Leaf Carbon Isotope Discrimination in Gossypium hirsutum under Drought Conditions
Apr 18, 2019
The breeding programme at CIFA Las Torres-Tomejil (Andalucia, Spain) has aimed at developing cotton cultivars with economic yield for conditions of restricted water supply since 1989. Increasing water-use efficiency may be one way for obtaining greater crop yield with limited water. The determination of carbon isotope discrimination (Δ) in plants provides time-integrated measures of physiological activity and plant interaction with the environment. The relationship found between Δ and water-use efficiency (WUE) supports the possibility of using Δ as a criterion to select for WUE in breeding programmes. In this study, we investigated the effects of the environment on Δ and gas exchange parameters in different cultivars of G. hirsutum. Cotton genotypes were cultivated under irrigation in Las Torresand dryland in Tomejil. Gas exchange measurements and samplings for Δ determination were carried out under different levels of water availability. The relationship between gas exchange parameters and Δ changed across the environments. No relationship was found between Δ and estimates of WUE after witholding irrigation but a positive association was found between Δ and photosynthesis/transpiration ratio (A/E) in dryland. Several factors affect gas exchange measurements that make them unreliable for estimating WUE, but variability of Δ across environments requires further studies for its use as a surrogate for WUE in breeding programmes.