ABSTRACT: Selection for heading date has been a decisive factor to increase areas cropped with oats in Brazil. Although important to oat breeders, genomic regions controlling heading date have not been completely identified. The objective of this study was to identify genomic regions controlling oat heading date in subtropical environments. A set of 412 oat genotypes, developed from 1974 to 2015, was assessed for heading date in contrasting environments and genotyped using genotyping–by–sequencing (GBS). Phenotypic and genotypic data were used in single and multi–environment association models. Quantitative trait loci (QTL) associated to heading date were identified on oat consensus groups Mrg02, Mrg05, Mrg06, Mrg12, and Mrg21. Some of the findings confirmed the association of genomic regions with heading date, while others emerge as new candidate regions associated to the trait. The genomic regions identified on Mrg02 and Mrg12 were associated to Vernalization 3 (Vrn3), while the genomic region identified on Mrg21 is associated with Vernalization 1 (Vrn1). The Vrn1 region was detected in Londrina, an environment with reduced vernalization condition, and in the multi–environment model. The results reveal that some genotypes of the panel are responsive to vernalization, increasing the days to heading without this environmental stimulus. Our results provide important contribution for a better understanding of heading date in subtropical environments and a strong basis for marker–assisted selection in oats.

Resumo:O objetivo deste trabalho foi caracterizar o desempenho de genótipos elite de trigo de diferentes programas de melhoramento do Brasil, para caracteres associados à produtividade de grãos e à germinação na pré-colheita. O estudo foi conduzido em 2010 e 2011 no Município de Capão do Leão, RS, em delineamento experimental de blocos ao acaso, com três repetições. Foram avaliados 33 genótipos de trigo quanto aos caracteres relacionados à germinação em pré-colheita e ao rendimento de grãos. A estimativa da distância genética foi utilizada para predizer combinações potenciais na seleção de plantas com alta produtividade de grãos e tolerância à germinação na pré-colheita. A análise combinada de grãos germinados e número de queda mostra que os genótipos TBIO Alvorada, TBIO Mestre, Frontana, Fundacep Raízes, Fundacep Cristalino e BRS Guamirim apresentam tolerância à germinação em pré-colheita. As combinações de TBIO Alvorada e TBIO Mestre com Fundacep Cristalino mostram alto potencial na recuperação de genótipos superiores para elevada produtividade de grãos e tolerância à germinação em pré-colheita.

Abstract:The objective of this work was to characterize the performance of elite wheat genotypes from different Brazilian breeding programs for traits associated with grain yield and preharvest sprouting. The study was conducted in 2010 and 2011 in the municipality of Capão do Leão, in the state of Rio Grande do Sul, Brazil, in a randomized complete block design with three replicates. Thirty-three wheat genotypes were evaluated for traits related to preharvest sprouting and grain yield. The estimate of genetic distance was used to predict potential combinations for selection of plants with high grain yield and tolerance to preharvest sprouting. The combined analysis of sprouted grains and falling number shows that the TBIO Alvorada, TBIO Mestre, Frontana, Fundacep Raízes, Fundacep Cristalino, and BRS Guamirim genotypes are tolerant to preharvest sprouting. Combinations of TBIO Alvorada and TBIO Mestre with Fundacep Cristalino show high potential for recovering superior genotypes for high grain yield and tolerance to preharvest sprouting.

O objetivo deste trabalho foi avaliar os efeitos da aplicação de concentrações do regulador de crescimento etil-trinexapac na altura de planta, no acamamento e na produtividade de grãos da cultivar de aveia-branca Barbarasul, em diferentes ambientes de cultivo e doses de nitrogênio. Os experimentos foram conduzidos nas safras 2010 e 2011 nos municípios de Capão do Leão e Augusto Pestana, no Estado do Rio Grande do Sul, e nas safras 2010 e 2012 no Município de Lages, no Estado de Santa Catarina. Utilizou-se o delineamento de blocos ao acaso, em arranjo fatorial 4x2x6 (dose de etil-trinexapac, estádio de desenvolvimento da planta e ambiente), com quatro repetições constituídas por parcelas úteis de 3,0 m2. Em cada ambiente, realizou-se adubação nitrogenada com 30 e 90 kg ha-1 de N. Foram avaliados os caracteres altura de planta, percentagem de acamamento e produtividade de grãos. A aplicação do regulador de crescimento etil-trinexapac nas doses de 100 a 150 g i.a. ha-1 em plantas de aveia-branca 'Barbarasul', nos estádios E31 e E32, reduz a altura das plantas e a percentagem de acamamento, sem prejuízos à produtividade de grãos. A intensidade da redução do acamamento depende das características do ambiente de cultivo.

The objective of this work was to evaluate the effects of the application of doses of the plant growth regulator trinexapac-ethyl on plant height, lodging index, and grain yield of the white oat cultivar Barbarasul at different cultivation environments and nitrogen doses. The experiments were conducted in the 2010 and 2011 crop seasons in the municipalities of Capão do Leão and Augusto Pestana, in the state of Rio Grande do Sul, and in the 2010 and 2012 crop seasons in the municipality of Lages, in the state of Santa Catarina, Brazil. A randomized complete block design was used, in a 4x2x6 factorial arrangement (dose of trinexapac-ethyl, development stage, and environment), with four replicates consisting of 3.0 m2 plots. In each environment, nitrogen fertilization was done with 30 and 90 kg ha-1 N. The evaluated traits were plant height, lodging index percentage, and grain yield. The application of the growth regulator trinexapac-ethyl, at the doses of 100 to 150 g a.i. ha-1 in 'Barbarasul' white oat plants, in the E31 and E32 development stages, reduces plant height and the percentage of lodging, without harming grain yield. The intensity of the reduction in lodging depends on the conditions of the cultivation environment.