Effects of Nitrogen Application Rate on Tillering,Post-anthesis Dry Matter Accumulation and Yield in High-yielding Wheat

Taking wheat cultivars Yumai 49-198 and Ping’an 8 as the test materials,field experiments were conducted at Wenxian site of Henan Province to study the effects of nitrogen fertilization on their population dynamics,yield and post-anthesis dry matter accumulation.Five nitrogen application rates,N0,N120,N180,N240,N360 were installed.The results show that the populations of the two test cultivars were all increased after tillering stage,reached the highest at jointing stage,and decreased afterwards.As for Yumai 49-198,its population had no significant differences at wintering,turning green stage,jointing stage and heading stage among the five nitrogen application rates,but differed significantly at the maturity with the nitrogen application rates.For Ping’an 8,its population had no significant differences among the nitrogen application rates at the wintering,turning green stage and jointing stage,but differed significantly after jointing stage with the nitrogen application rates.Wheat yield and dry matter accumulation of each treatment increased with the increase of nitrogen fertilization rate,but the grain yield decreased with excessive nitrogen fertilization.The dry matter accumulation performance of Yumai 49-198 in different treatments was N360N240N180N120N0,and the performance of Ping’an 8 was N240N360N180 N120N0.The post-anthesis dry matter accumulation and contribution rate of Yumai 49-198 and Ping’an 8 reached the maximum at N180 and N240,being 7 448.28 kg·hm-2,83.99% and 8 177.55 kg·hm-2,94.49%,respectively;Contribution rate of accumulation before flowering was 17.68% and 5.51%.Yumai 49-198 had the highest yield at N180 and N240,being 8 544.00 kg·hm-2 and 8 753.33 kg·hm-2,Ping’an 8 had the highest yield at N240,being 8 232.00 kg·hm-2.As a summary,the recommended nitrogen application is 180-240 kg·hm-2 under the current soil fertility condition.