To investigate the antioxidant physiological regulatory mechanisms during the germination of naturally aged alfalfa （Medicago sativa） seeds， this experiment used ‘Zhongmu No.1’ and ‘Zhongmu No.2’ alfalfa seeds stored for 4 and 7 years， respectively， as experimental materials. After being imbibed at different stages， seed germination indices， antioxidant enzyme activities of the ascorbic acid-glutathione （AsA-GSH） cycle， and antioxidant contents were measured to analyze the changes in antioxidant indices of alfalfa seeds during storage. The main results are as follows： storage for 7 years significantly reduced the germination capacity of alfalfa seeds， specifically manifested by decreases in germination potential， germination rate， germination index， vitality index， and seedling root length with increasing storage duration. Storage duration had little effect on the initial water absorption rate of seeds but influenced the progression of the imbibition stage. As storage time increased， the lag phase during the imbibition of alfalfa seeds was prolonged. Natural ageing leads to a decline in the function of the AsA-GSH cycle during imbibition. Compared to seeds stored for 4 years， alfalfa seeds stored for 7 years exhibited significantly reduced activities of catalase （CAT）， glutathione reductase （GR）， and monodehydroascorbate reductase （MDHAR） . Ascorbic acid （AsA） and glutathione （GSH） content decreased， and oxidised glutathione （GSSG） accumulated， indicating weakened reactive oxygen species （ROS） scavenging capacity and exacerbated membrane lipid peroxidation. Seeds stored for 4 years exhibited enhanced antioxidant capacity during the mid-to-late stages of imbibition by upregulating the activity of certain antioxidant enzymes， such as peroxidase （POD） and GR， thereby partially delaying the excessive accumulation of ROS. Using the membership function method， the germination capacity of alfalfa seeds was ranked as follows： ‘Zhongmu No.1’ 4 a > ‘Zhongmu No.2’. 4 a > ‘Zhongmu No.1’ 7 a > ‘Zhongmu No.2’ 7 a. Compared to the ‘Zhongmu No.2’ seeds， under natural ageing conditions， Zhongmu No. 1 exhibited relatively stable vigor and physiological status， demonstrating stronger storage tolerance.

To identify the SWEET genes in Avena sativa and its responses to drought and salinity-alkalinity stress， this study systematically characterized the AsSWEET gene family using bioinformatics approaches and analyzed their expression patterns under drought and salt-alkali stress conditions by RT-qPCR. A total of 37 AsSWEET genes were identified and mapped to 19 chromosomes. All AsSWEET proteins contained the conserved MtN3_saliva domain， most members possessed seven transmembrane helices （TMHs）， and subcellular localization prediction indicated that they were primarily located on the plasma membrane. Phylogenetic analysis revealed that AsSWEET proteins could be classified into four major clades and shared high homology with SWEET proteins from Hordeum vulgare. Promoter analysis showed that AsSWEET family members harbored numerous cis-acting elements associated with light responsiveness， hormone signaling， development， and abiotic stress responses. Expression profiling indicated that 10， 7 and 18 AsSWEETs genes were significantly upregulated in leaves under drought， salt and alkali stress， respectively. Among them， AsSWEET15a and AsSWEET15c exhibited consistently high expression levels across all stress conditions， suggesting that they might serve as key candidate genes involved in oat tolerance to drought and salt-alkali stress. These findings provide theoretical insights into the functional roles of the AsSWEET gene family in abiotic stress responses and offer potential gene resources for molecular breeding of stress-tolerant oat varieties.

To better understand the gene regulatory network during seed development in Pennisetum glaucum， this study performed transcriptome analysis using seeds at the flowering stage （F） and grain-filling stages （S₁， S₂， S₃）. The results revealed the highest number of differentially expressed genes （DEGs） in the S₁ vs F comparison， totaling 7166. Pathway enrichment analysis demonstrated that plant hormone signal transduction， starch biosynthesis， and phenylpropanoid biosynthesis played important roles in seed development， with 160， 19， and 51 DEGs enriched in these pathways， respectively. These genes exhibited stage-specific high expression during seed development； among which， AUX1 and GID1 were highly expressed in early seed development， while ethylene signaling genes （ETR， EIN2， EIN3） increased in expression as seeds matured. Among the DEGs， 859 transcription factors （TFs） were identified， including members of AP2/ERF and bHLH families， primarily involved in seed development-related pathways such as plant hormone signaling and circadian rhythm. This study constructed a gene expression profile for P. glaucum seeds development based on transcriptome data from different stages， providing a reference for further research of its molecular mechanism.

Larvae of Galeruca daurica are the major pest that severely damages the grasslands of Inner Mongolia. To explore the molecular mechanisms by which 20-hydroxyecdysone （20E） regulates the development of its larval， transcriptome sequencing was conducted on 3rd-instar larvae treated with 20E for 48 hours by using the Illumina HiSeq^TM 4000 platform. A total of 75 536 Unigenes were obtained， among which 40 161 were functionally annotated. Compared with the control group， a total of 500 differentially expressed genes （DEGs） were identified， including 258 upregulated and 242 downregulated ones. GO and KEGG analyses revealed that the DEGs were significantly enriched in terms/pathways such as ion transport， catalytic activity， longevity regulating pathway-multiple species， and FOXO signaling pathway. Furthermore， 11 ecdysone-related genes were screened out. The qRT-PCR verification results confirmed the reliability of the sequencing data. The results indicated that 20E may regulate the growth and development of G. daurica larvae by affecting multiple metabolic pathways. This study systematically analyzed the transcriptomic characteristics of G. daurica larvae in response to 20E regulation， providing a theoretical basis for clarifying its developmental mechanism and screening green control targets.

To determine the drought-tolerant capacity of bromus and to screen early drought-tolerant bromus seedlings， this study measured the adaptive response of 101 accessions of B. inermis at the seedling stage to drought stress. The morphological and physiological changes of the plants including roots were analyzed， and 17 growth indexes related to drought tolerance were determined. The drought tolerance of the seedlings was evaluated and screened by comprehensive evaluation， correlation analysis， principle component analysis， membership function and cluster analysis. The results showed that plant height， average root diameter， fresh weight above ground， total root volume， root surface area， root projected area， fresh weight below ground， total primary root length， dry-weight root aboveground ratio， maximum primary root long， fresh-weight root aboveground ratio and aboveground dry weight can be important indicators for the identification of drought tolerance in the seedlings of bromus. 101 bromus materials were divided into 4 different drought-tolerant grades by cluster analysis. There were 10 germplasm materials in class I with D value ranging from 2.00 to 2.55， which were highly drought-tolerant materials. There were 38 germplasm materials in Class II with D value ranging from 1.27 to 1.81， belonging to moderate drought tolerance. There were 42 germplasm materials in Class III with D value ranging from 0.77 to 1.25， belonging to low drought tolerance. There were 11 germplasm materials in Class IV， the D value ranged from 0.37 to 0.73， belonging to drought sensitive materials. The drought-resistant germplasm W1Z755， W1Z770 and W1Z696 were selected. The drought-sensitive materials were W1Z626， W1Z587 and W1Z763. This study can provide a theoretical basis and a material basis for the drought resistance evaluation of bromus seedlings and the selection of new varieties.

Multi-element stoichiometric coupling is critical for plant growth. To investigate the effects of mixed cultivation of leguminous and gramineous forages on their multi-element stoichiometric characteristics in the Bashang agro-pastoral ecotone， this study used the monoculture of Medicago sativa and Bromus inermis as the control treatment and further analyzed the influences of two mixed sowing combinations， i.e.， M. sativa+B. inermis （MW） and M. sativa+B. inermis+Elymus nutans （MWP）， on plant nitrogen and phosphorus stoichiometric characteristics， macro-element （potassium， calcium， magnesium， sulfur） contents， and microelement （iron， manganese， copper， zinc， nickel） contents. The results showed that the nitrogen and phosphorus contents of M. sativa and B. inermis in the monoculture treatment were higher than those in the MW and MWP mixed sowing treatments. The ratio of nitrogen to phosphorus （N∶P ratio） of M. sativa in the monoculture treatment showed no difference compared to those in the MW and MWP mixed sowing treatments （all exceed 16）， indicating the phosphorus limitation of M. sativa. However， the N∶P ratio of B. inermis in the monoculture treatment was lower than those in the MW and MWP mixed sowing treatments， indicating a shift from nitrogen limitation to phosphorus limitation or dual limitation of nitrogen and phosphorus of B. inermis. Except for the zinc content of B. inermis， no differences in the macroelement and microelement contents of M. sativa and B. inermis were observed between monoculture treatments and mixed sowing treatments. In conclusion， nitrogen and phosphorus limitations might still exist in the leguminous and gramineous mixed sowing grassland in the Bashang agro-pastoral ecotone.

Aiming at the problems of a single evaluation system for the regeneration ability of alfalfa （Medicago sativa L.） under high-frequency cutting and unclear mechanisms of varietal differentiation， this study took 9 alfalfa varieties as materials， determined the plant height， growth curve， biomass， photosynthetic parameters， and non-structural carbohydrate content after cutting， and conducted a comprehensive evaluation using the membership function method. The results indicated significant differences in regrowth performance among the various cultivars. Among them， ‘WL363HQ’ exhibited outstanding performance， with a mean daily plant height increase of 1.93 cm， which was significantly higher than that of the other tested cultivars. In contrast， the ‘Beiji Star’ cultivar demonstrated the weakest overall performance. Through systematic evaluation of the regrowth capacity differences among the alfalfa cultivars， this study confirmed that under high-frequency cutting conditions， ‘WL363HQ’ possessed the strongest regrowth ability among the nine tested cultivars， while ‘Beiji Star’ showed the weakest regrowth capacity. These findings provide a theoretical basis for the selection and breeding of alfalfa cultivars with enhanced tolerance to frequent cutting.

To evaluate the effects of intercropping arrangements on phosphorus use efficiency and interspecific competition in legume-grass mixtures， same-row intercropping （T） and alternate-row intercropping （Y） was conducted by the pot experiment. The study investigated the relationships among phosphorus use efficiency （PUE）， interspecific competition， and the overyielding effect in triticale-hairy vetch and triticale-common vetch systems. The results showed that for the triticale-hairy vetch mixture， yield and overyielding were higher in the same-row arrangement， whereas the triticale-common vetch mixture was the opposite. The relative yield （RY） was higher in the alternate-row arrangement for both systems. Metrics including encroachment rate （A）， competition rate （CR）， and relative crowding rate （K） indicated that triticale was the competitively dominant species. Phosphorus use efficiency varied in the triticale-hairy vetch system， and it was higher for triticale under alternate-row but higher for hairy vetch under same-row intercropping； in the triticale-common vetch system， both species showed higher PUE in the alternate-row arrangement. Threshold analysis revealed that highly competitive ability coupled with high PUE synergistically induced the overyielding effect under the alternate-row arrangement. In conclusion， for establishing annual forages in the cool region of Zhaosu， the alternate-row intercropping of triticale and common vetch is recommended.

To screen alfalfa （Medicago sativa L.） germplasm suitable for cultivation on saline soils， this study evaluated the salt tolerance of 59 alfalfa germplasm accessions during the germination stage. Six parameters—germination potential （GP）， germination rate （GR）， germination index （GI）， vigor index （VI）， root length （RL）， and shoot length （SL） were measured. A comprehensive evaluation was conducted using coefficient of variation analysis， correlation analysis， principal component analysis （PCA）， subordinate function analysis （SFA）， and cluster analysis. The results revealed significant variation in salt tolerance during germination among the 59 alfalfa accessions. Based on PCA and correlation analysis， four key indicators were selected for salt tolerance evaluation： relative germination potential （RGP）， relative germination rate （RGR）， relative germination index （RGI）， and relative shoot length （RSL）. Cluster analysis based on D-values derived from SFA classified the 59 germplasms into five salt tolerance categories： highly salt-tolerant （1 accession）， moderately salt-tolerant （22 accessions）， low salt-tolerant （11 accessions）， salt-sensitive （11 accessions）， and highly salt-sensitive （14 accessions）. Seven accessions exhibiting strong salt tolerance were identified： ‘Juneng 6’‘Ningmu No.1’‘Salt treasure’‘Shockwave’‘Aohan’‘Hunter River’ and ‘Challenger’. These findings provided a theoretical basis for alfalfa salt tolerance breeding.

To evaluate the differences in salt tolerance among different alfalfa （Medicago sativa L.） cultivarsunder salt stress conditions and screen high-quality salt-tolerant germplasm resources，this study used 25 alfalfa cultivars as experimental materials， with two treatments of salt stress （200 mmol·L^-1 NaCl solution）and control （ultrapure water）. Germination and growth parameters were measured during the germination period （eight indicators， such as germination energy and germination rate， etc.） and seedling stage （six indicators， such as plant height and branch number， etc.）， and a comprehensive evaluation of salt tolerance was conducted using methods such as membership function value， comprehensive salt tolerance （D value）， and cluster analyses. The results showed that salt stress significantly reduced all germination parameters， with the seed vigor index exhibiting the highest reduction rate （-92.26%）， whereas the seedling dry weight was the least affected （-11.76%）. Cluster analysis classified the 25 alfalfa cultivars into five salt tolerance grades at the germination stage： included 2 of the strongest salt-tolerant cultivars， 4 strong salt-tolerant cultivars， 5 moderate salt-tolerant cultivars， 10 weak salt-resistance cultivars， and 4 salt-sensitive cultivars. Further evaluation of salt tolerance of 12 representative alfalfa cultivars during the seedling stage revealed salt stress had extremely significant effects on the plant height， above-ground fresh weight， relative water content， and electrical conductivity of alfalfa （P<0.01）， with significant differences between cultivars. By integrating the indicators of both germination and seedling stages， the three strongest salt-tolerant cultivars， namely ‘Xinmu No.4’‘Zhongmu No.4’， and ‘Bara520YQ’， were ultimately selected as important germplasm resources for salt-tolerant breeding and cultivation in saline-alkali soil regions.