Identification of thermo tolerance urdbean [Vigna mungo (L) Hepper] genotypes using temperature induction response technique

High temperature stress in plants reduces crop yield because it negatively affects several plant physiological processes. Screening and identification of cultivars for high-temperature stress conditions is essential under changing environments. In the present study, the temperature induction response (TIR) technique was used for screening the high-temperature tolerant genotypes in urdbean (Vigna mungo (I) Hepper). In the present investigation, induction temperature and lethal temperature have been standardized based on percent growth reduction and survival percentage at the end of the recovery period. The induction temperature was observed at 38 to 48 ºC as sub-lethal i.e., challenging temperatures for 4 h and 30 min, while the lethal temperature was observed at 50 ºC for 3 h. This technique can be used as a potential tool to identify and select temperature-tolerant genotypes at the seedling stage from a large population. A total of nineteen urdbean genotypes were screened and evaluated for thermo tolerance. By using standardized optimum induction and challenging temperature, cellular level tolerance was assessed in the studied genotypes. Based on root length and shoot length of induced seedlings over control seedlings, the cellular level tolerance in terms of least reduction in growth and highest survival percentage was calculated and PGRU 95014 IPU 94-1, IPU 2K -22 and PGRU 95016 identified as heat tolerant genotypes. These can be used as donors in breeding programs.