LAUSR

Stand establishment and early growth are important for successful cotton (Gossypium hirstum L.) production, but in comparison with other crops, cotton seedlings develop slowly after emergence. The objectives of this study were to compare and contrast early vigor of diverse cotton genotypes under greenhouse and field conditions. A total of 144 genotypes were grown in a greenhouse and destructively sampled 34 d after planting (DAP). A range of seedling characteristics including areas and weights of the cotyledons and first, second, and third leaves were determined, and leaf weight ratio, specific leaf area, and leaf area ratio were calculated. Of the 144 genotypes that were grown in the greenhouse, a subset of 40 were selected and planted in the field where plant characteristics were assessed at 17, 27, 35, and 48 DAP. Genotypes differed in shoot and stem dry weights, as well as cotyledon, first, second, and third leaf, and total leaf area, as well as dry weight. A positive correlation of seed weight and rapid early growth as indicated by shoot biomass was observed at 34 DAP in the greenhouse through 48 DAP in the field. Shoot biomass of field-grown plants sampled at 17, 27, 35, and 48 DAP was positively correlated with the size of the cotyledons and the first leaf measured at 17 DAP, as well as with the seed weight. Further characterization of high- and low-seedling-vigor genotypes identified in this study may provide insights into the physiological and genetic mechanisms associated with early vigor of cotton.