In this experiment， the effects of single application of organic fertilizer and mixed application of organic fertilizer on the restoration of degraded natural mowing land were evaluated from the perspective of vegetation-soil-microorganism. The natural mowing land in Altay Mountains was used as the object of study. Three fertilization measures， single application of organic fertilizer （M）， mixed application of organic fertilizer and biological fertilizer （M+NY）， mixed application of organic fertilizer and compound fertilizer （M+NPK）， were used to explore the responses of grassland vegetation-soil-microorganism to fertilization. The results showed that fertilization significantly increased grassland community height， biomass， soil organic matter content， available nitrogen， available phosphorus， available potassium content and electrical conductivity （ P<0.05）， and significantly reduced soil pH value （ P<0.05）. There were significant differences in the richness of 5 phyla in soil bacteria （ P<0.05）， and there were significant differences in the richness of 2 phyla in soil fungi （ P<0.05）. The grey system correlation degree showed that compound fertilizer + organic fertilizer had the best effect on promoting vegetation growth， improving soil nutrients and increasing the number of microorganisms， and had a rapid recovery effect on the vegetation-soil-microbial system of reseeding natural mowing land. The results of the experiment provide theoretical basis， data support and technical support for the production and restoration of organic fertilizer single application and organic fertilizer mixed with other fertilizers in reseeding natural mowing land.

Melatonin is a small molecule indolamine hormone that widely exists in plants,and the studies have already clarified its synthetic pathway,catabolism and physiological functions. Melatonin can act as a signaling molecule to regulate plant circadian rhythms,seed germination,root and flower development,and also help to enhance the resistance of plants to various stresses. In this paper,the physiological functions of melatonin in regulating growth and development of herbaceous plants were summarized up,and its regulatory effects in response to abiotic and biotic stresses were particularly focused on. Additionally,functional study on melatonin in growth,development and stress resistance,as well as its application in stress resistance breeding in forage species were prospected. This review is expected to provide insight into improving the stress resistance,yield and quality enhancement of forage plants by using melatonin.

In this study,the yield,quality and feeding performance of 13 forage oat ( Avena sativa) cultivars were comprehensively evaluated for three consecutive years,to provide a basis for forage oat breeding in central region of Gansu Province. The results showed that the yield and its constituent characters were significantly affected by the interannual,varietal and interaction between the varieties ( P<0.01). The coefficient of variation of grain weight per spike was the largest with a value of 31.21%,and the average variation of leaf number and stem internode number was less than 5%. There were significant differences in the contents of crude protein,acid detergent fiber,neutral detergent fiber,water soluble carbohydrate,relative feeding value,relative forage quality,net energy of lactation and forage grading index among the different varieties;and'Zhangyan 4’had the highest relative feeding value of 126.18 and relative forage quality of 178.99；the forage grading index of 'Baiyan 7’ was the largest with a value of 35.01 MJ·d ^-1. The average net energy of lactation of 13 oat varieties was 7.08 MJ·kg ^-1,which reached the standard as super grade grass forage. Based on the correlation analysis between yield and quality,a linear evaluation function model was established on the basis of principal component analysis. It was concluded that'Longyan 3’'Bayyan 6’'Dingyan 2’'Zhangyan 4’and'Baiyan 7’had stable yield and outstanding feeding performance,which were suitable for popularly application.

Silage plays a very important role in the process of animal husbandry production,but the accumulation of nitrite during silage fermentation is seriously harmful to animal production performance,milk and meat quality. Nitrite poisoning is a common foodborne disease to livestock. Mild poisoning can affect the growth and development of livestock,severe poisoning can even lead to the death of livestock. To reduce the risk of nitrite in silage and improve the quality of silage and secure the safety of silage,this paper described the hazards,sources,transformation pathways,nitrite degradation pathways and control measures during the silage process,to provide an effective reference for nitrite degradation and regulation in silage feed.

Inner Mongolia grassland is an important livestock production base and northern ecological security barrier in China,and its economic development and ecological protection issues are the hot topics of research nowadays. Family ranch as a major typical form of livestock production organization has become an important element in the development of agriculture and animal husbandry in Inner Mongolia. In recent years,climate change and human disturbance have caused the degradation of grasslands. This not only brings about problems such as the decline of ecosystem function,but also has an important impact on the economic development of family ranches. This paper discussed the development and definition of family ranch,provided an overview of the roles produced and the impacts caused from the management strategies of family ranch under different grassland types in Inner Mongolia,and finally raised questions and outlooks on the business model,herders' business awareness,management system,financial system and social service system,and landscape remote sensing technology applications relevant to the family ranch in Inner Mongolia. It is expected to provide a scientific reference for achieving grass-livestock balance at the scale of farmer's household in Inner Mongolia,while improving the economic efficiency of farmers and herders.

Grasslands are important natural resource and ecological barrier in our country. Grassland ecological restoration is an important part of China's ecological conservation, as well as an important approach to enhance the ecosystem service function and carbon sequestration potential of grassland. Extensive studies have been conducted on degraded grassland, and many effective restoration practices have been proposed. However, there is a lack of comprehensive and target-oriented summaries of these restoration practices. This study conducted a systematic review of domestic and international research on grassland ecological restoration based on bibliometric research approach. We summarized the three stages of grassland ecological restoration in China and explored a regional-classified-hierarchical ecological restoration model for grasslands under different regions, different degradation types and different degradation degrees. Additionally, we provided relevant suggestions for the future development of grassland ecological restoration in China, and aimed to provide scientific basis for the ecological restoration and sustainable management of grasslands in our country.

Taking 1 329 core journal articles on the researches on saline-alkali soil improvement with plants from 2000 to 2022 retrieved in CNKI and Web of Science (WOS) databases as the data source,the data visualization software was used to qualitatively and quantitatively analyze the clustering,hot spots,co-occurrence,semantic network and other presence,and the current situation of plant improvement saline-alkali land at home and abroad was clarified from the perspectives of research trends,research hotspots and improvement effects of plant improvement saline-alkali land. The results show that the number of literature on saline-alkali land research is increasing year by year,and the effect of plants on improving saline-alkali land is a hot research problem. Herbaceous plants are the most commonly used plants in saline-alkali land improvement,and there are mainly 15 species of shrubs and trees. Planting plants can mainly reduce soil pH,salt content and salt ion concentration in saline-alkali land,improve soil physical characteristics,and increase soil fertility level. The improvement effect of different plants on saline-alkali land is different,and the establishment of saline-alkali plant bank as the basis for improving saline-alkali land is the focus of future research in this field,and the progress of saline-alkali land improvement is reviewed based on existing research,which has guiding significance for the subsequent ecological restoration and sustainable development of saline-alkali land.

This study examines the relationship and dynamic changes between soil particle size, fractal dimension, and soil nutrients under different grazing treatments in a desert steppe region. The goal is to provide a theoretical basis for the formulation of grazing management strategies and the restoration of soil erosion in the region. The study analyzed the effects of grazing on soil particle size, fractal dimension, and nutrients using plots with four different grazing treatments and one control group, and further explored the relationship among these factors. The results showed:(1) Compared to the control group, as grazing intensity increased, the clay and silt content in the soil exhibited a declining trend, with clay content decreasing by 0.14% to 0.88% and silt content decreasing by 1.21% to 4.65%. In contrast, the sand content increased with grazing intensity, with an increase ranging from 1.07% to 5.53%. Enclosure and grazing exclusion effectively increased the fine particle content in the soil. (2) The soil fractal dimension gradually decreased with increasing grazing intensity, with the D value of the fractal dimension being highest in the control treatment and significantly lower under heavy grazing than in other grazing treatments. The fractal dimension was significantly positively correlated with soil clay and silt content ( P<0.01) and significantly negatively correlated with sand content ( P<0.01). Soil particle composition was identified as an important factor limiting the fractal dimension, which can serve as a critical indicator for assessing soil quality. In desert steppe regions, moderate grazing can effectively improve soil quality, but grazing intensity should be controlled to moderate levels or lower.

Grape hyacinth ( Muscari spp.) included all species in the Muscari genus of Liliaceae,and is a model plant for the mechanism study on anthocyanin synthesis in monocots due to its rare blue color. In this study,the hygromycin sensitivity of callus induced from a common species M. armeniacum and the cultivar of M. aucheri 'Dark Eyes’ were tested,and an optimized genetic transformation system based on callus and Agrobacterium tumefaciens was developed. The results showed that the critical concentrations of hygromycin were 150 mg·L ^-1 and 120 mg·L ^-1for leaf-and-flower-derived calli of M. armeniacum and M. aucheri 'Dark Eyes’,respectively. There were no significant differences of transformation efficiencies among different genotypes,among different Agrobacterium strains and among different ultrasonic power,based on GUS staining. The highest transient genetic transformation efficiency of 98.73% was received for flower-derived calli cultured in liquid culture method. A total of 209 pieces of resistant calli were obtained,and the transformation success rate was 90% based on examinaitons of PCR and RT-PCR. The present study provides an efficient technical support for the functional researches of genes in grape hyacinth.

In order to reveal the dynamic changes of vegetation and its response to natural and anthropogenic factors in Yunnan Province，this study wasbased on the dataset of normalized difference vegetation index (NDVI),natural factors and anthropogenic factors from 2000 to 2020. We analyzed the spatiotemporal variation characteristics of NDVI in Yunnan Province by using Theil-Sen trend analysis and Mann-Kendall test,and explored the driving forces of NDVI spatial heterogeneity in different periods with Geographical detectors,and to explore the influence of the dominant factors on the changes of NDVI. The results showed that vegetation cover in Yunnan Province had a spatial distribution pattern as higher in the southwest and lower in the northeast. In terms of temporal variation,the proportion of regions with increasing NDVI from 2000 to 2020 was 83.15%,while the proportion of regions with decreasing NDVI 16.85%. The main influencing factors of spatial heterogeneity in NDVI were the land use type,precipitation and relative humidity,among which the land use type had the highest explanatory power,significantly higher than other factors. The transformation of land use type had a significant effect on the NDVI changes. The implementation of forestry ecological projects increased the area of forest lands and improved the regional vegetation cover,which played a positive role in the increase of NDVI;while the expansion of settlement land destroyed the regional vegetation,resulting in the decrease of NDVI. This study would provide a scientific basis for the development of future ecological planning strategies in Yunnan Province.

To better utilize alfalfa varieties and improve the efficiency and process of new variety selection,55 alfalfa varieties were used as materials in this study to analyze and evaluate agronomic and yield traits of alfalfa by coefficient of variation,genetic diversity index,correlation analysis,cluster analysis and principal component analysis. The results showed that the coefficients of variation of agronomic and yield traits were 6.89%~23.42%;the genetic diversity indexes 0.714 3~0.884 5 among which the highest diversity index was total leaf dry weight,while the lowest diversity index the stem-to-leaf ratio and fresh-to-dry ratio of the alfalfa varieties in second harvest. The 55 alfalfa varieties were divided into 3 main groups by cluster analysis,in which each group had obvious traits and characteristics;the varieties in group I and II need to be further mined for their excellent traits and can be utilized as complementary materials for breeding,and the varieties in group III can be directly introduced to the practical production,and can also be used as the parental materials in selection and breeding of highyield and good-quality varieties for the genetic improvement. Correlation and principal component analysis showed that number of branches,fresh-to-dry ratio,stem dry weight,leaf dry weight and plant height were the most important traits affecting the yield. The results of this study would provide a reference for the development and utilization of alfalfa varieties and the variety breeding of alfalfa in the semi-arid area.

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.

In order to investigate whether artificial grassland can be established in Nagqu area and what kind of forage species is suitable for planting,this experiment selected the cold and drought-resistant forage species to carry out an introduction and screening test artificial grassland in the area. Through the comparison and evaluation of the harvested forage yield with the yield of natural grassland in Nagqu and other artificial grassland in the four major grassland areas in China,it can be seen that the yield of the harvested forage in the experiment is exponentially higher than that of the natural grassland in Nagqu,and the average yield of the artificial grassland in the experimental area is not lower than that of the artificial grasslands in the other grassland areas in China,which indicate that high yielding artificial grassland can be established in Nagqu region under adequate water and fertiliser management conditions. At the same time,the screening of suitable pasture species was carried out based on the seedling emergence and growth of different pasture species in the year of sowing and the seedling emergence of perennial pasture species in the following year (i.e. overwintering ability). The results showed that Avena sativa, Triticum secale, Brassica rapa and Brassica napus were suitable for planting in the Nagqu area. Elymus sibiricus and Elymus nutans,which were able to overwinter successfully,can be used as screening species for perennial grassland,but their stability in the second and subsequent years after overwintering remains to be studied.

In order to explore the relative relationship between environmental and genetic variations in the ecological adaptation processes of Reaumuria soongorica,the leaf morphological characters and stoichiometric indexes of R. soongorica were determined by field investigation and cultivation experiment in common garden,the differences of leaf functional traits of the species grew in the native fields and cultivated in common garden were analyzed. The results showed that the leaf tissue density,degree of fleshiness and water content of R. soongorica cultivated in the common garden,even from the different growing provenances were lower than those grew in its native field,and the changings of leaf traits of the species both cultivated in the common garden and grew wild in their native field showed similar trends. However,the specific leaf area showed the opposite trends between them. The growth of R.soongorica in its native field was limited by both N and P,while those cultivated in the common garden only limited by N. The correlations between leaf water content and degree of fleshiness,tissue density and specific leaf area,N and specific leaf area,N and N/P ratio were consistent for R. soongorica cultivated in the common garden with those grew wild in its native field. But the correlations between C,N and P contents and other traits of R soongorica cultivated in the common garden were different from those wild in its native field. The contents of trace elements of Na,Mg,Fe and Mn were significantly different between the wild and the cultivated. In summary,the tissue density,fleshiness degree,water content and the trade-off relationship between some traits of R soongorica leaves were highly affected by genetics and the adaptation to the growing environment. Genetic factors of R soongorica had a little influence on the stoichiometric characteristics of its leaves,and environmental changes led to some changes in the utilization of N and P elements.

Grasslands take an important role in the construction of ecological civilization and the development of grassland husbandry in China. The grassland survey and monitoring is one of the main practices in grassland management. Overviewing the development courses of grassland survey and monitoring in China and the major grass-pastoral developed countries,it could be revealed that the grassland survey and monitoring domestic and abroad underwent the processes from focus on the production indicators to the ecological indicators,while the methods used in the grassland survey and monitoring domestic and abroad were the combination of the long-term and the short-term survey and monitoring approaches,with the long-term survey and monitoring approach dominant. All the countries analyzed in this study has developed a relatively complete system for the grassland survey and monitoring in the course of technology development in the light of the type,utilization and other characteristics of the grasslands in their country. We suggest the survey and monitoring of grasslands in China should set the grassland monitoring sites with the scientific layout, improve the long-term monitoring network of grasslands,establish a systematic space-ground-air integrated grassland monitoring technology system,strengthen the indicator system of multifunctional grassland monitoring;and reinforce the investment of grassland monitors and science and technology,in order to promote the sustainable development of grassland monitoring in China.

As one of the important industries in the field of agriculture,the grass seed industry is playing an increasingly important role in improving the efficiency of farming,increasing the income of farmers and herdsmen,and promoting high-quality economic and social development. The collection,preservation,identification,evaluation and innovative utilization of germplasm resources and the breeding of new varieties (lines) have become hot topics in the current research of grass seed industry. This paper mainly summarized and prospected the genetic diversity of grass germplasm resources from four aspects:morphology,biochemistry,cytology and molecular level,aiming to provide reference for the creation and breeding utilization of grass germplasm resources.

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.

In order to screen out the pre-emergence herbicides suitable for soybean-maize strip intercropping field,10 herbicides were tested in the study,and the effect on weed control and the safety of Glycine max and Zea mays were determined. The results showed that S-metolachlor,metolachlor,acetochlor,flumetsulam,prometryn,thifensulfuron-methyl and 2,4-D isooctyl ester were safe for soybean and maize at the recommended dosage,but pendimethalin caused a slight phytotoxicity to soybean. Both metribuzin and butachlor caused a slight phytotoxicity to both soybean and corn,which recovered after 25 days since those herbicides application. The control efficacies of S-metolachlor,metolachlor,pendimethalin and acetochlor on Setaria viridis and Digitaria sanguinalis were over 90%. The control efficacies of flumetsulam and prometryn on Amaranthus retroflexus and Chenopodium album reached above 90%,while the others had a lower control efficacies. The results above indicated that in soybean-maize strip intercropping field,S-metolachlor,metolachlor,and acetochlor should be applied when there were a large number of gramineous weeds;and flumetsulam or prometryn is the first choice to control broadleaf weeds.

To investigate the effects of exogenous IAA on the seed germination and early seedling growth of Onobrychis viciifolia under the drought stress, O. viciifolia seeds were soaked with different concentrations of indole-3-acetic acid (IAA) for 24 h;and the seeds were germinated subsequently, the seed germination, seedling phenotype, as well as physiological and biochemical characteristics were determined while treated with the drought stress. The results revealed that the seed germination of O. viciifolia was dramatically promoted under the drought stress when seeds were soaked with the 25 mg·L ^-1IAA, and the germination rate, germination potential, germination index and vital index of O. viciifolia seeds were optimum among four IAA treated groups with different concentrations of IAA. Furthermore, 25 mg·L ^-1IAA soaking treatment enhanced the primary root length, and improved the root/shoot ratio and chlorophyll content of early seedlings of O. viciifolia under the drought stress. In addition, 25 mg·L ^-1IAA soaking treatment was actually able to increase the activity of antioxidant enzymes and the content of osmotic regulator proline, decline the content of malondialdehyde (MDA) and hydrogen peroxide in early seedlings under the drought stress, and alleviate the oxidative damage caused by the drought stress. The high concentration of exogenous IAA (100 mg·L ^-1), however, inhibited the germination of seeds and the drought tolerance of early seedlings. Therefore, 25 mg·L ^-1 IAA soaking is helpful for the germination of O. viciifolia seeds and the drought tolerance of early seedlings, which would shed light on the efficient planting of high-quality forage O. viciifolia in arid regions.

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.

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.

In order to reveal the impacts of future climate change on grassland ecosystems and their responses,this study assessed the spatiotemporal dynamics of global grassland ecosystems and their net primary productivity (NPP) in 2020-2100 based on four future climate scenarios (including SSP126,SSP245,SSP370,and SSP585) using an improved comprehensive sequential classification system (CSCS) and a segmentation model. Results showed that the global mean annual temperature (MAT) and mean annual precipitation (MAP) would exhibit an overall upward trend in all four climate scenarios. In the SSP126 and SSP245 scenarios,the global grassland area was expected to decrease by 1.94 million km ² and 1.78 million km ² by 2090 s,respectively,mainly due to the reduction of tundra and alpine steppe. In contrast,the global grassland area was expected to increase by 0.68 and 1.37 million km ² by 2090 s in the SSP370 and SSP585 scenarios,respectively,which was mainly caused by the increase in the area of the tropical savanna. Global grassland NPP showed an increasing trend in SSP126,SSP245,SSP370,and SSP585 scenarios,expecting to increase by 0.25,1.96,5.78,and 7.52 Pg DW by 2090 s,respectively. Tropical savanna would contribute the most. In the context of global warming and humidification,tropical savanna and tundra and alpine steppe grasslands would be more vulnerable to future climate change.

Arbuscular Mycorrhizal Fungi （AMF） play an important role in maintaining the function of grassland ecosystems. Grazing is one of the main utilization modes of grasslands， which has a profound effect on the symbiotic relationship between plants and AMF. However， the regulatory effects of grazing on the Stipa breviflora-AMF symbiosis and its driving mechanisms remain unknown. This study， conducted in the S. breviflora grassland of Inner Mongolia， examined the effects of different grazing intensities—no grazing， light grazing （LG）， moderate grazing （MG）， and heavy grazing （HG）—on the AMF colonization rate in S. breviflora roots. The results revealed a significant decline in the AMF colonization rate with increasing grazing intensity. The colonization rates were 65.89%， 59.89%， 52.89% and 41.33% under different grazing intensities， respectively. Spore density and hyphal length density decreased with increasing grazing intensity. In addition， increased grazing intensity led to longer total root length and smaller root diameter in S. breviflora， along with higher soil density and pH but lower soil organic carbon and available phosphorus. However， soil moisture and nitrate nitrogen content peaked under light grazing. Soil nitrate nitrogen and available phosphorus were identified as the primary factors influencing the reduction in AMF colonization. In conclusion， grazing negatively affects AMF colonization in desert steppes by decreasing nitrogen and phosphorus nutrient effectiveness in the soil. This study provides empirical data and theoretical insights that support the development of sustainable grazing management strategies to maintain the health and resilience of desert steppe ecosystems.

Plant-endophyte symbioses play an important role in alleviating abiotic and biotic stresses to plants. Under drought and salt stresses, endophytic bacteria can enhance the resistance of plant to the stresses by regulating plant photosynthesis, concentration of hormones, content of osmoregulatory substances, activity of antioxidant enzyme, and expression of genes to ensure a normal growth and development of plant. In recent years, plant growth-promoting bacteria (PGPB) inoculants have also been widely studied and applied. In this paper, we reviewed the diversity of endophytic bacteria, the regulation of plant genes by plant symbiotic endophytes and PGPB under drought and salt stresses, and provided a reference for the in-depth study of the molecular mechanism of endophytic bacteria to improve the tolerance of plant to drought and salt stresses.

In order to establish a stable,rapid and efficient tissue culture system on different cultivated alfalfa ( Medicago sativa) varieties,this experiment took the varieties 'Tourist’'Paola’ and 'Sardi7’ as the research materials,investigated the effects of alfalfa explants,hormones ratio and metal ions (Cu ²⁺,Ag ⁺) on induction of embryonic callus. The results showed that hypocotyl was the best explants to induce callus. When MS+1 mg·L ^-1 2,4-D+0.2 mg·L ^-1 KT were cultured,embryogenic callus induction rates of 'Tourist’ and 'Paola’ were 24.7% and 16.7% respectively. And the embryogenic callus induction effect of 'Sardi7’ was 27.3% when MS+2 mg·L ^-1 2,4-D +0.2 mg·L ^-1 KT were cultured. 1 μmol·L ^-1 and 5 μmol·L ^-1 Cu ²⁺ could promote callus induction of 'Sardi7’,'Tourist’ and 'Paola’ significantly. 5 μmol·L ^-1 Ag ⁺ significantly induced embryogenic callus of 'Tourist’ and 'Paola’,and the induction rates increased by 25.3% and 46.7%,respectively ( P<0.05). In this study,we explored the best explants to induce alfalfa callus and their culture conditions,as well as the role of metal ions in promoting regeneration of different alfalfa varieties,which provided a solution for breaking through the genotypic restriction of autotetraploid cultivated alfalfa varieties and improving the healing rate of embryonic callus.

In order to accurately evaluate the stability and adaptability of major domestic and foreign forage oat varieties in different areas of Sichuan and the representativeness and differentiation ability of the different testing sites,the bipolt and BLUP prediction model were used to jointly analyze the yield data of 12 oat cultivars tested in five testing eco-geographical sites in 2018. The results showed that cultivar 'Sun God' and 'Charm' had a fecundity and stable yield with a high potential to be planted in a large scale in Sichuan Province. The cultivar 'shooter' achieved a high yield in Hong Yuan,Aba,and can be extensively planted in high altitude areas with similar ecological conditions. Hongya county of Meishan city has good representativeness and distinguishing power,and is an ideal place for testing trial and promotion showing of oat varieties. In this study,we objectively evaluated the adaptability of oat varieties and the representativeness and differentiation capability of the candidate sites,our results can provide a basis for the selection of the excellent oat varieties and/or testing sites for the production of high-quality oat forage in Sichuan Province.

Understanding the grazing lamb digestion,metabolism of energy and energy needs is critical for grazing management. The experiment chose 4 months lambs of Ujimqin×Dorper rams and ewes for a two-month grazing experiment to analyze the changes of forage nutrition available in grazing grassland,digestion,and metabolic energy requirements of the lamb. The results revealed that grazing grassland supplied around 200 g·m ^-2 of fresh weight and more than 100 g·m ^-2 of dry weight of forage;the crude protein,crude fiber content in the forage and their tendency raised up during grazing,but the content of ether extract was on the opposite direction. In general,the apparent digestibility of crude protein by rams and ewes increased from 27.4% to 54.6%,and from 16.2% to 58.7%,respectively;the apparent digestibility of ether extract and crude fiber in the forage was in a lower trend following the initial rising. Grass and lamb dung can vary with time;digestion and metabolism generally indicate an upward tendency. The weight gain of both ram and ewe was significant,along with a significant difference between the gains of rams and ewes from the experimental 14 to 35 days ( P<0.01). Comprehensive study on the all data in this experiment,the forecasting equations of digestible energy (DE) and metabolizable energy (ME) by the lamb of either ram or ewe can be developed the following,ram: DE=1.147×W^0.75+0.227×ADG ( R ²=0.920, n=160, P<0.001), ME=0.941×W^0.75+0.186×ADG ( R ²=0.920, n=160, P<0.001);ewe: DE=1.196×W ^0.75+0.034× ADG ( R ²=0.870, n=160, P<0.001), ME=0.981×W ^0.75+0.028× ADG ( R ²=0.870, n=160, P<0.001). The results could provide data support for the management of lamb grazing in grassland.

Abiotic stresses,especially low temperature,high temperature,drought,waterlogging,salt damage,etc.,are important factors affecting the growth and development of forages. Therefore,it is of great significance to explore the characteristics,indicators,evaluation methods and measures for improving forage stress resistance and stabilizing forage production. In this paper,the responses of forages to abiotic stresses such as temperature,water and salt were investigated through literature review and quantitative analysis. We reviewed the morphological structure,physiological and biochemical indicators and production performance resistance indices of forages,summarized the principles,advantages and disadvantages of six types of comprehensive evaluation methods for the abiotic stress resistance of forage,proposed four measures to improve the stress resistance of forages,and pointed out three aspects of future research in the field of abiotic stress resistance of forages. This review is expected to provide insight into selecting forage stress resistance indicators and evaluation methods to improve forage quality and yield.

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.

Grass seeds are the foundation of lawn industry,but we lack our own turfgrass varieties and the turfgrass seeds used in practice mainly rely on importation from abroad. Therefore,turfgrass breeding needs to be strengthened urgently. The conventional breeding cost a long period of time,low efficiency and is difficult to achieve precise targeted breeding. However,modern biotechnologies provide a new and effective way for turfgrass breeding,in which the key is a construction of an efficient regeneration system for turfgrass to accelerate the propagation speed,and be carried out its genetic transformation with regeneration system. This review mainly summarized the researches on the regeneration systems of some cold season and warm season turfgrasses in recent years,and focused on the key factors and existing problems affecting the regeneration process,and prospected the future development of turfgrass regeneration,with a view to provide a reference for the research,development,promotion,and application of new turfgrass varieties in the coming days.