Natural Selection on Winter Barley Composite Cross XXVI Affects Winter Survival and Associated Traits

Abstract

Winterhardiness of winter barley (Hordeum vulgare L.) has not been improved greatly during the last 40 yr. Explanations range from a presumed lack of genetic variance for hardiness to a lack of effective selection in winter barley improvement programs. Previous research in Montana utilized recurrent selection in composite crosses containing male sterility to increase genetic recombination and improve winterhardiness. Composite Cross XXVI (CCXXVI) was subjected to winter selection pressure at various Montana locations from 1966 to 1984. This research evaluated the effectiveness of natural selection on winter survival and various agronomic and morphological traits in CCXXVI. Field trials at 10 Montana locations from 1985 to 1987 were used to measure winter survival and agronomic traits. Changes in morphological traits were studied in field and controlled‐environment studies. Natural selection appeared to favor taller and later‐heading plants. No significant change in population grain yield over time was detected in CCXXVI. Natural selection improved winter survival in CCXXVI, but the selection was not uniform over generations and maximum population hardiness occurred midway through the experiment. The hardiest CCXXVI generation was lower in winter survival than a hardy winter wheat (Triticum aestivum L.) and the same as a nonhardy winter wheat and a hardy winter barley cultivar. No significant correlation was found between seedling leaf width, seedling leaf number, or subcrown internode and mean winter survival. Shorter seedling leaf length was associated with enhanced winter survival.