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.

Evolutionary Effects on Morphology and Agronomic Performance of Three Winter Wheat Composite Cross Populations Maintained for Six Years under Organic and Conventional Conditions

“…Results from experiments investigating the effect of natural selection on the winter survival of barley CCPs indicate that natural selection did increase winter survival although not uniformly over different generations [48]. In bulk populations of winter oats an improvement in winter hardiness could only be found in populations with low initial survival levels [49,50].…”

“…In bulk populations of winter oats an improvement in winter hardiness could only be found in populations with low initial survival levels [49,50]. Also, apparent advances made in winter survival in one year can reverse in later generations due to a lack of competitive ability of the hardy types later in the growing season [49], when non-hardy types that were not eliminated resurface and restore themselves as major components in the population [48]. This shows that complex traits such as winter hardiness, that were not a main focus when establishing CCPs, are hard to achieve through natural selection only.…”

Evolutionary Plant Breeding in Cereals—Into a New Era

“…One relatively easy way to test this would be to study the plant height of an evolving population over several generations. In an early study on barley populations, Allard & Jain [26] found no increase in plant height over the course of fifteen successive generations, while other studies on barley populations suggested that natural selection favoured taller plants [31,36].…”

Integration of breeding and technology into diversification strategies for disease control in modern agriculture

“…For barley, the CC approach has been shown to be extremely powerful: innumerable elite varieties released in the twentieth century trace their origin to the CC populations produced in California in the 1920s while the CC populations have remained genetically variable even after 50 generations of propagation at single sites (Allard 1988). When exposed to new environments including diseases that had not been important in the original environment, the CC populations proved to be readily adaptable to these (e.g., Danquah and Barrett 2002a, b;Hensleigh et al 1992;Webster et al 1986). Similarly, French work on dynamic management of wheat CCs shows that adaptive changes within the populations in response to local selection pressures occur, while simultaneously maintaining genetic variation and thus adaptability (Goldringer et al 2006).…”