RECURRENT SELECTION FOR TEST WEIGHT AND GRAIN-YIELD OF OAT

Continued advances in oat (Avena sativa L.) breeding rely in part on t he improvement of test weight and grain yield while maintaining geneti c variability. The objective or this study was to determine the effica cy of three cycles of recurrent selection for high test weight (HT pop ulation) or Smith-Hazel index of test weight and grain yield (HTG popu lation) in oat. The recurrent selection procedure consisted of interma ting selected S0:1 lines, growing the S0 seeds to produce S0:1 lines, and field evaluating the S0:1 lines. Each cycle took 1 yr to complete and about 300 lines were evaluated in each population of each cycle. T wenty S0:1 lines were selected from each population to initiate the ne xt cycle. Response to selection in a population was evaluated by testi ng 95 S0:1 lines randomly chosen from among Cycles 0, 1, and 2, the co mplete Cycle 3 population, parents from all cycles, and a set of check cultivars. There were significant (P < 0.05) increases in mean test w eight of 17.8 +/- 3.5 kg m-3 and 6.9 +/- 1.5 kg m-3 per cycle in the H T and HTG populations, respectively. For grain yield, there was a sign ificant decrease of 0. 11 +/- 0.03 Mg ha - 1 per cycle in HT populatio ns, and an increase of 0. 12 +/- 0.07 Mg ha - 1 per cycle in HTG popul ations. Broad-sense heritabilities and genotypic variances remained hi gh in all cycles of each population. The results of this study show th at recurrent selection in oat is an effective breeding procedure for i mproving test weight and grain yield without significant reductions in genetic variability.