In order to make significant, rapid progress in yield improvement we must understand the relative contribution of individual components to total harvestable yield and concentrate both genetic and management efforts on improvement of the most importantones. Cotton yield (pounds/acre; kilograms/hectare) can be partitioned into boll number and boll size. The boll number component accounts for over 80% of the variation in yield across variety and environment. Boll number is composed of plant density andnumber of fruiting nodes, total number of fruiting sites and fruit retention percentage on an individual plant basis. Plant density and total mainstem nodes were positively correlated (but with low R2’s) with boll number per acre across yields rangingfrom less than 200 pounds/acre to more than 2000 pounds/acre. Total fruiting sites and fruit retention contributed equally to total boll number. The major source of yield variation was percent of the plant population that had harvestable fruit between mainstem nodes 7 through 12. Boll size which accounts for approximately 10% of the variation in yield is comprised of number of seed per boll and lint mass per seed, each contributing approximately 30% to the boll size variation. Lint mass per seed is comprised of number of fibers per seed, fiber length, and linear density of the fiber (micronaire). Both fiber length and linear density were positively related to lint mass/seed; however, the partial regression coefficients were fairly small. Boll size hasappreciable genetic variation but also a large environmental influence within a cultivar. Genetic potential for lint yield is largely unchallenged in today’s cotton cultivars. In order to increase yield/acre, we must develop management strategies that reduce the risk of excessive environmental stress on the cotton plant during the first four weeks of flowering.
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