Optimal planting dates for diverse crops in Inner Mongolia

Abstract Climate warming and water resource shortage are severely threatening crop production in Inner Mongolia. Selecting optimal planting date (OPD) is recognized to be an effective way in alleviating water stress by matching crop water requirement with natural precipitation. However, optimal planting dates and drought resistance of staple crops have been not investigated in this region. In this study, the validated APSIM model was used to identify the OPD and crop drought degree for six staple crops including canola, edible sunflower, maize, oats, oil sunflower, and potato through comparing the potential and rainfed yields under different planting dates. The study results showed that OPD varied among crops and regions. Maize had the earliest OPD followed by canola, oil sunflower, oats, potato, and edible sunflower. Optimizing planting date could boost crop yields by increasing precipitation use efficiency. Compared with normal planting date, mean yields and precipitation use efficiencies for staple crops under OPD could be increased by 1%–54% and 7%–119%, respectively in Inner Mongolia. Oats, potato, and canola had higher drought-resistance than other three crops and showed less yield reduction rates and yield variations from potential to rainfed conditions. January–March precipitation (or mean temperature) could be used to determine the OPDs of oats and potato (or edible and oil sunflower), while April precipitation could be used to recommend the OPDs of canola and maize. The study results provide an important reference for selecting optimal planting dates of staple crops and adapting to warming and drying climate for single cropping systems in rainfed regions.