Abstract
Breeding efforts in Japan have improved the pest and disease resistance and food processibility in soybean, Glycine max (L.) Merr. However, progress in improving yields has been stagnant, making the development of high-yielding varieties one of the most urgent breeding objectives.
A new soybean variety, “Soramizuki,” was developed in 2022 by the Institute of Crop Science, National Agriculture and Food Research Organization (NARO). It resulted from crossing “Sakukei 76” (later registered as “Fukuyutaka A1 gou”), a breeding line well-suited for tofu production, with “UA4805,” a high-yielding variety from the United States.
Trial cultivation tests were conducted in Tsukubamirai, Ibaraki (36°00’ N， 140°02’ E). The seed coat color of “Soramizuki” was yellowish-white with light brown hila, and its hundred seed weight was approximately 18–22 g. Its date of maturation, dehiscence resistance, lodging resistance, and the lowest pod height were similar to those of “Sachiyutaka A1 gou,” a variety suitable for mechanized harvesting. Demonstration tests using a combine harvester in farmers’ fields revealed that “Soramizuki” yielded 37% more than conventionally grown varieties such as “Satonohohoemi” and “Fukuyutaka.” Although its protein content was 3% lower than that of “Sachiyutaka A1 gou,” “Soramizuki” displayed tofu processing suitability on par with the excellent processing suitability of “Fukuyutaka.”
Regional yield trials confirmed that “Soramizuki” is suitable for cultivation in all regions from Kanto to Kyushu. However, due to its susceptibility to soybean mosaic virus and soybean cyst nematodes, it should not be grown in fields severely impacted by these pathogens.
