annual precipitation. Alpine meadow did not show significantly correlations with these three indices. The inter-annual variability of NDVImax of steppe was controlled by both PCI and PC. NDVImax of alpine desert grassland was mainly controlled by annual precipitation. In addition to annual total amount of precipitation, the distribution characteristics of precipitation should be further considered when the influence of precipitation change on different types of vegetation on the Qinghai Tibet Plateau was studied.
    Temporal and spatial heterogeneity analysis of optimal value of sensitive parameters in ecological process model: The BIOME-BGC model as an example.
    LI Yi-zhe, ZHANG Ting-long, LIU Qiu-yu, LI Ying
    2018, 29(1):  84-92.  doi:10.13287/j.1001-9332.201801.016
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    The ecological process models are powerful tools for studying terrestrial ecosystem water and carbon cycle at present. However, there are many parameters for these models, and weather the reasonable values of these parameters were taken, have important impact on the models simulation results. In the past, the sensitivity and the optimization of model parameters were analyzed and discussed in many researches. But the temporal and spatial heterogeneity of the optimal parameters is less concerned. In this paper, the BIOME-BGC model was used as an example. In the evergreen broad-leaved forest, deciduous broad-leaved forest and C3 grassland, the sensitive parameters of the model were selected by constructing the sensitivity judgment index with two experimental sites selected under each vegetation type. The objective function was constructed by using the simulated annealing algorithm combined with the flux data to obtain the monthly optimal values of the sensitive parameters at each site. Then we constructed the temporal heterogeneity judgment index, the spatial heterogeneity judgment index and the temporal and spatial heterogeneity judgment index to quantitatively analyze the temporal and spatial heterogeneity of the optimal values of the model sensitive parameters. The results showed that the sensitivity of BIOME-BGC model parameters was different under different vegetation types, but the selected sensitive parameters were mostly consistent. The optimal values of the sensitive parameters of BIOME-BGC model mostly presented time-space heterogeneity to different degrees which varied with vegetation types. The sensitive parameters related to vegetation physiology and ecology had relatively little temporal and spatial heterogeneity while those related to environment and phenology had generally larger temporal and spatial heterogeneity. In addition, the temporal heterogeneity of the optimal values of the model sensitive parameters showed a significant linear correlation with the spatial heterogeneity under the three vegetation types. According to the temporal and spatial heterogeneity of the optimal values, the parameters of the BIOME-BGC model could be classified in order to adopt different parameter strategies in practical application. The conclusion could help to deeply understand the parameters and the optimal values of the ecological process models, and provide a way or reference for obtaining the reasonable values of parameters in models application.
    Temporal and spatial change of climate resources and meteorological disasters under climate change during winter crop growing season in Guangdong Province, China.
    WANG Hua, CHEN Hui-hua, TANG Li-sheng, WANG Juan-huai, TANG Hai-yan
    2018, 29(1):  93-102.  doi:10.13287/j.1001-9332.201801.015
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    Trend analysis method was applied to analyze the general variation characteristics of the climate resources and meteorological disasters of growing season of the winter planting in Guangdong before (1961-1996) and after climate warming (1997-2015). Percentile method was employed to determine thresholds for extreme cold and drought in major planting regions, and the characteristics of extreme disasters since climate warming were analyzed. The results showed that, by comparing 1997-2015 with 1961-1996, the heat value in winter growing season increased significantly. The belt with a higher heat value, where the average temperature was ≥15 ℃ and accumulated temperature was ≥2200 ℃·d, covered the main winter production regions as Shaoguan, Zhanjiang, Maoming, Huizhou, Meizhou and Guangzhou. Meanwhile, the precipitation witnessed a slight increase. The regions with precipitations of 250-350 mm included Zhanjiang, Maoming, Huizhou, Guangzhou and Meizhou. Chilling injury in the winter planting season in the regions decreased, the belt with an accumulated chilling of <2 ℃·d covered the major geographic parts of the involved regions as Zhanjiang, Maoming, Guangzhou and Huizhou; and the belt with an accumulated chilling of 8-16 ℃·d covered the major geographic parts of Shaoguan and Meizhou. Meanwhile, the drought days decreased, the belt with drought days ≥50 included the major geographic parts of Zhanjiang, Maoming, Huizhou, Guangzhou and the belt with drought days <50 included the major geographic parts of Shaoguan. The typical case of the extreme disasters showed that the extreme chilling injury and drought in the main producing regions should not be overlooked. Maoming, Huizhou and Meizhou were at higher risk of extreme chilling injury, followed by Shaoguan and Guangzhou. Zhanjiang and Maoming faced the highest risk of extreme drought, Huizhou and Guangzhou took the second place, Shaoguan and Meizhou went last. During 1997-2015, the heat of winter season increased significantly, the trend of chilling and drought decreased, however, the extreme disasters occurred frequently and the risks were higher in winter production areas. It was suggested that the winter planting should be closely integrated with climate resources and the occurrence law of meteorological disasters in growing season.
    Spatial-temporal variations of spring maize potential yields in a changing climate in Northeast China.
    LIU Zhi-juan, YANG Xiao-guang, LYU Shuo, WANG Jing, LIN Xiao-mao
    2018, 29(1):  103-112.  doi:10.13287/j.1001-9332.201801.012
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    Based on meteorological data, agro-meteorological observations, and agricultural statistical data in Northeast China (NEC), by using the validated Agricultural Production System sIMulator (APSIM-maize), the potential, attainable, potential farmers’ and actual farmers’ yields of spring maize during the period 1961 to 2015 were analyzed, and the effects of climate variation on maize potential yield in NEC were quantified. Results indicated that the potential yield of spring maize was 12.2 t·hm-2 during the period 1961 to 2015, with those in northeast being lower than southwest within the study region. The attainable yield of spring maize was 11.3 t·hm-2, and showed a similar spatial distribution with potential yield. Under the current farmers’ management practices, mean simulated potential and actual farmers’ yields were 6.5 and 4.5 t·hm-2, respectively. Assuming there were no changes in cultivars and management practices in NEC, the mean potential, attainable, and potential farmers’ yields of spring maize would decrease by 0.34, 0.25 and 0.10 t·hm-2 per decade in NEC. However, the actual farmers’ yields increased with the value of 1.27 t·hm-2 per decade averaged over NEC. Due to climate variation, year-to-year variations of spring maize potential, attainable, and potential farmers’ yields were significant, ranging from 10.0 to 14.4, 9.8 to 13.3, 4.4 to 8.5 t·hm-2, respectively.
    Effects of different colored plastic film mulching and planting density on dry matter accumulation and yield of spring maize.
    ZHANG Lin-lin, SUN Shi-jun, CHEN Zhi-jun, JIANG Hao, ZHANG Xu-dong, CHI Dao-cai
    2018, 29(1):  113-124.  doi:10.13287/j.1001-9332.201801.019
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    In order to investigate the effect of different colored plastic film mulching and planting density on spring maize dry matter accumulation and yield in the rain-fed area of the Northeast China, a complete combination field experiment which was comprised by three types of mulching (non-mulching, transparent plastic film mulching and black plastic film mulching) and five densities (60000, 67500, 75000, 82500 and 90000 plants·hm-2), was conducted to analyze the water and heat effect, dry matter accumulation and yield of spring maize (Liangyu 99). The results showed that, compared with the other mulching treatments, the black plastic film mulching treatment significantly increased the maize dry matter accumulation and maize biomass by 3.2%-8.2%. In mature stage, the biomass increased firstly and then decreased with the increasing plant density. When planting density was 82500 plants·hm-2, the biomass was the highest, which was 5.2%-28.3% higher than that of other plant density treatments. The mean soil temperature in prophase of transparent plastic film mulching treatment was 0.4-2.7 ℃ higher than that of other treatments, which accelerated the maize growth process and augmented the dry matter transportation amount (T), dry matter transportation efficiency (TE) and contribution rate of dry matter transportation to the grain yield (TC) of maize stalk and leaf. The T, TE, TC of leaf and leaf-stalk under 60000 plants·hm-2 treatment were the highest. The highest T, TE, TC of stalk were observed under 75000 plants·hm-2 treatment. In heading period, the water consumption and daily water consumption intensity of maize under the treatment of black film mulching were the largest, which were 9.4%-10.6% and 10.6%-24.5% higher than that of other mulching treatments, respectively. The highest water consumption and daily water consumption intensity were both obtained under 90000 plants·hm-2 treatment, which increased by 6.8%-15.7% and 7.0%-20.0% compared with other plant density treatments. The combination of black film mulching and density of 82500 plants·hm-2 significantly improved the water use efficiency of maize, which increased by 4.6%-40.9% compared with other treatments. In addition, it increased yield by 3.0%-39.7% compared with other treatments. At heading stage, the correlation between the dry matter amount of stalk and leaf and the yield and yield components was the biggest. Decreasing 1 kg·hm-2 dry matter amount of stalk and leaf would decrease the population yield by almost 0.79 kg·hm-2. Decreasing 10% dry matter amount of stalk and leaf would decrease the yield by almost 10%. Based on increasing plant density, black film mulching was beneficial for increasing the dry matter accumulation and improving grain yield and water use efficiency of spring maize.
    Impact of low temperature in young ear formation stage on rice seed setting.
    MA Shu-qing, LIU Xiao-hang, DENG Kui-cai, QUAN hu-jie, TONG Li-yuan, XI Zhu-xiang, CHAI Qing-rong, YANG Jun
    2018, 29(1):  125-132.  doi:10.13287/j.1001-9332.201801.036
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    A low temperature treatment in rice booting key period was executed on the north slope of Changbai Mountains to construct the impact model of low temperature on rice shell rate, and to reveal the effects of low temperature at different stages of rice young panicle on seed setting. The results showed that effects of low temperature in the young ear formation stage on rice shell rate generally followed the logarithmic function, the lower the temperature was, the greater the temperature influence coefficient was, and the longer the low temperature duration was, the higher rice shell rate was. The seed setting rate was most sensitive to low temperature in the middle time of booting stage (the period from formation to meiosis of the pollen mother cell), followed by the early and later stages. During the booting stage, with 1 ℃ decrease of daily temperature under 2-, 3- and 5-day low temperature treatments, the shell rate increased by 0.5, 1.7 and 4.3 percentage, respectively, and with 1 ℃ decrease of daily minimum temperature, the shell rate increased by 0.4,1.8 and 4.5 percentage, respectively. The impact of 2-day low temperature was smaller than that of 3 days or more. The impact of accumulative cold-temperature on the shell rate followed exponential function. In the range of harmful low temperature, rice shell rate increased about 8.5 percentage with the accumulative cold-temperature increasing 10 ℃·d. When the 3 days average temperature dropped to 21.6, 18.0 and 15.0 ℃, or the 5 days average temperature dropped to 22.0, 20.4 and 18.5 ℃, or the accumulative cold-temperature was more than 8, 19, 26 ℃·d, the light, moderate and severe booting stage chilling injury would occur, respectively. In Northeast China, low temperature within 2 d in rice booting stage might not cause moderate and severe chilling injury.
    Effects of loss-controlled urea on ammonia volatilization, N translocation and utilization efficiency in paddy rice.
    XUE Xin-xin, WU Xiao-ping, ZHANG Yong-fa, LUO Xue-hua, ZOU Bi-xia, WANG Da-peng, WANG Wen-bin
    2018, 29(1):  133-140.  doi:10.13287/j.1001-9332.201801.023
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    With the common urea split application (CU) as the control, a field experiment was conducted to examine the effects of loss-controlled urea by split application (LCUS) and loss-controlled urea by basal application (LCUB) on ammonia volatilization (NH3), nitrogen (N) nutrition status, grain yield and N utilization efficiency in rice plants. The results showed that the ratio of NH3 volatilization loss to total N application were 15.8%, 13.4% and 19.7% under the conditions of CU, LCUS and LCUB treatments, respectively. Compared to CU, LCUS significantly reduced the NH3 emission by 4.4 kg N·hm-2, with a decrease of 18.0%, while the LCUB significantly increased the NH3 emission by 7.2 kg N·hm-2, which increased by 24.7%. Compared to CU, LCUS increased the chlorophyll contents of leaf, the N content and N accumulation of seed and straw and grain yield, and significantly increased the N recovery efficiency by 7.6%, while significantly reduced the amount of N translocation, apparent N translocation rate and the rate of contribution to N in spike, respectively. However, compared to CU, LCUB significantly reduced the chlorophyll contents of leaf, the N content and accumulation of seed and straw as well as N utilization efficiency, but the grain yield, the amount of N translocation, apparent N translocation rate and the rate of contribution to N in spike were not affected. In conclusion, LCUS could maintain stable production, as well as decrease NH3 emission, improve N nutrition status and increase N utilization efficiency in rice plants.
    Effects of biochar application three-years ago on global warming potentials of CH4 and N2O in a rice-wheat rotation system.
    WU Zhen, DONG Yu-bing, XIONG Zheng-qin
    2018, 29(1):  141-148.  doi:10.13287/j.1001-9332.201801.028
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    To evaluate the long-term effects of biochar amendment on greenhouse gas emissions (GHGs), a field experiment was conducted to examine the effects of 3-year field-aged biochar (B3) and fresh biochar (B0) on global warming potential (GWP) and greenhouse gas intensity (GHGI) of methane (CH4) and nitrous oxide (N2O) in a typical rice-wheat rotation system. Four treatments were established as control without nitrogen fertilizer (CK), urea without biochar (N), urea with fresh biochar amended in 2015 (NB0), and urea with 3-year field-aged biochar amended in 2012 (NB3). Results showed that both the NB0 and NB3 treatments obviously increased soil pH, soil organic carbon (SOC), total nitrogen (TN) and influenced the potential activity of functional microorganisms related to GHGs compared to the N treatment. Relative to the N treatment, the NB3 treatment significantly improved crop yield by 14.1% while reduced the CH4 and N2O emissions by 9.0% and 34.0%, respectively. In addition, the NB0 treatment significantly improved crop yield by 9.3%, while reduced the N2O emission by 38.6% though increased the CH4 emissions by 4.7% relative to the N treatment. Moreover, both the NB0 and NB3 treatments could significantly reduce both GWP and GHGI, with NB3 being more effective in simultaneously mitigating the GHGs emissions and enhancing crop yield. Since field-aged biochar showed obvious effects on GHGs mitigation and carbon sequestration after 3 years, biochar incorporations had long-term effect on GHGs mitigation and crop production in the rice-wheat rotation system.
    Effects of exogenous growth regulators on plant elongation and carbohydrate consumption of rice seedlings under submergence.
    WU Hui, XIANG Jing, CHEN Hui-zhe, ZHANG Yu-ping, ZHANG Yi-kai, ZHU De-feng
    2018, 29(1):  149-157.  doi:10.13287/j.1001-9332.201801.021
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    This experiment was conducted to evaluate the effects of exogenous regulators on plant elongation and carbohydrate consumption of rice seedlings under submergence. IR64 and IR64-Sub1 with submergence tolerance gene Sub1 were used. Twenty-day-old seedlings were sprayed with 1-aminocyclopropane-1-carboxylic acid (ACC), paclobutrazol (PB), gibberellic acid (GA), or distilled water (as control) two days prior to the submergence. Plants were completely submerged and water depth was maintained for 0, 4, 8, 12, 16 days respectively in tanks. The plants were allowed to recover for seven days after submergence. We investigated the effects of ACC, PB, and GA on the survival percentage, shoot elongation, chlorophyll degradation and recovery, as well as non-structure carbohydrate (NSC) consumption. The results showed that complete submergence resulted in significant elongation of plant shoots, rapid decline of SPAD, and quick depletion of soluble sugars in leaves. However, the initial NSC content in shoots of IR64-Sub1 was higher than that of IR64, and the consumption rate during submergence was lower, and the starch content in shoots maintained after submergence was higher. PB could significantly enhance rice seedling survival by reducing plant elongation, chlorophyll degradation and NSC consumption, and the effect of PB pretreatment on IR64-Sub1 was more pronounced. Conversely, GA increased plant elongation, leaf chlorophyll degradation and depletion of NSC, which resulted in the lowest recovery capability and survival percentage. However, the inhibition of GA on submergence tolerance of IR64-Sub1 was much poorer compared with IR64. Plant elongation treated by ACC was much lower than by GA. In conclusion, PB could restrain plant elongation effectively, retarding chlorophyll degradation, decelerating NSC consumption and retaining more NSC after de-submergence. The results suggested that PB could increase rapid recovery of rice after submergence stress which was of significance in alleviating flood and waterlogging injury in flash-flood-prone areas.
    Effects of different fertilization regimes on nitrogen and phosphorus balance and eco-economic benefits in red paddy field.
    HONG Xi, GAO Ju-sheng, LUO Zun-zhang, ZENG Xi-bai, BAI Ling-yu, LUO Zhi-yong, YI Ping, CHEN Shu-ping
    2018, 29(1):  158-166.  doi:10.13287/j.1001-9332.201801.029
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    The nitrogen (N) and phosphorus (P) balance was studied and the eco-economic benefits of N and P were evaluated for the paddy field in a red soil area, under the fertilization treatments of no fertilization (CK), chemical fertilizer (NPK), organic fertilizer (M), and chemical fertilizers combined with organic fertilizers (NPKM, NPM, NKM), based on the long-term experiment started in 1982, to optimize fertilizer application and reduce N and P losses. The results indicated that the slight N surplus (27.10 kg·hm-2) and P deficit (-6.85 kg·hm-2) were obtained in CK, while the N and P surplus respectively with 110.94-243.98 kg·hm-2 and 19.06-67.49 kg·hm-2 in other treatments were obtained. The treatments NPK and M had no effects on the N and P balance. Under the same fertilization rates, the N surplus in treatment NPKM was lower than that in treatments NPM and NKM by 6.3% and 12.9%, while the P surplus was lower by 3.7% and 13.8%, respectively. The total-N, total-P, alkali-hydrolyzable N, and available P contents in the 0-20 cm soil layer increased under the treatments of NPKM. Comparatively, the available P contents were relatively higher in the 20-40 cm soil layer under the treatments of high P application rates. Furthermore, the NPKM treatment had the highest eco-economic benefit value of 0.762, which indicated the optimized fertilizer application for the paddy fields in the red soil area. The treatment CK had the lowest eco-economic benefit values with 0.560. Based on the observations, the N and P (in P2O5) fertilization respectively at the rates of 157.71 kg·hm-2 and 112.18 kg·hm-2 could well maintain the N and P balance for the paddy field in the red soil area.
    Responses of diurnal variation of flag-leaf photosynthesis and photosynthetic pigment content to elevated atmospheric CO2 concentration and temperature of Japonica rice during late growth stage: A FACE study.
    YUAN Man-man, ZHU Jian-guo, LIU Gang, WANG Wei-lu
    2018, 29(1):  167-175.  doi:10.13287/j.1001-9332.201801.022
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    A local popular Japonica rice (Oryza sating L.) cultivar, Nanjing 9108, was tested with free air controlled enrichment (FACE) approach to study the responses of photosynthetic pigment content and diurnal variation of flag-leaf photosynthesis to elevated atmospheric CO2 concentration and temperature. Four alternative treatments were designed with two CO2 concentration levels (ambient and elevated 200 μmol·mol-1) and two air temperature regimes (ambient and elevated 1-2 ℃). Diurnal variation of flag-leaf photosynthesis was measured in the middle full stage and the late full stage, and photosynthetic pigment of the leaf was analyzed afterward. Results showed that diurnal variation of net photosynthetic rate (Pn) in each treatment followed a double-peak curve with midday depression feature during late growth stage. Compared to Pn under ambient condition, Pn under elevated CO2 concentration increased by 47.6% and 39.1% on average at middle full stage and late full stage, respectively. There was a negative correlation between temperature and Pn with no significance. Both elevated CO2 concentration and temperature had a significant negative effect on stomatal conductance (gs), decreased by 17.0% and 11.8% on average, respectively. Elevated CO2 concentration significantly reduced transpiration rate (Tr), chlorophyll a (Chl a), chlorophyll b (Chl b), carotene (Car), total chlorophyll (Chl t) and chlorophyll a/b ratio (Chl a/b) during late growth stage of rice by 5.9%, 50.4%, 21.3%, 41.4%, 39.4% and 21.4% on average, respectively, whereas water use efficiency (WUE) increased by 47.9%. However, there were opposite effects on Tr, WUE and photosynthetic pigment content under elevated temperature, with Tr increased by 10.2% and WUE decreased by 20.4%. It could be concluded that elevated CO2 concentration had a greater effect on Pn, gs and photosynthetic pigment content of rice leaf than elevated temperature did during late growth stage. Therefore, it should be paid more attention to the colligate effects of elevated CO2 concentration and high temperature on photosynthesis and photosynthetic pigment content to reduce negative effect of high air temperature.
    Effects of successive incorporation of rice straw biochar into an alkaline soil on soil fertility, carbon sequestration and ammonia volatilization.
    ZHAO Jin, ZHAO Xu, WANG Shen-qiang, XING Guang-xi
    2018, 29(1):  176-184.  doi:10.13287/j.1001-9332.201801.030
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    A five-year successive rice straw-derived biochar (BC) amendment pot trial was conducted to investigate the BC effects on crop growth responses, soil properties and ammonia volatilization in a calcareous alkaline soil from 2010-2015 under the greenhouse condition. We adopted 0 (the control; BC0), 2.25 t·hm-2(BC2.25) and 22.5 t·hm-2(BC22.5) for each wheat/millet crop season with an identical dose of NPK fertilizers. The results showed that BC treatments (BC2.25 and BC22.5) improved soil fertility and crop growth compared to the no BC control. During the five rice/millet rotations, BC22.5 treatment increased the total yields of grain and straw by 24.1% and 74.1%, while the cumulative aboveground uptake amounts of N, P and K were significantly increased by 93.5%, 71.2% and 46.3%, respectively. After the rotations, soil available P, K, and CEC under the BC22.5 treatment were enhanced by 262%, 274% and 58.3%, compared to the control. By contrast, soil bulk density was decreased by 46.6%, while no difference was found in soil pH between the BC treatments and the control. Soil TOC and soil C/N ratio increased by 843% and up to 25 in response to the BC22.5 treatment, respectively. The annual apparent BC loss was 3.5%-5.7% in the BC2.25 and BC22.5 treatments. High level of BC application simulated ammonia volatilization, which increased by 102% in BC22.5 treatment over the course of the crop rotations compared to the control.
    Effects of extremely-late sowing on the grain yield, nitrogen uptake and utilization, and grain protein content in winter wheat
    WU Jin-zhi, HUANG Ming, WANG Zhi-min, LI You-jun, FU Guo-zhan, CHEN Ming-can
    2018, 29(1):  185-192.  doi:10.13287/j.1001-9332.201801.026
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    In order to explore the cultivation techniques for high yield, quality and nitrogen use efficiency of wheat and guide the production practice of late sowing, a two-year experiment of different sowing times and plant densities in fixed plots was conducted from October 2012 to June 2014. Weak-spring cultivar of Yanzhan4110 (YZ4110) and semi-winter cultivar of Aikang58 (AK58) were sowed with two cropping patterns: Normal sowing (sowing in the middle of October, 2.4×106 plants·hm-2) and extremely-late sowing (sowing in the middle of November, 6.0×106 plants·hm-2). The nitrate-N content in 0-40 cm soil, the nitrogen (N) uptake and utilization, grain yield, grain protein content and N uptake efficiency in winter wheat were investigated. Compared with normal sowing, extremely-late sowing significantly increased the nitrate-N content in 0-40 cm soil at jointing and anthesis stages, which in turn promoted the N uptake and accumulation of plants after jointing stage and increased the N distribution ratio of spikes at maturity. As a result, the grains with extremely-late sowing had higher protein contentin both YZ4110 and AK58, and higher protein yield and N uptake efficiency in YZ4110 than that with normal sowing. However, the effects of extremely-late sowing on grain yield were different in the two cultivars. Compared with normal sowing, extremely-late sowing clearly raised the grain yield of YZ4110, but significantly decreased that of AK58. These results indicated that extremely-late sowing is an alternative cropping technique to increase grain yield and protein content for winter wheat in irrigation zones through maintaining the soil N supply after jointing stage and increasing N uptake efficiency.
    Effects of light intensity on photosynthetic capacity and light energy allocation in Panax notoginseng.
    XU Xiang-zeng, ZHANG Jin-yan, ZHANG Guang-hui, LONG Guang-qiang, YANG Sheng-chao, CHEN Zhong-jian, WEI Fu-gang, CHEN Jun-wen
    2018, 29(1):  193-204.  doi:10.13287/j.1001-9332.201801.008
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    To explore the effects of light intensity on photosynthetic characteristics and light adaptation of the shade-demanding species Panax notoginseng, the responses of photosynthesis to photosynthetic photon flux density, CO2 and sunflecks in the two-year-old Panax notoginseng were investigated under different levels of light intensity (29.8%, 9.6%, 5.0%, 1.4% and 0.2% of full sunlight). Meanwhile, chlorophyll a fluorescence parameter and light energy partitioning were also recorded and calculated in the responsive process. P. notoginseng grown under 29.8% full sunlight (FL) had a lower apparent quantum yield (AQY), potential photochemical quantum yield (Fv/Fm) and potential photochemical activity (Fv/Fo), however, it had a higher maximum net photosynthetic rate (Pn max), maximum electron transport rate (Jmax), F/Fm′, electron transport rate (ETR), photochemical quenching (qP) and the proportion of light energy allocated to photochemistry dissipation (ΦPS), but the non-photochemical quenching (NPQ) was not the highest. There were no significant differences in Pn max, light compensation point (LCP), light saturation point (LSP), dark respiration rate (Rd) among 9.6%FL and 5.0% FL treatments, but these treatments had relatively higher values of NPQ, AQY, carboxylation efficiency (CE), maximum carboxylation rate (Vc max), Fv/Fm and Fv/Fo. In addition, the Pn max, CE, Vc max, Jmax, ETR,F/Fm′, qP, NPQ and ΦPSII decreased with the decrease in light intensity from 5.0%FL to 0.2%FL, and the proportion of light energy allocated to fluorescent dissipation (Φf,d) were increased. Under 500 μmol·m-2·s-1 light-flecks inducting, the ΦPS of P. notoginseng increased slowly with the extension of time except for the treatment of less than 5.0%FL, and under the circumstance of 1.4%FL and 0.2%FL, ΦPS reached significantly a perfect result, moreover, Φf,d increased rapidly. These results suggested that the enhancement in photosynthetic electron transport to use the light energy and the moderate photoinhibition of PSⅡ might avoid the irreversible oxidative damage of photosynthetic organization in P. notoginseng under high levels of light intensity. Moderate shading was beneficial to maintain its higher non-photochemical quenching ability. However, its photosynthetic capacity depressed and the proportion of light energy allocated to non-photochemical pathway increased obviously in excessive shading, and it easily caused a light oxidative damage.
    Effects of grass cover combined with different fertilization regimes on soil nutrients and enzyme activities in apple orchard in Weibei dryland, China.
    GONG Qing-li, ZHAI Bing-nian, ZHENG Wei, LIU Jie, ZHENG Zhao-xia, ZHAO Zhi-yuan, LI Zi-yan, WANG Zhao-hui
    2018, 29(1):  205-212.  doi:10.13287/j.1001-9332.201801.025
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    The split-plot design was adopted in this experiment, with main treatments of grass cover and control and sub-treatments included four fertilization regimes: no fertilization, CK; manure, M; N,P and K fertilizer, NPK; and NPK fertilizer combined with manure, MNPK. Microplate fluorimetry was used to study the effects of grass cover combined with different fertilization regimes on the enzyme activities in apple orchard. The results showed that after mowing the grass (the residues were left on the soil surface as mulch), the soil water content, available P, nitrite nitrogen and the activities of βX, NAG, βG, CBH were increased compared to the control, with no significant differences for total nitrogen, soil organic carbon, and AKP activity. For grass cover treatment, the total nitrogen, soil organic carbon, and the activities of βX, NAG, βG, CBH, AKP were both improved before and after mowing the grass. However, the soil water content, available phosphorus, and nitrate nitrogen of grass cover treatment were lower than that of the control before mowing the grass. Under grass cover condition, the total nitrogen, available P, and soil organic carbon of M and MNPK were higher than that of CK and NPK in both before and after mowing the grass periods, with the activities of βX, NAG, βG, CBH, AKP of MNPK higher than that of NPK. Under the control condition, the available P, soil organic carbon (SOC), nitrite nitrogen, total nitrogen and the activities of βG, CBH, AKP of MNPK higher than that of CK and NPK before and after mowing the grass. Redundancy analysis showed that the activities of soil enzymes were significantly correlated with the soil nutrients, and could reflect the soil fertility. Thus, grass cover combined with MNPK significantly increased the soil nutrient contents and soil enzyme activities, and was an important practice to prevent the decrease of soil fertility and benefit the sustainability of local apple industry.
    Effects of diverse stresses on gene expression and enzyme activity of glutathione reductase in Brassica campestris.
    ZHANG Teng-guo, NIE Ting-ting, SUN Wan-cang, SHI Zhong-fei, WANG Juan
    2018, 29(1):  213-222.  doi:10.13287/j.1001-9332.201801.010
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    A novel glutathione reductase gene (GR2) was isolated from Brassica campestris Longyou 6 by rapid isolation of cDNA ends (RACE). The full-length of cDNA of GR2 was 2073 bp, with an open reading frame (ORF) of 1692 bp. GR2 encoded a protein of 563 amino acids with a deduced molecular mass of about 60.7 kDa and an isoelectric point of 7.9. The real-time quantitative PCR results showed that GR2 was expressed in the roots, stems and leaves in B. campestris, among which the expression of GR2 in leaves was the highest. The transcript levels of GR1 and GR2, and the enzyme activity of glutathione reductase (GR) increased in response to cold temperature, high temperature, drought stress, and salt stress. The results suggested that GR played an important role in coping with diverse stresses in B. campestris. When abscisic acid (ABA) pretreatment was applied before cold temperature, high temperature, drought stress, salt stress, the expression levels of GR1and GR2, and the activity level of GR all significantly increased compared with the single stress, which indicated that ABA could induce GR1 and GR2 gene transcription and GR activity. However, when MAPKK inhibitor (U0126) pretreatment was applied before the above stresses, the expression levels of GR1and GR2 and the activity level of GR significantly decreased compared with the single stress suggesting that U0126 inhibited GR1 and GR2 gene transcription and GR activity.
    Exogenous NO application effectively alleviates the allelochemical stress on cucumber root border cells caused by Eupatorium adenophorum extracts.
    YANG Xiao-huan, YANG Wen-xiu, SUN Liang-liang, ZHAO Qian, CAO Yong-heng, MA Jin-hu
    2018, 29(1):  223-230.  doi:10.13287/j.1001-9332.201801.005
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    Using suspension cultures of cucumber (Cucumis sativus) cultivar Jinyou 35, we investigated the effects of allelochemical stresses induced by Eupatorium adenophorum extracts on root border cells (RBC), and the role of exogenous NO application in alleviation of the damage of root tips exposed to E. adenophorum extracts. The results showed that, 1000 mg·L-1 E. adenophorum extracts had significant damage to the cucumber root tip, resulting in severe tissue damage, exfoliated surface cells and irregular arrangement of inner cells, while those damages could be effectively alleviated by spraying exogenous NO. Compared with the control, E. adenophorum extracts (ZL) markedly reduced RBC numbers and survival rates by 54.5% and 97.2%, respectively, the RBC apoptosis rates were 12.3 times higher, the thicknesses of RBC adhesive layers were increased by 31.4%, and the root cap PME activities were markedly increased. Compared with the ZL treatment, exogenous NO application (ZN) significantly increased RBC numbers and survival rates by 72.4% and 146.0%, respectively, reduced the corresponding RBC apoptosis rates and the thicknesses of RBC adhesive layers by 30.7% and 15.0%, respectively, and inhibited the PME activities by 14.3% upon treatment for 72 hours. Our findings revealed that E. adenophorum extracts showed toxic effects on the cucumber RBC, resulting in cell apoptosis, abolishment of the RBC protection on root tips, and the destruction of root tip structure. Exogenous NO application, to some extent, could prevent the root tip and RBC from cell damage caused by E. adenophorum extracts.
    Effects of p-hydroxybenzoic acid and phloroglucinol on mitochondria function and root growth in cotton (Gossypium hirsutum L.) seedling roots.
    ZHANG Guo-wei, YANG Chang-qin, LIU Rui-xian, NI Wan-chao
    2018, 29(1):  231-237.  doi:10.13287/j.1001-9332.201801.027
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    With early-maturing cotton cultivar CCRI-50 widely grown in China as experimental material, water culture experiment was conducted to study the effects of p-hydroxybenzoic acid and phloroglucinol with different concentrations (0.8, 4.0, and 20.0 mmol·L-1) on generation rate of reactive oxygen, changes of antioxidant enzyme activities and mitochondria function of cotton roots. Results showed that p-hydroxybenzoic acid and phloroglucinol treatments inhibited the cotton root growth, reduced SOD, POD, CAT and H+-ATPase activities in root mitochondria, increased the generation rate of O2-· and H2O2 content. In addition, they also increased the opening of mitochondrial permeability transition pores (MPTP), decreased the membrane fluidity and cytochrome c/a (Cyt c/a). Difference of mitochondria function between p-hydroxybenzoic acid and phloroglucinol treatments was minor at concentration of 0.8 mmol·L-1, while the inhibition to root growth and mitochondria function under treatment of p-hydroxybenzoic acid at concentration of 4.0 and 20.0 mmol·L-1 was stronger than that of phloroglucinol. Above all, p-hydroxybenzoic acid and phloroglucinol inhibited antioxidant enzyme activity and mitochondrial function in cotton seedling roots, and the inhibition depended on dose of phenolic acids. The inhibition to root growth and mitochondria function between p-hydroxybenzoic acid and phloroglucinol treatment was different, and p-hydroxybenzoic acid had stronger inhibition than phloroglucinol at the concentration more than 4.0 mmol·L-1.
    Spatial interpolation model of soil organic carbon density considering land-use and spatial heterogeneity.
    WU Zi-hao, LIU Yan-fang, CHEN Yi-yun, GUO Long, JIANG Qing-hu, WANG Shao-chen
    2018, 29(1):  238-246.  doi:10.13287/j.1001-9332.201801.013
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    Soil organic carbon pool is an important component of terrestrial carbon pool. Soil organic carbon pool and its dynamic change have important influence on carbon cycle in terrestrial ecosystem. Soil organic carbon density (SOCD) is an important parameter of soil carbon storage, and it is also an important index to evaluate farmland soil quality. Accurate prediction of regional organic carbon density spatial distribution is of great significance to the development of precision agriculture. A total of 242 farmland soil samples collected from the Jianghan Plain were used to explore the effects of land use types on the spatial distribution of SOCD in plain areas. Moreover, in the presence of spatial heterogeneity and spatial outliers of SOCD, three Kriging approaches combining land use types were used for the spatial prediction of SOCD. They were dummy variable regression Kriging (DV_RK), mean centering ordinary Kriging (MC_OK1) and median centering ordinary Kriging (MC_OK2). Results showed that the difference of land use types between paddy field and irrigable land was one of the reasons for the spatial heterogeneity of SOCD in the study area, resulting in spatial non-stationary characteristics of SOCD and lowering the performance of OK. DV_RK, MC_OK1 and MC_OK2, however, eliminating the impacts of SOCD spatialheterogeneity caused by land use types while modeling, enhancing the model stability. Therefore, the prediction accuracy of these three models was higher than that of ordinary Kriging (OK). Moreover, MC_OK2 outperformed the others in terms of model reliability, prediction accuracy and the ability to explain the total variance of SOCD. In summary, as an easily accessed auxiliary variable, land use type could effectively decrease the effects of spatial heterogeneity and spatial outliers on SOCD spatial interpolation model, improving the prediction performance and reducing the model uncertainty. SOCD map with higher quality could also be achieved to help reveal the spatial characteristics of SOCD for guiding the agricultural production.
    Effects of vegetation and topography features on ecological stoichiometry of soil and soil microbial biomass in the hilly-gully region of the Loess Plateau, China.
    WANG Bao-rong, YANG Jia-jia, AN Shao-shan, ZHANG Hai-xing, BAI Xue-juan
    2018, 29(1):  247-259.  doi:10.13287/j.1001-9332.201801.039
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    The objectives of this study were to explore the effects of vegetation type, topographic features and their combined effects on soil microbial biomass stoichiometry, so as to better understand the interaction of soil, soil microbes and nutrient cycling under different vegetation types in the hilly-gully region of the Loess Plateau. Soils from three vegetation zones (forest zone, forest-steppe and steppe) and five slope positions (south/north backslope, south/north shoulder and summit) were chosen and the effects of vegetation types and topography features on soil and C:N:P ratios in soil microbial biomass were investigated in this study. The results showed that, among the five slope positions, the highest concentrations of soil and soil microbial biomass C, N, P were found at the backslope position and the north-facing slope. The effects of vegetation types on soil and soil microbial biomass C, N and P in the two soil layers were significantly different, whereas the effects of slope aspect and positions were only numerically different. As for different soil layers, the topsoil (0-10 cm) was more affected by slope aspect, while the subsoil (10-20 cm) was more influenced by slop position. While the effects of vegetation type on soil C:N, C:P and N:P and soil microbial biomass C:N, C:P were significant, slope aspect and slope position only influenced soil C:P and N:P. Consequently, on the Loess Plateau, the effects of vegetation type on soil and soil microbial biomass C, N, P were stronger than those of the topographic features. The standardized major axis tests showed that C:N:P stoichiometry in soil microbes was well-constrained, especially in the steppe zone. The soil microbial biomass N:P might be used as a useful tool to assess nutrient limitation of ecosystem processes in terrestrial ecosystems. If combined with plant leaf N:P, they could provide more accurate information to estimate the nutrient limitation of fragile ecosystem in hilly-gully region of the Loess Plateau.
    Effects of three Bacillus strains on growth promoting and rhizosphere soil microflora of tomato.
    LOU Yi, GUO Qiao, PENG Chu, SHI Meng-di, LI Hai-yang, LI Xiao, XUE Quan-hong, LAI Hang-xian
    2018, 29(1):  260-268.  doi:10.13287/j.1001-9332.201801.040
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    The effects of Bacillus Bs10, Ba12 and Bl10 on tomato growth and soil rhizosphere microorganisms were determined by Petri dish germination test and pot experiments. The results showed that Bs10, Ba12 and Bl10 exhibited remarkable promoting effect on the length of hypocotyl and radical, as well as the growth of plants. The length, surface area and volume of tomato roots increased significantly after treatment with Bacillus stains, the numbers and proportions of soil bacteria also increased markedly, while those of soil fungi decreased. The numbers of the dominant bacteria and fungi were changed, withBacillus methylotrophicus being much higher in root zone soil, surface soil and neouchi, while the plant pathogens Fusarium solani and Fusarium oxysporum decreased significantly in root zone soil and root surface soil. These results suggested that the addition of Bs10, Ba12 and Bl10 could improve the micro-ecosystem of the root domain of tomato, which might play an important role in growth promoting and disease prevention on tomato plants.
    Effects of drying and wetting cycles induced by tides on net ecosystem exchange of CO2 over a salt marsh in the Yellow River Delta, China.
    HE Wen-jun, HAN Guang-xuan, XU Yan-ning, ZHANG Xi-tao, WANG An-dong, CHE Chun-guang, SUN Bao-yu, ZHANG Xiao-shuai
    2018, 29(1):  269-277.  doi:10.13287/j.1001-9332.201801.035
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    As a unique hydrological characteristic, the tidal action can strongly affect carbon balance in a salt marsh despite their short duration. Using the eddy covariance technique, we measured the net ecosystem CO2 exchange (NEE) and its environmental factors and tidal change over a salt marsh in the Yellow River Delta. It aimed to investigate the effect of tidal process and drying and wetting cycles induced by tides on NEE. The results showed that the tidal process promoted the daytime CO2 uptake, but it didn’t clearly affect the nighttime CO2 release. Tidal inundation was a major factor influencing daytime NEE. The diurnal change of NEE showed a distinct U-shaped curve on both drought and wet stages, but not with substantial variation in its amplitude during the drought stage. The drying and wetting cycles enhanced the absorption of daytime CO2. Under drought stage, the mean of the maximum photosynthetic rate (Amax), apparent quantum yield (α) and ecosystem respiration (Reco) were higher than those in wet stage. In addition, the drying and wetting cycles suppressed the nighttime CO2 release from the salt marsh but increased its temperature sensitivity.
    Characterization of cadmium uptake kinetics in cadmium pollution-safe rice material.
    GUO Jing-yi, ZHANG Man, ZHANG Xi-zhou, LI Ting-xuan, ZHANG Lu, HUANG Fu, CHEN Dong-ming, SUN Xian-ming
    2018, 29(1):  278-284.  doi:10.13287/j.1001-9332.201801.033
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    The characteristics of cadmium (Cd) uptake kinetics in a pollution-safe rice variety of D62B were studied in a hydroponic experiment under different Cd levels and stress time, with a common variety Luhui17 as the control. The results showed that Cd uptake in root of D62B was significantly lower than that of Luhui17 under different stress times. The differences in Cd uptake of the two rice varieties increased with the extension of absorption time. Total Cd amount of Luhui17 was 1.3 times as much as that of D62B when the absorption time was 72 h. Meanwhile, the Cd uptake kinetic of the two varieties accorded to Michaelis-Menten equation, and little difference in Michaelis constants (Km) was observed in the two varieties. However, the maximum uptake rate (Vmax) of Luhui17 was 2 times as much as that of D62B. Once the stress time was more than 48 h, the transfer coefficients of D62B was lower than that of Luhui17, and the Cd distribution ratio in root of D62B was much higher, indicating that D62B had greater accumulation ability in root compared with Luhui17. In conclusion, the Cd uptake and transfer ability of D62B were lower than those of Luhui17.
    Interannual changes in fish community structure in the northern part of the coastal waters of Jiangsu Province, China in spring.
    WO Jia, MOU Xiu-xia, XU Bin-duo, XUE Ying, ZHANG Chong-liang, REN Yi-ping
    2018, 29(1):  285-292.  doi:10.13287/j.1001-9332.201801.038
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    Based on the data collected from the bottom trawl surveys in the coastal waters of northern Jiangsu Province from 2009 to 2014, multivariate statistical analysis and other integrated indices were used to analyze the variation in the community structure of fish assemblage over time in the waters. The results showed that 68 species had been caught in the coastal waters of northern Jiangsu Province. There were significant fluctuations in the relative density of fish resources. The mean catch mass per site ranged from 0.75 to 1.62 kg·h-1, and the mean catch individuals per site showed significant decrease in the survey period ranging from 370 to 203 ind·h-1. The mean trophic level (MTL) index varied between 3.58 and 3.72 from 2011 to 2014, being relatively low in 2009-2012 and fluctuating around 3.70 in 2011-2014. The mean body mass of fish community increased from 2.93 to 11.18 g between 2009 and 2014, showing a similar tendency with that of MTL index. Cluster analysis and MDS showed that the six survey years could be divided into two subgroups of 2009-2010 and 2011-2014. The main discriminating species were Syngnathus acus,Ctenotrypauchen microcephalus and Ammodytes personatus for the two subgroups. Further study showed that the pelagic and planktivorous fishes had gradually increased in dominance while cold temperate species and indigenous species had decreased over the years. It was suggested that fish communities in the coastal waters of northern Jiangsu Province underwent a remarkable succession. Advices for the fisheries management in the waters were provided according to the succession pattern, which might contribute to the sustainable utilization of fishery resources.
    Habitat suitability index of larval Japanese Halfbeak (Hyporhamphus sajori) in Bohai Sea based on geographically weighted regression.
    ZHAO Yang, ZHANG Xue-qing, BIAN Xiao-dong
    2018, 29(1):  293-299.  doi:10.13287/j.1001-9332.201801.032
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    To investigate the early supplementary processes of fishre sources in the Bohai Sea, the geographically weighted regression (GWR) was introduced to the habitat suitability index (HSI) model. The Bohai Sea larval Japanese Halfbeak HSIGWR model was established with four environmental variables, including sea surface temperature (SST), sea surface salinity (SSS), water depth (DEP), and chlorophyll a concentration (Chl a). Results of the simulation showed that the four variables had different performances in August 2015. SST and Chl a were global variables, and had little impacts on HSI, with the regression coefficients of -0.027 and 0.006, respectively. SSS and DEP were local variables, and had larger impacts on HSI, while the average values of absolute values of their regression coefficients were 0.075 and 0.129, respectively. In the central Bohai Sea, SSS showed a negative correlation with HSI, and the most negative correlation coefficient was -0.3. In contrast, SSS was correlated positively but weakly with HSI in the three bays of Bohai Sea, and the largest correlation coefficient was 0.1. In particular, DEP and HSI were negatively correlated in the entire Bohai Sea, while they were more negatively correlated in the three bays of Bohai than in the central Bohai Sea, and the most negative correlation coefficient was -0.16 in the three bays. The Poisson regression coefficient of the HSIGWR model was 0.705, consistent with field measurements. Therefore, it could provide a new method for the research on fish habitats in the future.
    The continuous trophic spectrum of food web in Dalian marine area, China.
    TIAN Jia-shen, HAN Jia-bo, LU Zhi-chuang, MA Zhi-qiang, LI Duo-hui, WANG Bai, LIU Yi-bing
    2018, 29(1):  300-308.  doi:10.13287/j.1001-9332.201801.031
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    This study analyzed the values of δ13C and δ15N by the application of stable isotope technique from the marine mammals (Phoca largha, Neophocaena asiaorientalis sunameri, Balaenoptera acutorostrata) and major biological species in Dalian marine area based on the animals collected due to stranding and death after bycatch from January, 2008 to June, 2017, and the fisheries resources investigation between autumn, 2016 and spring, 2017 in the same area. The trophic level was then calculated in order to establish the continuous trophic spectrum of the food web in Dalian marine area. The results showed that the value of δ15N ranged from 8.0‰ to 14.7‰ and the value of δ13C ranged from -21.1‰ to -16.7‰ of the food web in Dalian marine area. The major biological species could be categorized into three groups, namely primary consumer, secondary consumer and top predator. The analysis of δ15N revealed that the trophic level ranged from 2.63 to 4.59 for the major biological species. The trophic level of B. acutorostrata, N. asiaorientalis sunameri, P. largha, echinoderm, cephalopods, gastropod, bivalve, crustacean and fish were 3.16, 4.11, 4.25, 3.24-3.84, 3.81-3.93, 3.65-4.13, 2.63-3.15, 3.58-4.12 and 3.20-4.59, respectively. The characteristics of the trophic structure demonstrated that the primary consumer was bivalve, the secondary consumers were B. acutorostrata, cephalopods, Echinoderms, gastropod and crustacean, and top predators were N. asiaorientalis sunameri, P. largha and fish. The value of δ15N increased with the increase in the body length, indicating the feeding of N. asiaorientalis sunameri tended to be at a higher trophic level with the growth and feeding ability enhanced. This study established the continuous trophic spectrum of food web in Dalian marine area and would provide the information for the marine mammal and fisheries resources protection.
    Trophic niche partitioning of pelagic sharks in Central Eastern Pacific inferred from stable isotope analysis.
    LI Yun-kai, GAO Xiao-di, WANG Lin-yu, FANG Lin
    2018, 29(1):  309-313.  doi:10.13287/j.1001-9332.201801.037
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    As the apex predators of the open ocean ecosystems, pelagic sharks play important roles in stabilizing the marine food web through top-down control. Stable isotope analysis is a powerful tool to investigate the feeding ecology. The carbon and nitrogen isotope ratios can be used to trace food source and evaluate the trophic position of marine organisms. In this study, the isotope values of 130 pelagic sharks from 8 species in Central Eastern Pacific were analyzed and their trophic position and niche were calculated to compare the intra/inter-specific resource partitioning in the Central Eastern Pacific ecosystem. The results exhibited significant differences in both carbon and nitrogen isotope values among the shark species. The trophic levels ranged from 4.3 to 5.4 in the Central Eastern Pacific shark community. The trophic niche of blue sharks and shortfin mako sharks showed no overlap with the other shark species, exhibiting unique ecological roles in the open ocean food web. These data highlighted the diverse roles among pelagic sharks, supporting previous findings that this species is not trophically redundant and the trophic niche of pelagic sharks can not be simply replaced by those of other top predator species.
    Reviews
    Priming effect of biochar on the minerialization of native soil organic carbon and the mechanisms: A review.
    CHEN Ying, LIU Yu-xue, CHEN Chong-jun, LYU Hao-hao, WANG Yu-ying, HE Li-li, YANG Sheng-mao
    2018, 29(1):  314-320.  doi:10.13287/j.1001-9332.201801.024
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    In recent years, studies on carbon sequestration of biochar in soil has been in spotlight owing to the specific characteristics of biochar such as strong carbon stability and well developed pore structure. However, whether biochar will ultimately increase soil carbon storage or promote soil carbon emissions when applied into the soil? This question remains controversial in current academic circles. Further research is required on priming effect of biochar on mineralization of native soil organic carbon and its mechanisms. Based on the analysis of biochar characteristics, such as its carbon composition and stability, pore structure and surface morphology, research progress on the priming effect of biochar on the decomposition of native soil organic carbon was reviewed in this paper. Furthermore, possible mechanisms of both positive and negative priming effect, that is promoting and suppressing the mineralization, were put forward. Positive priming effect is mainly due to the promotion of soil microbial activity caused by biochar, the preferential mineralization of easily decomposed components in biochar, and the co-metabolism of soil microbes. While negative priming effect is mainly based on the encapsulation and adsorption protection of soil organic matter due to the internal pore structure and the external surface of biochar. Other potential reasons for negative priming effect can be the stabilization resulted from the formation of organic-inorganic complex promoted by biochar in the soil, and the inhibition of activity of soil microbes and its enzymes by biochar. Finally, future research directions were proposed in order to provide theoretical basis for the application of biochar in soil carbon sequestration.
    Relationship of AM fungi with non-mycorrhizal plants.
    CHU Ya-nan, ZHANG Hai-bo, QIN Ze-feng, GAI Jing-ping
    2018, 29(1):  321-326.  doi:10.13287/j.1001-9332.201801.001
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    As a kind of globally widely distributed soil microorganism, arbuscular mycorrhizal (AM) fungi form the symbiosis with the majority of land plants, which is important for plant nutrition and ecosystem functioning. Few vascular species are considered to be nonmycorrhizal, especially those within the families Amaranthaceae, Chenopodiaceae, Carophyllaceae and Brassicaceae. At present, the interactions between these non-host plants and AM fungi are few and scattered, lacking systematic summary. In this paper, the type of non-host plants, the reason of low mycotrophy, and the effect of AM network formed by neighbor plants on AM fungi colonization on the non-host, and the possible interaction between AM fungi and non-host, as well as the material exchange between plants and AM fungi and their possible ecological functions were reviewed in order to give some new ideas on the function of the nonmycorrhizal plants in the fragile ecosystems.
    Review of lime carbon sink.
    LIU Li-li, LING Jiang-hua, TIE Li, WANG Jiao-yue, BING Long-fei, XI Feng-ming
    2018, 29(1):  327-334.  doi:10.13287/j.1001-9332.201801.017
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    Under the background of “missing carbon sink” mystery and carbon capture and storage (CCS) technology development, this paper summarized the lime material flow process carbon sink from the lime carbonation principles, impact factors, and lime utilization categories in chemical industry, metallurgy industry, construction industry, and lime kiln ash treatment. The results showed that the lime carbonation rate coefficients were mainly impacted by materials and ambient conditions; the lime carbon sink was mainly in chemical, metallurgy, and construction industries; and current researches focused on the mechanisms and impact factors for carbonation, but their carbon sequestration calculation methods had not been proposed. Therefore, future research should focus on following aspects: to establish a complete system of lime carbon sequestration accounting method in view of material flow; to calculate lime carbon sequestration in both China and the world and explain their offset proportion of CO2 emission from lime industrial process; to analyze the contribution of lime carbon sequestration to missing carbon sink for clarifying part of missing carbon sinks; to promote the development of carbon capture and storage technology and provide some scientific bases for China’s international negotiations on climate change.
    The latest progress in ecosystem service flow research methods.
    YAO Jing, HE Xing-yuan, CHEN Wei
    2018, 29(1):  335-342.  doi:10.13287/j.1001-9332.201801.018
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    Ecosystem service flow is the key point and difficulty of ecosystem services research, which is now at the initial stage and show a developing trend of quantity and spatialization. However, the term “ecosystem service flow” is ambiguous. In this paper, we presented two descriptions about the term, and two corresponding theories and methods: the transmission of a service from ecosystems to people and distributed ecosystem model, and the flow of benefits accruing to people as generated by stocks of ecosystem structure and grey/black box theory. Then the latest researches related to the two descriptions were listed, and their merit and demerit were summarized. Finally, we pointed out several directions for future research in ecosystem service flow. Especially, the use of newest space technology and information technology (such as big data) and comprehensive understanding of ecosystem services (such as taking urban ecosystem services flow and abiotic flow into account) should be stressed in the future research.