Variability in heat tolerance in Bambara groundnut (Vigna subterranea (L.) Verdc.)

Abstract

Four Bambara groundnut landraces (Vigna subterranea (L.) Verdc.) of African origin (S-165 A, DodR, Uniswa red and SB-42), were grown at research farm of Central Arid Zone Research Institute, Regional Research Station, Bikaner to evaluate for heat tolerance based on the cell membrane thermostability of leaf tissue by using five temperature treatments (40, 45, 50, 55 and 60 C) and four heating durations (15, 30, 45 and 60 min). Lethal temperature and lethal heating duration was used as the selection criteria for heat tolerance. Significant genotypic variations were evident for both lethal temperature and lethal heating duration. A strong relationship between lethal temperature and lethal heating duration indicates that any one of two parameters can be used as selection criteria for screening Bambara groundnut genotypes for heat tolerance. However, the range of lethal temperature was too narrow (47.5–49.4 C), whereas the range of lethal heating duration was fairly longer (39.9–48 min) to distinguish the genotypes. Further, there was strong and significant relationship between lethal heating duration and relative injury under heat stress at 50 C. From this study it can be concluded that lethal heating duration at 50 C is a potential selection criterion for identifying heat tolerant genotypes in Bambara groundnut.