The response of two soya-bean varieties to the loss of apical dominance at the vegetative stage of growth

Abstract

SUMMARYIn three pot experiments and one field trial, the apical portion of the main stem of two soya-bean varieties (cv. Hampton and cv. Bossier) were removed at 3 weeks or 5 weeks after sowing in order to evaluate the response of the plants to the loss of apical dominance.The results showed that early loss of apical dominance in Hampton (an indeterminate variety) led to increased vegetative development but shorter plants, higher dry-matter accumulation and increased seed yield through the production of more and/or heavier pods. On the other hand, apical debudding of Bossier (a determinate variety) during the vegetative stage evoked no significant beneficial response and in the case of field debudding at 3 weeks after sowing, plant height was decreased and seed yield was significantly reduced.The response of soya bean to the loss of apical dominance therefore seems to be a function of the stage of vegetative development when the loss occurs as well as the growth habit of the variety.