播种时期与密度对关中灌区夏玉米群体生理指标的影响

Effects of planting date and density on population physiological indices of summer corn (Zea mays L.) in central Shaanxi irrigation area

采用二次饱和D最优试验设计,运用作物群体生理学方法,研究了关中灌区玉米密度、播期与群体生理指标的关系及其影响效应.结果表明,关中灌区夏播条件下,在6月13日—7月22日,播期与玉米籽粒产量、干物质积累量(DMA)、吐丝期叶面积指数(LAImax)、总光合势(LAD)、群体净同化率(NAR)、作物生长率(CGR)呈负相关,播期对CGR、LAD的影响较大,对LAImax和NAR的影响较小;在45000～65918株·hm-2范围内,密度与玉米籽粒产量、DMA、LAImax、LAD、CGR呈正相关,而与NAR呈负相关,密度对CGR、LAImax和LAD的影响较大,而对NAR的影响较小.播期对玉米群体生理指标的总影响效应显著大于密度,实际生产中应力争早播.对密度和播期与玉米群体生理指标建立的回归模型表明,陕单8806玉米在关中灌区夏播中实现高产的适宜播期为6月10—20日,密度应控制在57767～71706株·hm-2.

By using D-saturation optimum design and the methods of crop population physiology, this paper studied the effects of planting date and density on the population physiological indices of summer maize Shandan 8806 and its yield in central Shaanxi irrigation area. The results showed that in the period from 13 June to 22 July, the delay of planting had negative effects on grain yield, dry matter accumulation （ DMA）, maximum leaf area index （ LAImax ）, net assimilation rate （ NAR）, leaf area duration （LAD） and crop growth rate （ CGR）, with larger effects on LAD and CGR than on LAImax, and NAR. Within the range of 45 000-65 918 plants · hm^-2, planting density had positive effects on grain yield, DMA, LAImax,, LAD and CGR but negative effect on NAR, with larger effects on LAImax, LAD and CGR than on NAR. The effects of planting date were more significant than those of planting density, and thus, Shandan 8806 should be sowed as early as possible. The regressive model based on the population physiological indices indicated that for the high yield of summer maize Shandan 8806, the optimum planting date was from 10 to 20 June, and the optimum planting density was from 57 767 to 71 706 plants · hm^-2.