Selection for seed set in crosses of Avena sativa L. × A. Abyssinica Hochst.

Summary Precoz oat line, discovered in a mass planting of wild oats in Colombia, is a tetraploid belonging to Avena abyssinica. It crossed easily with Kyto, but not with Bacata, both hexaploid oat cultivars. Pentaploid hybrid plants of Precoz × Kyto and Precoz × Bacata had 35 chromosomes, tended to have seven bivalents and 21 univalents at meiosis, and were completely sterile, Colchicine treatment of pentaploid F₁ plants produced decaploid tillers from which five amphiploid seeds were obtained. Selection for high percentage of seed set in the third and fourth amphiploid generations of Precoz × Kyto gave fifth generation plants with 80–100% fertility. The chromosome numbers of these plants approximated the octoploid level. Some derivatives from crosses of third generation amphiploids with hexaploid cultivars had the hexaploid chromosome number and good fertility.Pentaploid hybrid plants and amphiploid derivatives from them were as early in heading as Precoz when tested at either 12-or 15-hour photoperiods. This suggests that the photoperiod response from Precoz is dominant and has good penetrance.Journal Paper no J-7408, Project 1752.