三熟制油菜秸秆还田条件下施氮量对早稻产量形成和氮肥利用率的影响

为明确油-稻-稻三熟制油菜秸秆还田条件下早稻的适宜施氮量,2017-2018年以超级常规早稻中嘉早17为材料,设置0、75、120、165、210kg/hm ²等5个施氮量,探究油菜秸秆还田条件下施氮量对早稻产量形成及氮素吸收利用的影响。结果表明：在油菜秸秆还田条件下,适宜施氮量有利于早稻分蘖成穗,灌浆期维持较高的叶面积指数、光合势和干物质积累量,同步增加单位面积有效穗数和保持较多的每穗粒数,从而扩大总库容量。在施氮量为165kg/hm ²时早稻即可达到较高产量,同时维持较高的氮肥吸收利用率。采用线性加平台模型拟合得出最佳施氮量,2017和2018两年分别为155.91、160.37kg/hm ²,产量潜力分别达8 241.17和8 387.32kg/hm ²。

Effects of Nitrogen Application Rate on Yield Formation and Nitrogen Use Efficiency of Early Rice under Rape Straw Returning in Triple Cropping

To explore the effects of nitrogen application rate on yield formation and nitrogen use efficiency of early rice under rape straw returning to the field in rape-rice-rice cropping system, the conventional super early rice Zhongjiazao 17 was used and five nitrogen fertilizers such as 0, 75, 120, 165, 210kg/hm ² were set up in 2017-2018. The results showed: under rape straw returning to the field, optimal nitrogen application rate is conducive to early rice tillering and effective panicle, maintaining a higher LAI, photosynthetic potential and amount of dry matter production during the grouting period, and simultaneously increasing the number of effective spikes per unit area, maintaining a higher number of grains per panicle, thus expanding the population storage capacity. Results also showed that the yield of crops and nitrogen absorption would reach to a high point when the rate of fertilizer was 165kg/hm ². The optimal nitrogen application rate was 155.91 and 160.37kg/hm ² in 2017 and 2018, respectively, with the yield potential reached 8 241.17 and 8 387.32kg/hm ² according to the model of linear plus plateau.