Long-term quantitative simulation and evaluation of potential productivity of winter wheat in Mengjin, Luoyang

DSSAT crop growth model was used to estimate potential productivity of photo-temperature and photo-temperature-precipitation of winter wheat using weather, soil, crop variety and field trial data in Mengjin, Luoyang. Potential productivity development status as well as the developmental measures of winter wheat was analyzed. From the study, the range of photo- temperature productivity of winter wheat is 7 571~10 965 kg·hm^-2 with a mean of 9 209 kg·hm^-2. This can serve as reference value for maximum yield in irrigated fields. The range of photo-temperature-precipitation productivity is 3 957~7 450 kg·hm^-2 with a mean of 5 510 kg·hm^-2. This accounts for 59.8% photo-temperature productivity, and can serve as reference value for maximum yield in rainfed fields. The average precipitation is 226.29 mm during the development stage of winter wheat, which is less than half of crop water requirement. Average water deficit is 72.5% of the precipitation at winter wheat development stage with an average water content ratio of 66.4%. This indicates that water deficit during growth is the primary obstacle to winter wheat development in Mengjin. As soil type and annual rainfall are different in the region, potential range of water use efficiency changes significantly —12.06~22.94 kg·hm^-2·mm^-1, with a mean of 16.94 kg·hm^-2·mm^-1 for the soil types and 46-year period. In the past eight years, the actual water use efficiency of winter wheat only accounts for 58.5% potential water use efficiency, while the exploitation degree of potential photo-temperature-precipitation productivity is 60.5%. The study shows that winter wheat has a very high water-saving potential in Mengjin. In order to enhance future winter wheat production, it is quite essential that reasonable agricultural water-saving measures are taken and water use efficiency are augmented by increasing use efficiency of precipitation and improving field conditions that enhances soil water storage capacity.