Caracterização morfofisiológica e germinação em baixa temperatura de genótipos de arroz irrigado

Abstract

Low temperatures are one of the main factors that can limit the cultivation of irrigated rice, they frequently occur during the growing season in the southern region of Brazil, and can cause a significant reduction in grain productivity. There are several studies on the search for low temperature tolerant cultivars at all stages of development. The morphological characterization, through the minimum descriptors, is important for the supply of information and classification of genotypes, discrimination of relevant characters that serve as base for the breeding programs. The objective of this work was to evaluate the genetic variability of 20 irrigated rice genotypes from different locations in the world and the BRS Pampa and BRS Pampeira controls using morphological descriptors, as well as to evaluate these genotypes for cold tolerance traits in the germinative stage. The genotypes were evaluated in two experiments, the first one being carried out in the field for phenotypic characterization and estimation of their genetic distances through the use of multivariate analyzes. In the second experiment, the genotypes were evaluated under temperature conditions of 13ºC for 28 days and 25ºC for 7 days in BOD chambers, comparing the relative performance, measured by germination, shoot length, root length and length of coleoptile. The results obtained indicated that among the studied genotypes there is a wide genetic base, and some genotypes have the potential to be used in the expansion of the genetic base in crop improvement programs. As well, in the phenotypic characterization, the studied genotypes showed great genetic variability.