改进施氮运筹对水稻产量和氮素吸收利用的影响

Modifying nitrogen fertilization ratio to increase the yield and nitrogen uptake of super japonica rice

【目的】秸秆还田不仅可改良土壤和增加土壤有机质,还能提高作物产量和品质。但秸秆还田后,土壤有机酸积累和微生物固氮,抑制水稻前期生长。在长江流域稻麦两熟地区,当地农户往往通过增加施氮量来解决秸秆还田的负效应,造成肥料浪费和氮污染。因此,探索研究秸秆还田条件下水稻优化的氮肥运筹措施,阐明水稻产量形成和氮素吸收与利用对氮素响应特征,对于提高水稻产量和氮素利用效率具有重要意义。【方法】2012 2013年,以超级粳稻武运粳24号和宁粳3号为材料,在江苏省兴化市进行大田试验,在秸秆全量还田条件下,设置常规施氮300 kg/hm2(N1)、增加施氮量345 kg/hm2(N2)和常规施氮运筹(CFP,基肥∶分蘖肥∶穗肥=3∶3∶4)、改进施氮运筹(MFP,基肥∶分蘖肥∶穗肥=4∶3∶3),以无氮处理为对照,研究施氮量和氮肥运筹措施对水稻产量及其产量构成、干物质积累、氮素积累、氮素吸收速率和氮肥利用效率的影响。【结果】随着氮肥水平提高,水稻穗数显著增加,每穗粒数、结实率和千粒重下降,最终增产不显著。与常规施氮运筹比较,改进氮肥运筹显著增加穗数,显著提高群体颖花量并增产,在N1水平下,改进施氮运筹增产幅度为5.18%7.10%,高于N2水平的2.70%4.29%。随着施氮量增加,水稻分蘖中期、拔节期、移栽期至分蘖中期、分蘖中期至拔节期干物质积累量、氮素积累量显著增加,最终成熟期干物质积累量和氮素积累量有所增加,但差异不显著,而氮肥农学利用率、氮肥吸收利用率和氮偏肥生产力显著下降。与常规氮运筹处理相比,改进氮运筹显著增加水稻移栽期至分蘖中期干物质积累量、氮素积累量和氮素吸收速率,增加成熟期干物质积累量和氮素积累量,提高氮肥农学利用率、氮肥吸收利用率、氮肥生理利用率和氮偏肥生产力,在N1水平下成熟期干物质积累量和氮素积累量分别增加6.52%和5.55%,氮肥农学利用率、氮肥吸收利用率、氮肥生理利用率和氮偏肥生产力分别提高13.36%、8.55%、4.44%和5.29%,差异均达显著水平。【结论】秸秆全量还田条件下,增加氮肥用量水稻增产不显著,且氮肥利用效率低。不增加氮肥用量,通过适当提高基肥比例(基肥∶分蘖肥∶穗肥=4∶3∶3),可实现提高水稻产量、干物质积累量、氮素积累量和氮肥利用效率。

【Objectives 】 Crop straw incorporation can increase soil organic matter and improve soil fertility,enhance crop yield and quality. However, it sometime inhibits rice growth in the vegetative stage due to accumulation of organic acids and N immobilization. Farmers usually deal with this phenomena through increasing the amount of nitrogen fertilizer in rice-wheat cropping system in the Yangtze Catchments. Excessive nitrogen inputresults in low nitrogen use efficiency and water and air pollution. Therefore,the optimization of nitrogen fertilization is important for the improvement of yield and nitrogen use efficiency of rice. 【Methods】Local popular japonica rice cultivars,Wuyunjing 24 and Ningjing 3,were selected as material,field experiments were conducted in Xinghua County,Jiangsu Province,China in 2012 and 2013. Two nitrogen rates( N1: 300 kg / ha and N2: 345 kg / ha) and two nitrogen application methods [conventional fertilizer-nitrogen practice( CFP,basal ∶ tillering ∶earring = 3 ∶ 3 ∶ 4) and modified fertilizer-nitrogen practice( MFP,basal ∶ tillering ∶ earring = 4 ∶ 3 ∶ 3) ] were designed. The yield,yield components,dry matter accumulation,nitrogen uptake and nitrogen use efficiency were investigated. 【Results】With the increase of the nitrogen fertilizer rate,the unit area panicles of rice are increased significantly,but the spikelet per panicle,filled-grain percentage and 1000-grain weight are decreased,finally,the grain yield increase is not significant. The grain yield is higher using MFP than CFP,owing to the more panicles per unit area and the significant enhanced population spikelet as a result. The range of yield increase with the MFP in N1 is 5. 18%-7. 10%,higher than that in N2( 2. 70%-4. 29%). With the increase of nitrogen rate,the dry matter accumulation and nitrogen uptake at the middle tiller stage and the jointing stage,from transplanting stage to the middle tiller stage,and from the middle tiller stage to the jointing stage are significantly improved,but the dry matter accumulation and nitrogen uptake increases at the maturity are not significant,the nitrogen agronomic efficiency, nitrogen recovery efficiency and nitrogen partial factor productivity are consequently decreased significantly. In comparison with CFP,the dry matter accumulation and nitrogen uptake amount and rate from the transplanting stage to the middle tiller stage are improved significantly under MFP. The dry matter accumulation and nitrogen uptake at the maturity and nitrogen agronomic efficiency, nitrogen recovery efficiency, nitrogen physiological efficiency and nitrogen partial factor productivity of MFP are higher than those of CFP and the differences of those are significant in N1,and the dry matter accumulation and nitrogen uptake at the maturity,nitrogen agronomic efficiency,nitrogen recovery efficiency,nitrogen physiological efficiency and nitrogen partial factor productivity are increased by 6. 52%,5. 55%,13. 36%,8. 55%,4. 44% and 5. 29%,respectively.【Conclusions】Under the straw completely incorporation,increasing the nitrogen fertilizer rate will not increase the rice yield,but decrease the N use efficiency. Keeping the normal nitrogen fertilizer input,modifying the ratio of nitrogen fertilizer input of basal ∶ tillering ∶ earring from 3 ∶ 3 ∶ 4 to 4 ∶ 3 ∶ 3 will be capable of significant increase of yield,dry matter accumulation,N uptake and N use efficiency in mechanical transplanted super japonica rice with wheat straw return.