Mechanical Mass Selection Methods for Improvement of Oat Groat Percentage

Abstract

Three methods of mechanical mass selection for seed density, aspiration (ASP), gravity table selection (GT), and gravity table selection with a seed polishing pretreatment (P‐GT), were evaluated and compared for effectiveness of increasing caryopsis (groat) percentage and test weight in oat (Avena sativa L.). Selection using these methods in two heterogeneous F5 populations resulted in absolute differences in the groat percentage between high and low density treatments of 0.3 and 0.5% for ASP and P‐GT, respectively. The GT selection resulted in a lower groat percentage in the high‐density treatment. Selection methods interacted with populations and seed size classes. These interactions were due to different levels of variation in the populations for seed size and shape. Two cycles of selection for high groat percentage beginning in F3 segregating bulk populations showed little overall improvement. Selection increased the number of fertile florets per spikelet. This increase in fertility was due primarily to a 22% increase in tertiary florets per panicle per cycle of selection. Tertiary floret number exhibited a negative genotypic correlation with groat percentage, which limited improvement for groat percentage. There also were significant changes in plant height, days to flowering, and harvest index in these experiments with direction and magnitude dependent on the individual population. Effectiveness of mechanical mass selection for groat percentage could be increased by avoiding selection for characters such as tertiary kernels which have undesirable correlated effects on milling quality.