Ecofisiologia do crescimento inicial e metabolismo da cevada sob restrição hídrica, altas temperaturas e tratamento de sementes

Abstract

The objective of the present study was to evaluate the effects caused by the unfavorable water and thermal environment in association with seed treatment and its influence on the physiological performance of seeds, on the ecophysiology of growth and on seedling metabolism. The experimental design was completely randomized, in a 5x6x2 factorial scheme (5 cultivars, 6 seed treatments and 2 water conditions). The seeds to germinate and develop from the different ones were arranged in B.O.D at temperatures of 20°C and 30°C and under two hydric conditions, being substrate retention capacity and water restriction. The Danielle, BRS Korbel and BRS Brau cultivars were more sensitive to water restriction, since their germination and initial growth were lower, in addition to the fact that the enzymatic activity, as well as the metabolite content, also showed reduced values for these cultivars. Cultivar BRS Quaranta showed greater tolerance for the imposition of water restriction, obtaining higher values, in comparison with the other cultivars, for germination variables and for initial growth variables. Enzymatic activity and metabolite content were also higher for the BRS Quaranta cultivar. Cultivar BRS Korbel showed greater tolerance when subjected to heat stress and water restriction simultaneously with heat stress, obtaining higher values for the variables of germination and initial growth, higher enzymatic activity and higher levels of metabolites. Most products used in seed treatment did not cause negative effects on barley, regardless of the stress to which the crop was exposed. The water restriction condition decreased germination and initial growth variables, and increased enzymatic activity and metabolic content.