Mass Selection for Plant Height in Oat Populations 1

The effectiveness of mass selection for uniform plant heights in a heterogeneous and segregating oat population was evaluated. The mass‐selection procedure consisted of clipping the panicles of the bulk population of plants to a uniform height equivalent to the height of the panicle tips of ‘Cherokee’ oat variety. At maturity, only the top 4 inches of the clipped plots were harvested. The procedure was repeated for 4 consecutive generations (F3 ‐ F0). Check populations originating from the same material, but receiving no artificial selection pressure, were grown each year. Remnant seeds of each generation of the check and mass selected populations were kept in cold storage for future studies. In 1962, 500 randomly selected seeds from each of the 5 check populations (F 2 ‐ F 6 ), from each of the 4 mass‐selected populations, (F 3 ‐ F 6 ) and from a pure line, were space planted in the field. At maturity, the surviving plants were harvested individually. In 1963, the progenies from 75 random lines (a line was derived from a spaced plant in 1962) from each of the 10 populations were sown in a randomized block experiment with 4 replications. The attributes measured were plant height, heading date, and grain yield. The mass‐selection procedure was successful in reducing the mean plant height and the genetic variance of the oat population. In the check population the plant height increased. Mean heading date of the mass selected population was shifted earlier and the mean grain yield higher by the mass selection procedure. Positive phenotypic and genetic correlations were found between plant height and heading date and between heading date and grain yield, whereas, the corresponding correlations between plant height and grain yield were negative.