Caracterização de genótipos de trigo quanto a tolerância à seca e variabilidade genética para caracteres de importância agronômica

Abstract

Wheat is one of the main cereals used for food and has been present in animal and human diet for millennia. However, with population growth, there is a significant demand in the cereal production that encounters obstacles, such as the stresses caused by water deficit in the main development stages, such as the germination and grain filling. Brazil is not self-sufficient in wheat production, and the cultivation area is currently expanding in regions with period of rainfall shortage. Genetic variability characterization for drought tolerance and other traits of agronomic importance can help the wheat genetic breeding process. In this way, the general objective of this study was to characterize the wheat genotypes response subjected to drought conditions in the germination stage and evaluate the traits of agronomic interest in field conditions in South region of Rio Grande do Sul state. The study was divided into three parts, with the objectives of: I) morphologically characterizing a collection of wheat genotypes under PEG-induced drought conditions during the germination and seedling establishment phase; II) to evaluate the genetic variability and heritability of agronomic traits related to yield in a wheat collection grown in the southern region of Rio Grande do Sul; and III) to elucidate the involvement of total phenolic compounds, flavonoids and proline in the drought response in wheat seedlings. The results obtained in this study has shown genetic variability for drought tolerance in the early stages of development that can be used in breeding programs that seek new cultivars with tolerance to the stress caused by water deficit. Among the genotypes evaluated, the FPS Nitron can be highlighted, with a good response to drought at an early stage of development. The results obtained in study II show genetic variability for the agronomic traits evaluated, as well as high heritability in the broad sense for yield and other traits related to yield, indicating the possibility of obtaining genetic gain in this environment. Study III suggests that the contents of phenolic compounds, flavonoids, proline and antioxidant capacity were not directly related to drought tolerance or sensitivity in wheat seedlings subjected to induced drought conditions. The results obtained in this study can help breeders in the selection of parents with better tolerance to drought and with superior agronomic characters, aiming at the development of wheat cultivars with greater tolerance and more productive.