Impact of Cultivar Variation in Cotton Seed Characteristics and Nitrogen Application Rate on Crop Development and Yield Component Responses

Seed and nitrogen application costs represent a substantial portion of the total cotton production budget. Fertilization rates are best utilized at a level that promotes crop development while diminishing excess nutrients that are hazardous for the environment and overall operational profitability. Cotton production goals are primarily focused on the yield of high quality lint. To obtain this goal, an understanding of the plant response to nitrogen application for a given cultivar is required. With  commercially available cultivars changing often, there is a need to find a fundamental rationale that associates seed physical and chemical characteristics across numerous cotton varieties to their respective crop development and yield components under given nitrogen application rates. The study created for this goal was executed in a 2.9 acre field at The University of Georgia Lang farm in Tifton, Georgia. It entailed the use of six cultivars with physically (mass) and chemically (oil and protein content) distinguishable seeds grown at six separate nitrogen application rates. Measurements included seedling vigor, chlorophyll fluorescence and pigment analysis, growth, maturity, yield, yield components, and fiber quality. Because seed-associated proteins are the main sink for nitrogen in the cotton plant and because seed mass can strongly influence seedling vigor, it is expected that seed mass and protein content will influence cultivar responses to nitrogen.