Resposta do sistema antioxidativo à indução do estresse gradativo e choque osmótico pelo NaCl em cana-de-açúcar

Abstract

Sugarcane (Saccharum officinarum) is a grass considered moderately sensitive to salinity. Although traditionally cultivated in the soil of the Atlantic Coast and the Northeast, the cultivation of sugarcane is expanding to semi-arid regions. The poor quality of irrigation water, high rates of evaporation and low rainfall, combined with other factors contribute to the process of soil salinization in semi-arid. For the development and selection of tolerant genotypes, it is necessary to understand the physiological mechanisms with which plants face the salt stress. Techniques for in vitro plant tissue for studies of physiology and biochemistry of plants under stress are important tools to allow control and uniformity of culture conditions. In this study, two genotypes of sugarcane (RB931011 and RB872552) developed within the Program of Genetic Improvement of Sugarcane of rides, for the Northeast region (RIDESA) were evaluated for sudden and gradual action of salt stress-induced by adding NaCl to the culture medium during in vitro development of plants. The varieties of sugarcane were subjected to three concentrations of NaCl (0 mM, 50 mM and 100 mM) in a gradual and sudden. At 35 days of experiment, enzyme activities (CAT, POX, APX, PPO), levels of sodium (Na+), potassium (K+), soluble protein content and free proline were recorded. It was possible to observe differences in responses of varieties depending on the condition of induced salt stress, shock or gradual, rather than depending on the concentration of NaCl in the culture medium. The stress response is therefore not only conditioned by salt concentration, but by way of exposure to salt.