Comparison of the anatomy and physiology of seeds of two varieties of winged bean ( Psophocarpus tetragonolobus)

Abstract

Seeds of winged bean ( Psophocarpus tetragonolobus L. DC) cultivar ‘KUS-1’ are largely impermeable to water and showed a very low percentage of germination, whereas seed germination in ‘KUS-8’ was higher, presumably due to greater permeability. Scanning electron microscopy revealed more extensive surface deposition in the seed coat of ‘KUS-1’ than in that of ‘KUS-8’. The cell layers of the mature seed coat structures are more highly developed than those of the immature seed coat. The seed coat structure of ‘KUS-1’ showed a compact arrangement of cell layers and a thicker hilar region including seed coat in comparison to ‘KUS-8’. Gibberellin-like substances were higher in the embryo-cotyledon of 35-day-old seeds of ‘KUS-8’ than in those of ‘KUS-1’, and they declined with maturation. Indole-3-acetic acid increased with maturation. More abscisic acid (ABA) was found in the embryo-cotyledon of ‘KUS-1’ than in that of ‘KUS-8’. The impermeability of the ‘KUS-1’ seeds may be related to the dense surface deposits, thick hilum with highly developed sclereid cells, compact arrangement of cell layers, and a greater accumulation of gibberellic acid and ABA in the embryo-cotyledon of immature and mature seeds, respectively.