Relationship of root and shoot traits and canopy temperature of upland cotton to drought resistance, lint yield, and fiber quality

Studies were conducted in the field under irrigated and non-irrigated treatments to determine differences among six cotton genotypes for root traits, fruiting dynamics, lint yield, canopy temperature, and fiber quality. Greenhouse experiments were performed to quantify differences among genotypes for root growth and water use efficiency.;Genotypes differed for root traits at the seedling, preflowering, and mature stages of plant development. Consistent differences occurred among genotypes for root-to-shoot ratio and total root dry weight. Results indicated genotypes CABU;Genotypes differed for flower and boll production and boll retention. A positive relationship between total root dry weight at squaring and boll abscission indicated that decreases in normal fruit retention due to water stress may occur when necessary photosynthates are directed toward root growth rather than boll development.;In 1986 and 1987, yield differences occurred among genotypes in the non-irrigated treatment only, with CABU;Canopy temperature differed among genotypes and between treatments, with mean canopy temperature of the non-irrigated genotypes being 5;An experiment in glass front boxes demonstrated the potential of utilizing greenhouse studies for characterizing field root growth. A second greenhouse study indicated that Tamcot CD3H, a drought resistant cultivar, had greater seedling vigor and water use efficiency than did Paymaster 303, a drought susceptible cultivar. Results from these studies indicate that currently available cotton germplasm sources possess traits which allow the plant to delay onset of water stress, while achieving high yields.