在水稻育种中普遍采用低脚乌尖作为矮源(含sd-1半矮秆基因),而导致了在改良品种中遗传基础的狭窄。尽管在籼稻和粳稻的不同品种中已获得了许多有价值的半矮秆基因,但发现这些基因均与sd—1基因等位。而极大多数与sd—1非等位的半矮秆基因,农艺性状却都表现较差。作者从一个高秆、长粒型籼稻品种 californiaBelle 通过 r-射线处理的后代中,选到了二个 Low-stalked U. dunks are commonly used as low sources (including the sd-1 semi-dwarf gene) in rice breeding, resulting in a hereditary stenosis in improved varieties. Although many valuable semi-dwarf genes have been obtained from different varieties of indica and japonica rice, they were all found to be allelic to the sd-1 gene. However, most of the semi-dwarf genes with non-allelic to sd-1 showed poor agronomic traits. The authors selected two offspring r-ray treated from a tall, long-grain indica variety californiaBelle