Evaluation of Pigeon Pea (Cajanus cajan (L.) Millsp.) Genotypes for Thermotolerance Tolerance Based on Temperature Induction Response (TIR) technique

Thirty-seven selected pigeon pea (Cajanus cajan (L.) Millsp.) genotypes were evaluated for temperature tolerance employing a technique called Temperature Induction Response (TIR) technique, where four days old seedlings were exposed to gradual increase of temperature from 30°C to 42°C in 3 hours and finally subjected to the lethal temperature (54°C for 3 h). Pigeon pea seedlings exposed to induction temperature prior to challenge temperature, exhibited higher recovery growth compared to seedlings which were directly exposed to challenge temperature. The genotypes showing maximum survivability at 54°C for 3 h and growth were considered to be temperature tolerance and those, which showed less or no survivability and recovery growth were considered to be temperature susceptible. The result of this study revealed a significant genetic variability among the genotypes for temperature tolerance. By using this technique, genotypes like ICP 15761 and ICP 7076 were identified as tolerant and IPAC-79, ICP-11477, Amar and IPA-9F as thermotolerance susceptible genotypes. The physiological basis of thermo tolerance was studied with contrasting genotypes through membrane integrity. Even the oxidative stress damage was relatively less in the thermotolerance tolerant genotypes.