Identification of Hermaphroditism and Self-fruitfulness in the Wild Actinidia Found in Warm Region of Japan

Abstract

Reproductive characteristics of the tetraploid plants of Actinidia collected in a warm Pacific region on Kyushu Island, Japan, were investigated and compared with those of diploid A. rufa, which grows in the same area. Morphological characteristics of tetraploid plants, such as skin color and lenticel of fruit, were similar to those of A. rufa; however, the number of petals, color and hair of calyx, and shape of fruit were distinguished from A. rufa. All the tetraploid plants bore only morphologically hermaphroditic flowers. Pollens collected from these flowers germinated at a high rate of 40–61%. By self-pollination, the flowers of the tetraploid plant set fruit over 97%. The seeds obtained by self-pollination germinated at a high rate of 81%. By the cross between the tetraploid plant and tetraploid cultivars of A. chinensis, viable seeds were obtained. The seeds germinated at 65–92%. These results showed that tetraploid Actinidia plants are functionally hermaphroditic and self-fruitful, implying a potential as breeding materials.