Regression Analysis of General Adaptation in Hard Red Winter Wheat (Triticum aestivum L.)¹

The general adaptation of 12 hard red winter wheat varieties ( Triticum aestivum L.) grown in regional performance nurseries was studied by regression analyses. Nursery mean yield was utilized as an index of environment. Linear regression coefficients were computed from yields of individual varieties on nursery mean yields at each location in each year. The regressions permitted comparisons of predicted varietal performance over a range of environments. Substantial progress in developing varieties with both improved stability of performance and high yield potential in the Central and Southern Plains could be shown. Less progress could be demonstratedin winter varieties for the Northern Plains. Some varieties whose mean yields, in regional tests were nearly equal, exhibited, sharply different yields when the levels of productivity (environments) were specified.