Patterns of changes of dormant genotypes in Avena fatua populations under different agricultural conditions

Abstract

Experimental evidence is provided to support earlier suggestions that summer-fallowing of cropland enhances the relative abundance of dormant wild oats at the expense of nondormant ones. Two heterogeneous populations of wild oats, Avena fatua L., were synthesized, each composed of a different set of true-breeding dormant and nondormant lines in equal initial frequencies. Subsequent generations of these mixed-stand populations were grown without conscious selection under two cultivation conditions: (i) propagation in every growing season (continuous cropping) and (ii) a 2-year rotation consisting of a year of propagation followed by a year of summer-fallowing. These experimental populations responded differently to the two cultivation practices. The relative frequency of dormant lines increased substantially in both populations propagated under the summer-fallow regime, compared with the continuous-cropping regime. Implications of this finding for weed control are discussed.