Studies on the breeding of adzuki bean cultivars resistant to adzuki bean brown stem rot (BSR) and Phytophthora stem rot(PSR)

摘要

In Hokkaido, there are three diseases of adzuki bean [Vigna angularis (Willd.) Ohwi & Ohashil, brown stem rot (BSR) caused by Phialophora gregata f. sp. adzukicola, Phytophthora stem rot (PSR) caused by Phytophthora vignae f. sp. adzukicola, and wilt caused by Fusarium oxysporum f sp. adzukicola. These are very serious problems for adzuki bean production. These fungi are soil-borne and are therefore difficult to control through chemical or cultural methods. The cultivation of resistant cultivars is the most effective method of controlling these diseases. At Tokachi agricultural experiment station in Hokkaido, breeding for BSR and PSR resistance has been carried on since the late 1970's, and wilt resistance breeding has been done since 1986. At present, many resistant cultivars, including Kita-no-otome and Syumari, have been raised and extended. These cultivars are very effective at controlling the diseases in commercial fields. However, it was recently recognized that new races of BSR and PSR may exist. Therefore, I first proved the existence of pathogenic races of BSR and a new race of PSR. Next, I researched the distributions of these new races in adzuki bean fields in Hokkaido. This is important for managing the damage to adzuki bean production by new races in the future. I then selected new resistant gene sources from adzuki beans or wild adzuki bean. New resistant lines were developed from the cross with new resistant gene sources. Additionally, I attempted to develop multiple resistance lines that were resistant to both new races. The following is an outline of these studies.