N-alkenes-determination techniques are used to identify diet composition, feed intake, and to evaluate nutritional status of grazing animals. This article summarizes the sampling of representative diet, actual releasing rate of alkenes control release capsule, the background value of even n-alkenes in feces, the necessity and suitable methods of measuring fecal recovery of n-alkenes and principle component analysis of diet components n-alkenes patterns which are important and easy to be ignored in this field. The basis of applying n-alkenes technique for studying grazing animal nutrition and ecology accurately is provided.

Glutathione (GSH), an important antioxidant in plants, can scavenge the redundant active oxygen free radicals produced during cell metabolism processes and relieve the damage caused by membrane lipid peroxidation. GSH contributes to the role of adversity stress resistance in plants. This review summarizes GSH activities including the types of GSH in plants, the application of GSH and the physiological mechanism of GSH protecting plant cells including scavenging intracellular active oxygen free radicals, forming non-toxic compound by combining with toxic heavy metal material, absorbing and transporting amino acid, resisting to adversity stress (temperature stress, drought stress, heavy metal stress and salt stress). GSH metabolism plays a positive role for understanding the physiological function of plant antioxidants, knowing the mechanism of scavenging active oxygen free radicals, and studying plant resistance.

Seed dormancy and germination are complex adaptive traits of plants influenced by a great number of genes and environmental factors.Although the utilization of quantity genetics methods(such as QTL analysis) and mutant approaches have made great development for dormancy and germination,the detailed mechanisms of dormancy and germination are not yet fully reported.Hormone,a factor to initiate seed germination,plays a key role in the regulation of seed dormancy and germination.Therefore,the relation between hormones and both germination and dormancy continues to be a research focus of seed physiology and biochemistry.With advancing understanding of the molecular biology and the discovery of a large number of mutants,regulatory mechanisms for a single hormone and interactions among hormones during seed dormancy and germination processes are better known.However,little knowledge about key points of networks for different hormones is known.This paper will focus on the functions of abscisic acid(ABA),gibberellin(GA),ethylene(ETH),brassinosteroids(BR) and other hormones during seed dormancy and germination progress,and further discusses the signaling relationship among these four hormones.

Forage is an important material basis for the benign development of herbivorous animal husbandry,and forage industry is an important part of its development,which plays an important role in optimizing agricultural structure. At present,Hulunbuir forage industry resources (27.96 million tons annual output) include mainly three plates:natural forage,artificial forage and straw forage,accounting for 32.8% of the effective utilization of resources. However,focusing on the industrial level,there are still many problems:no quantitative standard for classification and grading,loss and waste of grass resources,information asymmetry between market supply and demand,scientific and technological low level of forage industry,difficult formation of industrial chain,etc. At the same time,it is also facing with problems in resources,technology,policy and so on. This paper combed the present situation of the production of natural forage,artificial forage and straw forage industry in Hulunbuir,and comprehensively analyzed the problems existing in the development of Hulunbuir forage industry. Measures and suggestions were proposed,including optimized forage industry,strengthened forage storage construction to reduce waste and loss,diversified grass product technology research and development,artificial grassland construction to reduce grassland bearing pressure,supporting forage industry leading enterprises,and others,to provide reference for the high-quality development of Hulunbuir forage industry.

This study was conducted to evaluate the effects of different cover cropping strategies on the soil's physical and chemical properties,as well as the bacterial community structure in organic kiwifruit ( Actinidia chinensis) orchards in the Guanzhong Area. This experiment was conducted in 2021 at the Yangling Baiheng Organic Kiwi Orchard in Shaanxi Province. Three artificial cover cropping measures were tested: Lolium multiflorum+ Astragalus sinicus, Lolium multiflorum+ Glycine max, Lolium multiflorum+ Vicia villosa,with natural grass used as a control. The chemical properties and bacterial community structure of the soil in the topsoil(0~20 cm) were determined. The results showed that the organic matter of artificial grass increased by 8.8%~11.9% compared to the control,with the organic matter content of Lolium multiflorum+ Vicia villosa reaching 26.69 g·kg ^-1;The activities of soil urease,alkaline phosphatase,catalase were increased ( P<0.05),with Lolium multiflorum+ Vicia villosa having the most significant effect ( P<0.05). The bacterial beta diversity and the interaction relationship between bacterial communities in artificial cover cropping measures increased,while the abundance of metabolic functional genes in organismal systems significantly decreased( P<0.05). In summary,planting Lolium multiflorum+ Vicia villosa. and Lolium multiflorum+ Astragalus sinicus in organic kiwifruit orchards in the Guanzhong area can enhance the soil micro-ecological environment.

Grassland is the largest terrestrial ecosystem in China, serving as the cornerstone for safeguarding national ecological security, fostering ethnic unity, and propelling regional economic-social development. In the new era, the ecological conservation of grassland and the green and high-quality development of grass industry are confronting with both new opportunities and challenges. This article delves into several aspects, including grassland technological innovation, the utilization of “the third national land resource survey” data in grassland management, the establishment of germplasm resource breeding and multiplication base of native grass, and the cultivation of local advanced talents in the western region. The aim is to provide references for cultivating new quality productive forces in the grass industry and promoting its high-quality transformation and development under the new circumstances.

This paper reviews the different results and varying courses of taxonomic study on genus Medicago L.during the past century and places emphasis on the classification difference of taxonomic system between China and the western countries.By the Chinese system, Medicago, Trigonella L., Melissitus Medik.,and Turucania were separated as the difference genus,however all of them were classified to Medicago by the western system and the concept of M.sativa L.complex was established including ssp.sativa,ssp. falcata,and ssp. varia.In order to fully exert the advantage of Medicago germplasm resources in China and realize the genetic improvement function of excellent gene,it is suggested to recheck and study the current gene bank status of genetic resources and taxonomic system at molecular level.

Oat ( Avena sativa L.) is one of the main sources of roughage for ruminants,and it is beneficial to rumen health and production performance of cows because of it is rich in carbohydrates. Silage is one of the main forms of safe storage of oat,which has the advantages of good palatability and high digestibility. As for oat silage,predecessors have carried out a lot of researches,mainly focusing on the moisture,harvest period,additives,mixing and feeding of oat silage. Based on these,this paper summarized the researches on oat silage. The constraints affecting the fermentation and nutritional quality and the utilization value of oat silage were summarized,which would promote the concoction and utilization of high-quality oat silage.

Fusarium oxysporum is one serious soil-borne pathogenic fungus and is listed as one of the top ten plant fungal pathogens in the world. This fungus can infect more than 100 economically important crops such as cotton,soybean,watermelon,banana,tomato and alfalfa,causing wilt and root rot. The detection and quantification of F. oxysporum in soil and plant root tissues is the basis for early diagnosis and effective control of the disease. This article summarizes the research progress and application of F. oxysporum detection and quantification methods at domestic and overseas,mainly including medium colony plate dilution method,conventional PCR and real-time fluorescent quantitative PCR,etc. This review provides theoretical guidance for F. oxysporum detection and quantification in agriculture.

Turf grass industry stepped into a stage of comprehensive development with rapid economic development and accelerating urbanization of China. It became a new growth point of national economy for the greatly enriched boundary. The concept and industrial structure of turf grass industry were defined and discussed in this paper. The industrial developments in the past ten years were respectively summarized from market, production, service and scientific education system. Main tasks of turf grass industry development in the future were summed up respectively to include industry standard, enhancing industry management, strengthening education and scientific research, and improving scientific and technological output.

The high-quality forage is the basis of the healthy development of modern animal husbandry, which requires scientific control of planting, field management, harvesting, and processing. Drying is a key link in the post-harvest processing of forage, which significantly affects the quality of forage. To provide reference and technical support for the development of China's forage post-production processing industry, this paper summarizes the technology of forage harvesting and drying, and reviews and analyses the research advances of forage drying characteristics and drying equipment under the main drying methods in China and other countries. The main drying methods of forage grass include natural drying, hot air drying, high-temperature-fast-drying, solar drying, etc. In recent years, domestic scholars have studied the drying characteristics of forage grass under different drying methods. The domestic forage drying technology has been gradually improved, but it still lags behind the mechanized production technology of forage drying in foreign countries. There are problems of domestic forage drying technology, such as the mismatch between harvest and drying process, the lack of design standards for drying equipment, and small enterprise scale. Thus, the development direction of our country's forage mechanized drying processing industry is to formulate standardized forage drying processing technology, strengthen the research of forage drying technology, realize intelligent and integrated forage drying equipment.

Grassland accounts for about 40% of the total land area in China,but the long-term excessive resource utilization by farmers and herdsmen results into large-scale grassland degradation,as output and input of grassland ecosystem in terms of energy flow and material circulation are out of balance. Since the 18th National Congress of the Communist Party of China,great efforts of grassland protection and restoration have been continuously made,and therefore the deterioration of grassland ecology has been preliminarily prevented. The construction of perennial mixed sowing artificial grassland is an important measure for animal husbandry development and ecological restoration of degraded grassland,and has great strategic significance for the sustainable development of grassland ecosystem and the construction of ecological civilization. In this paper,we reviewed the progress of the relevant researches in the recent 20 years,and put forward a theory of Quasi-stable state for the mixed sowing artificial grassland. We define the contents and significance of Quasi-stable state,and construct a technological system to maintain the Quasi-stable state in perennial mixed-sowing artificial grassland. This work provides guidance for the healthy and sustainable development of animal husbandry and ecological restoration in China.

To uncover the effects of arbuscular mycorrhizal fungi (AMF) on reseeding species at different growth period,a microcosm experiment was carried out using Bromus inermis, Agropyron cristatum, Leymus chinensis,and Poa pratensis as test material. This experiment was set up as a factorial design containing two AMF inoculation treatments (with AMF,without AMF) and three growth period (seedling,jointing,jointing after mowing). We measured above-ground and below-ground biomass,root colonization,soil hyphal density,mycorrhizal growth response,and plant-available phosphorus. Our results showed that AMF inoculation increased the above biomass and below biomass of B. inermis and L. chinensis,compared with none inoculation. However,AMF inoculation did not affect the above biomass and below biomass of A. cristatum and P. pratensis at jointing after mowing period,compared with none inoculation. Mycorrhizal growth response (MGR) of four species was positive at each period,and the lowest MGR of A. cristatum, L. chinensis,and P. pratensis was at jointing period after mowing. From seedling to jointing period,AMF root colonization of these four species significantly increased. Soil hyphal density in B. inermis, A. cristatum,and L. chinensis reached the maximum level at jointing period after mowing. Therefore,the symbiotic relationships between AMF and plants depend on growth periods of plants and were species specific. Overall,from seedlings to adults,the abundance of AMF in roots and outside roots increased,while the response of MGR showed a decreasing trend. This indicated that AMF had a strong growth-promoting effect on plant seedlings,and this growth-promoting effect was not related to AMF abundance.

Ethephon (2-chloroethyl phosphonic acid, an ethylene-releasing compound) is a plant growth regulator with various systemic properties. It is widely used on wheat, coffee, tobacco, cotton, and rice in order to help fruit to mature more quickly. Various effects of ethephon treatment on plants have been published. This article focused on reviewing the effects of foliar ethephon application on plant drought tolerance. To date, either promotion or inhibition of drought tolerance by ethephon treatment was reported. The effect of ethephon treatment on plant drought response was dependent on many factors, such as the concentrations of ethephon solution, plant species and cultivars, plant developmental stages, and treatment methods. In addition, the possible mechanisms of ethephon treatment affecting plant drought tolerance were discussed.

To explore the changes of ratio of root to soil and soil physiochemical properties, a yield experiment was carried out at different degraded successional stages (PV: Primary vegetation, LD: Light degradation, MD: Moderate degradation, HD: Heavy degradation) in Haibei Research Station of Alpine Meadow Ecosystem. The results showed that the ratio of root to soil increased with the degradation of alpine meadow, while significantly decreased with the increase soil depth. Meanwhile, soil bulk density significantly increased with the increase of soil depth, but soil water content, total nitrogen, total phosphorus, available phosphorus, and available potassium were significantly reduced. In the process of degradation, the grazing had a significant effect on the contents of topsoil (0～10 cm) nutrient (total nitrogen, available phosphorus, available potassium) and soil physical characteristics (soil water content, soil bulk density).

China has large area of grasslands, accounting for about 40% of the national total areas. Inner Mongolia grassland comprises more than 20% of China's total grasslands. In the recent past, Inner Mongolia grassland has been undergoing successive degradation driven by both natural factors and human disturbance, which exerts negative influence on carbon sequestration ability of the ecosystem. This paper reviewed the criteria, degree and current situation of grassland degradation in Inner Mongolia. Driving forces of grassland degradation in the region were probed in the aspects of human activities, climate change and material inflow and outflow in the grassland ecosystem. The basic progress of carbon cycle and the impact of grassland degradation on carbon sequestration were discussed. This paper also introduced the carbon sequestration potential of degraded grassland under varied restoration implementations. Finally, the strategy for preventing grassland from degradation and for enhancing the carbon sequestration ability was recommended.

The carbon cycle of grassland ecosystem and its impact factors has become a study focus in the field of ecology, geology, botany and agronomy due to drastic global change in recent years. The present paper introduces the process of carbon cycle of grassland ecosystem and discusses the circulation of carbon among atmosphere sink, vegetation sink, herbivores sink and soil sink. Furthermore, the influences of climate factors, soil factors, CO₂ enrichment and human activities on carbon cycle were also analyzed here. The main problems and prospects of the study on grassland ecosystem carbon cycle are proposed.

In order to investigate the effects of abandonment years on cropland soil, a field survey was conducted in August,the peak season of plant growth. Soil samples were collected from unabandoned cropland (CK) and croplands with different abandoned years (7 years,7a;15 years,15a;30 years,30a). Soil physicochemical properties,soil moisture and nutrients were analyzed and calculated. The results showed that abandonment had a significant improvement on soil bulk density,and significantly decreased soil porosity and pH. Compared with unabandoned cropland,abandonment significantly elevated the contents of soil organic carbon (SOC),total nitrogen (TN) and total phosphorus (TP). Consequently,long-term abandonment had a significant improvement effect on soil nutrient status. Soil water content and soil nutrient indicators exhibited a significant positive correlation at different abandoned years. The results showed that less evapotranspiration reduced soil water loss and accumulated soil nutrients under long-term abandonment. Further,there were significant positive correlations between soil water content and at least one variable related to soil nutrients. Therefore,long-term abandonment had positive effects on soil nutrients content,which might be due to the fact that less evapotranspiration reduced the loss of soil water content,and further promoted the accumulation of soil nutrients. This study can provide theoretical support for rational planning of abandoned cropland in the agro-pastoral ecotone in Bashang of Hebei Province.

Different degree degradation of grassland ecosystem has been found under the stress of population increasing and impact of modern agricultural and industrial demands.The degradation of grassland ecosystem includes qualitative and quantitative changes in grassland composition,structure,process and function.They are the foundation and precondition of ecological restoration for the understanding of degraded grassland concept,driving forces,process and diagnosis of degradation degree.A series questions about grassland degradation was discussed systematically in this paper by summarizing former studies,and a conceptual model of grassland degradation was made."Natural grassland ecosystem" characterized by mild disturbance from human beings or nature was suggested to be "Model Grassland Ecosystem" for degradation research from an ecological point of view.Diagnostic approaches of grassland degradation were summarized as biological approach,habitat approach,function/service approach.The available diagnostic methods and their indices(system) related to grassland degradation degree were analyzed;and integral critical point during diagnosis of degradation degrees and the restoration precautions of degraded grassland were discussed.

The net ecosystem exchange of carbon dioxide (NEE) between terrestrial ecosystems and atmosphere is a major component of carbon cycle of terrestrial ecosystems called "breathing" of the terrestrial biosphere, and is great concerned in the research of global climate change. Grasslands, as a major component of the terrestrial ecosystems, comprising approximately 40% of the world's terrestrial surface, is sensitive to climate change. Grazing plays a significant role in the land use and management of grasslands. With the change in global climate, the impacts of different grazing intensities on grazing ecosystems have different ways. In this review, the effects of grazing on the characteristics of NEE in grassland ecosystems are focused in general based on factors in NEE composition and the pathways of grazing effects on NEE in grasslands. Grazing mainly disturbs the soil-vegetation interface of grasslands then affects grassland NEE through the disturbances on 1) plant, including effects on plant community composition, above and below-ground net primary production and litter; 2) soil, including the effects on soil respiration, soil nutrients especially soil carbon and nitrogen, soil temperature and moisture. The pathways of grazing effects on grasslands can also be applied in disturbances such as cultivation and defoliation and is of great importance in the investigating of NEE characters and carbon flux of different grassland ecosystems, particularly grasslands in different land-use, whether in carbon source or sink in certain degrees and their carbon storage capacity.

Cellulose is a biopolymer of considerable economic importance,it has a profound effect on human food, clothing and the development of new energy. In recent years, research focus on the cellulose is purified cellulose synthase proteins and synthesis cellulose in vitro, for that reason acquire new knowledge of structure and function about cellulose synthase(CESA)and cellulose synthase complex (CSC) is particularly important. Crystallography and 3D modeling technology application in protein structure prediction, overthrew the microfibril synthesis of the original model, and puts forward new speculation on the basis of the data. This paper summarizes the latest researches of CESA proteins biochemical structure, function, regulation of transcription and translation after modification, provides a new basis for follow-up study.

Grassland ecosystems are a vital part of terrestrial ecosystems. China's grasslands are rich in resources and have significant potential as carbon sinks. Therefore,it is urgent to enhance the capacity of grassland carbon sinks to achieve the goal of carbon neutrality as soon as possible,in line with the 'two-carbon’ strategy. Currently,the development of carbon sinks in grasslands faces numerous challenges and uncertainties. Measures to enhance the function of carbon sinks in grassland ecosystems remain unclear. This paper summarized recent research on the carbon stock of grassland ecosystems in China,including the characteristics of carbon sources and sinks,clarified the key factors that affected grassland ecosystems as carbon sinks and analyzed the challenges of the enhancement of grassland carbon sinks. The proposal recommended balancing and coordinating the protection and utilization of grasslands,scientifically rehabilitating degraded grasslands,supporting the development of grasslands for low-carbon industries,strengthening policy guidelines,promoting carbon trading in grasslands,and advocating for green and low-carbon production and life in pastoral areas.

Plant growth promoting rhizobacteria (PGPRs) exist in soil or are attached to plant roots with the functions of growth promotion and yield improvement. In addition,PGPRs can enhance plant resistance to biotic and abiotic stresses. Nowadays,with the development of green and sustainable agriculture,microbial fertilizer has become a new type of popular of fertilizer. Therefore,researches on isolation and characterization of PGPRs,their interaction with plants and the development of microbial fertilizer containing PGPRs are attracting more and more attentions. In this paper,the research advances on PGPRs,including their growth promotion mechanisms (nitrogen fixation,phosphorus solubilization,potassium releasing,iron solubilization,plant hormone secretion,release of volatile organic compounds etc..) and tolerance enhancement of biotic stresses (pathogens and pests) and abiotic stresses (drought,salinity and heavy metals),were reviewed. Finally,the research directions on PGPRs in the future were prospected.

Natural grassland is the survival and development basis of inhabitant in pastoral areas. In recent years, grassland degradation resulted from human factors and subsequent natural factors have posed a threat to the sustainable development of animal husbandry. Poisonous-weeds growth grassland is an important index of grassland degradation. The category and distribution of poisonous weeds, the situation of integrated control and the reasonable utilization of poisonous weeds were summarized in this paper. The 1300 species of poisonous plants (140 families) were found in China, in which 23 species caused serious damage to livestock industry. The locoweeds (species of Oxytropis and Astragalus), Stellera chamaejasme and drunken horse grass ( Achnatherum inebrians) of 23 species were mainly distributed in Qinghai, Tibet, Xinjiang and Inner Mongolia where were the main grassland regions of China, and their damage to livestock industry accounted for 80% of all livestock losses in the temperate grasslands of China. Therefore, the restoration of grassland ecosystem is a key of effective poisonous plant control. It is necessary to establish a technical system of integrated poisonous weed management, including an ecological management, chemical and mechanical removal.

The type and quantity of silage microbes play an important role in the whole fermentation of silage. Exploring and utilizing of silage beneficial microbes has become an important research direction to improve the fermentation quality. The microbial species in the different types of mixed silage are quite different,which makes the fermentation characteristics diverse. The succession process and community structure of fermenting microbes often determine the fermentation quality. Monitoring the dynamic changes of the composition of microbial flora can provide a theoretical basis for regulating the fermentation of silage. In this paper,the succession process of silage microbial community,the microbial diversity of different mixed silage types,and the factors affecting microbial diversity of mixed silage were reviewed. At the same time,the problems of antibacterial activity of lactic acid bacteria,the promotion of mixed silage and the performance of mixed silage on animal production are pointed out and the prospects were put forward,which could provide reference and new ideas for the practical application of silage microbes.

Artificial grassland establishment is an effective method for managing grassland degradation in the Sanjiangyuan area. This study analyzed the availability of soil nutrients and the mechanism of carbon,nitrogen,and phosphorus cycling and balancing by examining the content of key nutrient elements and their proportional relationships in soils sown with different pasture grasses in the Sanjiangyuan area. The finds suggest that the contents of soil organic carbon,total nitrogen,and total phosphorus in the artificial grassland were significantly higher than those in the degraded grassland. Additionally,the soil nutrient improvement effect of mixed-seeded artificial grassland was better than that of single-seeded artificial grassland. Further correlation analyses revealed that soil C:N was limited by carbon and nitrogen,soil C:P was limited by carbon,and soil N:P was limited by carbon and nitrogen. In summary,the main limiting nutrient elements in the region are carbon and nitrogen. Therefore,supplementing these nutrients appropriately can improve the soil quality of artificial grassland. This study's results provide an valuable reference forsoil quality improvement in the Sanjiangyuan area through rational pasture mixing.

Samples of root rot disease of Medicago sativa were collected from Langfang of Heibei, Linhe of Inner Mongolia and Yanggao of Shanxi in 2013, to determine the dominant pathogens of alfalfa in these places. Pathogens were isolated from the samples and purified in PSA and MGA plate. Representative strains were selected based on biological characteristics,and then rDNA-ITS and TEF-1α sequences of the fungi were amplified and sequenced. Morphological and molecular biological methods were used for identification of the representative fungi, and then determined pathogenicity by back infestation test. We isolate 6 representative strains, named C1, C2, C3, C4, C5 and L1. The results showed that:C1 and C2 were identified to be F. tricinctum, C3, C4 and C5 were F. solani, L1 was F. proliferatum, which revealed that F. tricinctum was the main pathogens of alfalfa root rot in Langfang of Hebei province, F. tricinctum and F. solani were the dominant pathogens of this disease in Linhe of Inner Mongolia, and F. solani and F.tricinctum were the chief pathogens of Yanggao County of Shanxi province. The results of inoculation showed that L1 (DI 80.88%, DSI 61.35%) and C4 (DI 82.22%, DSI 59.6%) strains had higher pathogenicity, and C2 showed weakest pathogenicity (DI 54.44%, DSI 29.63%). There were no significant differences at disease incidence and disease severity index in C1, C3 and C5 strains, the disease incidence was 66.66%, 62.22% and 65.55% respectively; Disease severity index was 42.59%, 40.37% and 38.89%, respectively.

Chlorophyll fluorescence parameters were measured in alfalfa varieties with different fall dormancy under room temperature and low temperature (-8℃),respectively.The influence of low-temperature on chilling index and the chlorophyll fluorescence parameters were analyzed in different alfalfa varieties.Results show that after cryogenic stress,maximum photochemical efficiency ( F _v/ F _m) of PS Ⅱ in both Dona Ana and Pierces varieties decreases significantly.Electron transfer rate (ETR) and actual photochemical quantum yield (Y) decreased suggesting that the leaves of both cultivars suffer heavier cold injury.There were small change of fluorescent parameters for Vernal and 5246.The non-photochemical quenches (NPQ) value increases significantly in non-fall dormancy varieties (CUF101 and UC-1465),but other parameters show no significant change.Under light cryogenic stress,non-photochemical quenches (NPQ) value increased suggesting that the dissipation of excess light energy is conducive to protecting photosynthetic apparatus.Therefore fluorescence parameters of alfalfa varieties are closely related with cold resistance.

White clover ( Trifolium repens ‘Haifa’) was selected as experimental material in this study,and effects of seeds soaking with gamma-aminobutyric acid (GABA) on germination and tolerance to aluminium (Al ³⁺) stress were studied. The results showed that 1 mmol·L ^-1 Al ³⁺ solution significantly inhibited seeds germination,and the damage becomes more obvious with the increase of Al ³⁺ concentration. The germination and root length of seeds soaking with GABA significantly increased under Al ³⁺ stress with the most obvious effect under 4 mmol·L ^-1 Al ³⁺ stress. The antioxidant enzyme activity and non-enzymatic antioxidants content of seeds soaking with GABA significantly increased as well,thereby reducing oxidative damage effectively and improving cell membrane stability during germination under Al ³⁺ stress. In addition,seeds soaking with GABA also significantly increased genes expression of dehydrins under Al ³⁺ stress. Therefore,GABA-induced Al ³⁺ tolerance could be related to the enhancement of antioxidant defense to reduce oxidative damage caused by stress and the up-regulation of dehydrins genes expression during white clover seeds germination.

Studying the diet composition of rodents and their trophic niche not only can reveal the feeding adaptation characteristics of species under the changing alpine meadow environment,but also explore the interspecific relationships of rodents. In Gannan meadow,the diet composition and trophic niche characteristics of plateau pika ( Ochotona curzoniae),plateau zokor ( Eospalax baileyi),and Himalayan marmot ( Marmota himalayana) in harm subregion of rodent pest of subalpine meadow were studied by fecal microstructure analysis. The results showed that the plant species the three rodents ate were basically the same,but the proportion of the same plant was different. The plants that the plateau zokor ate on were mainly Polygonum viviparum and Potentilla edulis,and the intake of Cyperaceae plants was significantly higher than the other two animals. The plateau pika mainly ate Poaceae grasses,the Himalayan marmot mainly ate Poaceae and Asteraceae. The order of trophic niche width was as follows:Himalayan marmot> plateau zokor > plateau pika,the trophic niche overlap between plateau pika and Himalayan marmot was the largest (0.52). Food proportions differentiation and nutritional niche separation of the three species of rodents are the important reasons for their coexistence and resource sharing.