Combining Ability of Response to Photoperiod in Peanut

Abstract

Photoperiod insensitivity plays an important role in the adaptation of peanut (Arachis hypogaea L.) genotypes across environments. Howeverl,i ttle is knowno f its genetic control. Theo bjective of this study was to determine the combining ability of response to photoperiod in peanut. The Ft progenies from a six-parent diallel cross excluding reciprocals were studied together with their parents for response to photoperiod under short and long day conditions in the field for three seasons. The experimentw as conductedi n a split plot design with photoperiod as main plots and genotype as subplots. The response to photoperiod (Dst) was computed as the difference in harvest index (adjusted pod weight/adjusted biomass) between short and long day treatments. The mean square for response to photoperiod was highly significant for parents and their crosses. Season by cross interaction was the only significant interaction effect. The response to photoperiod was mainly associated with general combining ability variance. ICG2 405 and ICGV8 6031 were good general combiners for insensitivity to photoperiod. All crosses of sensitive × sensitive and sensitive × insensitive parents were sensitive to photoperiod. However, in several cases, this response was not consistent across seasons and resulted in a significant season × cross interaction. The F1 between insensitive parents was insensitive to photoperiod in the three seasons tested. A comparison of Ft response with parents and midparent value of crosses between photoperiod sensitive and insensitive parents suggested additive gene action in some crosses and partial dominance to dominance in others