Effects of cultivar and nitrogen application rate on lint, seed, oil, and protein yields of field-grown cotton

Cotton (Gossypium hirsutum L.) is not only the dominant fiber crop grown worldwide, but it is also an important source of plant-based oil and protein. Previous research has documented a significant effect of cotton cultivar and nitrogen application individually on lint yield and seed composition, but very limited studies have evaluated the lint, seed, oil, and protein yield responses of cultivars with different seed mass and composition to a broad range of N application rates. The objective of this study was to evaluate the lint, seed, oil, and protein yield responses of cultivars with different seed mass and composition to N application rates (0-168 kg N ha(-1)) for field-grown cotton. A field experiment was conducted in Tifton, GA, USA during the 2019 and 2020 growing seasons that included six cultivars and six N application rates. Cultivar significantly affected seedcotton, lint, seed, and seed reserve yields in both growing seasons. Lint yield did not follow identical trends as seed yield mainly due to cultivar variation in lint percent. Similarly, protein and oil yield were influenced by cultivar variation in seed composition. Seedcotton, seed, protein, and oil yields continually increased with increases in N application from 0 to 168 kg N ha(-1), whereas for lint yield, all fertilized treatments produced comparable yields that were significantly higher (68%) than the 0 kg N ha(-1) treatment. We conclude that variability in the distribution of photosynthates to fiber and seed as well as seed oil and protein composition can significantly alter trends in fiber, seed, and seed component yields in response to cultivar or N application rates for field-grown cotton.