Breeding for tolerance to high plant density (HPD) stress resulted in remarkable increase in grain yield per unit area in temperate maize. In spite of improved germplasm and reasonable adoption of hybrid technology, average maize productivity in tropics is still much below the achievable potential, primarily due to natural abiotic stresses and poor management due to lack of access to key inputs. A tropical maize plant, inherently distinguished with tall stem, numerous long dropping leaves, bushy tassel, rapid postsilking leaf senescence and prone to lodging, needs to be redesigned for amenability to HPD stress. With reference to the historical outlook on plant type modifications in temperate maize for adaptation to HPD and, hence, to minimize decrease in grain yield per plant resulting from crowding stress, we delineated HPD adaptation traits, which need to be focused during selection to enhance the productivity in tropical maize, a source of food, feed and livelihood to millions of resources-poor farmers.

中文翻译：

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适应热带玉米高植株密度的育种植物类型——提高生产力的一步

培育对高植物密度 (HPD) 胁迫的耐受性导致温带玉米单位面积的谷物产量显着增加。尽管改进了种质并合理采用了杂交技术，但热带地区的平均玉米生产力仍远低于可实现的潜力，这主要是由于自然非生物胁迫和缺乏关键投入物导致的管理不善。一种热带玉米植物，固有地以高茎、长长的落叶、浓密的流苏、快速的后丝叶衰老和易倒伏着称，需要重新设计以适应 HPD 胁迫。参考温带玉米为适应 HPD 而改变植物类型的历史展望，因此，为了尽量减少因拥挤胁迫导致的单株谷物产量下降，我们描绘了 HPD 适应性状，