Optimization of Temperature Conditions for Screening Thermotolerance in Sugarcane through Temperature Induction Response (TIR) Technique

An experiment was conducted with the objective of standardizing temperature conditions for screening thermotolerance in sugarcane variety Co 86032 under in vivo and in vitro conditions. Lethal temperature condition for settlings (in vivo) and callus (in vitro) were identified by subjecting the 30 days old settling and callus 7 temperatures condition (39, 41, 43, 45, 47, 48 and 49 ºC) with four time durations (5, 10, 15 and 20 hrs). Temperature conditions at 48ºC with 20 h and 48 ºC with 15 h of heat stress treatment were identified as critical temperature condition for settlings and callus respectively. To determine the optimum induction temperature conditions (sub lethal temperature) for settlings, the variety Co 86032 was exposed to gradual increase in temperature from 38, 40, 42 to 44 ºC with two time durations (10 and 15 h), followed by lethal temperature (48 ºC with 10 h). The optimum induction temperature condition for developing thermo tolerance in settlings was worked out to be 40 ºC with 10 h stress treatment. Similarly, the optimum induction temperature condition for calli for develop thermo tolerance was worked out as 42ºC with 10 h. Adaptive response of Co 86032 by heat acclimation was investigated under in-vivo and in-vitro conditions through temperature induction response technique. It was found that induced settlings and calli for thermotolerance recorded higher soluble protein, proline, glycine betaine, total phenols, POX activity and SOD activity than non-induced.