Spatio-temporal analysis of winter wheat yield gaps in Henan Province using AEZ model

Global climate change has become one of the most severe environmental problems facing human society. Agriculture is among the sectors with the most sensitive response to climate change. The analysis of yield gaps could reveal the factors limiting the growth and production of crops in various regions. Henan Province is the most important commodity grain base in China, with rich climatic resources and remarkable climate change. Analysis of yield gaps and change trend of winter wheat yield in Henan Province are critical for understanding the impact of climate change on the potential productivity of winter wheat in the province. It also can be used to draw on advantages and avoid disadvantages of climatic change, making full and rational use of climatic resources of winter wheat. Current researches on the impact of climate change on crop yield gaps have often focused on large-scale analysis, few people divided the study area into small pieces. To improve the accuracy of simulated effects of climate change, Henan was divided into five planting areas, which were northern Henan planting area (Ⅰ), eastern Henan planting area (Ⅱ), shallow mountain hilly basin planting area (Ⅲ), Huaibei Plain and Nanyang Basin planting area (Ⅳ) and southern Henan planting area (Ⅴ). Data obtained from 14 meteorological stations were used in AEZ model to simulate potential productivities of winter wheat for 1961-2013 in Henan Province. Then yield gaps were calculated, which were gap between photosynthetic potential productivity and light-temperature potential productivity (YG_1-2), gap between light-temperature potential productivity and climate potential productivity (YG_2-3) and gap between light-temperature potential productivity and average field yield (YG_2-a). The results showed that photosynthetic potential productivity of winter wheat in Henan Province decreased in 1961-2013. The light-temperature potential productivity increased and climate potential productivity remained basically unchanged. Analysis of average field yield showed significant differences in average outputs at 14 meteorological stations and the trend in winter wheat output gradually increased. YG_1-2 of winter wheat decreased, while YG_2-3 followed a Ⅴ-shaped trend with the valley occurring in 1981-1990. YG_2-a in Ⅰ, Ⅱ and Ⅴ areas had a decreasing trend, while that in Ⅲ and Ⅳ areas initially increased and then decreased. In terms of spatial change, YG_1-2 and YG_2-3 of winter wheat declined from north to south, while YG_2-a increased from east to west in Henan Province. The order of yield increase potential of winter wheat for each area was Ⅲ > Ⅴ > Ⅳ > Ⅱ > Ⅰ. Agronomic conditions were the main factors driving the dwindling gaps in winter wheat yield in Henan Province. By improving agronomic conditions (e.g., varieties, modern agricultural technology, reasonable pesticide and fertilizer use, and rational arrangement of high-quality regions), it was possible to reduce the gaps in winter wheat yield in the study area.