Quality in conventional and moti rice seeds under saline stress conditions

Abstract

Rice is an important grass grown in Brazil, being consumed in various ways, providing in human food a high content of calories and protein, as well as vitamins and minerals. The Ribeira de Iguape River Basin has a great diversity of terrestrial and aquatic environments, involving extensive areas of coastal plains with farming, including rice cultivation. Coastal plains may have soils with high salinity and the excess salt causes reduction of soil water potential, resulting in lower water absorption capacity, negatively influencing the germinative response of rice seeds. Thus, this study aims to determine the sodium levels in some rice producing areas, to verify the influence of this salt level on the physiological quality of the seeds produced as well as to determine the critical salinity content in the germination and vigor of four rice cultivars. (Oryza sativa L.) used in the Ribeira de Iguape river basin region.For this purpose, soil samples will be collected in rice producing areas in the municipalities of Iguape, Pariquera-açú and Registro, in which the average sodium content will be determined. Such analyzes will be performed at the Laboratory of Soil, Plant and Plant Physiology Diagnosis at UNESP Experimental Campus of Registro. Rice seeds of the conventional cultivars (IAC 127 and IAC 165) and Japanese rice/ Moti (IAC 400 and BRS 358), produced in the areas studied in the 2019/2020 crop, will be analyzed for their tolerance (critical content) to salinity in different storage periods. Four saline concentrations will be tested, from the sodium concentration found in the productive soils, and one control treatment, to verify the effects of the treatments will be applied, every three months tests that evaluate the critical level of salinity for each cultivar: seed water, first germination count, germination (% normal seedlings), average germination time, germination speed index, seedling length, seedling dry weight and field emergence. After each storage period, the water absorption capacity and the membrane stability of seeds subjected to saline stress will also be determined. Tests will be installed and conducted according to criteria established by the Seed Analysis Rules. The experimental design will be completely randomized in a 5x4 factorial scheme (saline concentrations and cultivar ) with 4 replications of 100 seeds each for germination evaluations and four replications of 10 seeds for vigor variables. Data regarding storage periods will be submitted to analysis of variance, mean tests and polynomial regression analysis.