Micromorphological Observations on Flower Bud Differentiation and Development of Okra (Abelmoschus esculentus (L.) Moench)

Abstract

The objective of this study was to investigate morphologically flower bud differentiation during floral organ development of 'Green Rocket' okra by using a scanning electron microscope (SEM). Flowers were formed at the axillary positions and were initiated successively from the node bearing the first flower up to the node below the shoot apex. Flower buds were divided into 8 developmental stages: 0) vegetative stage; 1) dome stage; 2) epicalyx initials; 3) calyx initials; 4) petal and stamen primordial appear; 5) carpel and stamen differentiating; 6) further carpel and stamen development; 7) anthesis. Formation of the epicalyx in okra revealed that it is the first floral organ to differentiate, such that the onset of floral differentiation is signaled by the appearance of epicalyx initials. The characteristic staminal column is formed whose base is fused with calyx and petal. These fused calyx, petal and stamen simultaneously wilted and abscised soon after anthesis. From the fusion of these floral organs and the elevated position of these fused parts other than the ovary, an okra flower is classified as being perigynous. A large number of anthers are formed on the staminal column. Five loculi with anatropous ovules are present in an ovary, exhibiting a central marginal placentation.