Outcrossing rate of barley genotypes with different floral characteristics in drought-stressed environments in Jordan

The flowering characteristics of a highly inbreeding species such as barley might influence the extent of outcrossing that can be expected. Increased outcrossing is a prerequisite to exploit heterosis in inbreeding species, which can lead to considerable yield increase as has been demonstrated for barley grown under marginal conditions. Anther extrusion (AE) in barley has been demonstrated to be a genetically controlled, quantitative trait with intermediate to high heritability. Some authors consider AE and open flowering in barley as identical. The present study was conducted to investigate whether barley genotypes with increased AE exhibit increased outcrossing rates under field conditions in comparison with genotypes showing no AE. Field experiments were conducted in three contrasting environments in Jordan in the 2001/02 growing season using six adapted barley genotypes, three with high AE and three with no AE. Outcrossing rates were investigated employing codominant DNA markers (microsatellites). No significant difference in outcrossing rates was detected between anther-extruding and non-extruding barley genotypes. Results indicate that high AE is not a sufficient condition to cause increased outcrossing rates and thus cannot be termed open flowering. © 2008 The Authors.