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由于直立性和抗胁迫能力的改良,当今玉米生产系统中有增加种植密度的倾向。因而,更现代的杂交种需有较高的种植密度以保证最高的籽粒产量。但是,除抗茎腐改良导致了直立性改良之外,对造成抗胁迫能力的改良及高密度下产量增加的生理因素,却没有清楚的认识。有些证据表明,现今杂交种的叶片光合作用对胁迫不敏感(Dwyer 等,1989)。但是,叶片光合作用、种植密度及产量间的相关
Today’s maize production systems have a tendency to increase planting density due to improvements in uprightness and resistance to stress. Thus, more modern hybrids need to have higher planting density to ensure the highest grain yield. However, there is no clear understanding of the physiological factors that result in improved resistance to stress and increased yield at high densities, in addition to improvements in stem integrity that result in improved uprightness. There is some evidence that leaf photosynthesis in today’s hybrids is insensitive to stress (Dwyer et al., 1989). However, there is a correlation between leaf photosynthesis, plant density and yield