Abstract
Even though high temperatures significantly reduce both vegetative growth and yield in cotton, very little is known about the effects of heat stress on cotton antioxidant system. Thus, the effects of gradual heat stress on cotton growth in controlled conditions were investigated in the present study. At squaring stage, cotton plants were subjected to two different temperatures, 38 and 45°C to determine the influence of heat stress on the plants. The results of the present study showed that heat stress did not significantly altered the levels of malondialdehyde (MDA) and hydrogen peroxide (H2O2) in the leaves, whereas there was a remarkable decline in proline quantity of the leaves of plants subjected to 45°C heat stress. As for the amount of total chlorophyll content, a slight increase at plants treated with 38°C temperature was observed. Furthermore, the activities of some enzymes such as superoxide dismutase (SOD), which were associated with heat stress response in other plants was also investigated. For example, there was decline in the activitity ofSOD in the plants exposed to high temperatures. On the contrary, catalase (CAT)activity increased at 45°C; peroxidase (POX) activity increased at 38°C and ascorbate peroxidase (APX) activity increased at 38 and 45°C. The results from this study suggest a potential role for CAT, POX and APX in the reduction of elevated levels of H2O2 in cotton plants grown under heat stress condition. To sum up, it could be concluded that, diurnal gradual heat stress caused a low oxidative injury in cotton. Key words: Antioxidant enzymes, cotton, heat stress, lipid peroxidation, proline.
Highlights
Both plant growth and yield are adversely affected by abiotic stresses such as high or low temperatures, drought, salinity and high-light intensity
The purpose of this study was the investigation of antioxidant enzyme activities, lipid peroxidation, H2O2 production, chlorophyll content and proline accumulation in cotton leaves at squaring stage under heat stress conditions
MDA levels were measured as 21.00, 20.90 and 24.03 μmol/g fw in the leaves of the plants exposed to no heat stress and the plants, treated with 38 and 45°C, respectively
Summary
Both plant growth and yield are adversely affected by abiotic stresses such as high or low temperatures, drought, salinity and high-light intensity. Heat stress induces oxidative stress in plants caused by the generation and the accumulation of super-oxides (O2 ), hydrogen peroxide (H2O2) and hydroxyl radicals (OH ), which are commonly known as active oxygen species (AOS) or reactive oxygen species (ROS) (Breusegem et al, 2001). Plants get rid of these harmful ROS products by converting them to less reactive chemicals. One of the most common responses of many plant species exposed to different abiotic stresses is the accumulation of compatible organic solutes such as proline, glycine betaine and choline O-sulfate (Rhodes and Hanson, 1993; Ashraf and Fooland, 2007). Proline accumulation has been observed in many plant species treated with a variety of abiotic stresses. From these observations, it has been suggested that proline may play
Sign-in/Register to view highlights & summary 
Published Version
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call