Cotton Seedling Vigor: Biomass Partitioning and Carbon Dynamics

Stand establishment and early growth set the stage for the entire cotton growing season.  Rapid early growth enhances the chances that cotton seedlings can outgrow damage by biotic stress factors, and may also improve their ability to tolerate abiotic stress conditions.  However, our understanding of the genetic and physiological mechanisms governing early vigor in cotton is very limited.  We have identified genotypes with low, medium, and high vigor and examined factors contributing to the observed differences.  Measurements revealed that cotyledons of the high- and medium-vigor lines were greater than those of the low-vigor genotype.  In addition, the cotyledon dry weight of the most vigorous line tended to be greater than that of the other lines during the first 30 days after planting.  The greater cotyledon dry weight was not only caused by greater leaf area, but was also the result of increased specific leaf weight.  Characteristics of the first and second true leaves as well as photosynthesis measurements have also been conducted to elucidate the physiology underlying differences in early vigor.