Impact of future climate change on climatic resources and potential productivity of maize in Sichuan Basin

Maize is a major cultivated grain crop in Sichuan and has contributed significantly to total grain production in the province. Sichuan Province has a complex topography and various landforms where climate change has caused temperature and precipitation anomalies, adversely affecting local maize production in the past 50 years. However, studies of future changes in agricultural climatic resources and corresponding impacts on maize production in Sichuan have rarely been reported. Predicting temporal and spatial changes in climatic resources and potential productivity during the entire growth period of maize under global climate change in the Sichuan Basin can lay key theoretical basis for developing response strategies of climate change and macroscopic policy decisions on maize production. Based on baseline climatic condition (1961 1990) and daily data for A2 and B2 climate scenarios (2071 2100) from the PRECIS regional climate model, the spatial and temporal characteristics of climatic resources (accumulated temperature ≥10 ℃ of daily average temperature, sunshine hours, precipitation, reference crop evapotranspiration and water deficient ratio) and potential productivity (photosynthetic potential productivity, photo-temperature potential productivity and climatic potential productivity) of maize in Sichuan Basin were analyzed. The results showed that accumulated temperature ≥10 ℃, sunshine hours and reference crop evapotranspiration during the entire growth period of maize increased in 2071 2100 under A2 and B2 climate scenarios compared with the 1961 1990 baseline climate conditions. Accumulated temperature ≥10 ℃ increased respectively by 460 641 ℃·d and 376 492 ℃·d under A2 and B2 climate scenarios with the highest increase in the western basin. Sunshine hours would increased respectively by 15 225 h and 33 202 h, with the highest increase in Ya'an. Reference crop evapotranspiration increased respectively by 76 144 mm and 73 123 mm with the highest increase in Ya'an. Precipitation decreased in most of the regions of Sichuan Basin with the highest decrease in Ya'an. For individual region, however, precipitation apparently respectively increased within 87 56 mm and 73 47 mm under the A2 and B2 climate scenarios. Water deficient ratio of maize respectively increased by 2% 18% and 5% 16% under the future A2 and B2 climate scenarios, suggesting increasing maize drought disaster risks in Sichuan Basin. Compared with the 1961 1990 baseline climate conditions, photosynthetic potential productivity of maize respectively increased by 228 3 277 kg·hm^-2 and 485 2 960 kg·hm^-2 during 2071 2100 under A2 and B2 climate scenarios with the highest increase in Ya'an and northern basin. Photo-temperature potential productivity respectively increased by 2 923 5 874 kg·hm^-2 and 2 697 4 909 kg·hm^-2 during 2071 2100 under A2 and B2 climate scenarios with the highest increase in Ya'an. Climatic potential productivity respectively increased by 984 2 975 kg·hm^-2 and 293 2 090 kg·hm^-2 during 2071 2100 under A2 and B2 climate scenarios with the highest increase in western basin. Future changes in climatic resources were apparently beneficial to maize yield in Sichuan Basin.