Biochemical responses of Lentil (Lens culinaris Medik.) to elevated temperature stress

The effect of high temperature stress was studied in three varieties of lentil (Lens culinaris Medik.) which were subjected to high temperature ranging from 30 0 C to 50 0 C. Growth of plants and germination of seeds were found to be retarded at 45 0 C and significantly inhibited at 50 0 C in which was considered as near lethal temperature. One month old plants of Lens culinaris could not tolerate a maximum temperature of 50 0 C. Based on tolerance index (TI) and antioxidant activities among the three varieties IPL 81 and IPL 406 were found to be more tolerant than Sehore. Tolerance and susceptibility of varieties were further confirmed by cell membrane stability test. Lipid peroxidation, as determined by accumulation of malonealdehyde, was found to be highest in Sehore. Non-enzymatic antioxidants like ascorbic acid and carotenoid initially increased and then declined in IPL 81 and IPL 406 but abruptly declined in Sehore. Hydrogen peroxide content showed an increase with the increase of temperature in Sehore, but in IPL 81 and IPL 406, H2O2 initially declined and then increased. Chlorophyll content also increased initially in 2 of the varieties before declining but in Sehore it decreased at all high temperatures. Phenol contents increased initially but decreased at higher temperatures. Proline content also initially increased and then declined. All results taken together indicate that Sehore is the most temperature susceptible variety, while IPL 81 and IPL 406 are more tolerant.