N uptake and yield response of wheat in main wheat production regions of China

【Objectives】 Investigating the regional variation in N use efficiency and yield is helpful to guild regional fertilization and planning of wheat all over the country. This differences of N absorption among wheat-planting regions and their grain yields response of wheat were compared in this paper. 【Methods】 Based on mass data published in journals and field experiments in China after 2000, the wheat yield, N concentrations in grains and straw, and N uptake among Huang-huai-hai winter wheat planting region (HH), Northwest China winter-spring wheat planting region (NW) and Yangtze River winter wheat planting region (YR) were summerized, and 100 kg grain N absorption by wheat under different yield levels was proposed. 【Results】The results show that wheat grain yield, N contents in grains and straw, above-ground N uptake and N needed per 100 kg-grains have significant regional variations. The mean grain yield in China is 6.18 t/hm2 with a variable coefficients of 34.37%. The highest grain yield is 7.05 t/hm2 in whinter wheat area in HH and the lowest is 4.71 t/hm2 in mixed spring and wheat area in NW, and the yield in whinter wheat area in midle and lower area of YR is 5.60 t/hm2. The N needed per 100 kg grain in China is 2.87 kg with a variable coefficient of 25.43%. The highest N needed per 100 kg-grains production is 2.98 kg in HH and the lowest is 2.60 kg in YR, and mid is 2.84 kg in NW. The mean N concentrations in grains and straws and the plant N uptake are 2.17%, 0.55% and 180.9 kg/hm2, with the corresponding variable coefficients of 23.96%, 38.18% and 44.50%, respectively. The N concentrations in grains and straw and the plant N uptake are all the highest in HH with values of 2.24%, 0.56% and 211.1 kg/hm2, following is in YR with values of 1.92%, 0.5% and 146.7 kg/hm2 and in NW 2.14%, 0.53% and 138.0 kg/hm2, respectively. The N requirement per 100 kg grain, N concentrations in grains and straw increase with increasing wheat yields. The N requirement amounts are 2.79 kg, 2.80 kg, 2.91 kg, 3.03 kg and 3.05 kg for wheat yields 4.5 t/hm2, 4.5-6.5 t/hm2, 6.5-8.5 t/hm2, 8.5-10.5 t/hm2, and 10.5 t/hm2, respectively. The N concentrations in grains are 2.01%, 2.11%, 2.27%, 2.26% and 2.40% and the N concentrations in straw are 0.46%, 0.53%, 0.58%, 0.61% and 0.63% for the corresponding wheat yields, respectively. 【Conclusions】 The differences of temperature, water and soil among the wheat-planting regions cause the differences of N absorption characteristics. The difference should be taken into account for improving wheat yield and N use efficiency, and wheat grain yield and N absorption for special regions.