Low water availability and high temperatures occur under field conditions and we hypothesize that the critical temperature for photochemical damage (TC) in common bean (Phaseolus vulgaris L.) plants is increased by the occurrence of previous water deficit in a genotype-dependent manner. Five common bean cultivars A320, A222, Carioca, BAT477 and Ouro Negro were evaluated. Thirty days after seedlings emergence, one group of plants was exposed to water deficit for ten days and rehydrated and another one was maintained well hydrated during the experimental period. The minimum chlorophyll fluorescence (FO) was monitored in leaf discs exposed to temperatures ranging from 25 to 45 oC and the TC values estimated. The previous water deficit did not affect TC, which varied between 38.8 and 43.8 oC when considering all cultivars and water regimes. Under well-watered conditions, BAT477 (41.9 oC) and Carioca (43.8 oC) presented higher TCthan Ouro Negro (38.8 oC). Our findings indicate a significant genotypic variation in thermal tolerance in Phaseolus vulgaris, an important crop trait to be considered in breeding programs.
chlorophyll fluorescence; hardening; heat stress; Phaseolus vulgaris ; tolerance
Thumbnail
Thumbnail
