Crossability between mulberry (Morus spp.) and Broussonetia kazinoki Sieb

Abstract

Intergeneric crossing between mulberry and Broussonetia kazinoki SIEB. was performed in order to determine whether intergeneric hybrids could be obtained by this procedure. A large number of mature soroses were obtained when mulberry trees were used as seed parents, while all the flowers fell or withered before the soroses matured in the reciprocal cross. A remarkable variability was observed in the fruit set percentages among mulberry varieties or strains used as seed parents. In addition, the fruit set percentages considerably increased after treatments with 30 to 50 ppm β-naphthoxy acetic acid solution, but decreased remarkably after treatment with 75 to 100 ppm gibberellin solution. Many seeds were gathered from mature soroses, though no seed wes obtained from the soroses of the mulberry strain C4801-G7. Most of the seeds obtained were empty and they floated on tap water, but some of them sank. The morphological traits and the peroxidase isozyme patterns of six plants developed from the seeds that sank were investigated in comparison with those of mulberry trees and B. kazinoki, and it was found that there was no difference in these traits between the six plants and mulberry trees. On the basis of these results, it is concluded that the plants obtained in the present experiments are not intergeneric hybrids between mulberry and B. kazinoki, and that there exists an intergeneric incompatibility between them. © 1985, The Japanese Society of Sericultural Science. All rights reserved.