Effect of the sowing period on the yield and quality of seven oat varieties grown in the semi-arid region of Longxi

In order to select suitable varieties for Avena sativa cultivation in the semi-arid mountainous region of western Gansu and to determine the best sowing date, the production performance and nutritional quality of seven oat varieties at four sowing dates (May 6th, 15th, and 26th, and June 5th, 2020) were studied, and a comprehensive evaluation was carried out using the grey correlation cluster analysis. The results showed that, together, the sowing date and variety had significant effects on hay yield, forage quality, and seed yield (P < 0.01). Among the 28 treatments, ‘Menglong’ variety sown on May 26th had the highest hay yield at 13 550.80 kg·ha⁻¹, ‘Monika’ sown on June 5th had the highest seed yield at 2 147.31 kg·ha⁻¹, and ‘Qingyan No. 1’ sown on May 26 had the highest crude protein content at 6.94%. Based on the relative values of hay yield, crude protein content, neutral detergent fiber, acid detergent fiber, and soluble sugar content, the comprehensive evaluation of the grey correlation degree showed that ‘Longyan No. 3’ planted on May 6 was the best variety/sowing date combination, followed by that of ‘Menglong’ planted on May 26th. Through systematic clustering, the 28 treatments were divided into four groups according to hay yield, seed yield, and crude protein content. Thus, selecting the appropriate sowing date is a suitable management strategy for oat grasslands in this area.