Production Response and Stability Characteristics of Oat Cultivars Developed in Different Eras1

Abstract

Grain yield data for 66 oat cultivars, developed over the past 4 decades in the midwestern U.S., were used to determine whether genetic changes had occurred for mean grain yield, yield response to improving environments (measured via linear regression), and stability of yield (measured via coefficients of determination). The 4 decades were divided into seven periods of cultivar development, and the productivity indexes for the test environments were measured by the means of the yields of two cultivars, ‘Richland’ and ‘Cherokee’, that were grown as longtime checks in all environments. Mean productivity for all cultivars was 9.0% higher than the yield of the checks. This increase occurred in the earliest era (i.e., 1932 to 1942), and no additional increase was detected throughout the 4‐decade period. Three‐quarters of the new cultivars yielded significantly greater than the checks, and only one yielded significantly less. The mean regression response index ranged from 0.89 to 0.98 for the seven eras, and there was no evident trend for this parameter over time. It is suggested that the oat germplasm of Avena sativa L., originally introduced from northern Europe into the midwestern U.S., may have contained little genetic variability for grain yield. Seemingly, the only times when bursts of yield improvement have been made in cultivated oats have followed introgression of germplasm from other species or ecotypes.