Method to Evaluate the Earliness in Strawberry Seedlings Grown under Forcing Culture

Abstract

We developed an evaluation method and the inheritance mode of earliness in strawberry seedlings grown under forcing culture. 1. A bimodal frequency distribution with respect to the date of flower bud occurred in a clonally propagated population of 'Nyoho' which should have been genetically uniform. Therefore, it is difficult to clarify the existence of genetic segregation of earliness in a seedling population with respected to the date of flower bud emergence. 2. The dates of flower bud initiation of clonal lines could be estimated by observing the transplanting date of the first flower bud emergence. The data were derived by planting two plants of each clone every three or four days from Sept. 4 to 28. The resulting frequency distribution of the date of the first flower bud to be initiated was unimodal in 37 clones derived from a cross, indicating that there is no one single major gene for earliness. 3. A significant correlationship was found between the date of flower bud emergence of seedlings raised in the first year and the estimated date of flower bud initiation of clonal plants propagated from each seedling. These results indicate that the selection of the earliness in the seedling stage is possible by establishing the emergence date of the first flower bud, a simple, convenient method.