Maize (Zea mays L.) yield is often reduced when the in-row plant spacing is not uniform. I used a variant of the KNMAIZE model to investigate the mechanisms responsible for the reductions. KNMAIZE determines kernels per plant from the relationship between the proportion of the assimilate supply from photosynthesis that is partitioned to the kernels and the assimilate required to sustain kernel growth. Kernels abort when their assimilate requirement exceeds the supply. Algorithms were developed to create variation of in-row plant spacing (characterized by CV) and emergence percentage. The effect of spatial variation on kernels m⁻² depended upon the ability of the dominant plants (higher plant growth rates associated with larger in-row spacing’s) to increase kernels per plant to compensate for the reduction on the dominated plants (lower plant growth rates resulting from smaller in-row spacing’s). When the ability of the dominant plants to respond was zero (kernels ear⁻¹ = florets ear⁻¹, excess capacity = 0), kernels m⁻² started decreasing as soon as the CV > 0. When the dominant plants had excess capacity (i.e., kernels per ear < florets per ear), the beginning of the decline occurred at progressively larger CVs depending upon the magnitude of the excess capacity. Populations greater than the minimum needed for maximum yield provide the excess capacity on dominant plants to buffer kernels m⁻² and yield against variation of in-row spacing and reductions in emergence.

当行距不均匀时，玉米（Zea mays L.）的产量通常会降低。我使用了 KNMAIZE 模型的一个变体来研究导致减少的机制。KNMAIZE 根据分配给籽粒的光合作用同化物供应比例与维持籽粒生长所需的同化物之间的关系来确定每株植物的籽粒。当同化需求超过供应时，内核中止。开发了算法来创建行内植物间距（以 CV 为特征）和出苗百分比的变化。空间变化对内核 m ^-2的影响取决于优势植物的能力（较高的植物生长速率与较大的行间距相关）增加每株植物的籽粒以补偿优势植物的减少（较低的植物生长速率导致较小的行间距）。当优势植物的反应能力为零时（籽粒穗^-1 = 小花穗^-1，产能过剩 = 0），籽粒 m ^-2一旦 CV > 0 就开始下降。当优势植物具有过剩产能时（即每穗粒数 < 每穗小花），下降的开始发生在逐渐变大的 CV 上，这取决于产能过剩的幅度。大于最大产量所需的最小值的种群为优势植物提供了多余的能力来缓冲米粒m ^-2和产量，以应对行内间距的变化和出苗的减少。