Both Avena sativa and Avena nuda, which are highly valued for their use in food and fodder, demonstrate considerable potential in the management of saline-alkali soils. This study aimed to establish a foundation for the selection of salt-tolerant oat cultivars by assessing the impact of varying salt concentrations (0, 50, 100, 150, and 200 mmol L⁻¹) on agronomic traits, photosynthetic characteristics, physiological and biochemical properties, and leaf anatomical structures in both covered oat cultivars and naked oat cultivars. The measured parameters indicate the level of salt tolerance in Avena sativa and Avena nuda, which is influenced by both salt concentration and cultivar. Both Avena sativa and Avena nuda demonstrate strong adaptation to mild and moderate salt stress conditions. However, Avena sativa exhibits a significantly greater capacity to withstand severe salt stress compared to Avena nuda. Affinity function analysis ranked the cultivars’ salt tolerance as follows: ‘Qinghai 444’ > ‘Mengyan No. 1’ > ‘Baiyan No. 18’ > ‘Qingyin No. 3’. These results suggest that the selection of oat cultivars for salinity improvement should be tailored to the specific salinity levels present in different regions.

This study addresses the challenge of establishing alfalfa (Medicago sativa L.) in the desertified saline–alkali region of the Qaidam Basin, where seedling survival and productivity are considerably constrained. A two-year field experiment was conducted to identify suitable companion crops by comparing an alfalfa monoculture (control) with alfalfa intercropped with oat (Avena sativa L.) (O+A), forage pea (Pisum sativum L.) (P+A), or triticale (xTriticale Wittmack) (T+A). Agronomic traits, yield, and nutritional quality were measured, and a comprehensive evaluation was performed using the TOPSIS (Technique for Order Preference by Similarity to Ideal Solution) model. The results indicated that intercropping with oat produced the highest fresh and dry matter yields in the establishment year, while triticale and pea treatments exhibited strong yield potential in the subsequent year. Triticale significantly enhanced alfalfa’s nutritional quality by increasing crude protein content and relative feed value (RFV) while reducing fiber content. The TOPSIS model ranked the oat treatment highest for overall performance, effectively balancing yield and quality. In conclusion, oats are recommended as a companion crop to enhance alfalfa establishment in this saline–alkali environment, whereas triticale offers distinct advantages for improving the nutritional value of the forage.