Plant architecture influences growth and yield response of upland cotton to population density

Plant architectural characteristics directly affect inter-plant interactions and cotton crop management. Field studies were conducted in the 2010 and 2011 growing seasons at the University of Arizona Maricopa Agricultural Center to investigate the influence of plant architecture on the crop growth, biomass partitioning, and lint yield response of upland cotton to population density under irrigated desert conditions. Two cotton varieties of contrasting architecture, a tall stature columnar type, Delta and Pine 164B2RF (DP164), and a short stature bush type, Stoneville 4498B2F (ST4498), were evaluated under three plant population densities: low density (LD, 57,300–66,500 plants ha−1), medium density (MD, 77,300–109,800 plants ha−1), and high density (HD, 126,700–146,000 plants ha−1). While high population densities significantly increased plant height of both varieties at early growth stages, plant height at late growth stages were not significantly different. High plant population reduced main stem node number of both varieties. However, the effect was more pronounced with ST4498 where the HD treatment had 2.9 and 2.5 nodes less than the LD treatments in 2010 and 2011, respectively. Plant population affected the height to node ratio of DP164 more than ST4498. The taller, columnar type DP164 partitioned more biomass into stems than the bush type ST4498 at all three plant populations. The LD treatment significantly reduced cotton growth and yield of DP164 in 2010. This study suggests the existence of differences in responses to plant population density among upland cotton varieties, attributable to canopy architecture. Additionally, results indicate that shorter bush type varieties might have higher growth plasticity and thus accommodate a broader range of plant densities than taller stature columnar type varieties.