华北热资源限制区实现夏玉米高产高效和机械粒收的适宜种植密度和施氮量

Optimizing planting density and nitrogen application of summer maize to achieve high yield and efficiency,and mechanical grain harvesting in the thermal resource-limited area of North China

【目的】华北平原夏玉米高效生产不仅取决于产量和肥料利用率,也依赖于高效的机械粒收。本研究探讨了密度与氮肥用量对夏玉米产量形成和收获期籽粒水分含量的影响。【方法】以玉米‘京农科728’为材料,采用裂区试验设计,主区设置2个密度:7.5×10^(4)株/hm^(2)(D_(7.5))和9.0×10^(4)株/hm^(2)(D_(9.0)),副区设置5个施氮(N)水平:0、180、240、300和360 kg/hm^(2)(分别表示为N_(0)、N_(180)、N_(240)、N_(300)和N_(360))。测定了不同密度和氮肥用量下玉米叶片SPAD值、叶面积指数(LAI)、干物质积累(DM)、籽粒灌浆、产量及其构成因素、氮肥偏生产力(PFP_(N))和农学利用效率(AE_(N))。【结果】与D_(7.5)相比,D_(9.0)处理V 6和R 1期L A I和DM分别提高5.0%~26.3%和3.7%~34.8%;籽粒最大灌浆速率(G_(max))提高0.35~1.33 g/(100-grain·d),灌浆速率最大时日期(T_(max))提前4.4天但灌浆持续期缩短6.9~12.2天,穗粒数减少15.0~51.3粒,实现增产2.4%~28.3%,达7.36×10^(3)~12.22×10^(3) kg/hm^(2);PPFN和AE_(N)分别显著提高10.1%~17.2%和72.0%~94.4%。与N_(0)相比,夏玉米叶片SPAD值随施氮量增加显著提高,施氮处理LAI和DM分别提高3.5%~171.3%和5.0%~177.7%;N_(240)~N_(360)水平G_(max)达峰值1.33~1.39 g/(100-grain·d),施氮处理T_(max)提前4.1~4.6天,灌浆速率最大时生长量(W_(max))提高5.7%~9.4%;百粒重提高0.5%~18.4%,穗粒数显著增加62.8~79.2粒,产量提高3.2%~115.7%,达10.10×10^(3)~11.33×10^(3) kg/hm^(2)。在D_(7.5)和D_(9.0)下,随施氮量增加夏玉米PFP_(N)、AE_(N)分别显著降低24.2%~46.6%和21.2%~43.1%、21.1%~32.5%和13.0%~32.9%。【结论】较高的夏玉米密度可以有效提高玉米干物质积累速度,降低籽粒含水量至15.4%~24.8%,满足籽粒机收的要求。施氮量控制在180~240 kg/hm^(2),可进一步降低籽粒收获时的含水量,提高叶片SPAD值、叶面积指数及干物质积累,改善籽粒灌浆提高粒重,实现产量稳定在10.5×10^(3)~11.2×10^(3) kg/hm^(2),氮肥偏生产力和农学利用效率高达47.0~59.7和27.6~30.9 kg/kg。因此,机收夏玉米适宜的密度为9.0×10^(4)株/hm^(2),施氮水平为180~240 kg/hm^(2)。

【Objectives】The efficient summer maize production relies on academic management and machinal grain harvesting.The optimum plant density and nitrogen application for efficient summer maize production in North China plain were studied.【Methods】Summer maize cultivar Jingnongke728 was used as the research materials.The split-plot experiment design was adopted:the main plots were two plant densities[7.5×10^(4) plants/hm^(2)(D_(7.5))and 9.0×10^(4) plants/hm^(2)(D_(9.0))],while five N application rates(0,180,240,300 and 360 kg/hm^(2) tagged as N_(0),N_(180),N_(240),N_(300) and N_(360),respectively)were the sub-plots.The plant’s leaf SPAD value,leaf area index(LAI),dry matter accumulation(DM),grain filling,grain yield and its components,nitrogen partial factor productivity(PFP_(N))and agronomic efficiency(AE_(N))of maize under different planting densities and N application were measured.【Results】Compared with D_(7.5),LAI and DM of D_(9.0) treatments at V6 and R1 stage were increased by 5.0%-26.3%and 3.7%-34.8%respectively.The maximum grain filling rate(G_(max))of D_(9.0) treatment was 0.35-1.33 g/(100-grain·d)higher than that of D_(7.5),and the date of reaching the G_(max)(T_(max))was 4.4 d earlier in D_(9.0).The grain filling duration in D_(9.0) were shortened by 6.9-12.2 days,but ear grain number reduced by 15.0-51.3 grain.The grain yield of D_(9.0) was 2.4%-28.3%higher than D_(7.5),which was 7.36×10^(3)-12.22×10^(3) kg/hm^(2).The D_(9.0) significantly increased PFP_(N) and AE_(N) by 10.1%-17.2%and 72.0%-94.4%,respectively.Compared with N_(0),summer maize leaves SPAD values increased significantly with increase in N application.The LAI and DM also increased by 3.5%-171.3%and 5.0%-177.7%,respectively,with increase in N application.The G_(max) reached the highest 1.33-1.39 g/(100-grain·d)at N_(240)-N_(360) levels,and the T_(max) of N treatments were 4.1-4.6 days earlier than N0.The G_(max) weight(W_(max))also increased by 5.7%-9.4%with increase in N application.Therefore,with increase in N application,100-grain weight increased by 0.5%-18.4%,grain number per ear increased significantly by 62.8-79.2 grain,and yield increased by 3.2%-115.7%(i.e.,10.10×10^(3)-11.33×10^(3) kg/hm^(2)).With increase in N application,PFP_(N),AE_(N) were reduced by 24.2%-46.6%and 21.2%-43.1%,21.1%-32.5%and 13.0%-32.9%,respectively,under D_(7.5) and D_(9.0) treatments,respectively.【Conclusions】Higher density of summer maize can effectively improve the dry matter accumulation,reduce grain moisture content to 15.4%-24.8%,and satisfied grain mechanical harvesting.Controlling nitrogen application rate at 180-240 kg/hm^(2) could further reduce the moisture content at grain harvest,improve leaf SPAD value,LAI and dry matter accumulation,improve grain filling and increase grain weight.The yield was stable at 10.5×10^(3)-11.2×10^(3) kg/hm^(2),and the PFP_(N) and AE_(N) were 47.0-59.7 kg/kg and 27.6-30.9 kg/kg.Therefore,the suitable density of summer maize for machinal grain harvesting was 9.0×10^(4) plants/hm^(2),and the nitrogen application level was 180-240 kg/hm^(2).