Plant pathogens and water, are two limiting factors to dryland cotton production. Potential increases in the production of cotton under these adversities may result from genetic improvement. For genetic improvements to take place we must identify traits by which the plant resists the consequences of the adversities, and then optimize the trait; in future cotton varieties.

Many studies are presently underway to identify and evaluate traits of root systems that differ among varieties and to relate them to performance under different environments. Scientists have demonstrated that significant genetic variability exists among exotic strains of Gossypium hirsutum L. for root length and number of lateral roots. Genetic studies have measured large amounts of additive, dominance, and additive by additive epistatic effects in seedling root length and relative root weight.