氮肥运筹处理对机插水稻产量及氮素吸收利用的影响

Effects of nitrogen fertilizer management practices on yield,nitrogen uptake and utilization of machine-transplanted rice

机插秧苗素质普遍较弱,为了获得足够的穗数,江苏省苏北地区不少生产者采取增加分蘖肥施用次数、施氮量和密度的生产方式,但产量和氮素吸收利用并未增加。为此,以淮稻5号和南粳9108为试材,设计施氮量与栽插密度、秧苗素质和分蘖肥互作及秸秆还田与穗肥施用比例互作3个试验,针对上述问题开展相应的研究。结果表明:1)在施氮量与栽插密度互作试验中,随着施氮量的增加(N1、N2、N3分别为225、300和375 kg·hm^(–2)),M1(22.5万穴·hm^(–2))处理的产量呈增加的趋势,M2(27万穴·hm^(–2))和M3(33万穴·hm^(–2))处理的产量呈先增加后下降的趋势,以N2M3处理产量最高;产量显著受到单位面积穗数和每穗粒数的影响;增氮增密增加了成熟期氮素累积量,但是增氮降低了氮素籽粒生产效率和氮肥利用率,而增密则增强了氮素籽粒生产效率和氮肥利用率。2)在秧苗素质和分蘖肥互作试验中,壮苗产量较弱苗处理平均增加13.66%,氮肥利用率较弱苗增加1.7%;壮苗1次施用分蘖肥就能充分发挥水稻产量的潜力,弱苗适度增施分蘖肥可提高水稻的产量;壮弱苗过度施用分蘖肥均不能获得高产,适度增施分蘖肥有利于壮弱苗氮肥利用率的提高。3)在秸秆还田与穗肥施用比例互作试验中,秸秆还田条件下,增加促花肥比例及减少保花肥比例有利于水稻产量和氮肥利用率的提高。

The quality of machine-transplanted seedlings is generally lower.To achieve sufficient panicle numbers,many farmers in northern Jiangsu Province have adopted practices such as increasing the frequency of tillering fertilizer applications,nitrogen application rates,and planting density.However,these adjustments have not resulted in higher yields or improved nitrogen absorption and utilization.To address these issues,three experiments were conducted to investigate the interactions between nitrogen application rate and planting density,seedling quality and tillering fertilizer,as well as the effects of straw incorporation and panicle fertilizer application ratio,using Huaidao 5 and Nanjing 9108 as test varieties.The results were as follows.1)In the experiment on the interaction between nitrogen application rate and planting density,with increasing of nitrogen application rate(N1,N2 and N3 were 225,300 and 375 kg·hm^(–2),respectively),the yield in M1(22.5×10^(4) holes·hm^(–2))treatment showed an upward trend,while the yields in M2(27×10^(4) holes·hm^(–2))and M3(33×10^(4) holes·hm^(–2))treatments first increased and then decreased,with the N2M3 treatment achieving the highest yield.The yield was significantly influenced by the number of panicles per unit area and the number of grains per panicle.Increased nitrogen application and planting density led to higher nitrogen accumulation at the maturity.However,increasing nitrogen application reduced nitrogen use efficiency for grain yield and nitrogen fertilizer use efficiency,while higher planting density improved both the nitrogen use efficiency for grain yield and nitrogen fertilizer use efficiency.2)In the experiment on the interaction between seedling quality and tillering fertilizer,the yield of strong seedlings increased by an average of 13.66%,compared to weak seedlings,with nitrogen fertilizer use efficiency increased by 1.7%;for strong seedlings,a single application of tillering fertilizer was sufficient to fully realize the rice yield potential,while for weak seedlings,a moderate increase in tillering fertilizer application improved the yield.Excessive application of tillering fertilizer to both strong and week seedlings did not result in higher yields.A moderate increase in tillering fertilizer was beneficial to the improvement of nitrogen fertilizer use efficiency in both strong and weak seedlings.3)In the experiment on the interaction between straw incorporation and the ratio of panicle fertilizer application under the condition of straw incorporation,increasing the proportion of flowering-promoting fertilizer and reducing the proportion of flowering-maintaining fertilizer was beneficial for the improving rice yield and nitrogen fertilizer use efficiency.