• Y.V.Bharathi

High temperature stress in plants reduces crop yield because it negatively affects several plant physiological processes, including photosynthesis, respiration, growth, development and partitioning. Pulses are more sensitive to high temperature stress at reproductive stage. Blackgram is an important source of protein and widely used in daily diet. It has much economic value as about 70% of worlds black gram production comes from India. (Wikipedia). Hence it necessitates the identification and improvement of stress tolerant varieties of black gram with adaptation to local conditions. TIR is a potential tool for identification of heat tolerant varieties from the large population. This technique involves standardization of lethal and sub lethal temperatures based on percent growth reduction and percent survival at the end of recovery. PU-31(c) is used for standardization of lethal and sub lethal temperatures. The induction temperature range was standardized as 32 to 48 °C (with 2°C rise, at 30 mnts for each temperature) and followed by lethal temperature at 52 °C for 1 hour. A total of 14 blackgram genotypes were screened and evaluated for thermo tolerance, using standardized optimum induction and challenging temperature. Black gram seedlings exposed to induction temperature prior to challenging temperature exhibited higher recovery growth compared to seedlings which were exposed directly to challenging temperature. 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. Among the 14 genotypes LBG-823, PU 31 (c), and LBG-45 has shown more susceptibility to heat stress, where as LBG-806, and LBG-808 has shown highest intrinsic heat tolerance and therefore this can be explored as donor source in breeding program aimed for global warming.

"Screening of Black gram [Vigna mungo (L.) Hepper] genotypes with acquired thermo-tolerance using temperature induction response (TIR) technique:", International Journal of Emerging Technologies and Innovative Research (www.jetir.org), ISSN:2349-5162, Vol.5, Issue 12, page no.588-598, December-2018, Available :http://www.jetir.org/papers/JETIR1812178.pdf

"Screening of Black gram [Vigna mungo (L.) Hepper] genotypes with acquired thermo-tolerance using temperature induction response (TIR) technique:", International Journal of Emerging Technologies and Innovative Research (www.jetir.org | UGC and issn Approved), ISSN:2349-5162, Vol.5, Issue 12, page no. pp588-598, December-2018, Available at : http://www.jetir.org/papers/JETIR1812178.pdf