Heterosis and combining ability in hybrids ofAvena sativaL. andA. byzantinaC. Koch.

Abstract

SUMMARYThree varieties ofAvena byzantinaC. Koch., Sierra, Avon and Anita, originating respectively in California, Australia and South Africa, together with the Dutch variety Condor (A. sativaL.) were used as ‘subject’ varieties in crosses with a range of nine tester varieties of mainly north-west European origin. The results of a yield trial of spacedF1transplants and a drilledF2trial are presented.In theF1trial there was marked heterosis for grain yield, the thirty-six crosses yielding, on average, 109 % of the higher yielding parent, with individual cross values ranging from 68 to 139%. Heterosis was more marked insativa × byzantinacrosses than insativa × sativacrosses and the variety Sierra showed particularly high general combining ability. In theF2trial, heterosis was considerably reduced and the thirty-six crosses yielded, on average, only 96% of the higher yielding parent. In someF1crosses, heterosis for grain yield was accompanied by transgression of the higher yielding parent in number of panicles per unit area. The number of grains per panicle was positively correlated with grain yield in theF2trial but no heterosis was observed for this component. Grain size was negatively correlated with yield in theF2trial and heterosis for this component was observed in a few crosses in which yield heterosis occurred.Straw height was positively correlated with grain yield in theF1trial but negatively correlated in theF2trial. Crosses showing heterosis for yield exceeded the mid-parent but not the taller parent in straw height. The ratio of grain yield to straw yield was higher for the progenies of thebyzantinavarieties Sierra and Avon than for the progenies of thesativasubject Condor. Grain yield was positively correlated with number of days to 50% panicle emergence in both trials.It is concluded that theA. byzantinavarieties Sierra and Avon could, with advantage, be used for hybridization with adapted genotypes ofA. sativa, thereby enlarging the gene pool available to oat breeders in north-west Europe.