氮肥减量后移改善植株光合特性提高麦-玉周年产量及经济效益

Nitrogen Fertilizer Reduction and Postponing for Improving Plant Photosynthetic Physiological Characteristics to Increase Wheat-Maize and Annual Yield and Economic Return

【目的】针对黄淮海平原传统施氮技术下,小麦-玉米两熟体系作物生育后期土壤氮肥供应不足导致籽粒减产等问题,探讨氮肥减量后移对植株光合特性、干物质积累及周年籽粒产量和经济效益的影响,为进一步优化施氮制度提供理论依据。【方法】2020—2023年,于山东济阳典型麦-玉两熟种植区,设置周年施氮400 kg·hm^(-2)传统农户处理(CK,小麦季200 kg·hm^(-2):65%基肥+35%返青肥,玉米季200 kg·hm^(-2):100%基肥)、周年减氮10%(SN,小麦季180 kg·hm^(-2):50%基肥+50%返青肥,玉米季180 kg·hm^(-2):100%基肥)、周年减氮20%(NH,小麦季180 kg·hm^(-2):22.2%基肥+33.3%返青肥+44.5%抽穗肥,玉米季140 kg·hm^(-2):28.6%基肥+71.4%大喇叭口肥)和周年减氮30%(NL,小麦季140 kg·hm^(-2):43%返青肥+57%抽穗肥,玉米季140 kg·hm^(-2):100%大喇叭口肥)4种施氮制度,研究不同施氮制度下麦-玉两熟体系的光合特性、籽粒产量和经济效益。【结果】氮肥后移优化了氮肥减量条件下作物光合特性,其中,叶面积指数3年均值,小麦拔节和开花期NL较CK、SN和NH处理分别显著提高19.0%—40.1%和21.6%—36.7%,夏玉米吐丝期NL较CK和SN处理显著提高6.8%—7.3%;叶片SPAD值3年均值,冬小麦拔节和开花期NL较CK、SN处理分别显著提高7.7%—10.0%和7.4%—12.9%,灌浆中期NL较CK、SN和NH处理显著提高5.2%—16.2%;夏玉米大喇叭口期NL和NH较CK、SN处理3年均值分别显著提高9.0%—9.4%和6.7%—7.1%,吐丝和灌浆中期NL较CK、SN和NH分别显著提高5.1%—9.4%和4.1%—9.2%;净光合速率3年均值,小麦拔节、开花和灌浆中期NL较CK、SN处理分别提高8.9%—13.3%、14.0%—18.1%和20.1%—24.4%;夏玉米大喇叭口、吐丝和灌浆中期NL较CK、SN处理分别提高4.2%—5.7%、8.7%—13.4%和7.7%—12.8%。NL处理通过增加氮肥后移量,改善了各生育阶段地上部干物质积累强度,稳定或提高了各生育时期地上部干物质积累量,冬小麦拔节、开花和成熟期地上部干物质积累量的3年均值较CK分别显著提高26.7%、27.4%和18.1%,夏玉米吐丝期显著提高14.4%。氮肥后移通过改善氮肥减量条件下光合特性,促进了各生育时期地上部干物质积累,最终实现冬小麦、夏玉米及周年籽粒产量的3年均值,NL较CK处理分别显著提高20.5%、18.1%和19.1%,经济效益分别显著提高32.4%、23.8%和27.9%。【结论】黄淮海平原麦-玉两熟体系,周年减氮30%制度下通过增加氮肥后移量,改善了作物光合特性(叶面积指数、叶片SPAD值和净光合速率),优化了各生育阶段地上部干物质积累强度和干物质积累量,从而促进冬小麦、夏玉米及周年总产和经济效益的提高。

【Objective】Under the traditional nitrogen(N)fertilizer application technology in Huang-Huai-Hai Plain,insufficient soil N supply in the late growth stages of the wheat-maize double cropping system has resulted in significant yield reduction issues.In this study,the effects of N fertilizer reduction and postponing on plant photosynthetic physiological characteristics,aboveground dry matter accumulation,annual grain yield,and economic benefits were investigated,in order to provide the theoretical basis for further optimization of N fertilizer management.【Method】From 2020 to 2023,the field experiment was conducted in the typical wheat-maize double cropping system in Huang-Huai-Hai Plain.The following treatments are set up in the experiment:annual N fertilizer application 400 kg·hm^(-2)of traditional farmer treatment(CK,wheat season 200 kg·hm^(-2):65%basal fertilizer+35%regreening fertilizer,maize season 200 kg·hm^(-2):100%basal fertilizer),10%reduction of annual N fertilizer(SN,wheat season 180 kg·hm^(-2):50%basal fertilizer+50%regreening fertilizer,maize season 180 kg·hm^(-2):100%basal fertilizer),20%reduction of annual N fertilizer(NH,wheat season 180 kg·hm^(-2):22.2%basal fertilizer+33.3%regreening fertilizer+44.5%heading fertilizer,maize season 140 kg·hm^(-2):28.6%basal fertilizer+71.4%pre-tasseling fertilizer),and 30%reduction of annual N fertilizer(NL,wheat season 140 kg·hm^(-2):43%regreening fertilizer+57%heading fertilizer,maize season 140 kg·hm^(-2):100%pre-tasseling fertilizer).The photosynthetic physiological characteristic,grain yield,and economic benefits of the wheat-maize double cropping system were tested.【Result】Under the condition of N reduction,the photosynthetic physiological characteristic of crops were optimized by N fertilizer postponing.Averaged across the three years,NL significantly increased leaf area index by 19.0%-40.1%and 21.6%-36.7%at jointing and anthesis of winter wheat,respectively,compared with CK,SN,and NH treatments.Meanwhile,NL was 6.8%-7.3%higher at silking of summer maize than CK and SN.Similarity,for winter wheat,averaged across the three years,NL significantly increased SPAD value by 7.7%-10.0%and 7.4%-12.9%at jointing and anthesis,respectively,compared with CK and SN.Additionally,it showed a 5.2%-16.2%increase at mid-filling compared with CK,SN,and NH,respectively.Meanwhile NL and NH were 9.0%-9.4%and 6.7%-7.1%higher at pre-tasseling of summer maize,respectively,compared with CK and SN,and 5.1%-9.4%and 4.1%-9.2%at silking and mid-filling under NL treatment,respectively,compared with CK,SN,and NH.Averaged across the three years,NL significantly increased Pn by 8.9%-13.3%,14.0%-18.1%,and 20.1%-24.4%at jointing,anthesis,and mid-filling of winter wheat,respectively,compared with CK and SN.Meanwhile NL was 4.2%-5.7%,8.7%-13.4%,and 7.7%-12.8%higher at pre-tasseling,silking,and mid-filling,respectively,compared with CK,SN,and NH,respectively.NL treatment improved the aboveground dry matter accumulation rate and stabilized or increased the aboveground dry matter accumulation at different growth stages by N fertilizer postponing.Average across the three years,the aboveground dry matter under NL significantly increased by 26.7%,27.4%,and 18.1%at jointing,anthesis,and maturity of winter wheat,respectively,compared with CK.Additionally,there was a 14.4%increase in dry matter accumulation at silking of summer maize under NL compared with CK.N fertilizer postponing improved the photosynthetic physiological characteristics and promoted aboveground dry matter accumulation at each growth stage under the condition of N reduction,and increased winter wheat,summer maize,and annual grain yield and economic benefits.Compared with CK,the results averaged from 2020 to 2023 showed that NL treatment significantly increased the grain yield and economic benefits by 20.5%,18.1%,19.1%and 32.4%,23.8%,27.9%,respectively.【Conclusion】In the wheat-maize double cropping system on Huang-Huai-Hai Plain,a 30%reduction of annual N fertilizer by N fertilizer postponing could optimize crops photosynthetic physiological characteristics(such as leaf area index,leaf SPAD value,and Pn),as well as enhance aboveground dry matter accumulation rate,and aboveground dry matter accumulation at different growth stages.This would ultimately lead to improved winter wheat,summer maize,and annual grain yield,resulting in enhanced economic benefits.