Selection Among Early Generation Peanut Progeny for High and Low Acetylene Reduction and Plant Weight*

Abstract

AbstractSelection of superior host genotypes in symbiosis with native Bradyrhizobium has been suggested as a means of increasing nitrogen fixation m peanut (Arachis hypogaea L.). In this study progeny from a cross of cultivars ‘Florigiant’ and ‘Florunner’ inter‐mated twice and selected for yield formed the base population. The 44 selected S2,1 families, ‘Florigiant’ and ‘Florunner’ were evaluated at two sampling dates at each of two locations for traits indicative of nitrogen fixation. Five families were selected in each of four selection groups — high and low acetylene reduction and high and low plant weight. Selected families were retested in a second year and inter‐mated. S2,1 progeny within each selection group were bulked and evaluated for nitrogen‐if using characteristics at two ‘sampling dates at two locations. After intermating, the mean of the high acetylene reduction group, 62.9 μ/moles C2H4/plant hr, was Significantly greater than the mean of the low acetylene reduction group, 52.5 μmoles C2H4/plant/hr, and of the mid‐parent, 55.8 μ/moles C2H4/plant/hr. The associated estimate of realised heritability was 55 ± 08 indicating the response to selection was approximately halt the selection differential and that the distinction between families selected for high and low acetylene redaction was maintained after intermating. However, the realized heritability estimate obtained from the means of the base population and the selected families inbred one generation was .14 ± .06 indicating a failure to maintain distinct groups after one generation of inbreeding. The utility of early generation selection for enhanced N: fixation is, therefore, doubtful in this population.Selection based on plant weight was not effective. A significant difference in the plant weight means of the high and low plant weight groups was not detected when selections were retested or after inter‐mating. Plant weight was not a useful indirect selection criterion for enhanced N2 fixation.