Phenotypic variation and heritability of heading date in hexaploid oat

The onset of flowering is decisive to the reproductive success of plants. The objectives of this study were to characterize the phenotypic variation in heading date and estimate its heritability in segregating populations of oat (Avena sativa L.). F-2 and F-3 generations of two large populations, derived from crosses 'URS Taura x Leggett' and 'FL0206B-S-B-S1 x UFRGS 078030-1', were evaluated. A wide phenotypic variation in the number of days to heading was observed in both populations. Heritability coefficients of 0.68 and 0.46 were estimated for the 'URS Taura x Leggett' and 'FL0206B-S-B-S1 x UFRGS 0780301' populations. Our results demonstrate that genetic differences derived from parents in response to photoperiod and temperature explain most of the phenotypic variation in heading date of oat populations. Understanding genetic and environmental effects on flowering expression is essential to increase the response to selection for well-adapted and high-yielding oat cultivars.