Combining Ability Estimates in Arachis Hypogaea L. III. F2 Generation of Intra- and Intersubspecific Crosses1

A hybridization program was initiated to investigate the breeding potential of crosses among diverse peanut (Arachis hypogaea L.) lines. Fifteen crosses in F2 generation generated by crossing six peanut lines representing Valencia, Virginia, and Spanish botanical varieties in diallel without reciprocals were used to estimate combining ability in drilled and space-planted tests. Estimates of both general (GCA) and specific (SCA) combining ability were significant for percent extra large kernels, percent sound mature kernels, kernels/kg, pod length, and yield measured in the drilled test. The GCA estimates were also significant for all characters measured in the space-planted test, while estimates of SCA were significant for five of the six characters. Estimates of GCA were of greater magnitude than SCA estimates for all characters except one. A Spanish line, C2, had the highest GCA effects for yield and sound mature kernels in both drilled and space-planted tests. Although most F2 cross means, especially for the intersubspecific crosses, were less than the midparent value, the presence of transgressive segregants indicated an opportunity for breeding improvement. The depression of F2 means probably resulted from recombination of genes responsible for adaptation of the parental lines. Comparison of results from the space-planted and drilled tests indicates that data from space-planted tests can provide useful information on the performance of crosses in early generation.