Cross tolerance by heat and water stress at germination of common beans

Resumo

Common beans are legumes of extreme importance for the food security of developing countries. Because it is widely cultivated in tropical and subtropical regions, it is subject to the stress effects caused by this type of climate, such as water stress and heat. Cross-tolerance allows plants to acclimate to a range of different stresses after exposure to a specific short-term stress. The present work had as objective to evaluate the induction of cross-tolerance by heat stress at 38ºC and water stress simulated by polyethylene glycol (PEG) in 3 different osmotic potentials in the germination of the brazilian cultivars IPR Uirapuru and IPR Campos Gerais in a randomized block design, setting up a 2 x 2 x 3 factorial scheme, with eight replicates of 25 seeds. The following variables were evaluated: percentage of germination, root and shoot length, and fresh root and shoot mass. The data were submitted to Tukey test with 5% significance. The results indicate a possible memory to the primary stress when the IPR UIRAPURU and IPR Campos Gerais varieties are subjected to an initial stress of 38°C, making them better adapt to an osmotic stress at the evaluated stages. The results indicated that there was a statistically significant difference of the treatments applied in relation to the germination of the cultivars where the cultivar IPR Uirapuru obtained higher germination indexes for all treatments evaluated when compared to the cultivar IPR Campos Gerais. The results indicate that in both cultivars there was induction of cross tolerance by heat followed by water stress.