A study on the breeding of Easter lily. (I)

On the test of cross-combinations for hybridization

Abstract

1. For the purpose of Easter lily breeding, tests of cross-combinations for hybridization have been carried out as a fundamental study of the breeding.
2. Seedlings of first generation hybrids from 36 cross-combinations among 10 principal Japanese and American varieties of Lilium longiflorum, which had been crossed in 1953 were grown. These three-year-old seedlings were examined as to the following characteristics in 1956: stem length, stem color, density of foliage, direction of leaf, leaf shape, leaf color, flower size, time of flowering, severity of virus diseases, frequency of secondary sprouting, and rate of superior seedlings.
3. Superior seedlings suited to pot culture for Easter use were derived from 13 cross-combinations, especially from intravarietal crossing of the variety Saga green-stemmed (probably a type of insiare), Croft×K2002 (one of insulare), Estate×Saga green-stemmed, Ace×K2002, Ace×Tôguro (near the variety Tôgô), and nobile (type B)×Saga green stemmed. On the other hand, giganteum and Croft which have been the leading varieties for Easter use scarcely produced the superior seedlings.
4. The reason for the superiority of Saga green-stemmed, K2002, and Ace as parents of the breed-ing for Easter use is that these varieties have superior characteristics as shown next.
Saga-stemmed: Short stem, ascending direction of leaves, broad leaf, dark green foliage, and early flowering.
K2002: Short stem, dark green foliage, large size of flower, early flowering, and virus disease resistance.
Ace: Short stem, dense foliage, broad leaf, and virus disease resistance.
5. The characteristics of the first generation hybrids other than the stem color and frequency of secondary sprouting were remarkably segregated. In general, the F, hybrid between varieties having-similar characteristics tend to have those of their parents. But the combination between varieties of far different characteristics seems to show remark-able variation, and their peak seems to be in the intermediate position in their characteristics.