Estimation of Quantitative Genetic Parameters for Outcrossing-Related Traits in Barley

Abstract

Unpredictable drought conditions combined with extreme heat stress are major constraints limiting the production of barley (Hordeum vulgare L.), one of the most important rain-fed crops in West Asia and North Africa. Yield and yield stability might be improved by raising levels of both heterozygosity and heterogeneity, which could be achieved through increased outcrossing in barley landrace populations. Selection for outcrossing-related traits such as high anther extrusion, large anther sizes, and vigorous stigmas may increase the level of outcrossing. This investigation was conducted to quantify the genetic variance and calculate correlation coefficients for spikelet traits related to mating characteristics. For this purpose, F 3 -line populations derived from nine crosses between genotypes showing contrasting expression of anther extrusion were produced. F 3 -line populations were grown in field trials at three locations in Jordan during the 2001-2002 growing season. Anther extrusion was higher in the more favorable environment than in environments with low and variable precipitation. Anther extrusion and outcrossing-related spikelet traits were influenced by genetic and environmental factors. Early heading F 3 -lines within populations showed a tendency toward higher anther extrusion, presumably because of escape from drought stress expected later in the growing season. The variation of outcrossing-related spikelet traits in F 3 -line populations was continuous, suggesting a polygenic inheritance, and exhibited transgressive segregation in some populations toward high anther extrusion. Most populations showed intermediate to high broad sense heritabilities for anther extrusion and anther length. However, low to intermediate heritabilities were detected for all other outcrossing-related traits. Positive genetic correlations were recorded between anther extrusion and anther and stigma size. Results suggest that outcrossing-related spikelet traits may respond to selection in particular in the case of anther extrusion and anther and stigma size.