Large yield differences between reciprocal families of Solanum tuberosum

Abstract

A number of reports have indicated differences in reciprocal families of Solanum tuberosum when intergroup hybrids were studied. Questions have been raised concerning the potential magnitude, frequency, and genetic basis for such differences. In this study, exact reciprocal crosses were made using parents characterized by different maturities and having different cytoplasmic sources within Solanum tuberosum in order to substantiate previous claims of reciprocal differences and to clarify the nature of such differences. Field trials revealed reciprocal differences which were large and highly significant. Reciprocal yield differences of up to 115% were observed when parents of opposite maturities were used. In seven crosses, the higher-yielding reciprocal always had the higher-yielding parent as the maternal parent. Significant reciprocal differences for flowering and vine maturity were also observed between some families. The F2 populations were generated for one set of reciprocals and the reciprocal differences in the F2 generation seemed to be substantially reduced relative to the F1 generation. It is concluded that the occurrence of large reciprocal differences seems to depend more upon having parents of opposite maturity than upon the taxonomic origin of the parent's cytoplasm. This, in conjunction with the reduced F2 reciprocal differences, suggests that observed differences may be due to very persistent maternal effects or a type of dauermodification, rather than true cytoplasmic inheritance.