We investigated how two planting patterns, twin row (TR) and narrow row (NR), affected maize grain yield compared with conventional row (CR) cultivation at five different planting densities, ranging from 7 to 12 plants/m², over 2 years using early and late cultivars. For all the planting patterns, the relationship between grain yield and planting density could be fit using the quadratic curve Y = a (X − b)² + c at the <1% level of significance, where a represents grain yield response to planting density, and c represents the maximum yield. Regardless of the cultivar’s maturation period, the magnitude of a was smaller for TR than for NR and CR. Although the late cultivar had a higher c value than the early cultivar, the a value and annual difference were larger. For the early and late cultivars, TR at 10.8 and 9.9 plants/m², respectively, easily achieved stable high grain yields. The large magnitude of the grain yield response to planting density for the late cultivar was caused by the large decrease in the number of grains per ear and the harvest index at an above optimum planting density. This large decrease and instability in yield-related traits resulted from a high maximum leaf area index, the frequent mutual shading of leaf blades and the large differences between the years.

中文翻译：

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早晚玉米品种双生窄行栽培产量对种植密度响应的差异

我们调查了两种种植模式，双行 (TR) 和窄行 (NR)，与传统行 (CR) 种植相比，在 5 种不同种植密度下如何影响玉米籽粒产量，从 7 到 12 株/m ²，超过 2 年使用早期和晚期栽培品种。对于所有种植模式，可以使用二次曲线Y  =  a ( X − b ) ²  +  c在 <1% 的显着性水平下拟合粮食产量和种植密度之间的关系，其中a代表粮食产量对种植密度的响应, c代表最大产量。无论品种的成熟期，幅度的一个TR 小于 NR 和 CR。虽然晚品种的c值高于早品种，但a值和年差异较大。对于早期和晚期品种，TR 分别为 10.8 和 9.9 株/m ²，很容易实现稳定的高籽粒产量。晚熟品种的籽粒产量对种植密度的大幅响应是由于在高于最佳种植密度时每穗粒数和收获指数大幅下降所致。产量相关性状的大幅下降和不稳定是由于最大叶面积指数高、叶片频繁相互遮蔽以及年份之间的巨大差异造成的。