Phenotyping Drought Tolerance in Cotton.

Defining drought tolerance in cotton (Gossypium spp., L.) is complex. Cotton is a perennial shrub in its wild and natural state. Through domestication it can be cultivated as an annual crop, but still has many remnant physiological characteristics in reaction to drought conditions. Multiple evaluation techniques have been investigated by the Cotton Improvement Lab at Texas A&M University in College Station, TX. Among these include seedling drought mortality, leaf temperatures, performance field trials, and most recently soil tubes to recover root systems. It has been determined that a single screening technique cannot fully characterize a cotton phenotype as being drought tolerant or susceptible. The best indicators appear to be seedling mortality, but preliminary data indicates root mass may also be a good method of determining which genotypes are drought tolerant. Results from these studies will enable plant breeders to more efficiently improve the productivity and water use efficiency of cotton.