Combining ability of interspecific oat matings (Avena sativa x Avena sterilis)
Ten A. sterilis lines of Mediterranean origin were crossed with six A. sativa cultivars from the North Central U.S.A. in a North Carolina Design II mating plan. Seven intervarietal matings also were made among the A. sativa cultivars. Approximately 40 F(,2)-derived lines from each mating were evaluated at three locations in Iowa during 1982;Gene action for grain yield, biomass, and vegetative growth rate was largely additive. GCA variance components for A. sterilis for these three traits were about two to two and one half times greater than the comparable components for SCA and about five times greater than the GCA components for A. sativa;Mean percentages of transgressive segregates one LSD(,.05) above the high parent for vegetative growth rate and biomass were 9.0 and 9.8%, respectively, from interspecific matings, but only 4.5 and 2.9%, respectively, from intraspecific matings. However, there were two and one half times more high transgressive segregates for grain yield from intra- than from interspecific matings. The ten A. sterilis accessions ranged from 28 to 64% in percentages of transgressive progeny for vegetative growth rate;Performances of the A. sterilis accessions, per se, generally were good predictors of mean progeny performance for vegetative growth rate and biomass. Correlations of GCA effects of A. sterilis parents and percentage of high transgressive segregates for grain yield, biomass, and vegetative growth rate were 0.62, 0.95, and 0.93, respectively. Generally, predictive criteria based on population means were more effective in determining superior parents for A. sativa x A. sterilis matings, than were A. sterilis performances per se;The maximum vegetative growth rate among segregates from interspecific matings was 0.2 q/da/ha greater than the highest segregate from intraspecific matings. However, mean harvest index was reduced materially by the introgression of A. sterilis germplasm. Because there was no genetic association between vegetative growth rate and harvest index, however, it should be possible to improve both harvest index and vegetative growth rate, and thus, the grain yield of cultivated oats.