To explore the optimal legume-grass sowing ratio for synergistically improving yield and quality, a two-year field experiment with multiple mowings was conducted on the Loess Plateau. Five sowing patterns of white clover (Trifolium repens) and tall fescue (Festuca arundinacea) were evaluated, including monocultures of each species and mixtures at legume-to-grass ratios of 1:1, 1:2, and 1:3. The study aimed to assess the seasonal dynamics of forage yield and nutritional quality under different patterns and to identify the optimal strategy using a coupling coordination degree model. The results indicated that mixed sowing exhibited significant overyielding effects. Specifically, the mixtures with 1:2 and 1:3 ratios achieved the highest total yields, which were significantly increased by 23.92%-62.71% compared to monocultures (P<0.05). Regarding quality, compared with the monoculture of tall fescue, mixed sowing effectively increased crude protein content and reduced fiber content. The coupling coordination degree analysis of yield and quality demonstrated that the 1:2 legume-grass ratio is the optimal pattern for achieving synergistic development. This pattern not only achieved synchronous optimization in yield and quality but also maintained a high-level coordination state throughout the growing season. Consequently, it extends the window period for optimal utilization, making it the ideal strategy for establishing high-yielding, high-quality, and stable grasslands.
Salt stress is a major abiotic stress limiting sustainable agricultural development. Screening and identifying salt-tolerant forage soybean varieties is crucial for enhancing high-protein forage yield and utilizing saline-alkali land in China. In this study, seven forage soybean cultivars (S001-S007) were evaluated, with wild soybean (GS) and cultivated soybean Williams 82 (W82) used as controls. Under 150 mmol/L and 200 mmol/L NaCl stress, emergence indicators (emergence rate, emergence potential, and emergence index) and seedling morphological traits (plant height, leaf area, root length, and shoot and root fresh/dry weights) were measured. The salt tolerance at the seedling stage was comprehensively evaluated using the membership function method and cluster analysis. The results showed that all evaluated indicators decreased significantly with increasing salt concentrations, and distinct differences in salt tolerance were observed among the varieties. The membership function analysis ranked the salt tolerance of the nine soybean varieties from high to low as follows: S007>S002>S003>S004>S005>W82>S001>S006>GS. Furthermore, cluster analysis categorized the nine varieties into three groups: highly salt-tolerant (S002, S003, and S007), moderately salt-tolerant (S004), and salt-sensitive (GS, W82, S001, S005, and S006).
Sucrose synthase (SUS) is a key regulatory enzyme in plant sugar metabolism and plays a central role in plant responses to abiotic stresses. This study employed an integrated bioinformatics and transcriptomics approach to systematically identified the SUS gene family (designated as MsSUSs) in Medicago sativa ‘Xinjiang Daye’ and elucidated their transcriptional regulatory mechanisms under drought stress. The results showed that the genome of M. sativa ‘Xinjiang Daye’ contains 31 SUS genes distributed across 25 chromosomes, which are classified into three subfamilies: SUS Ⅰ, SUS Ⅱ, and SUS Ⅲ. The MsSUS proteins are predominantly hydrophilic and acidic, with most localized in the cytoplasm. Proteins interaction analysis revealed that MsSUSs interact with members of the glycoside hydrolase (GH) family. Expression analysis revealed that ten MsSUS genes were significantly upregulated under drought stress, among which MsSUS7 and MsSUS24 exhibited the greatest increases, with expression levels under severe water deficit (soil moisture content at 20%-50% of field capacity) reaching 3.74 and 8.34 times that of the control, respectively. The promoter regions of MsSUSs contain abundant abiotic stress-responseve elements, such as ABRE and MBS, as well as numerous binging sites for MADS transcription factors. Among them, 15 MsMADS genes were highly expressed under drought stress, with MsMADS33 showing sustained up-regulation following stress treatment. Molecular docking analysis suggested that the MADS-box domain may bind to the promoter regions of MsSUS9 and MsGH5 via hydrogen bonds. In summary, this study predicts that MsSUSs may cooperate regulate sucrose metabolism with MsGHs under drought stress, thereby enhancing osmotic balance and cell wall stability to improve the drought tolerance of M. sativa ‘Xinjiang Daye’, a process potentially positively regulated by MsMADS33.
Pennisetum centrasiaticum is a typical pioneer species on the abandoned farmlands of the Loess Plateau. Based on ten years of continuous field monitoring data, the responses of P. centrasiaticum population dynamics to the abandonment duration and climatic factors were analyzed. The results showed that with increasing abandonment duration, the plant height and canopy diameter of P. centrasiaticum decreased significantly by 2.26 cm and 6.01 cm, respectively, after ten years of abandonment compared to the first year. Reproductive branch density and tiller density exhibited an initial increase followed by a decline, in which tiller density peaked in the fifth year of abandonment. Tiller density reduced by 2.31 tillers/ m2 in the ten years of abandonment compared to the peak. Seedling density decreased by 4.00 plants/m2 after ten years abandonment compared to the first year. Population density and aboveground biomass showed significant decreasing trend with abandonment duriation, with annual average reductions of 0.82 plants/m2 and 1.92 g/m², respectively, by the tenth year relative to the first year. The abandonment duration was identified as the dominant factor affecting plant growth, reproductive characteristics, and biomass accumulation of P. centrasiaticum populations, independently explaining 33% to 79% of the variation in each of the indictors. Structural equation modeling further revealed that the abandonment duration not only directly suppressed the aboveground biomass of P. centrasiaticum, but also exerted an indirect negative effect by limiting seedling density. Furthermore, the abandonment duration indirectly reduced the proportion of P. centrasiaticum aboveground biomass within the community by suppressing plant height, canopy diameter, seedling density, and population density.
To evaluate the effects of habitat factors on plant communities and biological soil crusts (BSCs) across different restoration stages of alpine meadows patches, field investigation was conducted in Henan Mongolian Autonomous County (3 615-3 681 m), Maqin County (3 673-3 904 m), and Maduo County (4 245-4 282 m) in Qinghai Province. The influences of altitude and slope (i<7°, 7°<i<25°, i>25°) on plant communities and BSCs were analyzed across different patches, including active patches, inactive patches, restored patches, and non-patchy areas, as well as restored patches of varying sizes (S<1 m², 1 m²<S<5 m², S>5 m²). The results showed that species richness and diversity of plant communities in patchy alpine meadows initially increased and then declined with rising altitude, decreased with increasing slope, and gradually increased during patch restoration. The abundance of BSCs generally declined with increasing slope. No BSCs were detected in active or inactive patches, whereas they occurred in restored patches, and their abundance increased with patch size. In patches larger than 5 m², BSC abundance did not differ significantly from that in non-patchy alpine meadows. Correlation analysis indicated that the abundance of lichens, mosses, and algae was negatively correlated with slope and altitude, and significant positively correlation with vegetation diversity and patch restoration stage (P<0.05). Structural equation modeling demonstrated that patch type significantly enhanced vegetation species diversity (path coefficient 0.87, P<0.001), which in turn promoted BSCs development (path coefficient 0.69, P<0.001), with additional positive effects of patch size (path coefficient 0.21, P<0.05). Slope (path coefficient -0.34, P<0.001) exerted indirect negative effects on BSCs by reducing vegetation species diversity. In summary, higher altitudes, steeper slopes, and smaller restored patch areas constrain BSCs development. As degraded meadows recover and plant diversity increases, BSCs abundance gradually improves. These findings provide a scientific basis for the ecological restoration of degraded alpine meadows on the Qinghai-Xizang Plateau.
Nitrogen (N) is a key limiting factor for plant growth, and the increase in N deposition has become a crucial driver influencing the soil-plant nutrient cycle in grasslands. However, the mechanisms underlying the effects of different N addition rates and frequencies on soil-plant stoichiometric relationships remain unclear. A field experiment was conducted in a temperate typical grassland to examine the effects of three N addition rates: 0, 10, and 20 g N/(m2·a) and two N addition frequencies (twice a year and twelve times a year) on the nutrient stoichiometric characteristics of surface soil and on the relationship between plant biomass and carbon (C), nitrogen (N), and phosphorus (P) contents in the dominant plants Leymus chinensis and Stipa grandis. Results showed that N addition significantly increased soil C and N contents while decreasing soil P content, thereby reducing the C∶N ratio and increasing the C∶P and N∶P ratios. Under the high-frequency addition, the decrease in soil P content and the increases in C∶P and N∶P ratios in the 20 g N/(m2·a) treatment were lower than those in the 10 g N /(m2·a) treatment. In addition, increasing the N addition rates elevated plant N content while reducing plant P content, resulting in a decreased plant C∶N ratio and increased plant N∶P and C∶P ratios. However, N addition frequencies had no significant effects on plant or soil nutrient contents or their stoichiometric ratios. Partial least squares path model revealed that N addition rates indirectly regulated plant stoichiometric ratios by modifying soil and plant nutrient contents, thereby promoting increases in the aboveground and belowground biomass of the two dominant plant species. In contrast, N addition frequencies had no significant impact. This study demonstrated that N addition transitions plants from N limitation to N saturation and further intensifies P limitation, which may become a critical process constraining the productivity increases in grassland ecosystems.
This study aimed to investigate the differences in plant community characteristics and soil nutrient stoichiometry among three grassland types： temperate desert， temperate steppe， and mountain meadow on the northern slope of the Tianshan Mountains in Xinjiang， China， as well as the relationships between them. Field sampling and laboratory analysis were conducted to determine plant community traits， soil carbon （C）， nitrogen （N）， and phosphorus （P）contents， microbial biomass carbon， nitrogen， and phosphorus （MBC， MBN， MBP）contents， and soil enzyme activities. Redundancy analysis （RDA） was used to identify the key environmental factors driving plant community composition. The results showed that： From temperate desert to mountain meadow， plant community height decreased significantly （P<0.05）， while the coverage， density， and diversity indices （except for evenness） increased. The highest contents of soil organic carbon， total nitrogen， total phosphorus， MBC， MBN， and MBP were found in mountain meadow， whereas the soil N∶P ratio was lowest in temperate desert. The activities of β-glucosidase and alkaline phosphatase were highest in mountain meadow， while the activities leucine aminopeptidase and N-acetyl-β-D-glucosaminidase were highest in temperate steppe. From temperate desert to mountain meadow， soil nutrients accumulated， and vegetation trended to be shorter and denser. Among three types， temperate desert grasslands were nitrogen-limited. RDA indicated that MBC∶MBN ratio and MBP were key factors driving plant community characteristics （cumulative explanation rate： 66.7%）. In conclusion， this study provides a theoretical basis for understanding of nutrient cycling and guiding the restoration of degraded grasslands in arid ecosystems.
Enclosure is an important management practice in grassland ecosystems. To clarify the effects of enclosure duration on the niche characteristics and interspecific associations of plants in desert steppe, this study employed methods including importance value, niche breadth, niche overlap, Chi-square test, Ochiai index, and Percentage of Co-occurrence (PC) to investigate the niche characteristics and interspecific associations of dominant plants species in a Stipa breviflora steppe under different enclosure durations (1, 10, 19, and 25 years). The findings reveal that enclosure duration significantly influenced the importance values and niche breadths of the main plant species. In the early stage of enclosure, Cleistogenes songorica was the dominant species in the community. As enclosure duration extended to 10 and 19 years, the dominance species shifted, and Convolvulus ammannii became the most important species. By 25th year of enclosure, the perennial plant Cleistogenes songorica had regained its status as the absolute dominant species. With increasing enclosure duration, the niche overlap index of the main plant species exhibited a pattern of decrease-increase-decrease, indicating intense interspecific competition. Under different enclosure durations, interspecific associations among the main species in the steppe were predominantly negative. Chi-square analysis revealed that negatively associated species pairs accounted for a large proportion, while the Ochiai index and PC values were generally low, indicating weak species associations. Overall, with increasing enclosure duration, a trade-off pattern was observed between annual and perennial species, leading to shifts in the status of dominant species within the community. The overall species association remained negative, suggesting considerable community fluctuations and strong interspecific competition, reflecting an unstable community structure.
To investigate the effects of artificial restoration on soil organic carbon (SOC) content and carbon sequestration capability in degraded grasslands, a field experiment was conducted in a degraded desert steppe in Yanchi County, Ningxia. Three reseeding regimes were established: grass mixture (P1), legume mixture (P2), and grass-legume mixture (P3), with a non-reseeded site serving as the control (CK). Soil physicochemical properties,organic carbon (SOC) and its active components, including easily oxidizable organic carbon (EOC), dissolved organic carbon (DOC), and microbial biomass carbon (MBC), were analyzed years after reseeding. The results showed that soil pH and water content significantly increased following reseeding (P<0.05). Soil total nitrogen content increased significantly under P1 and P2, and the electrical conductivity in the 20-40 cm layer under P1 and P3 were significantly higher than that in the CK (P<0.05). SOC content was significantly higher than the CK in the 0-20 cm layer under P3 and in the 20-40 cm layer under P2 (P<0.05). Reseeding generally increased EOC content while decreasing DOC content, with significant changes observed under P1 (P<0.05). Soil MBC content decreased significantly under P2 (P<0.05). The DOC/SOC ratio declined after reseeding, whereas the EOC/SOC ratio under P1 was significantly higher than that under CK, P2, and P3 (P<0.05). In the 0-20 cm layer, the MBC/SOC ratio under P1 was significantly higher than in the CK (P<0.05). Correlation analysis revealed significant negative correlations between EOC and DOC in both soil layers (P<0.05), and between SOC and EOC in the 0-20 cm layer (P<0.05). In conclusion, among the treatments, P3 demonstrated superior performance in promoting SOC sequestration and maintaining carbon pool stability, indicating that grass and legume mixture reseeding is a suitable strategy for restoring degraded desert steppe ecosystems.
In order to explore an optimal fertilization strategy in alpine pastoral area, six fertilization treatments were established: control (CK); organic fertilizer alone (5 250 kg/hm2); organic fertilizer (4 200 kg/hm2) combined with inorganic fertilizer (urea 45.6 kg/hm2, superphosphate 87.45 kg/hm2); organic fertilizer (5 250 kg/hm2) combined with biofertilizer (75 kg/hm2); organic fertilizer (4 200 kg/hm2) combined with inorganic fertilizer (urea 45.6 kg/hm2, superphosphate 87.45 kg/hm2) and biofertilizer (75 kg/hm2); and organic fertilizer (4 200 kg/hm2) combined with inorganic fertilizer (urea 45.6 kg/hm2, superphosphate 87.45 kg/hm2), biofertilizer (75 kg/hm2), and micronutrient fertilizer (450 mL/hm2). Forage yield was measured at the full flowering stage, and natural grass was ensiled for 60 days to determine the nutrient composition, fermentation characteristics, and aflatoxin B1 (AFB1) content of the silage. The results showed that the fertilization treatments significantly increased forage yield compared with CK (P<0.05), whereas no significant improvement in forage quality was observed. The combined application of organic fertilizer, inorganic fertilizer, biofertilizer, and micronutrient fertilizer, as well as the combination of organic fertilizer, inorganic fertilizer, and biofertilizer, improved the silage quality of natural grass. Among these, the treatment with organic fertilizer, inorganic fertilizer, biofertilizer, and micronutrient fertilizer exhibited the best performance, with water-soluble carbohydrates and lactic acid content increasing by 74.36% and 15.33%, respectively, compared with CK (P<0.05), while neutral detergent fiber, acid detergent fiber, ammonia nitrogen content, and pH decreased by 17.80%, 18.39%, 65.67% and 4.04%, respectively. In addition, fertilization treatments significantly affected AFB1 content in the silage (P<0.05), with detected values ranging from 8.33 to 11.81 μg/kg, all below the national safety standard for feed. Comprehensive evaluation indicated that the combined application of organic fertilizer silage, inorganic fertilizer, biofertilizer, and micronutrient fertilizer achieved the best utilization of forage. This strategy is recommended for promotion and application in alpine pastoral areas based on local conditions.
The grassland subsidy and reward policy is an important instrument for protecting grassland ecosystems and safeguarding the livelihoods of herder households. However, existing studies have focused mainly on its effects on herder livelihoods, while relatively little attention has been given to how livelihood capital influences part time employment from the dual perspective of capital level and capital structure under the policy context. Based on questionnaire data collected from 1,042 herder households in Inner Mongolia, this study employed the entropy method to quantify livelihood capital and applied a Logistic regression model to examine how total livelihood capital, its dimensional components, and its structure composition affect part time on employment. The results showed that both the level and structure of livelihood capital significantly affected part time employment among herder households. At the aggregate level, higher total livelihood capital increased the likelihood of part time employment. At the dimensional level, human capital promoted part time employment, whereas natural capital, physical capital, and social capital had inhibitory effects. In terms of capital structure, a livelihood profile dominated by human capital was more conductive to part time employment. Heterogeneity analysis further showed that livelihood capital had a stranger positive effect on part time employment in pure pastoral areas than in agro pastoral areas. Compared with older generation herder households, livelihood capital had a greater promoting impact on part time employment among the younger generation, while it significantly restrained part time employment among middle generation households. In addition, livelihood capital had a stronger effect on households engaged in two part time activities than on those engaged in only one
Leymus racemosus (Lam.) Tzvel is a perennial tetraploid herbaceous species in the Triticeae tribe of the Poaceae family, exhibiting both high disease resistance and stress tolerance. This species not only serves as an excellent ecological grass for sand fixation, but also hold broad application prospects in wheat disease resistance breeding and ecological management in the desert regions of Northwest China. This article provides a systematic review of Chinese and international research on L. racemosus, including aspects such as germplasm distribution, morphological characteristics, genetic traits, stress tolerance mechanisms, wheat breeding, and forage resource utlization. Given the current status of breeding, promotion, and application of new L. racemosus varieties, this review provides an in-depth analysis of the application value in soil improvement, windbreak and sand fixation, and soil and water conservation. Based on current status, research aspects are proposed for future:while also emphasizing the development of new L. racemosus varieties with greater stress resistance and biomass; and breeding stress-resistant wheat cultivars, using L. racemosus and wheat varieties lacking incompatible distant hybridization genes as parents; strengthening whole-genome research of L. racemosus to explore genes related to stress resistance and disease resistance, and screening potential genetic resources for wheat breeding; systematically conducting restoration research on L. racemosus in marginal lands such as sandy and saline-alkaline soils, improving its standardized cultivation techniques and adaptability evaluation system, thereby providing scientific support for the promotion and application of the L. racemosus; carrying out conservation studies on wild germplasm resources of L. racemosus to preserve the foundation for breeding.
