种植密度与施氮量对陇中旱农区玉米产量及光合特性的影响

在陇中旱农区,依托2012年布设的田间定位试验研究了种植密度与施氮量对全膜双垄沟播玉米光合特性、产量及产量构成要素的影响。采用裂区设计,主处理为种植密度:4.5(D₁)、5.25(D₂)、6(D₃)、6.75万株·hm^-2(D₄);副处理为施氮水平:施纯氮200(N₂)和300 kg·hm^-2 (N₃)。结果表明:1)随着玉米种植密度和施氮量的增加,玉米的叶面积指数增加,但叶片的叶绿素含量减小;2)施氮量对玉米的光合作用影响不显著,但玉米光合作用随种植密度增加而减弱;3)D₂N₂处理下的玉米产量最高,D₂的籽粒产量和生物产量较D₁分别增加了15.2%和14.5%,N₂的籽粒产量和生物产量较N₃增加了10.9%和4.8%。4)玉米籽粒产量与穗数、穗粒数显著正相关,与百粒重无显著相关关系。因此,在陇中旱农区应用全膜双垄沟播技术种植玉米,密度为5.25万株·hm^-2,施纯氮200 kg·hm^-2左右时,叶片光合作用关系协调,有利于穗数和穗粒数的增加,从而提高玉米籽粒产量。

Effects of planting density and nitrogen fertilizer rate on maize yield and photosynthetic characteristics in arid areas of central Gansu,China

This research evaluated the effects of planting density and nitrogen fertilizer rate on maize photosynthetic characteristics, yield and yield components under full film double ridge plastic mulch. The research relied on a field experiment that was set up in 2012 at Dingxi, in the Longzhong region. The experiment used a split plot design, with four planting densities as the main plot factor: 45000 (D₁), 52500 (D₂), 60000 (D₃), 67500 plants·ha^-1 (D₄). The sub plot treatment comprised two nitrogen fertilizer rates: 200 (N₂) and 300 kg N·ha^-1 (N₃). It was found that the leaf area index of maize improved with increase in planting density and nitrogen fertilizer rate, while the chlorophyll concentration decreased with increasing planting density. With increased planting density, the photosynthesis rate of maize decreased. Nitrogen fertilizer rates had no significant effect on the photosynthesis of maize. The treatment (D₂N₂) had the highest yield. The grain yield and biomass of D₂ were, respectively, 15.2% and 14.5% higher than D₁, while the grain yield and biomass under N₂ were, respectively, 10.9% and 4.8% higher than those of N₃. There was a significant positive correlation between grain yield and ear number and kernel number, but no significant correlation with hundred-grain weight. Therefore, under double furrow sowing with full film mulch in dryland farming areas of central Gansu, China, a planting density of 52500 plants·ha^-1 and nitrogen fertilizer application of 200 kg N·ha^-1 was found to be optimal for sustainable cultivation of maize. This cultivation regime facilitated leaf photosynthesis, leading to increased numbers of ears and kernels, thus enhancing maize grain yield.