The frequency of natural cross-fertilisation in sequential sowings of winter barley

Abstract

Estimations of random mating frequency were computed for a series of sequential autumn sowings of populations of winter barley . The estimations were by means of the maximum likelihood scoring method and three varieties, each carrying a recessive genetic marker, provided three independent estimations for each population . High levels of out-crossing were found in sowings made early in September, and a trend towards absence of out-crossing in populations sown in late November was evident . Although fluctuations in this trend could be accounted for by fluctuations in meteorological factors, a more profound underlying effect was evident in that the three marker varieties behaved similarly, though to different degrees . It is postulated that the principle effect of sowing date, as it affects out-crossing, is upon the development of the flowering apex, and that environmental conditions at flowering time merely modify flowering behaviour .

Estimation of Quantitative Genetic Parameters for Outcrossing-Related Traits in Barley

“…On the other hand, Sage and Isturiz (1974) and Chhabra and Sethi (1991) reported for wheat that lodicule size is genetically determined and is associated with the degree of chasmogamy. Correspondingly, Giles (1989) reported for barley that the most important varietal characteristics which influence outcrossing are lodicules which exhibit even wider variation in morphology than the lodicules of other cereals. Giles (1989) stated that genotypes with no expansive tissues with which to force the lemma and palea apart, always results in closed flowering, which prevents oucrossing.…”

“…Correspondingly, Giles (1989) reported for barley that the most important varietal characteristics which influence outcrossing are lodicules which exhibit even wider variation in morphology than the lodicules of other cereals. Giles (1989) stated that genotypes with no expansive tissues with which to force the lemma and palea apart, always results in closed flowering, which prevents oucrossing. Consequently, the intermediate‐to‐high heritability estimates for anther extrusion observed in this study may have resulted from both uptake and retention of water by the lodicule as a function of moisture supply and genetic differences in lodicule sizes among the F 3 –lines.…”