Respostas de mutantes de arroz à temperaturas infraótimas nos estádios iniciais de desenvolvimento

Abstract

Rice (Oryza sativa L.) is one of the most important staple crops in the world. However, the increase in rice production is not keeping up with the demand increase this cereal. The occurrence of low temperatures is one of the main limiting factors to rice yield increase in temperate and tropical regions with high altitude. This study aimed to verify the differential tolerance to low temperatures in eight rice mutant genotypes in relation to their cvs. of origin during periods of germination and growing, and analyze the genetic variability between them through microsatellite markers. For the germination period, the tolerance indicators germination percentage (PG), mean germination time (GMT) and germination speed index (GSI) were used, while for the vegetative stage enzymatic indicators, chlorophyll concentration and electrolyte leakage (EL) were used. In the 13 °C condition, the genotypes BRS Querência, QUE 07 and BRS Fronteira decreased significantly (p ≤ 0.01) PG values relative to 25 ° C. Comparing the genotypes setting the temperature, the mutants QUE 30, QUE 33 and QUE 47 presented IVG values higher than the cv. BRS Querência in cold condition. tolerance indicators cold germination cv. BRS Fronteira did not differ significantly from their mutants. Based on cluster analysis and principal component, genotypes BRS Querência and QUE 07 were grouped as moderately tolerant and the other genotypes as tolerant to low temperatures during germination. In the growing season could not find statistical difference (p ≤ 0.05) between mutant genotypes and their cvs. origin for the variables analyzed, except for the electrolyte leakage after 24 h of exposure to the cold, where the cv. BRS Querência showed values greater than QUE 30, QUE 33 and QUE 47, but not differ in other exposure times. After DNA amplification, it was found that the 42 primers, eighteen did not show a pattern of sharp bands, twenty one bands showed monomorphic and only three microsatellites were polymorphic (OS 1, OS 48 and OS 25). Genotypes QUE 30, QUE 33 and QUE 47 are more cold tolerant in the germinal period when compared with cv. BRS Querência. Microsatellite primers OS 01 and OS 48 have a high ability to discriminate the mutant genotype FRO 09 of your cv. origin BRS Fronteira and its other mutants studied.