Improvement of soybean yield in northern Japan using genetic resources from western Japan with high plant density and nitrogen application

We used high-yielding soybean genetic resources (Fukuyutaka and Akimaro) from western part of Japan (warm region) to develop high-yielding lines suitable for Hokkaido (cool region). Two breeding lines, Tokei-1334 (derived from Fukuyutaka and Akimaro) and Tokei-1335 (derived from Fukuyutaka), were compared with Toyomusume for three years in combinations of two plant densities and two nitrogen treatments. Both of high plant density and nitrogen application increased yield in all three materials. The increase in yield with a combination of both treatments was higher in the two breeding lines than that in Toyomusume. The yield was 7% higher in Tokei-1334 and 8% higher in Tokei-1335 than in Toyomusume. Molecular marker analysis showed Tokei-1334 carried three loci derived from Fukuyutaka that are associated with high yield, although Tokei-1335 carried no loci. These results demonstrated incorporating high-yielding genetic resources from warm regions would be effective to improve yield in cool regions.