Assessment of Cotton Leaf and Yield Responses to Water-Deficit Stress During Flowering and Boll Development

Rainfall future events are predicted to decline to 30 to 127 mm in the majority of counties of the Texas High Plains and Rolling Plains because of climate change. Cotton (Gossypium hirsutum L.) is the major crop grown on the High Plains of Texas, and the lower humidity associated with the predicted reduction in rain raises the possibility of increased vegetative water-deficit stress and reproductive dehydration stress. This study assesses the vegetative and reproductive developmental processes of commercial cotton cultivar-response following water-deficit stress, specifically during flowering and boll development. Cultivars showed a significant relationship between the leaf water-deficit stress levels during boll development and final seed cotton yields. However, the cultivar Phytogen 72 (PHY72) was an exception to this observation. PHY72 exhibited excellent leaf water-deficit stress tolerance yet had reduced seed cotton yields compared with the other cultivars evaluated. Genetic analysis of the sensitivity of the PHY 72 pollen suggested a maternal deficiency in the tapetum development of the PHY 72 pollen coat resulting in increased dehydration sensitivity. Structural differences in pollen coat development in two cultivars (PHY 72 and NM67) were observed under both scanning electron and transmission electron microscopy. Predicted reduced rainfall and higher temperatures in the future, may necessitate approaches to improve not only vegetation tolerance to stress but also reproductive tolerance both of which may be important for breeding the new generation of crops.