KANBE Kazumoto Department of Agriculture, Akita Prefectural College of Agriculture, Professor Emeritus, 農学科, 元教授 (60073962)
IMANISHI Hiroyuki College Farm, Akita Prefectural College of Agriculture, Assistant, 附属農業, 助手 (10320607)
|Budget Amount *help
¥3,200,000 (Direct Cost : ¥3,200,000)
Fiscal Year 1999 : ¥900,000 (Direct Cost : ¥900,000)
Fiscal Year 1998 : ¥1,300,000 (Direct Cost : ¥1,300,000)
Fiscal Year 1997 : ¥1,000,000 (Direct Cost : ¥1,000,000)
In cross breeding of apple, triploid cultivars (3x) have been scarcely employed hitherto as the breeding materials. Namely, it has been a practice to perform intercrosses among diploid cultivars (2x). Under these circumstances, this study aims at establishing a method of cross breeding between triploid and diploid apple cultivars. Thus, seedlings were grown from reciprocal crosses between triploid and diploid cultivars and comparison was made on the tree growth, flowering, bearing, fruit characteristics, etc.
1. Regarding the growth of young trees, seedlings of 2x * 3x crosses were superior to 3x * 2x seedlings. Among the 2x * 3x seedlings, those showing vigorous growth comparable to 2x * 2x seedlings amounted to 39 to 54%. A considerably large number of the 2x * 3x seedlings showed dwarfness.
2. When the 2x * 3x seedlings were grafted on vigorating rootstocks, Malus prunifolia, about 50% of the seedlings showed dwarfness evaluated on the basis of trunk circumference index. Thus, it was clearly recognized that dwarf cross seedlings of 2x * 3x also showed when grafted onto vigorating rootstocks.
3. In flowering and fruiting, the cross seedlings of 2x * 3x were inferior to the 2x * 2x seedlings but clearly superior to the 3x * 2x ones.
4. Seven years after sowing, the cross seedlings showed difference in fruit characteristics depending on cross combination, though no clear difference was observed between the 2x * 3x seedlings and the 2x * 2x ones. However, these seedlings have just attained the bearing age and therefore the investigation should be continued further.
These results indicate that cross breeding can be well performed by using a diploid cultivar as the seed parent and a triploid cultivar as the pollen parent, and that there is a high possibility of creating a dwarf cultivar.