Narrow Row and Dense Planting of New Black Soybean Cultivar ‘Kuroshofuku’ in Southwestern Japan

Abstract

Labor-productivity is a major problem in the hilly and semi-mountainous areas in Southwestern Japan, due to small and dispersed paddy fields. Recently, narrow row and dense planting with selective post-emergence herbicide is being used to reduce labor. The combination of narrow row and dense planting with the new black soybean cultivar ‘Kuroshofuku’, suitable for mechanical harvest, can be a solution for labor-saving production in hilly and semi-mountainous areas. The objective of this study is to compare the agronomic characteristics of ‘Kuroshofuku’ with those of ‘Sachiyutaka A1 gou’, one of the leading cultivars in Southwestern Japan, and to consider narrow row and dense planting. The field experiment was conducted in 2021 and 2022, at two sowing dates and three planting densities at Western Region Agricultural Research Center, Fukuyama. In addition, ‘Kuroshofuku’ was grown in a farmer’s field in a hilly and semi-mountainous area. ‘Kuroshofuku’ showed higher lodging tolerance than ‘Sachiyutaka A1 gou’ in late sowing at the research center. Though significant year × cultivar interaction was observed in normal sowing, the difference in yield between the two cultivars was not significant in late sowing. In the farmer’s field, ‘Kuroshofuku’ reached maturity normally in both two years. In 2022, ‘Kuroshofuku’ showed a higher yield when the entire field was harvested than ‘Sachiyutaka’. These results showed that ‘Kuroshofuku’ can be grown by narrow row and dense planting in late sowing, which will contribute to labor-saving production in Southwestern Japan.