Selection of succeeding crops for a double-cropping system in alpine pastoral areas of the Qinghai–Tibetan plateau

To establish artificial grassland annually, oats, a traditional forage species, are normally cultivated in Qinghai–Tibetan alpine pastoral areas in spring and harvested the same year. Selection a suitable autumn-sown forage species and succeeding crop, thus harvest of two crops per year, would increase forage yield and quality. We used the triticale variety Gannong No. 2 as an autumn-sown crop and evaluated the performance of different succeeding crops: B1 (50% triticale and 50% common vetch), B2 (40% rye and 60% common vetch), B3 (50% oats and 50% common vetch), B4 (triticale), B5 (rye), and B6 (oats). We analysed crop productivity and nutrition at two sites in China in 2019 and 2020: Hezuo, and Lhasa. The highest hay yield (15.03 t ha⁻¹) and crude protein content (12.22%) of autumn-sown triticale as well as the highest average hay yield (6.05 t ha⁻¹) and comprehensive evaluation value (0.80) of the six succeeding crops were obtained at the Lhasa site. At both sites, the succeeding crop with the highest average hay yield (6.30 t ha⁻¹), crude protein content (13.08%), and comprehensive evaluation value (1.00) was B1. In regard to the interaction of environment and succeeding crop, the highest hay yield (8.07 t ha⁻¹) and comprehensive evaluation value (0.95) were obtained with B1 at the Hezuo site. Forage yield and nutrition can be significantly elevated by using autumn-sown triticale double-cropped with B1. The results first examine double cropping in alpine pastoral areas, provide a theoretical basis for establishing a double-cropping cultivation system in this region.