Delayed sowing can increase lodging resistance while maintaining grain yield and nitrogen use efficiency in winter wheat

Lodging resistance of winter wheat(Trnticum aestivum L.) can be increased by late sowing.However, whether grain yield and nitrogen use efficiency(NUE) can be maintained with delayed sowing remains unknown. During the 2013-2014 and 2014-2015 growing seasons, two winter wheat cultivars were sown on three dates(early sowing on October 1, normal so,wing on October8, and late sowing on October 15) to investigate the responses of lodging resistance, grain yield,and NUE to sowing date. No significant differences in lodging resistance, grain yield, or NUE between early and normal sowing were observed. Averaging over the two cultivars and years,postponing the sowing date significantly increased lodging resistance by 53.6% and 49.6%compared with that following early and normal sowing, respectively. Lodging resistance was improved mainly through a reduction in the culm height at the center of gravity and an increase in the tensile strength of the base internode. Late sowing resulted in similar grain yield as well as kernel weight and number of kernels per square meter, compared to early and normal sowing.Averaging over the two cultivars and years, delayed sowing resulted in a reduction in nitrogen uptake efficiency(UPE) by 11.0% and 9.9% compared to early and normal sowing, respectively,owing to reduced root length density and dry matter accumulation before anthesis. An average increase in nitrogen utilization efficiency(UTE) of 12.9% and 11.2% compared to early and normal sowing, respectively, was observed with late sowing owing to a reduction in the grain nitrogen concentration. The increase in UTE offset the reduction in UPE, resulting in equal NUEs among all sowing dates. Thus, sowing later than normal could increase lodging resistance while maintaining grain yield and NUE.

Effect of synergistic urea by nitrification inhibitor coated with resin on wheat growth and soil nitrogen supply

Combining nitrification inhibitor and urea can improve crop yield and nitrogen(N)use efficiency(NUE).However,the inhibitor easily gets inactivated in soil,making it difficult to achieve the desired effect.To develop a synergistic urea for increasing the inhibitor action time,soil N supply,and wheat growth,dicyandiamide(DCD)was coated after granulation with epoxy resin and then mixed with urea to develop new resin-coated DCD(RCD)synergistic urea.Scanning electron microscopy(SEM)and hydrostatic release tests were used to evaluate the membrane microstructure and the controlled-release performance of RCD.Five fertilization treatments were set up in the field:zero-N control(CK),urea(U),urea+common DCD particles(SUD1),urea+RCD(SUD2),and urea+both common DCD particles and RCD(3:7,weight/weight)(SUD3)to investigate the effects of the DCD synergistic urea on wheat growth,yield,and NUE and soil available N content.The SEM results showed that RCD had a complete coating,smooth surface,and small and rugged channels for DCD release in the profile.The hydrostatic release test at 25?C showed that the release period of DCD was extended to ten days due to resin coating.In the three DCD synergistic urea treatments,only SUD3 resulted in a significant increase in wheat yield(18.47%)compared with U.The NUE in SUD3 was significantly higher than those in SUD2,U,and SUD1.The treatment SUD3 had higher soil available N content than the other treatments during the key wheat growth stages,while effectively reducing the risk of soil nitrate leaching during wheat maturity.In summary,SUD3,a mixture of urea,DCD particles,and RCD,was the best treatment for significantly increasing wheat growth,yield,and NUE and soil N supply.