Expressão dos descritores de Avena spp. em resposta à aplicação de trinexapac-ethyl em Avena sativa

Abstract

Lodging is one of the factors that can limit the production and quality of white oats (Avena sativa L.), which could be controlled with trinexapac-ethyl. The use of this product in fields certified for the production of seeds would be highly beneficial, if there were no changes in the expression of the descriptors and with that, it would be difficult to identify the cultivar, which could lead to production field cancellation. The aim of this study was to verify if trinexapacethyl promotes changes in the expression of Avena spp., in order to evaluate the effects on morphological, phenological and agronomic characters, plant lodging, yield and grain quality. There were tested six cultivars of different height classes and coded as: L1 and L2 (short height), M1 (medium height), H1, H2 and H3 (high height). The experiments were conducted in contrasting years for rainfall (2017: below regional normal, 2018: above regional normal), in a two-factorial scheme (genotype x trinexapac-ethyl). The experimental design was subdivided plot, with three replicates. The growth regulator was applied at the stem elongation stage (1st visible node and 2nd perceptible node) at the dose of 400 mL/ha. There were evaluated the official descriptors of Avena spp. and additionally, the response to lodging, height, culm diameter and thickness, internode number and length, floral peduncle length, phenology, yield, one thousand grain mass and hectoliter weight. In 2017, there were also measured the width and length of the flag leaf blade and the leaf before the flag leaf, the width and length of the flag leaf ligule length and the sheath length; in 2018 were evaluated crown diameter, leaf blade angle anterior to the flag leaf and lodging type. Data were submitted to analysis of variance, correlation and multivariate. In 2017 there was significant product x genotype interaction for plant length, floral axis, number of internodes and lodging. In both years there was effect on the hectoliter weight. In 2017, trinexapac-ethyl affected, regardless of genotype: panicle density, plant height, first to third internode length, peduncle length, internode mean length, flag leaf width and sheath length; in 2018, this effect was observed only for height, number of internodes, mean length of internode and lodging. The application of trinexapac-ethyl minimized the white oats lodging, independent of the high genotype; reduced the floral axis length and the hectoliter weight, in different magnitude according to the genotype. Among the 25 descriptors of Avena spp., five characters were altered by the use of trinexapac-ethyl: cycle, branching position, panicle density, plant length and floral axis, showing low impact of the product in the identification of cultivars.