Effects of Restriction of Tillers Per Plant on Steely Grain Rate of Hulless Barley (Hordeum vulgare var. nudum)

Abstract

Reducing the steely grain rate is important for improving the grain quality in hulless barley. Flowering date and nodal tillers are related to steely grain rate. In this study, we investigated the effects of high planting density, low nitrogen application, and removal of the higher nodal stems on stem number per plant and the steely grain rate by a two-year field experiment. By doubling the sowing rate in conventional cultivation, the stem number per plant was significantly decreased with the reduction of higher nodal stems. Additionally, the steely grain rate in the treatments with a lower stem number per plant was significantly lower in the other treatments, and there was a significant positive correlation between stem number per plant and steely grain rate in the two-year study. These results suggested that the cultivation methods that reduce the stem number per plant could lead to a lower steely grain rate. Additionally, the number of days between flowering of the first panicle and that of 50% of the panicles significantly correlated with the number of stems per plant, and the steely grain rate at 5% and 10% levels in 2022/23 and 2023/24, respectively. Moreover, the panicles with later flowering had a higher steely grain rate. These results suggested that the treatments with a lower number of stems per plant had a lower number of panicles with later flowering, which led to a lower steely grain rate than the other treatments.