Actinidia interspecific hybrids: Valuable resources for the selection and breeding of kiwifruit rootstocks

Abstract: Interspecific hybridization is an effective way to create desirable rootstocks for grafting of fruit crops such as kiwifruit. Previous studies showed that interspecific hybrids in the genus Actinidia could be obtained through in vitro embryo culture. In attempts to develop vigor-controlling rootstocks, conventional intraploid crosses between two species that differ in the vigor of their root systems-A. arguta (Issai selection) and A. chinensis var deliciosa (four male genotypes)-were successfully performed without resorting to embryo rescue. A wide variation in root architecture characteristics was detected among the hybrid progenies. The identification of hybrids with less vigorous root systems than those of A. chinensis var deliciosa further highlights the potential of the intraploid hybridization between these species to develop rootstocks with size-controlling potential for kiwifruit. Statistically significant effects of male parent on seed set (xenia), and percentage of germination and normal hybrid seedlings were also detected in this investigation.