Abstract
Early maturity has been one of the important breeding objectives in wheat (Triticum aestivum L.) in the southwestern part of Japan, because this trait is suitable for double cropping with summer crops such as rice, and for avoiding pre-harvest sprouting which often occurs in the rainy season. However, early maturing cultivars are usually spring type cultivars which are prone to sustain frost damage in early spring because of their earliness in ear primordia initiation and stem elongation. To develop early maturing wheat cultivars with tillers that can avoid frost damage, winter type near-isogenic lines were bred for the extremely earlJ maturing spring cultivars Asakazekomugi and Salkal l07 (latel reg Istered as "Abukumawase") by backcrosslng to a winter type cultivar Ebisukomugi (Fig. l).
