An estimation of the combining ability of barley genotypes and heterosis for some quantitative traits

ABSTRACT- Barley (Hordeumvulgare L.) is one of the most important cereals in the world which is used as human and cattle feed and for malt production. One of the most important steps in a hybrid and selection breeding program of barley is the selection of suitable parents with high general (GCA) and specific combining ability (SCA) for grain yield. In order to estimate the combining ability and heterosis in barley for a number of qualitative traits, seven genotypes were crossed in one-way diallel crosses using Griffing (Method II). Grain number per spike, grain weight per spike, spike weight, 1000-grain weight, number of spikelet, plant height, spike length, peduncle length, days to physiological maturity, and spikelet density were measured. Results of variance analysis showed that there were very significant differences between genotypes for all the measured traits. General combining ability (GCA) effect was significant for all traits, 166/352 genotype had the highest value of GCA for grain number per spike (4.757), grain weight per spike (0.245), spike weight (0.378) traits, whereas Specific combining ability (SCA) effect was significant for all traits except for plant height, days to physiologic maturity, and spikelet density. Three crosses 67/110×283/352, 95/110×216/352 and Sahra×216/352 showed the highest values of SCA for grain number per spike (7.704), grain weight per spike (0.371) and 1000-grain weight (8.619), respectively. Moreover, dominance variance was the most effective factor in genetic control of traits. Three crosses 216/352×283/352, 104/110×216/352 and Sahra×216/352 showed the highest values of heterosis for grain number per spike (4.95), grain weight per spike (44.13) and 1000-grain weight (31.6), respectively. Maximum and minimum broad sense heritability was obtained in the number of grains per spike (87/7%) and spike density (47/36%) respectively. Lowest and highest narrow sense heritability was obtained for peduncle length (15/72%) and weight of grains per spike (50/5%), respectively. Estimates of SCA showed that 95/110×216/352, such as 67/110×283/352 crosses could be used in breeding programs to release cultivar to increase yield-related traits.