Adjusting sowing window to mitigate climate warming effects on forage oats production on the Tibetan Plateau

Adjusting the sowing date represents an effective strategy to mitigate the adverse effects of climate change on crop production across the world. However, its effect on oats (Avena sativa) forage production on the Tibetan Plateau is still unclear. This study aimed to determine the optimal sowing window for forage oats in the semi-arid area of the Tibetan Plateau by assessing forage yield and water productivity (WP) across historical and future climate scenarios. APSIM-oats was calibrated and validated using two-year field data on oats phenology, biomass yield, and soil moisture. Five oats sowing windows were designed in the scenario analysis, namely, early sowing 20 days (April 23), early sowing 10 days (May 3), conventional sowing (May 13), late sowing 10 days (May 23), and late sowing 20 days (June 2). Under historical climate conditions, conventional sowing (as practiced by farmers) resulted in the highest biomass yield and WP. However, future climate trends led to an average decrease of 16.0 % and 13.5 % in oats forage yield and WP, respectively, averaged over RCP4.5 and RCP8.5. Nevertheless, late sowing mitigated the adverse effects of the climate risk. In comparison to conventional sowing, delaying sowing by 20 days increased oats biomass yield, ET, and WP in both near and far future under both RCPs. Rainfall during the growing season of oats demonstrated a significant positive correlation with biomass yield under both RCPs, emphasizing the importance of synchronizing the sowing date with the rainfall pattern to minimize oats yield penalty. Therefore, late sowing of oats in the Tibetan Plateau region proved to be an effective approach to counteract the negative impacts of climate change and minimize oats yield losses. This study provides valuable insights for forage oats production management in the semi-arid areas of the Tibetan Plateau and offers strategies to cope with future climate risks.