Potencial fisiológico de sementes de genótipos de arroz submetidos ao estresse salino

Abstract

Rice (Oryza sativa L.) is one of the most important cereals for human consumption, with China being the world's largest producer. In South America, Brazil stands out with about 42% of the continent's rice production. In Maranhão, 213 of the 217 municipalities that compose the state produce rice, highlighting the social importance of culture. Although relevant, the average yield of about 1.400 kg / ha-1 in Maranhão rice production is below the national average of 5.200 kg / ha-1 due to salinization of soils and / or water. The objective of this study was to evaluate the physiological potential of O. sativa seeds and the initial development of salinity tolerant seedlings, selecting the genotypes with greater vigor. Fifteen seed lots were submitted to the following levels of osmotic potential: 0, 100, 200, 300 and 400 mM NaCl / L-1. The seeds were evaluated for water content, germination tests, first germination count, germination speed index and seedling root and shoot lengths. The experimental design was completely random, with treatments distributed in four replicates in a factorial scheme, 15 x 5 (number of lots and osmotic potentials). Germination tests, first germination counts, germination speed index, and seedling root and seedling lengths are efficient in assessing the physiological potential of rice seed lots, providing sufficient information to classify lots as to the level of vigor. The genotypes of rice respond differently to saline stress, with lot 2 being the most tolerant to salinity when evaluated by the physiological potential of the seeds up to the limit of 100 mM NaCl concentration