Studies on the breeding of Fusarium-wilt resistant varieties; of sponge gourd (Luffa cylindrica. ROEM) : III On the development by hybridization

Abstract

In previous papers we have already discussed about (1) the development by tetraploids and (2) the development by direct selection. But in this one we are going to described about (3) the development by hybridization. Hybridizations were made between the varieries (A) Tokado and Daruma, (B) Daruma and Beikan and also by (C) three-way-crossing, and we have got two new Fusariulee-wilt resistant varieties developed from (B) and (C). Materials and Methods Varieties. (1) Daruma (D) : An excellent commercial fiber-using variety. This was considered previously as susceptible, because the population of this variety, used as parents of these hybrids, was nighly susceptible to the wilt. Later, some resistant lines weredeveloped from the progenies of this population as shown in report 2. (II) Tokado (T) : A Formosan edible variety of poor fiber. This had been considered as a highly resistant variety. In our recent research, it was infected by inoculation in seedling stage. Mature plants also were injured in September by wilt together with nematode rootknot. (III) Beikan (B) : A Formosan edible variety not suitable for fibber-quality as these fibers are too short, thick and at the sametime coa, rse. But it has been considered as a resistant variety. About 70% of the Beikan population, used in the hybridizations, survived under the infected field condition. (IV) Tsurukubi (Tu) : A fiber-using variety having somewhat longer and weaker fiber than Daruma. It has been considered as a perfect susceptible variety. Methods. Methods used in this research were the same as in report 2, except the crossing practice. First, intervarietal crossing was used. Then, seeds were grown by selfing after F2 generation.