Effects of light quality on pod elongation in soybean (Glycine max (L.) Merr.) and cowpea (Vigna unguiculata (L.) Walp.).

Soybean pods are located at the nodes, where they are in the shadow, whereas cowpea pods are located outside of the leaves and are exposed to sunlight. To compare the effects of light quality on pod growth in soybean and cowpea, we measured the length of pods treated with white, blue, red or far-red light. In both species, pods elongated faster during the dark period than during the light period in all light treatments except red light treatment in cowpea.