Proline accumulation in response to drought and heat stress in cotton.

Abstract

Water and heat stress are the most important environmental variables affecting cotton growth and development. The main objective of our study was to evaluate the effect of water stress and a combination of water and heat stress on proline accumulation in six cotton cultivars (Gossypium hirsutum) and to determine the suitability of using this proline accumulation in a drought index. Drought and a combination of drought and heat stress were induced in three-week-old seedlings in the greenhouse. It was detected that with decreasing water content there was a progressive increase in free proline in all six cultivars, as well as differences in the proline level between the different cultivars. Maximum accumulation of free proline in drought stressed cotton occurred at 11 days without water. The combination of heat and drought stress exhibited an increase in proline concentrations in five cultivars. Different proline profiles were observed for the different treatments and different mechanisms for heat and drought are proposed for this phenomenon.