Effect of plant density and vegetative branch retention on within-plant yield distribution and maturity performance of cotton

A multi-site field experiment was conducted in the counties of Linqing, Xiajin and Huimin in Shandong Province to analyze effects of plant density and vegetative branch (VB) retention on within-plant yield distribution, sink/source ratio, and maturity performance of cotton. Economic yields of VB-excised cotton plants are all derived from fruiting branches (FB), while those of VB-retained plants are most from FB (85%), and the rest is from VB (15%). Cotton yield is mainly distributed in the lower and middle FB (72%) and the inner fruit nodes (74%) of FB, whereas less occurs in upper FB (23%) and extra fruit nodes (26%). Plant density and pruning have significant effects on within-plant yield distribution with an insignificant interaction. While yield distribution from inner to extra fruit nodes is mainly affected by plant density, changes in yield distribution from upper to lower FB is mainly attributed to pruning. Greater yield distribution in inner fruit nodes is noted with increasing plant density whereas VB-retention results into a longitudinally dispersing distribution. Branch pruning does not significantly affect maturity performance, but plant density significantly affects maturity performance and sink/source ratio. Light premature senescence with high sink/source ratio, and late maturity with low sink/source ratio are respectively observed under low and high plant densities. Moderate plant density (5.25 plants per m^-2) presents an appropriate sink/source ratio and desired maturity performance.