Screening of mulberry genotypes suitable for fruit production and development of high-yielding strains with large fruits

In order to screen mulberry genotypes suitable for fruit production, fruit traits of 260 genotypes were examined. Forty-three genotypes were classifie d into staminate, 137 were pistillate and 78 were hermaphrodite. Fruit quan tity and size showed wide variations among the genotypes. Itouwase, Shizens ei-roso and Tenmokuyotsume bore more fruits than the other genotypes. Okara guwa bore the largest fruits, which were 4.9 cm long and weighed 7.15 g. Th e sugar content of the fruit ranged from 6.6 to 20.8%, and the highest cont ent was observed in Myurienoaaru. Most of the taste panelists rated Okaragu wa and Kataneo higher than the other genotypes. Thus, these 2 genotypes wer e selected as the most suitable fur fruit production. In the next step, we attempted to develop polyploids from these genotypes by colchicine treatmen t to achieve a high productivity. After the treatment, we propagated the sh oots with putative tetraploids to obtain the strains. The 2 strains thus de veloped were mixoploids of diploids and tetraploids, but it is considered t hat they were both peripheral chimeras and that their structure remained st able. One of the strains, FRM-01 developed from Kataneo, bore many fruits i n the second year after planting in the field. Almost all the fruit traits of this strain were the same as those of the original strain, except that t he size became larger and the fruit yield was increased by about 60%.