Comparison of the Establishment Efficiency of Well-grown Seedlings at the Early Growth Stage from Reciprocal Crosses between Diploid and Triploid Apple Cultivars, and the Possibility of These Cultivars Cross Breeding

Masashi Sato, Kazumoto Kanbe
2007 Horticultural Research (Japan)  
This study investigated the possibility of performing cross breeding between diploid (2x) and triploid (3x) apple cultivars. Well-grown king flowers of 2x were hand-pollinated with an abundance of pollen grains from the 3x; thinning for openpollinated fruitlets on the experimental trees was carried out twice for the 2x × 3x, 3x × 2x and 2x × 2x crosses. Thereafter, the three types of crosses were compared for fruit set, seed formation, seedling growth at the early growth stage, and the number
more » ... well-grown seedlings established from 100 flowers crossed. Fruit set 60 days after pollination was 71.1 to 81.6% and 92.9 to 98.0% for 3x × 2x and 2x × 2x, respectively. For 2x × 3x, however, fruit set ranged from only 16.5 to 36.5%. Rate of normal seed formation was 76.5 to 77.5% for 2x × 2x, but only 16.5 to 42.6% for 2x × 3x and 9.4 to 33.6% for 3x × 2x. Rate of wellgrown seedlings 1 year after sowing ranged from 47.3 to 54.0% and 2.4 to 7.2% for 2x × 3x and 3x × 2x, respectively, and 72.4 to 94.1% for 2x × 2x. Number of well-grown seedlings established from 100 flowers crossed was 456 to 772 for 2x × 2x, 24 to 93 for 2x × 3x and 1 to 13 for 3x × 2x; it was found that more well-grown seedlings can be obtained for 2x × 3x than for 3x × 2x, using the techniques of pollinating and fruit thinning described above. These findings show that cross breeding for a new apple cultivar will be successful for 2x × 3x, though the cross is less efficient for breeding than the 2x × 2x. Breeding from a 3x × 2x cross will have little success. Key Words:fruit set, pollen parent, seed formation, tree height, viability キーワード:着果,樹高,花粉親,生存率,種子形成 緒 言 経済栽培されているリンゴ品種の大部分は,二倍性品種 (2n = 2x = 34)と三倍性品種(2n = 3x = 51)である.我が
doi:10.2503/hrj.6.347 fatcat:cir3rdvafvb7bnydhjy7b5vgnm