Appropriate Growth Stages for Tip-clipping in Perilla (<i>Perilla frutescens</i> (L.) Briton var. frutescens) Grown in Tokachi Region

Abstract

To understand the effectiveness of tip-clipping in the production of perilla (Perilla frutescens (L.) Briton var. frutescens) grown in the Tokachi region, we compared the growth and yield of plants receiving tip-clipping treatment at different growth stages. Tip-clipping was performed on a local variety, Hokkaido-zairai, at the eight-leaf stage (V8), ten-leaf stage (V10), or flower bud formation stage (R). Plants without tip-clipping treatment were grown in the control plot. The plants in the V8 and V10 plots had fewer primary branches, but more inflorescences than those in the control plot. The total number of florets in the V10 plot was similar to that in the control plot. This may be due to the disruption of apical dominance or increase in allocation of resources to the branches. The plants in the V8 and V10 plots were shorter, resulting in a lower degree of lodging than those in the control plot. On the other hand, the plant form and degree of lodging in the R plot were similar to those in the control plot. Tip-clipping did not show a significant effect on the yields of grain and oil. However, the yield may be reduced due to harvest loss in the control and R plot that showed severe lodging. Our results indicated the effectiveness of tip-clipping for stabilizing perilla production in the Tokachi region, and the appropriate growth stage for tip-clipping was suggested to be the ten-leaf stage.