Scientia Agricultura Sinica

Progress and Challenge of Crop Genetic Improvement via Genome Editing

WANG FuJun, ZHAO KaiJun

Scientia Agricultura Sinica. 2018, 51(1): 1-16. doi:10.3864/j.issn.0578-1752.2018.01.001

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Site-specific genome editing refers to the genetic manipulation techniques that can precisely modify DNA sequences at the genomic level, which holds a great application value in analysis of gene function, plant genetic improvement or development of new varieties. The general working principle of genome editing is that the sequence-specific nucleases (SSNs) are used to create DNA double-strand breaks (DSBs) at the genomic target sites that will be repaired through non-homologous end joining (NHEJ) and/or homology-directed repair (HDR) pathways, resulting in nucleotide insertion, deletion, or DNA fragment replacement in the targeted gene(s). Nowadays, genome editing technologies including Zinc finger nucleases (ZFNs), transcription activator-like effector nucleases (TALENs) and clustered regularly interspaced short palindromic repeats/CRISPR-associated proteins (CRISPR/ Cas）system have been successfully applied in genetic improvement of crops. From the perspective of development trend, CRISPR/ Cas system-based genome editing technology will become the core technology in genetic improvement and molecular design breeding of crops. This review starts with brief introduction of the concepts and working principles of ZFNs, TALENs and CRISPR/Cas system, and focus on the recent progress of genome editing-based crop improvement of yield, quality, disease resistance, abiotic stress resistance and rice male sterile line development. Then the authors sorted out the technological innovation and application of CRISPR/Cas-based single-base editing for plant genomes and the DNA-free plant genome editing system in details. After comparing the advantages and disadvantages of different genome editing techniques, some general principles of adoption of genome editing technologies in crop improvement were put forward. Finally, the regulations on genome-edited crops, as well as the opportunities and challenges of genome editing-based crop breeding were discussed.

QTL Identification for Awn Length Based on 90K Array Mapping in Wheat

ZHANG ChuanLiang, JIAN JunTao, FENG Jie, CUI ZiXia, XU XiaoWan, SUN DaoJie

Scientia Agricultura Sinica. 2018, 51(1): 17-25. doi:10.3864/j.issn.0578-1752.2018.01.002

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【Objective】The awn has a significant influence on stress resistance and spikes photosynthetic characteristics in wheat. The objective of this study is to explore the principal-effect QTLs which control the stable expression of awn and their close chain or total separation of molecular markers, and to provide evidences for molecular marker assisted breeding, constructing near-isogenic line, screening candidate gene and cloning novel genes.【Method】Two F₉ RIL (recombinant inbred lines) populations derived from XY81/Z8425B and XY81/XN1376 were used as drawing population, and two linkage maps were constructed by using 90K array which covering 21 chromosomes of wheat, and the two F_9﹕10 families which including 102 and 120 lines, respectively, were used for the identification of field traits. The two F9:10 families were planted in Yangling District (Shaanxi Province), Nanyang City (Henan Province) and Zhumadian City (Henan Province) from October 2016 to June 2017, respectively. The phenotypic data of awn length of two populations were used to detect QTLs by using the complete interval mapping and multi-environment joint analysis at the ripening stage.【Result】Two genetic maps covering 21 chromosomes of wheat were constructed, the total length of map was 4 412.14 and 4 281.67 cM, respectively. And the average genetic distance was 2.65 and 2.31 cM, respectively. The number of linkage markers in the two linkage maps indicated that the 90K marker was unevenly distributed in wheat genomes A, B and D, but was all expressed as the number of markers in genome B＞that in genome A＞that in genome D. The common marker of D genome was the least for the common markers of two linkage maps, and it indirectly reflected that the D genome was highly conserved. Six QTLs were found in two RIL populations from Yangling District (Shaanxi Province), Nanyang City (Henan Province) and Zhumadian City (Henan Province). The major QTL, Qal5A-1, showed a strong stability in two populations under three environments and was belonged to environment-insensitive QTL. The phenotypic variance explained by Qal5A-1 ranged from 46.01% to 79.82%. It showed inhibitory effects on awn length, and the additive effects came from parent Xiaoyan 81. This major QTL was mapped at the end of chromosome 5A and was closely linked to the molecular marker RAC875_c8121_1147. The phenotypic variance explained by 5 QTLs, including Qal6B-1, Qal1B-1, Qal3B-1, Qal2D-1 and Qal2D-2, were 1.39%, 3.66%, 3.93%, 5.53% and 3.51%, respectively, which were micro-effect QTLs. Two QTLs were found in the RIL group derived from XY81/Z8425B, including one major OTL Qal5A-1 and one micro-effect QTL Qal6B-1, the two loci explained the phenotypic variance was 79.91%. Five QTLs were found in the RIL group derived from XY81/XN1376, including one major OTL Qal5A-1 and four micro-effect QTLs Qal1B-1, Qal3B-1, Qal2D-1 and Qal2D-2, the five loci explained the phenotypic variance was 63.96%. Six QTLs were obtained by multi-environment analysis, and the contribution rate of phenotypic variation of their interaction effects was much lower than that of additive effect, which indicated that the interaction between QTL and environment was not the main factor of influencing awn length. The additive effect values were approximately equal in different environments, further indicating that these six QTLs had a stable genetic effect among the three environments. 【Conclusion】The dominant QTL, Qal5A-1, was detected in two groups. It can be stably expressed and closely linked to the molecular marker RAC875_c8121_1147. It explains the phenotypic variance from 46.01% to 79.82%, which has a strong inhibitory effect on awn length.

The Present Situation and Prospects of Cotton Industry Development in China

LU XiuRu, JIA XiaoYue, NIU JiaHui

Scientia Agricultura Sinica. 2018, 51(1): 26-36. doi:10.3864/j.issn.0578-1752.2018.01.003

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Cotton is the longest chain of field commercial crops of China’s planting industry, which the commodity rate is as high as more than 95%, but still exists many shortcomings of the cotton industry which require further attention from cotton enterprises, cotton farmers, scientific and technical personnel, and scholars, such as independent seed industry, brand cultivation, cleaner production, unified management and pest control, dependence on foreign trade, industrial security and economies of scale, industrial organization and other factors that influence China's cotton industry competitiveness and sustainable development. The major production areas of cotton in China are Xinjiang, the Yellow River basin and the Yangtze river basin, for example, Xinjiang cotton production accounts for 67% of the national output and has formed scale and mechanization planting, but the Yangtze river basin and the Yellow River basin still practice the small scale economy, not full play the leading role of the new type of management main body, the scale planting and mechanized production, is lack of the integrated data platform of cotton production can not be formed, and processing and marketing, and only several departments are engaged in professional service, one-on-one full service and hosted service. The development direction and goal of cotton production in China should be improved the level of cotton production scale, mechanization, intelligence, informationization, socialization service, development of light-simplified production technology that makes cotton farmers to grow cotton more happily and with more dignity, reduce production cost, solve the problem who is going to a tiller of the ground, control tightly cotton industry chain. From the Angle of the cotton industry chain of supply and demand, this paper expounded the present situation of development of cotton industry that the Chinese cotton planting area and output decreased, the industrial layout in Xinjiang outshines others, the domestic consumption has decreased, but the supply and demand situation has been improved, the imports are greater than the exports over a long period of time and the advantages of textile industry decreased gradually, and so on. A series of problems about Chinese cotton industry in the production process, the industrial layout, organization and management, and platform construction were analyzed. Based on the practice of the growing experience and development advantages of the United States and Australia in cotton varieties, production technology, mechanization and national policy, combining with the policy background of China's reform of structure of the supply side, the corresponding countermeasures and suggestions were put forward including cultivating new cotton varieties, researching new technology of light-simplified and mechanized production, the input of agricultural machinery equipment, optimization of varieties, quality and area layout, scientifically preventing and controlling plant diseases and insect pests to improve the quality of cotton, develop cotton price target system, improve the insurance amount of cotton production, increase subsidies and policy support dynamics of cotton farmers, cotton business, agricultural machinery manufacturers, textile companies, exporters and so on, giving play to the advantages of production and cotton association function, building platforms of production-supply-sales integration, perfecting the regulation system of cotton supply and demand, construction of the modern cotton industry service system, driving the cotton and textile industry abroad with the help of One Belt And One Road, and so on, in order to stimulate domestic effective supply, achieve the equilibrium of supply and demand of China's cotton industry as soon as possible. Finally, the prospects for China's cotton industry were presented, the three cuts-one reduction-one subsidy (cut overcapacity, cut stores, cut levers-one-reduction-one subsidy) should be used in cotton industry and conform to the pattern of global cotton to get rid of the inventory, and cotton prices will be higher in the coming two years.

Characteristics of High-Yield Double Rice Varieties in Rice-Rice-Rapeseed Cropping System

Scientia Agricultura Sinica. 2018, 51(1): 37-48. doi:10.3864/j.issn.0578-1752.2018.01.004

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【Objective】This study was conducted to determine the characteristics of high-yield double rice cultivars by using high-yield rice cultivars with suitable growth period in triple cropping pattern of early rice-late rice-interplanting early-maturing rapeseed (rice-rice-rapeseed cropping system), which would provide grounds and references for breeding and cultivation of high-yield double rice cultivars.【Method】9 early rice cultivars and 10 late rice cultivars were employed in field experiments of rice-rice-rapeseed cropping system, and characteristics of high-yield double rice cultivars were studied by using cluster analysis and variance analysis methods.【Result】(1) There were no significant differences in panicle number, seed setting rate, 1000-grain weight and growth period among the three yield types (high-yield (HY), middle-yield (MY) and low yield double rice cultivars (LY) ). However, the number of grains per spike, total spikelet volume, yield and daily yield of HY were significantly higher than that of LY. (2) There were no significant differences in increase rate of tillering, decrease rate of tillering and number of peak tiller between HY and LY, while the rate of effective ear of HY was significantly higher than that of LY. (3) For early rice, HY showed higher biomass in heading and biomass per stem in heading and maturity, followed by MY and LY, with no significant differences among them, yet the total biomass and biomass per stem of HY were significantly higher than that of LY. As for late rice, there were significant differences in total biomass and biomass per stem in heading and maturity between HY and LY. As to harvest index, there were no significant differences among the three yield types of both early and late rice. (4) HY showed higher leaf area index (LAI) and leaf area per stem in heading and maturity, as well as lower reduction rate of leaf area form heading to maturity, followed by MY and LY, with significant differences between HY and LY. And also, HY showed higher spikelet number per leaf area, followed by MY and LY, with significant differences between HY and LY of early rice.【Conclusion】In rice-rice-rapeseed cropping system, high-yield double rice cultivars were characterized by medium tillering ability, high earing rate, powerful abilities of dry matter per stem and high LAI as well as high leaf area per stem in mid and latter stages, large number of spikelets and high daily production. While some differences were existed between early rice and late rice. For early rice, it was about 105-110 d of growth duration, 75-78 kg·hm^-2·d^-1 of daily yield, 125-140 spikelets per panicle, and 26-28 g for 1000-grains. As for late rice, it was about 115 d of growth duration, 77-81 kg·hm^-2·d^-1 of daily yield, large number of the grains (140-160 spikelets per panicle), and 24-28 g for 1000-grains.

Responses of Heading to Flowering to Maturity of Early Rice to Climate Change and Different Transplant Periods

LIU Wei, LI YiJun, Lü HouQuan

Scientia Agricultura Sinica. 2018, 51(1): 49-59. doi:10.3864/j.issn.0578-1752.2018.01.005

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【Objective】To study the temperature condition of early rice from transplanting to Maturity in southern China during 1961-2015, combined with different transplant periods of early rice, characteristics of temporal and spatial distribution of temperature suitability and high temperature days from heading - flowering to milk ripe and Maturity of early rice were quantitatively analyzed under the climate change and different transplant periods.【Method】Four planting regions of early rice were divided into Hainan (region 1), South China (region 2), the north of Guangxi (region 3) and the south of the Yangtze River (region 4). The temperature suitability and high temperature days from heading to Maturity were calculated in three scenes of normal and 5 d and 10 d in advance transplant in 4 regions during 1961-2015. Every five days was used to be the study scale. The evaluation index of temperature suitability in critical growth stage of early rice was established based on pentad scale to analyze the responses of heading to flowering and milk ripe and Maturity of early rice to climate change and different transplant period. 【Result】The results showed that: (1) The annual temperature from transplant to Maturity in different regions of early rice was slowly rising and the tendency rate was between 0.097 ℃·(10a)^-1 to 0.192 ℃·(10a)^-1. The 1990s was the fewest days of high temperatures from heading to Maturity, while the most in 21st century. (2) The highest temperature suitability was in region 3 in different ages in the space, while the lowest in region 4. The high temperature suitability distribution in the 1990s was greater than other ages. (3) It was beneficial to improve the temperature suitability in advance transplant in region 1, 2 and 4, but it was opposite in region 3. The high temperature days were reduced in advance transplant in region 2, 3 and 4, but it was opposite in region 1. (4) The characteristic of the temperature suitability in typical station of Meixian in Guangdong province was “down-up-down”, while it was declined significantly after entering 2000. The characteristics of high temperature days were continue to rise, which were 9.6 days in 1960s and 17.2 days during 2011-2015. Meanwhile 5 d or 10 d in advance transplant could raise the temperature suitability and reduce high temperature days. 【Conclusion】In general, it was beneficial to improve temperature suitability from heading to flowering and milk ripe and Maturity of early rice and reduce high temperature days in South China and South of the Yangtze River, which could reduce the influence of high temperature on early rice.

Effects of Rainfall at Emergence on Stand Establishment and Yield of Cotton Under Different Seeding Patterns

LU HeQuan, DAI JianLong, LI ZhenHuai, LI WeiJiang, XU ShiZhen, TANG Wei, ZHANG DongMei, KONG XiangQiang, LUO Zhen, XIN ChengSong, DONG HeZhong

Scientia Agricultura Sinica. 2018, 51(1): 60-70. doi:10.3864/j.issn.0578-1752.2018.01.006

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【Objective】Plastic mulching after seeding followed by artificial freeing of seedlings from mulching at full emergence (seeding before mulching, SBM) is widely adopted in the Yellow River valley, but it is labor-intensive and costly. Plastic mulching in advance and seeding on plastic film (seeding after mulching, SAM) can remove the process of seedling freeing and has been widely applied in the drought northwest inland, but it is still unclear if it can be applied in the Yellow River valley and whether the cotton emergence rate and stand establishment will be reduced in case of rain. The objective of this study is to determine the effects of rainfall at emergence on stand establishment and yield of cotton in relation to different seeding patterns, most importantly, is to determine an easy and light planting pattern with good stand establishment and less labor consumption. 【Method】A two-year field experiment was conducted to evaluate the effects of rainfall and seeding patterns on stand establishment, leaf area index, yield and yield components. A split-plot design with three replicates was used for the study. The main plots comprised two simulated rainfalls (0 mm and 10 mm), while seeding patterns including seeding without mulching (SWM), SBM, SAM and seeding under double mulching (SDM) constituted the subplots.【Result】Significant interaction was detected between rainfall and seeding pattern on emergence rate, dry matter accumulation, leaf area index, boll density and cotton yield. Without rainfall, emergence rate, dry matter, leaf area index, boll density and yield of SAM and SDM were similar to those of SBM, but those of SWM were reduced by 13.6%, 19.0%, 13.3%, 24.7% and 27.7% relative to SBM, respectively; Under 10 mm rainfall, these parameters were decreased by 32.2%, 43.1%, 26.3%, 25.8% and 29.2% for SAM, respectively, 42.8%, 55.8%, 47.2%, 35.0% and 40.1% for SWM, respectively, relative to SBM, but all the parameters of SDM were similar to those of SBM.【Conclusion】SAM reduced stand establishment and cotton yield relative to SBM under 10 mm rainfall, but SDW exhibited comparable stand establishment and yield to SBM regardless of rainfall. Therefore, choosing a suitable seeding pattern is an important way to guarantee full stand establishment and high yield in terms of local ecological conditions, especially the rainfall probability.

Hyperspectral Estimation of Cadmium Content in Tumorous Stem Mustard Based on the Wavelet-Fractal Analysis

WANG Ting, ZHOU Cui, GU YanWen, MA WenChao, LIU Yuan, WEI Hong

Scientia Agricultura Sinica. 2018, 51(1): 71-81. doi:10.3864/j.issn.0578-1752.2018.01.007

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【Objective】The aim of this study was to reveal the relationship between the cadmium contents of tumorous stem at mature period and leaf spectral reflectance at the early stages of tumorous stem mustard (Brassica juncea var. tunida), a famous local vegetable in the Three Gorges Reservoir Region. The results could provide theoretical guidance for predicting cadmium contents of tumorous stem of tumorous stem mustard rapidly and accurately, which was helpful to know the edible quality in the early growth stage of vegetable. 【Method】A pot experiment was conducted to set up 0, 0.1, 0.2, 0.3 and 1 mg·kg^-1 with different concentrations of cadmium in soil (calculated according to dry soil weight) based on the present situation of soil cadmium contamination in the main planting area of tumorous stem mustard. The leaf spectral reflectance and cadmium contents were synchronously determined in the main four growth periods of vegetable. Wavelet-Fractal Analysis was used to obtain detailed information about leaf spectral reflectance based on db2-db8 wavelet bases under the fifth dimension. Using correlation and regression analysis, non-linear models were constructed for estimating cadmium contents of tumorous stem of tumorous stem mustard advanced in the early growth stage. 【Result】There was a relatively intense accumulation of cadmium in the leaves and tumorous stem of tumorous stem mustard, which increased with the increased cadmium concentrations in soil. There was a significant positive correlation between the cadmium contents of the tumorous stem and the leaves. The leaf spectral reflectance in four growth stages, especially in the early enlargement stage of tumorous stem, could well respond to the contaminated cadmium in soil. The fractal dimension coefficients of leaf spectral reflectance based on "db2-db8" were significantly negatively correlated with the leaf cadmium contents in the early enlargement stage of tumorous stem. The models were simulated based on the relationships among the cadmium concentration in the tumorous stem at mature period of tumorous stem mustard, the leaf fractal dimension coefficients in the early enlargement stage of tumorous stem and the contaminated cadmium in the soil. The model based on "db5"was the optimal simulation, which R²was 0.929 and Root Mean Square Error (RMSE) was 1.0540. 【Conclusion】The results showed that cadmium could accumulated in leaf and tumorous stem of tumorous stem mustard, which could threaten the human health and the food safety, so it should be paid more attentions. Wavelet-Fractal Analysis was suitable to assess the situation of heavy metal contamination of vegetable due to its sensitivity for subtle spectral information. The optimal model was established based on wavelet db5 of leaf spectral reflectance, that was Y=-0.029+32.878X^-7.656, with R² and RMSE was 0.929 and 1.0540, respectively, which could accurately predict the cadmium content of tumorous stem at the mature stage by using the spectral data from the early growth stage, and provide a theoretical foundation for knowing the edible quality in the early growth stage of tumorous stem mustard.

Analysis of Toxigenic Chemotype and Genetic Diversity of the Fusarium graminearum Species Complex

MA HongXia, SUN Hua, GUO Ning, ZHANG HaiJian, SHI Jie, CHANG JiaYing

Scientia Agricultura Sinica. 2018, 51(1): 82-95. doi:10.3864/j.issn.0578-1752.2018.01.008

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【Objective】The objective of this study is to clarify the toxigenic chemotype and genetic diversity of Fusarium graminearum species complex (FGSC) causing maize ear rot from different provinces (autonomous region).【Method】The toxigenic chemotypes of 92 FGSC isolates collected from 11 provinces (autonomous region) were analyzed by using the specific primer designed based on Tri13 and Tri3 sequences. Thirteen primers with abundant bands, good repeatability, strong signal and clear background were screened from 100 universal primers developed by Columbia University (UBC) and used for ISSR-PCR amplification of these isolates. The Popgen32 software was used to calculate the percentage of polymorphic loci, Shannon’s diversity index, genetic distance and genetic similarity among populations. According to Nei’s genetic distance, UPGMA cluster analysis was carried out using NTsys2.10e software, and the dendrogram of different geographical populations was constructed. 【Result】 Four different toxigenic chemotypes including DON, 15-ADON, DON+15-ADON and NIV+15-ADON were detected among 92 FGSC isolates. One and 20 isolates represented the DON and 15-ADON chemotypes, respectively. One isolate produced both 15-ADON and NIV, and 55 isolates carried both 15-ADON and DON producing segments. The PCR amplification of all FGSC isolates was performed with 13 ISSR primers and a total of 102 fragments were obtained, of which 101 fragments displayed polymorphic and accounted for 99.02% in the total amplified fragments. The average number of fragments amplified per primer was 7.85. At population average level, the Nei’s gene diversity index (H) was 0.3129 and the Shannon’s information index (I) was 0.4774, which indicated that there was a high genetic diversity in FGSC isolates. The diversity existed among fungal populations from different geographic regions. Hebei, Shanxi, Heilongjiang and Jilin had the highest genetic diversity, while Anhui and Henan had the lowest genetic diversity. The genetic differentiation coefficient (Gst) of geographical populations was 0.2722, indicating that there were some genetic variations among different geographical populations, but most of the genetic variation (72.78%) occurred in the population. The Nm=1.3372 (＞1) indicated that there was a certain gene flow among different geographical populations. The results of genetic relationship showed that the populations of Hebei, Shanxi, Heilongjiang, Jilin, Liaoning, Inner Mongolia and Gansu were relatively close, and the populations of Shandong, Jiangsu, Henan and Anhui also displayed a close relationship, whereas the population isolated from Anhui had the lowest similarity with population isolated from Inner Mongolia. Cluster analysis showed that the similarity coefficient of all isolates was 0.43-0.95. All the isolates were divided into two groups with the similarity coefficient of 0.43. Group 1 included 4 isolates of northern spring sowing region (Jilin, Shanxi and Zhangjiakou, Hebei), which did not produce NIV and DON. Group 2 consisted of the remaining 88 isolates which originated from northern spring sowing region (Shanxi, Heilongjiang, Jilin, Liaoning, Gansu and Hebei (Zhangjiakou and Tangshan)) and Huang-Huai-Hai summer sowing region (Henan, Shandong, Jiangsu, Anhui and Shijiazhuang, Hebei), and the toxins produced by these isolates were mainly DON and 15-ADON. When the similarity coefficient was 0.664, each group was divided into different subgroups, and the results of subgroups were related to the source of the isolates.【Conclusion】The main toxigenic chemotypes of FGSC from northern spring sowing region and Huang-Huai-Hai summer sowing region are DON and 15-ADON. There are abundant genetic variations in the populations of FGSC causing maize ear rot. There are certain gene exchanges among different geographical populations. The genetic diversity was related to the geographical origin.

Induction Effect of Sharp Eyespot of Wheat and the Effect of Wheat Growth After Ganoderma lucidum Polysaccharides (GLP) Seed Dressing

ZHANG ZhongXiao, WANG HongYan, WANG KaiYun, WANG Dong, JIANG LiLi

Scientia Agricultura Sinica. 2018, 51(1): 96-104. doi:10.3864/j.issn.0578-1752.2018.01.009

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【Objective】 Fungal polysaccharides can regulate plant growth, activate plant defense responses, and induce plant resistance to plant fungal and viral diseases. The objective of this study is to investigate the induction effect of sharp eyespot of wheat and the effect on wheat growth after Ganoderma lucidum polysaccharides (GLP) seed dressing.【Method】Three wheat cultivars including highly susceptible cultivar Jimai 22, middle susceptible cultivar Shannong 23 and resistant cultivar Luyuan 502 were chosen to test. Using the pot culture method, each pot was added with 20 mL of pathogenic fungi suspension, seeds were treated with the GLP, the control group was treated with water. The disease index and disease reduction against sharp eyespot of wheat were investigated. The mechanism of induced resistance in terms of defense enzyme activity, chlorophyll and malondialdehyde (MDA) content were evaluated. At the same time, the germination rate, plant height and root vigor were determined. 【Result】After GLP seed dressing, Jimai 22, Shannong 23, Luyuan 502 cultivars had the same rule on sharp eyespot of wheat. GLP seed dressing promoted the growth of wheat, 4, 8 g a.i./100 kg seed dose of GLP of Jimai 22 seed germinating potential were 53.50% and 52.75%, significantly higher than that of the control. After 7 d of wheat emergence, the plant height of wheat treated with GLP was significantly higher than that of the control group, and the higher the treatment dose, the more obvious the effect of induction enhancement. GLP seed dressing could significantly improve the root activity and the chlorophyll content of wheat, the root activity of 8 g a.i./100 kg seed dose of GLP of Jimai 22 was 0.26 mg·g^-1·h^-1, which was 2.77 times than that of the control. The chlorophyll a and b contents of 8 g a.i./100 kg seed dose of GLP were 1.96, 0.96 mg·g^-1, respectively, which was 1.52, 1.44 times than that of the control. GLP seed dressing could produce certain effect on prevention and control of sharp eyespot of wheat. Take the highly susceptible cultivar Jimai 22 as an example, 8 g a.i./100 kg seed dose of GLP in wheat seed dressing, the control effects on sharp eyespot of wheat were 33.7%, 31.9% and 30.4% on the 7, 14 and 21 d after wheat completely germination. At the same time, the protective enzyme activity of PAL, POD, SOD of leaves increased obviously, while the content of MDA decreased. Eight g a.i./100 kg seed dose of GLP by seed dressing in Jimai 22, the activity of PAL, SOD and POD was 60.72 U·min^-1·g^-1 FW, 2.45 U·g^-1 FW and 135.67 U·min^-1·g^-1 FW, respectively, which was 1.10, 1.32 and 1.13 times than that of the control. The content of MDA was 1.48 μmol·g^-1, which was 26.1% lower than that of the control group.【Conclusion】The wheat seed dressed with GLP can promote the germination of wheat seeds and the growth of wheat seedlings, increase the content of chlorophyll. At the same time, it can also induce wheat sheath blight disease resistance, increase the activity of defense enzymes and decrease the content of MDA in wheat leaves.

Fitness of Herbicide-Resistant BC₃F₄ between two herbicide-resistant transgenic Brassica napus and wild Brassica juncea

YAN Jing, WANG XiaoLei, ZHANG YuChi, ZHANG QingLing, WANG Jian, QIANG Sheng, SONG XiaoLing

Scientia Agricultura Sinica. 2018, 51(1): 105-118. doi:10.3864/j.issn.0578-1752.2018.01.010

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【Objective】 If herbicide-resistant transgenes escape from transgenic oilseed rape (Brassica napus, AACC, 2n=38) to their weedy relatives through pollen flow, weeds with the herbicide-resistant trait might produce new problems for weed control. Wild B. juncea (AABB, 2n=36), relative weed of transgenic B. napus, has become a major weed of crop systems across western China, and extended eastward along the Yangtze River valley. In order to provide experimental data for whether the transgene could successfully escape to wild B. juncea, it is necessary to evaluate the fitness of backcross generation between herbicide-resistant transgenic B. napus and wild B. juncea before it is released. 【Method】Wild B. juncea and herbicide-resistant BC₃mF₄R, BC₃pF₄R and BC₃mF₄L, BC₃pF4L (R and L denote glyphosate- and glufosinate-resistant backcross progeny obtained with glyphosate- and glufosinate-resistant transgenic B. napus, respectively. m and p denote backcross progeny obtained with wild B. juncea as maternal plants and paternal plants, respectively) were planted at low (15 plants per plot) and high density (30 plants per plot) in pure and mixed stands (wild B. juncea﹕backcross generation were 4﹕1, 3﹕2 and 1﹕1). the vegetative components (plant height, stem diameter, the first branch number/plant, above-ground dry biomass/plant) and reproductive components (silique number/plant, total seed weight/plant, silique length, seed number/silique) of these backcross generations were measured. The differences of the composite fitness between BC₃F₄ and wild B. juncea were analyzed. 【Result】 Under pure stands, there was no significant difference in the fitness components and composite fitness of BC₃F₄R with that of wild B. juncea. The composite fitness of BC₃F₄L was also similar to wild B. juncea although the stem diameter, above-ground dry biomass/plant, and silique number/plant of BC₃F₄L at high density were significantly lower than that of wild B. juncea. Therefore, either glyphosate- or glufosinate-resistant BC₃F₄ was as fit as wild B. juncea regardless of density under pure stands. Under mixed stands, at low density, there was no significant difference in composite fitness of glyphosate- or glufosinate-resistant BC₃F₄ with that of wild B. juncea. At high density, there was no significant difference in fitness components and composite fitness of BC₃F₄R with that of wild B. juncea regardless planting proportions. However, the plant height, stem diameter, the first branch number/plant, above-ground dry biomass/plant, silique number/plant, total seed weight/plant and composite fitness of BC₃F₄L were significantly lower than that of wild B. juncea. The correlation analysis showed that the fitness components of BC₃F₄ were only related to the planting density. 【Conclusion】Glyphosate- or glufosinate- resistant BC₃F₄ between glyphosate- or glufosinate-resistant transgenic B. napus and wild B. juncea have a strong survival ability and potential possibility of establishing populations in the field. Moreover, the ecological risk of gene flow is higher from glyphosate-resistant transgenic B. napus than glufosinate-resistant transgenic B. napus. Therefore, preventing gene escape from herbicide-resistant B. napus to wild B. juncea should not only prevent their initial hybrids, but also should prevent the backcross between wild B. juncea and F₁ or subsequent generations, so as not to produce higher fitness backcross generation.

A Meta-Analysis of Manure Application Impact on Soil Microbial Biomass Across China’s Croplands

REN FengLing, ZHANG XuBo, SUN Nan, XU MingGang, LIU KaiLou

Scientia Agricultura Sinica. 2018, 51(1): 119-128. doi:10.3864/j.issn.0578-1752.2018.01.011

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【Objective】Application of organic manure can promote soil microorganisms growth and improve soil fertility. However, very rare studies were conducted to quantify the effects of manure application on soil microbial biomass carbon (SMBC) and nitrogen (SMBN) in croplands at national scale. Therefore, quantifying the effects of manure application on the contents of SMBC and SMBN under different climate regions and soil conditions is important to provide theoretical basis for reasonably applying manure, so as to enhancing of soil fertility and microbial activities for China’s croplands. 【Method】In current study, all of 70 literatures, including application of impacts on the contents of SMBC and SMBN in croplands in China during 1990 and 2017, were collected (336 for SMBC and 222 data for SMBN from individual study). The meta-analysis was used to quantify the magnitude of manure application impacts on the contents of SMBC and SMBN at three aspects: Climatic regions, land use types and soil pH levels.【Result】At national scale, the contents of SMBC and SMBN in manure applied soils were significantly increased by 128.1% and 70.2% when compared with no fertilizer (CK), respectively, while those were increased by 57.1% and 34.2% when compared with mineral fertilizer (NPK), respectively. The increments of SMBC and SMBN contents improved by manure in subtropical monsoon climate (66.7% and 57.5%, respectively) were significantly higher than those in temperate continental climate (26.0% and 20.9%, respectively) and temperate monsoon climate (37.0% and 56.7%, respectively) compared with NPK. Furthermore, manure application could significantly increase the contents of SMBC and SMBN in paddy soils (69.1% and 67.1%, respectively) compared with NPK, which were higher than those in upland (34.7% and 26.4%, respectively) and upland-paddy soils (50.2% and 63.9%, respectively). For the neutral soils (6＜pH＜8), the increment of SMBC and SMBN contents by 64.4% and 63.7% in the treatment with manure applied were higher than those in the alkaline (pH＞8, 29.4% and 21.9%) and acidic soils (pH＜6, 44.4% and 45.5%) compared with NPK, respectively. In addition, the correlation analysis showed that the contents of SMBC and SMBN were positively correlated with annual carbon and nitrogen input from manure, respectively. 【Conclusion】Overall, the application of manure can dramatically improve the contents of SMBC and SMBN, indicating manure supplementation provided sufficient carbon and nitrogen for microbial growth and reproduction, and nutrient retention. Nevertheless, the effect of manure application on the contents of SMBC and SMBN relative to CK and NPK were significant different among climatic regions, land use types and soil pH levels. Therefore, climate types and soil conditions should be taken into consideration for applying manure in different regions in China.

The Response of Maize Yield to Inherent Soil Productivity and Fertilizer in the Southwest

XU ChunLi, XIE Jun, WANG Ke, LI DanPing, CHEN XuanJing, ZHANG YueQiang, CHEN XinPing, SHI XiaoJun

Scientia Agricultura Sinica. 2018, 51(1): 129-138. doi:10.3864/j.issn.0578-1752.2018.01.012

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【Objective】The objective of this study was to explicit the effect of inherent soil productivity and different fertilizer measures on maize (Zea mays L.) yield in southwest China, so as to provide scientific basis for improving soil fertility and proper fertilization of the maize belt in southwest China.【Method】Based on 508 maize field trials in southwest China since 2006, we have chosen 5 treatments, including non-fertilizing control (CK), nitrogen and phosphate (NP) fertilizer, nitrogen and potassium (NK) fertilizer, phosphate and potassium (PK) fertilizer, and NPK fertilizer (NPK), to measure maize yield and nutrient absorption, and to analyze the yield, soil and contribution characteristics of inherent soil productivity, as well as yield response and agronomic efficiency. And we evaluated the relationship between the soil foundation and maize yield (or yield gap) by using the line fitting and boundary line method, and assessed the effect of the soil foundation on the stability and sustainability of fertilizer-induced yield by using the stability index and the sustainability index in the maize planting area.【Result】The maize yield based on soil fundamental fertility in the southwest region ranged from 3.9 to 4.7 t·hm^-2 (average: 4.4 t·hm^-2). Fertilization could significantly increase the maize yield. The average yield in the fertilizer (NPK) application area was 7.7 t·hm^-2, which increased 3.3 t·hm^-2 than the yield based on the soil fundamental fertility. The results based on the boundary analysis showed that the high yield potential was 11.5, 12.7, 12.6 t·hm^-2 (average11.7 t·hm^-2) in Chongqing, Sichuan and Guizhou, respectively. The contribution rate of maize yield and fertilizer contribution averaged 57.1% and 42.9%, respectively; the contribution rate of soil productivity increases with the increase yield based on inherent soil productivity. The effects of fertilizers on the increase of maize yield from high to low were as followed: the nitrogen fertilizer > phosphate fertilizer > potash fertilizer in southwest China. The fitting line decision coefficient between maize realistic productivity and inherent soil productivity in Chongqing, Sichuan, Guizhou and the entire southwest was 0.356, 0.356, 0.393 and 0.434 (P<0.001), respectively. And with the increase of inherent soil productivity, the fertilizer-induced yield gap decreased, whereas the stability and sustainability of the yield increased. 【Conclusion】Improving inherent soil productivity could increase the maize yield and increase the stability and sustainability of the yield, reduce the dependence of maize on fertilizer, and promote the high and stable yield of maize in the southwest China.

Effects of Different Special Controlled Release Urea Dosages on Yield and Nitrogen Uptake of Oilseed Rape

ZHANG YaWei, LIU QiuXia, ZHU DanDan, FAN XiaoLin, REN Tao, ZHANG LiMei, LI XiaoKun, CONG RiHuan, LU JianWei

Scientia Agricultura Sinica. 2018, 51(1): 139-148. doi:10.3864/j.issn.0578-1752.2018.01.013

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【Objective】This study investigated the effects of different dosage of special controlled release urea (CRU) on the yield and nitrogen (N) uptake of winter oilseed rape in different areas. Our aim was to evaluate the suitable rate of the special CRU for oilseed rape and provide the basis for guiding light simplification of oilseed rape production.【Method】Field experiments were conducted in Hengyang (Hunan Province), Jiujiang (Jiangxi Province), and Wuxue (Hubei Province) during the period of 2015-2016, investigating nutrient release and fertilization effects of the special CRU. Each site included 5 nitrogen application rates being 0, 60, 120, 180 and 240 kg N·hm^-2, respectively.【Result】Field bagging experiment showed that the release time of special CRU was about 150 days, with the accumulative release amount of 83.4%, which coincided with the N demand of oilseed rape. The application of special CRU could control the harvest density of winter rapeseed, increasing the number of pods per plant and seed number per pod. Compared with no N treatment, the number of pods per plant and seed number per pod increased 15.0-81.5 pods per plant and 0.2-2.4 seeds per pod, respectively. Harvest density changed the coordination group and individual with N fertilizer variation. Oilseed rape production performed the highest grain yield when applying 180 kg N·hm^-2 among the sites, which increased by 1 118 and 1 088 and 2 049 kg·hm^-2, Compared with the without N treatment, respectively. By fitted with linear and platform model, optimal special CRU dosages were 174, 180 and 192 kg N·hm^-2 in Hengyang, Jiujiang and Wuxue, respectively. The biomass, N concentration and N accumulation of aboveground biomass were significantly increased with the application of the special CRU. With the increase of N application rate, the proportion of N in the stem was raised gradually, and the proportion and distribution of N in the seed decreased, while the ratio of N distribution in the shell kept about 10%. The nitrogen use efficiency (NUE) was different in different periods. The NUE was 50.69%-56.89% at flowering period, 39.39%-46.71% at harvested period, and only 9.20%-23.45% at seedling stage, respectively. At seedling and flowering stages, the NUE showed increase first and then decrease with N application rate increase, reaching the maximum when the amount of the special CRU dosage was 180 kg N·hm^-2. However, at harvest stage, the NUE reduced with the increase amount of nitrogen application. 【Conclusion】The special CRU for winter oilseed rape could improve N uptake and promote the growth and development of rape in each growth period, especially in regulating the harvesting density, increasing the pod number per plant and seed number per pod, and eventually enhancing the rapeseed yield. The recommended amount of special CRU was 180 kg N·hm^-2 among the sites.

Comparative Proteomic Analysis in Different Developmental Stages of Sugar-Apple (Annona squamosa L.) Flowers

LIU KaiDong, MO YiWei, FENG ShaoXian, WU WanYi, LI HaiLi, ZHONG JunDi, YUAN ChangChun

Scientia Agricultura Sinica. 2018, 51(1): 149-159. doi:10.3864/j.issn.0578-1752.2018.01.014

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【Objective】In order to reveal the molecular mechanism of sugar-apple flower development, the function of differential expression proteins among four flower developmental stages were studied by using an approach of plant proteomics. 【Method】Flower samples were collected at four flower developmental stages: floral bud stage, bud stage, the mature flowers with partially opened petals stage and mature flowers with opened petals stage. The expressed proteins of flowers in four stages were detected using two-dimensional gel electrophoresis (2-DE) technology. All expressed proteins and their functional annotation were analyzed by MALDI-TOF-MS mass spectrometry .【Result】The results of protein profiling showed that there was more than 800 protein spots in each gel electrophoresis and 50 of them showed differences in different stages of sugar apple flowers. 36 proteins were identified by spectrum analysis as well as MASCOT online retrieval. These proteins could be divided into 7 functional categories, including respiration and energy metabolism (11 proteins), protein synthesis and metabolism (8 proteins), transcription and translation (3 proteins), stress and defense (2 proteins), cell proliferation and differentiation (3 proteins), secondary metabolites (8 proteins) and unknown proteins (1 protein). Furthermore, the 36 identified proteins could be grouped into 20 GO classifications. Among 11 respiration and energy metabolism related proteins, three proteins (A07, C28, C42) were continuously decreased with flower development while the other four proteins (A36, A37, B13, B29) were significantly increased; among the proteins related synthesis and metabolism, two proteins (A13 and A22) expressed at low level for all four flower developmental stages, while other five proteins (B17, B20, A19, A21 and C21) expression increased significantly with the flower development. A stress and defense related protein (B32) showed highest expression in last flower developmental stage. The expression of two cell differentiation and proliferation related proteins (B27 and C57) expression was gradually increased. Five secondary metabolism related proteins expression (A06, A29, A34, C100 and C110) gradually decreased with flower development, while proteins C79 and D38 reached the maximum value in the bud stage, and then gradually decreased. 【Conclusion】Comparing the protein spectrum of the sugar-apple at four different flower developmental stages, 36 proteins were identified as differentially expressed proteins. The respiration and energy metabolism related proteins accounted as the largest proportion, such as two ATP synthase alpha subunits and pyruvate decarboxylation isozyme. Differential expression of these proteins suggested the flower development process requires a lot of energy. In addition, our study first reported two pentatricopeptide repeat-containing proteins, and the expression of them changed with the flower development process. However, the function of these proteins remains to be further study. The results suggest that energy metabolism, secondary metabolism, protein synthesis and other biological processes may be involved in the process of flowering regulation of sugar-apple.

Different Response of Apple Root Physiology and Leaf Photosynthesis to Mulching of Different Materials

HUANG Ping, CAO Hui, ZHANG RuiXue, JI Tuo, LI YanGe, YANG HongQiang

Scientia Agricultura Sinica. 2018, 51(1): 160-169. doi:10.3864/j.issn.0578-1752.2018.01.015

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【Objective】The effects of straw mat and other mulching materials on apple roots and leaves in different seasons were revealed, which provided a basis for the reasonable mulching in the orchard.【Method】In the spring (April 18), the materials of straw mat, agricultural carpet, horticultural fabric and transparent plastic film were mulched on the ground of 3-year-old Starkrimson apple tree (Malus domestica Borkh), respectively, the clean tillage was used as control. It was measured that the changes of root activity, nitric oxide (NO) production rate, nitrate reductase (NR) activity, nitric oxide synthase (NOS) activity in roots, net photosynthetic rate and other physiological parameters in the next mid-spring, late summer, mid-autumn and early winter. The plant growth root architecture were analyzed in autumn and winter.【Result】The changes of root activity, root NO production rate, leaf Pn and other physiological parameters were significantly different among the four mulchings in different seasons. In spring, the root activity, root NR and NOS activity, and NO production were increased after the mulching treatment, especially the transparent plastic film and agricultural carpet increased them more. In summer, they were also increased under the straw mat and agricultural carpets treatments, but were significantly reduced under transparent plastic film treatment. In the autumn, the activities of NR and NOS were increased under the four mulching treatments. In the early winter, the values of above root physiological parameters all increased significantly under the mulching of straw mat, agricultural carpet and horticultural fabric. Straw mat had more significant effects on root physiological characteristic than other mulching materials in the year except spring. The four treatments reduced the coefficient of variation of all the root physiological parameters, among which the agricultural carpet was the smallest, while transparent plastic film was the largest. The four mulching enhanced the leaf Pn in late summer, mid-autumn and early winter, improved leaf water use efficiency (WUE) in the autumn, increased the total length, diameter, volume and fractal dimension of the roots in the early winter, and promoted shoot growth and trunk thickening. The effects of straw mat and agricultural carpet mulching were more significant than other two materials. The straw mat had the most significant effects on the improvement of root physiological characteristics, and morphological structure, the increase of leaf photosynthetic characteristics and the promotion of plant growth. The effect of agricultural carpets on root fractal dimension is similar to that of straw mat, which is higher than that of horticultural fabric and transparent plastic films in autumn, and the stability of agricultural carpets on the changes of root physiology is most prominent. The effects of horticultural fabric on leaf Pn were less than that of straw mat in late summer and mid-autumn, and its effect on root physiological parameters was less stable than that of agricultural carpet. The transparent plastic film reduced the root activity in the late summer and mid-autumn. In the four treatments, transparent plastic film had the least effect on leaf WUE as well as on plant growth in autumn, and the stability on root physiological changes was also minimal.【Conclusion】From the beneficial effects of the four mulching materials on root activity, root architecture, photosynthesis, water use efficiency, plant growth and root physiological changes, straw mat is the best.

Multivariate Analysis of Fruit Leaf Mineral Elements, Soil Fertility Factors and Fruit Quality of Vaccinium uliginosum L.

BAI YongChao, WEI XuFang, CHEN Lu, WAN RuMeng, HOU ZhiXia

Scientia Agricultura Sinica. 2018, 51(1): 170-181. doi:10.3864/j.issn.0578-1752.2018.01.016

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【Objective】In order to improve fruit quality through the soil and fertilizer management technology, this study explored the relationship between fruit and leaf nutrients, soil fertility and fruit quality (total phenols, flavonoids, anthocyanin, glucose, fructose, soluble sugar) of V. uliginosumin the Greater Xing'an Mountains, screened the main soil fertility factors affecting the accumulation of flavonoids and saccharides in the fruit of V. uliginosum by influencing the content of mineral elements in the leaf. 【Method】The V. uliginosum which grew in three site types were used as material. The three site types included Meadow bog with soil layer type, meadow bog Carex soil layer type and mountain slope type. The canonical regression analysis was used to study the correlation between soil fertility, leaf and fruit mineral element and fruit quality. Multivariate linear regression analysis was used to establish the regression equation, and to filtrate the main soil fertility factors which affected leaf mineral element in V. uliginosum. 【Result】The total contents of monosaccharide glucose and fructose in the fruits grew in Meadow bog with soil layer type and mountain slope type accounted for 84.20% and 95.11% of soluble sugar, respectively. Glucose and fructose were mainly accumulated at fruit maturity in terms of soluble sugar. The phenomenon only occurred in Meadow bog with soil layer type and mountain slope type, the total content of monosaccharide glucose and fructose in the fruits grew in meadow bog Carex soil layer type was measured only 56.95% of soluble sugar. The contents of total phenol and anthocyanin showed significantly differences in three different site types (P＜0.05). The canonical regression analysis indicated that the content of total phenol showed high significant positive correlation with the contents of Ca, Mg, Fe, Mn in fruit, and significant negative correlation with P element. Fruit K and Zn contents significantly influenced fruit quality characteristics, and K content had high significant positive correlation with flavonoid and significant positive correlation with anthocyanin and soluble sugar, the content of Zn was highly negatively correlated with flavonoids, anthocyanin, glucose and fructose in fruit. The contents of Ca and Fe in leaves had significantly positive and negative correlation with flavonoids, anthocyanin, glucose and fructose, respectively, but Ca in leaf had high significant correlation with Zn. Soil fertility had weak relation to the indexes of fruit quality. The contents of N, P, K in leaf were significantly positively correlated with N, P, K in fruit. P in leaf had high significant correlation with K in fruit, Zn in leaf was negatively correlated with Ca and Fe in fruit. Only Mg and Cu in fruit were significantly correlated with soil nutrients, and the soil nutrients mainly affected the leaf mineral content. Besides, the relationship between mineral elements in leaf and soil fertility was complex. Multivariate linear regression analysis indicated that soil pH had the greatest effect on mineral element in leaf, followed by soil organic matter. The content of N, P, K, Mn in leaf increased as the increase of soil organic matter, but the content of Zn decreased. 【Conclusion】The key technical strategies for soil management of V. uliginosum are to improve soil organic matter and ammonium N content, and enhance acidity in soil. Improving the content of K, Ca, Mg, Fe, Mn contents and reducing the content of Zn element in fruit are important measures to improve the fruit quality of V. uliginosum.

Enzymatic Reaction System and Structural Characterization of Phloridzin Oxidation Products POP2

WANG Juan, DENG Hong, LIU Yun, GUO YuRong, MENG YongHong

Scientia Agricultura Sinica. 2018, 51(1): 182-190. doi:10.3864/j.issn.0578-1752.2018.01.017

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【Objective】 Phloridzin oxidation product 2 (POP2) is a final polyphenol oxidation product generated by enzymatic oxidation in the process of fruit juice, and it has an important impact on the browning and deterioration of fruit juice. In order to detect POP2 effects during process and storage of apple juice, the phloridzin polyphenol oxidase reaction system was established, POP2 was separated and purified, structural characterization was analyzed. 【Method】 The three reaction factors of pH, temperature and substrate concentration were tested first, and then enzyme reaction in ethanol solution were studied, and content changes of phloridzin, intermediate products, POP2 during oxidation process were detected by HPLC method. The POP2 was isolated and purified by ethyl acetate extraction, anhydrous ethanol desalting and recrystallization, the structure of POP2 was characterized by the methods of ESI-MS and IR.【Result】 The optimal conditions for the enzymatic oxidation of phloridzin were pH 6.5, 35℃, substrate concentration 3 mg?mL^-1. The addition of different concentrations of absolute ethanol had a significant increase in the rate of enzymatic oxidation of phloridzin, the highest reaction conversion rate was 2.4 times at 20% ethanol concentration. The color of the phloridzin reaction fluid changes from slightly yellow, bright yellow, orange to orange-red at the beginning, middle and final reaction stage. The HPLC results showed that the conversion rate of phlorizin was 90.2% when the substrate concentration was 3 mg?mL-1 and the reaction time was 48 h. Intermediates X1 and POP1 were almost close to trace, the accumulated POP2 was stable. The residual phloridzin in the reaction solution could be removed by ethyl acetate extraction. The purity of 96.8% POP2 was obtained by anhydrous ethanol desalting and recrystallization from methanol. The molecular weight of POP2 was 467 by positive mode ESI-MS analysis, molecular formula is C₂₁H₂₂O₁₂. IR results showed that POP2 had characteristic ether, ketone, benzene ring and carboxyl functional groups, and it was consistent with the structure of the predicted phlorizin oxidation product structure. 【Conclusion】 The major oxidation products of phloridzin in enzymatic system is POP2, POP2 content can be established a landmark test indicators in apple juice browning and deterioration.

Advances in Ecological Theories and Management Models Regarding Rangeland Management

LI XiangLin

Scientia Agricultura Sinica. 2018, 51(1): 191-202. doi:10.3864/j.issn.0578-1752.2018.01.018

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The introduction of Clementsian succession theory in early twentieth century represented a substantial advance in rangeland ecology. Succession theory as a central concept of equilibrium ecology had profound influence on development of rangeland science and natural resource management models. However, equilibrium ecology and the steady-state management model received severe criticism in 1970s and 1980s. On one hand, nonlinear vegetation dynamics was recognized in rangeland ecosystem research, which is inconsistent with the interpretation of the traditional succession and steady-state management. On the other hand, research in other parts of the world indicated that the rangeland concepts and range models developed in United States did not well apply to the ecosystems in Africa and Asia where the prevailing environments are characterized by frequent disturbances and alternative conceptual frameworks are called for to provide more realistic, accurate interpretations of range vegetation dynamics and scientific support to natural resource management. In this context, equilibrium ecology emerged in response to the dissatisfaction of the prevailing ecological theory. In particular, an ecosystem-level research in east Africa presents a view of pastoral ecosystems that are nonequilibrial but persistent (persistent nonequilibrium model), and further research resulted the recognition of the importance of relative proportion of key resource in the dry/cold season as the determinant of animal numbers and their potential impacts on vegetation. The state and transition models which emerged in 1980s represented an important alternative conceptual framework and were applied in 1990s to rangeland assessment as a replacement of range condition in USA. Resilience is currently replacing nonequilibrium as the dominant ecological concept because ecosystems that were previously considered nonequilibrium is now more appropriately interpreted as multiple equilibria in many cases. The advances in rangeland ecological theory have been accompanied by parallel progression of rangeland management model, notably a transformation of the role of human from resource users to resource stewards. The rangeland models in twentieth century were generalized as steady-state management with the overall goal of maximizing sustainable production of forage and livestock. The application of resilience as the most recent and important ecological advance has been extended to coupled social-ecological systems, leading to the development of the concept and procedures of adaptive management. Currently the above described models are in application to a greater or less extent and synthesis of different models for rangeland assessment and management will help develop improved framework for complex, adaptive social- ecological systems.

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