Respostas ecofisiológicas, enzimáticas e bioquímicas de cultivares de cevada expostas à restrição hídrica em diferentes estádios de desenvolvimento

Abstract

This work aimed to evaluate the physiological, enzymatic and biochemical performance of barley cultivars submitted to water restriction at different stages of development. For this purpose, seeds of different cultivars were used and water restriction was imposed at different stages of crop development. In the laboratory, experiments were carried out studying the relationship between cultivars x water restriction x temperature, under the initial growth, enzymatic and biochemical performance of the cultivars. In a greenhouse, the relationship between cultivars x water restriction and periods of exposure to stress, under the growth, development and quality of seeds produced from barley cultivars, was evaluated. As a result, it was observed that water limitation, associated or not with high temperature, negatively affected the attributes of germination, vigor and initial growth of cultivars. Furthermore, when subjected to water stress and high temperature, barley seedlings expressed higher values in enzymatic activity and biochemical composition. In a greenhouse, water suspension promoted the reduction of attributes such as shoot length, total length, leaf area, chlorophyll a, b and total, leaf area ratio and leaf mass ratio of the plants, however, there was a differential response of the characteristics depending on the cultivar and length of stay of the stress. When subjected to water limitation, the cultivars showed higher values for the activity of the enzymes superoxide dismutase, catalase and ascorbate peroxidase, in addition to lipid peroxidation and total soluble sugars. Also in the greenhouse, the lowest contribution of total dry mass, dry mass production rate, relative growth rate, net assimilation rate and solar energy conversion efficiency was observed when the plants were subjected to stress. In addition, stress affected the quality of the seeds produced, with a reduction of about 17% in the percentage of seeds with first-class dimensions, an increase of up to approximately 291% of third-class seeds, in addition to a reduction of about 23% in the germination and 18% in shoot length, with difference in response between cultivars. Therefore, carrying out this study showed that stress due to water restriction can affect the performance of barley cultivars at different stages of development.