The GRAS protein family is involved in plant growth and development, plant disease resistance, and abiotic stress response. Although the GRAS protein family has been systematically studied and reported in many plants, it has not been reported in oat, an excellent foodstuff crop of Gramineae. We identified 90 AsGRAS genes and all of the AsGRAS genes were randomly distributed on 21 chromosomes with 6 tandem duplicated genes and 49 pairs of segmental duplications, which may be the main reason for the expansion of the GRAS gene family. According to the phylogenetic tree, 90 AsGRASs were classified into 10 distinct subfamilies. Gene structure revealed introns varying from zero to seven, and all genes have conserved motifs and GRAS structure domain. Protein–protein interaction and miRNA prediction analysis showed that AsGRAS proteins mainly interacted with GA signalling, cell division, etc., and that the AsGRAS genes were targeted by miRNA171. RNA-seq and qRT–PCR data showed that GRAS genes were expressed at different growth and developmental stages and under different abiotic stresses in oat, indicating the potential role of GRAS genes in promoting growth and stress tolerance in oat. Overall, our evolutionary and expression analysis of AsGRAS genes contributes to the elucidation of a theoretical basis for the GRAS gene family. Moreover, it helped reveal gene function and laid the foundation for future agricultural improvement of oats based on functional properties.

Elymus sibiricus plays a crucial role in ecological protection and animal husbandry. However, after many years of growth, the biomass of E. sibiricus decreases, and the plants degrade. Moreover, there is no good solution to the problem of degradation of Elymus sibiricus; the addition of nitrogen (N) and phosphorus (P) fertilizers is the primary measure of cultivation management to improve yield, so it is crucial to find the appropriate level of fertilization. This study performed a two-factor split-plot experiment, including four levels of N (0, 45, 60, and 75 kg·hm⁻²) and four levels of P (0, 60, 75, and 90 kg·hm⁻²), to investigate the effect of N and P fertilizers on yield, yield components, and photosynthesis characteristics of E. sibiricus. The results showed that the forage yield in 2017 was higher than in 2018. The forage yield in 2017 was highest at N₇₅P₀ with a value of 29,926 kg·hm⁻², and in 2018 it was highest at N₄₅P₀ and N₇₅P₀ with a value of 12,266 kg·hm⁻² and 12,233 kg·hm⁻², respectively, which demonstrates the large impact of year effects on the forage yield. All traits increased with the increase in N and P fertilizer application, but with excess fertilizer application, the photosynthesis was limited, leading to a slowdown in growth and a decrease in yield. In addition, under adequate N fertilization, the role of P fertilization was not significant (p > 0.05). N, P, and N × P can significantly (p < 0.05) affect the yield traits and forage yield of E. sibiricus. According to the PCA, it is clear that N fertilizer has the largest effect, and the growth capacity of degraded E. sibiricus grassland can be restored by adding 75 kg·hm⁻² of nitrogen fertilizer.

Early senescence of alpine pasture grass, manifested as rapid yellowing at the onset of autumn on the Qinghai–Tibet Plateau, constrains the sustainable development of grassland animal husbandry. Breeding stay-green forage germplasm is key to mitigating this problem. To identify superior stay-green germplasm and preliminarily elucidate the main drivers of senescence, we evaluated six stay-green lines of Elymus sibiricus with non-stay-green materials as controls. Fixed-site field observations were conducted for three consecutive years in Haiyan County, Qinghai Province. We quantified dynamic changes in phenotypic, photosynthetic, and physiological traits during senescence, applied mixed-effects models to identify factors associated with stay-green, and used the TOPSIS model for comprehensive evaluation. The results showed that plant height, green leaf area, chlorophyll content, net photosynthetic rate, and root activity of stay-green E. sibiricus were significantly higher than those of non-stay-green materials at all planting years, and the senescence rate was significantly slower. All traits performed optimally at the third year. Relative to HB-2, HB-4, HB-8, HB-10, HB-11, and HB-15 (stay-green E. sibiricus), plant height, green leaf area, chlorophyll content, net photosynthetic rate, and root activity of CK (non-stay-green E. sibiricus) were 0.83, 0.95, 0.79, 0.82, 0.80, and 0.78; 0.37, 0.37, 0.34, 0.35, 0.31, and 0.35; 0.82, 0.84, 0.80, 0.86, 0.82, and 0.75; 0.86, 0.86, 0.74, 0.89, 0.77, and 0.70; and 0.72, 0.74, 0.66, 0.78, 0.70, and 0.61, respectively. Mixed-effects modeling identified chlorophyll, root vitality, soluble sugars, and photosynthesis as the primary determinants of stay-green in E. sibiricus. The TOPSIS model indicated that HB-15 maintained the highest fitting degree values in years 2–4. These values were 0.69, 0.62, and 0.71, respectively. Therefore, HB-15 was the most ideal stay-green germplasm. These findings provide a theoretical basis and elite parental materials for breeding new stay-green varieties of E. sibiricus.