Influence of deflowering on dry matter production of soybeans

Abstract

Abstract Soybeans ( Glycine max (L.) Merr.) of maturity group 00 were grown in a greenhouse to investigate the effect of continuous flower removal on growth and dry matter partitioning. After growth stage R1 (initial bloom) one-half of the plants were deflowered daily for 50 days. Plants were harvested at 10-day intervals, beginning at R1, and continuing until control plants reached maturity. Total dry matter (all vegetative plant parts plus fruits, where present) was similar for both treatments at 30 days after R1; however, the total dry matter of the deflowered plants was greater than the controls at 40 and 50 days after R1. There was no difference in the photosynthetic rate of single leaves for 30 days after R1. Deflowering had only a minimal effect on the leaf area, number of branches, number of branch nodes, and plant height. Thus, the increase in the mass of the vegetative plant parts in the deflowered plants resulted primarily from an increase in specific leaf weight and thicker stems and branches. The relative proportion of the total vegetative weight represented by a given vegetative component was not greatly altered by flower removal. The results suggest that the vegetative plant parts in soybeans can serve as strong sinks for photosynthate when reproductive structures are not allowed to develop.