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.

Grassland is an important ecosystem and a natural ecological security barrier in the north of China with its important ecological and production values. In recent years, due to the unreasonable use of grasslands and abnormal changes in climate, grassland pests have been aggravated year by year, which seriously restricted the livestock production and ecological civilization construction in China. Based on historical data, this article summarized the characteristics of China grassland pests with many types, strong damages, and heavy losses, analyzed the staged effects of prevention and control, and objectively pointed out the current prevention and control work's lack of monitoring capabilities, funding, equipment, scientific research support, and lagging policies and regulations, and other major issues. It then systematically put forward working goals and specific measures for strengthening grassland pest control in terms of rationalizing management systems, strengthening system construction, improving monitoring and early warning levels, innovating control mechanisms and technologies, and increasing publicity and training efforts, which provide ideas for the next step in grassland biological disaster prevention and control.

In order to explore the estimation method and driving factors of carbon storage in the Tibetan Plateau, carbon storage was estimated according to the measured data on basis of InVEST model, and then the driving forces were analyzed via structural equation model including meteorological and soil factors. The results showed that the overall carbon density in the Tibetan Plateau tended to be high in the southeast but low in the northwest. Furthermore, the carbon storage of alpine Kobresia and weedy meadow was the largest, reaching to 1.97×10 ¹¹ Mg. The aboveground carbon density was most sensitive to the change of total carbon density, with a slope of 44.73. Besides, precipitation, pH, cation exchange, organic matter, total nitrogen and available nitrogen were the important driving factors of carbon density in the Tibetan Plateau. The results can provide a scientific basis for the carbon pool management and human activities regulation of alpine ecosystem.

Whole-plant wheat ( Triticum aestivum) has high feeding value,and it has become one of the main sources of roughage for ruminants in some countries or regions. The purpose of this study was to screen high-yield and high-quality wheat varieties,and to determine the differences in yield,nutrition and silage fermentation quality among varieties and correlation between measured characteristics. For 24 wheat varieties tested,their dry matter (DM) yield ranged from 5.20 to 9.81 t·hm ^-2,and the crude protein (CP) ranged from 0.40 to 0.85 t·hm ^-2. Among them,‘SM1’ and ‘CM61’ had high DM and CP,and ‘SM1’ and ‘HG35’ had high relative feed value. The relative feed value of ‘CM61’ and ‘HG35’ was significantly lower than ‘SM1’ ( P<0.05). The thousand-seed weight of wheat had positive effect on the DM yield of whole-plant ( P<0.05). The DM yield of whole-plant wheat had negative effects on lactic acid and butyric acid contents of silage ( P<0.01). The CP content of whole-plant wheat had positive effect on butyric acid content of silage,but neutral detergent fiber had negative effect on butyric acid content ( P<0.05). The result showed that ‘SM1’ and ‘HG35’ were more suitable for planting in winter fallow fields in Guangdong Province.

Species diversity and biomass are two important indicators to characterize the quantitative characteristics of grassland ecosystem. The changes of species diversity and biomass are discussed in depth to provide a theoretical basis for species protection and productivity maintenance of grassland ecosystem. In this paper, taking Xilingol grassland as the research object, the vegetation characteristics of meadow steppe, typical steppe and desert steppe were investigated by sample method. The changes of above-ground biomass and species diversity of different steppe types and the relationship between them and environmental factors were analyzed. The results showed that the above-ground biomass was significantly positively correlated with community coverage, community height and plant density, except that the community density was the highest in typical steppe, and the characteristics of each community were meadow steppe>typical steppe>desert steppe ( P < 0.05). The diversity and richness of plant species increased from desert steppe to typical steppe and then to meadow steppe, and the evenness of species distribution was the highest in desert steppe. Soil nutrients and precipitation had great influence on plant growth. Precipitation and altitude had great influence on species diversity and richness, and evenness was mainly affected by altitude, soil pH and climate.

The monitoring of grassland aboveground biomass is an important basis for the rational utilization of grassland resources and understanding of the grassland ecological succession process.However,real-time observation of grassland aboveground biomass requires a lot of manpower and material resources,so it is urgent to use remote sensing,mathematics,and other indirect observation methods.This review systematically concluded the domestic and foreign methods of grassland aboveground biomass estimation including statistical models and mechanism models such as grassland growth models,crop growth models,light use efficiency models,and ecological process models for grassland aboveground biomass estimation.We summarized the characteristics and applicable conditions of the current models,and the relevant scientific concepts and strategies in researches.By reviewing researches on agricultural remote sensing data assimilation meeting the realistic requirements of grassland yield estimation,this review presents a less popular approach of estimating grassland yield based on the remote sensing data assimilation method,which provides a large-scale and high-precision way on grassland growth simulation.

Seed germination,growth,and development of plants are restricted by many environmental factors.An adverse environment will cause postponing seed germination,irregular emergence,slim seedlings and so on,and may lead to severe responses of plants to the stress.(γ-Aminobutyric acid,GABA) is a signal substance widely used in regulating plant stress adaptation in recent years.This study described the role of GABA in plants,analyzed the physiological mechanism of GABA production under environmental stresses,and reviewed how GABA regulates plant seed germination,seedling morphological development,plant antioxidant effect,photosynthesis,nitrogen metabolism,endogenous GABA metabolism,and polyamine metabolism under environmental stress.Finally,we discussed some unsolved scientific questions about GABA in regulating plant stress resistance and prospected the application prospect of GABA.This review may provide theoretical reference for the research related to GABA and the practical application of this substance.

Forage is of the indispensable importance to herbivores. The strategy of utmost spurring the development of the high-quality forage industry can be adopted by the measures of expansion of the forage sources,increment of the forage yields and extension of the animal products application in the line of the vital technical approaches such as,increasing grain production with the exploring of forage,saving grain supply with the exploring of forage,and replacing grain supply with the exploring of forage. In this way,we can achieve the conversion of forage into grain,and make an important contribution to enhance the level of national food security and comprehensively consolidating the foundation of food security.

In order to screen and evaluate plant species with higher cadmium (Cd) tolerance,in this study, Medicago sativa, Lotus corniculatus, Coronilla varia, Elymus dahuricum, Agropyron trachycaulum,and Buchloe dactyloides,six common herbaceous plant species were selected. We set 0 mg·kg ^-1 Cd treatment concentration as control (CK),and potted simulation experiments of different concentrations of cadmium were used to explore the effects of Cd stress on plant enrichment characteristics and root morphological changes,and to evaluate their Cd tolerance threshold. The main findings were as follows:the biomass and root morphology of the six herbaceous plants under different concentrations of Cd showed a phenomenon of "promotion at low Cd concentration and suppression at high Cd concentration". Different species had different tolerance to Cd. The tolerance threshold of Cd was between 50 mg·kg ^-1 and 100 mg·kg ^-1 for Medicago sativa and Coronilla varia,and the tolerance threshold of Lotus corniculatus, Elymus dahuricum, Agropyron trachycaulum and Buchloe dactyloides to Cd was above 100 mg·kg ^-1. Under the stress of 100 mg·kg ^-1 Cd, Lotus corniculatus, Elymus dahuricum and Buchloe dactyloides could be used for restoration of heavy metal contaminated soil by means of plant extraction. When Agropyron trachycaulum was treated at 100 mg·kg ^-1 Cd,the root enrichment coefficient was still greater than1,and the root biomass and tolerance coefficient had a trend of increasing with the increasd of Cd stress. Agropyron trachycaulum is an ideal herb material with high Cd tolerance and high resistance for repairing heavy metal contaminated soil.

Grazing is one of the most important uses of grassland ecosystems,and different grassland types,grazing intensities,herbivore assemblages,grassland use types and climate change all influence the structure and function of grassland ecosystems. It is very important to understand the mechanisms of grazing and climate change on grassland ecosystems for their sustainable development. In order to provide a theoretical reference for the adaptive management and sustainable development of grassland ecosystems,this paper provided a systematic review of the mechanisms by which grazing affects the structure and function of grassland ecosystems,and provided an outlook on several important research directions in this theme,and future research issues as the following:(1) to improve spatial coupling analysis in grazing grassland ecosystems;(2) to focus on multifunctionality studies of grassland ecosystems;(3) to elaborate the multi-factorial nested experiments on grasslands in the context of global change;(4) to refine the mixed grazing experiments with different herbivore assemblages;(5) to standardize the methods of grassland ecological experiments.

Based on the multi-source remote sensing,meteorological and social statistical data,the evaluation system of grassland ecosystem service value was constructed to evaluate the ecosystem service value of China's grassland ecosystem from 2000 to 2016,including organic matter production,nutrient cycling,soil conservation,carbon fixation and oxygen release,and water conservation. The results showed that:during the study period,the average total value of grassland ecosystem services in China was 1381.565 billion yuan·a ^-1,and the average total value per unit area was 412 400 yuan·km ^-2·a ^-1. The proportion of water conservation value of grassland was higher (28.95%),but the nutrient cycling value was lower (9.98%). The high value areas of grassland ecological value were concentrated in Yunnan,Guangxi and Western Sichuan. The total value of ecological services of Alpine subalpine meadow was the highest (415.688 billion yuan · a ^-1),while that of plain grassland and slope grassland was the lowest (138.861 billion yuan · a ^-1 and 144.998 billion yuan · a ^-1). The most prominent value of water conservation was observed in Ningxia,Inner Mongolia,Shaanxi,Tibet and Yunnan,while the most prominent value of organic matter production was mainly found in Qinghai,Gansu and Shanxi. The value of grassland ecological services showed a significant increasing trend during the 17 years ( P=0.01;2 200 yuan·km ^-2). The value of grassland ecosystem services increased in 54.69% of the areas,mainly in the south of Qinghai Province and its border with Tibet.

1 388 research papers about grassland remote sensing studies from 2000 to 2019 were retrieved from the Web of Science (WOS) database and the China National Knowledge Infrastructure (CNKI) database. Then publication trends,journals,disciplines,countries,institutions,authors,research hotspots,vitality,etc.,were analyzed from qualitative and quantitative perspectives by using the software CiteSpace (version Ⅴ) in the form of literature visualization. The results indicated that Grassland Remote Sensing research has the characteristics of multi-field and multi-disciplinary integration. The number of published papers in both Chinese and foreign languages is increasing,and the core journals are led by Remote Sensing. China has high enthusiasm in this field,but its influence is smaller than that of the United States and Germany. A total of 488 scientific research institutions in 83 countries have carried out cooperation for 793 times in the field of grassland remote sensing research,and the domestic cooperation and exchanges among the institutions are more frequent than those among the international ones. There is no stable group of authors among core authors,and the intra-group communication and cooperation among common authors is much more than those between groups. Research hotpots in Chinese and foreign languages are focused on grassland ecological governance and resource utilization. Compared with foreign studies,Chinese studies concentrate on solving problems of current grassland ecology. The 5 references cited with the highest citation frequency have a short half-life period (2.5~3.5 years) and a faster aging rate.

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.

Samples of frozen-thaw patch and the area between the grass patches in different degraded alpine wetlands were taken from Maqin Dawutan in the source zone of the Yellow River. The soil humus and its relationship with soil factors in the samples were determined. The results showed that the soil humus of the frozen-thawing patch and the grass patches decreased with the intensification of the degree of degradation of the alpine marshland. There was a significant difference between the humus carbon,humin and humic acid of the frozen-thaw patch in undegraded wetland and those in the light and heavy degradations ( P<0.05). It is more sensitive to the degradation than that of between patches. The contents of humus carbon,humic acid,fulvic acid and humin in the frozen-thaw patch and in the areas among the grass patches were all significantly positively correlated with soil water content and total nitrogen ( P<0.05). The frozen-thaw patch had a significant negative correlation between the humus components of mound soil and soil bulk density ( P<0.01). The cellobiohydrolase (CBH), β-1,4-xylosidase (BXYL), α-1,4-glucosidase ( αG), β-1,4-glucosidase (BG),leucine peptidase (LAP), β-1,4-N-acetylglucosaminidase (NAG) and urease (UR) for humin and the formation of humic acid had a significant promoting effect in the frozen-thawing patch,and the enzyme activity and microbial biomass between the grass patches had a significant promoting effect on the formation of soil humus. In summary,the degradation of alpine marshland leads to the reduction of soil humus,and the supplement of soil moisture and organic fertilizer should be strengthened in the restoration of alpine marshland in the source zone of the Yellow River.

In recent years,due to the continuous development of urban industry and the excessive use of chemical fertilizers,the lack of mineral elements and pollution in soil have seriously affected the sustainable development of agriculture. As a natural biological bacterial fertilizer,arbuscular mycorrhizal fungi (AMF) is able to effectively promote the absorption of mineral elements and improve growth conditions around plants. At the same time,in heavy metal contaminated soils,AMF can reduce the toxicity of heavy metal to plants and enhance the adaptability of plants to environmental changes. Up to now,great progress has been made in the researches on the physiological and molecular mechanism of AMF regulating the absorption of mineral elements by plants. A large number of mycorrhizal-induced genes have been identified,but a systematic and comprehensive summary is still lacking. Based on this,this paper summarized the relevant studies on AMF regulating the absorption of mineral elements in plants at home and abroad,and reviewed literature on the physiological and molecular mechanisms of AMF affecting the uptake of macroelements and trace elements by plants,and the mechanism of AMF alleviating the heavy metal toxicity to plant. According to the challenges and deficiencies of existing researches,the outlook is put forward,which aims to provide a certain scientific basis for the in-depth understanding of the mechanism of AMF affecting the absorption of mineral elements by plants and the agricultural application of biological bacterial fertilizer.

Carex L. was a perennial herbaceous plant of the Cyperaceae family,characterized with strong shade tolerance,strong self-reproduction ability,perennation and abundant germplasm resources. Carex plants were playing an increasingly important role in landscaping,grass husbandry production,ecological restoration and other aspects. With the wide application of Carex,further exploring germplasm resources and breeding new cultivars has become the major objective,whereas genetic diversity studies are the basis. In this study,the progress of Carex genetic diversity researches at the morphological,cellular and molecular levels were described. Moreover,the application of genetic diversity analysis in cultivar breeding,germplasm classification,origin and phylogenetic relationship of species and genetic map construction were introduced. In the end,the prospect of genome development and new variety breeding of Carex were discussed to lay a foundation for studies on genetic breeding and further development and application in future.

To explore the relationship between the soil fungal community characteristics and soil physicochemical factors in the rhizosphere of 4 leguminous forages. Illumina HiSeq PE250 high-throughput sequencing technology was used to analyze the fungal diversity of the rhizosphere soil of four legumes, Medicago ruthenicu, Medicago sativa, Onobrychis viciifolia, Vicia faba L. And analyze the correlation between the physicochemical properties of soil and the dominant groups of soil fungi. The results showed that there were significant differences in the physicochemical properties of the rhizosphere soil of the four legumes. High-throughput sequencing yielded a total of 267 532 effective sequences and 966 OTUs (Operational taxonomic units). The Chao1 index of the fungal communities in the rhizosphere soil of the four plants was Vicia faba L.> Medicago sativa> Onobrychis viciifolia> Medicago ruthenicu;Shannon index was broad Vicia faba L> Medicago ruthenicu> Onobrychis viciifolia> Medicago sativa. At the level of phylum classification,Ascomycota,Mortierellomycota,and Basidiomycota were dominant groups. Correlation analysis showed that there was a certain correlation between soil fungal diversity and soil physical and chemical factors. Fungal communities in the rhizosphere of the four legumes were significantly different. Total nitrogen,total phosphorus,total potassium,available phosphorus and organic matter were the main environmental factors affecting the distribution of soil fungal communities.

This research aimed to select corn ( Zea mays L.) varieties suitable silage for planting in Henan province. Total herbage dry matter yield, grain yield, quality, and lodging resistance were recorded, and relationships among agronomic characters of 21 maize varieties were compared, and a comprehensive evaluation was conducted using the Grey Model theory. The results showed that ‘Dajingjiu 26’, ‘Huamu 3’, ‘Xianyu 1366’, ‘ Weike 601’, ‘Dafeng 30’ had better comprehensive performance in terms of yield. The dry matter yield of ‘Huamu 3’ reached 21.34 t·hm ^-2.‘Dajingjiu 26’ had more yellow leaves, poor green retention, and ‘Huamu 3’ had serious lodging, so they were not suitable for popularizing corn varieties used for both grain and forage, ‘Weike 601’ and ‘Dajingjiu 26’ had the highest starch content(>35.5%) and the lowest neutral detergent fiber content and acid detergent fiber content, so they belong to the varieties with better nutritional quality (ADF<48%, NDF<27%). According to the comprehensive comparison of 21 corn varieties by using the Grey Model, ‘Weike 601’, ‘Dafeng 30’ and ‘Xianyu 1366’ are the most ideal varieties, which are suitable to be popularized and planted as grain and silage corn varieties in Henan area.

Plateau pikas ( Ochotona curzoniae,hereafter pikas) has been considered as a keystone species in the Qinghai-Tibetan Plateau. Pikas' activities create the landscape pattern with different patches mosaic. As a consequent,the change of underlying surface intensifies the spatial heterogeneous of organic carbon and vegetation productivity and eventually alters ecosystem carbon exchange process. However,our knowledge about the quantitative effects of pikas' disturbance on carbon cycle and the potential influencing mechanism is still insufficient,which hinders the accurate estimation of the carbon budget. We therefore reviewed the influence of pikas' disturbance on ecosystem carbon storage and carbon exchange. As an allogenic engineer,pikas directly affected ecosystem structure and function of alpine grasslands by the ways of clipping,foraging and burrowing. Additionally,pikas caused patchiness by creating bare piles and digging tunnels,which exerted indirectly impact on ecosystem function due to the erosion,expansion and heat island effect of bare patches. There was debate over the burrowing effect of pikas on soil organic carbon. On one hand,it reported that pikas burrowing was conducive to the accumulation of organic carbon by enhancing the nutrition cycle. On the other hand,the erosion of bare piles and patchiness potentially led to organic carbon loss. Pikas burrowing broke the original carbon exchange balance between ecosystem and atmosphere,which caused CO ₂ dissipated into pikas tunnels and sharply released from pikas holes. Notably,pikas' disturbance and patchiness altered ecosystem respiration process by impacting vegetation species composition,vegetation biomass redistribution and soil drought. Although great progresses in the effect of pikas' disturbance on carbon cycle have been made,future attention should be paid to (1) quantitatively assessing the effects of pikas' disturbance on ecosystem organic carbon storage at large scale;and (2) carrying out the comprehensive study on coupling ecosystem organic carbon storage and carbon budget.

Vegetation change caused by environmental change has a significant impact on ecosystem processes. However,the research on vegetation growth and its response to multiple related control factors is still insufficient. This paper explored spatial-temporal variation and driving factors of grassland Normalized Difference Vegetation Index (NDVI) using Theil-Sen median trend analysis,Mann-Kendall test,coefficient of variation,ridge regression analysis and structural equation model. The results showed that from 2001 to 2020,the spatial variation of grassland Normalized Difference Vegetation Index (NDVI) gradually decreased from southeast to northwest in the Qinghai-Tibet Plateau (QTP),the interannual variation showed an upward trend,the distribution of grassland was more concentrated in the area with smaller slope,and the growth of shady slope grassland was better. In the region,grassland growth improved due to the increase of water use efficiency (WUE) and temperature,and the grassland WUE was the main factor affecting the change of grassland NDVI on the QTP. This study improved our understanding on how multiple variables worked together to influence grassland growth and highlighted the importance of WUE for vegetation growth.