MORPHO-ANATOMICAL AND PHYSIOLOGICAL CHANGES OF OKRA (Abelmoschus esculentus (L.) Moench var. 'Smooth Green') FRUIT AND SEED DURING DEVELOPMENT

Abstract

Abelmoschus esculentus (L.) Moench commonly known as lady finger or okra, is a popular tropical plant that produces green, slender, finger-shaped fruits. The fruits are commonly harvested when young and consumed as green vegetable. The study primarily investigated the morphological, anatomical and physiological changes that occur in the lady finger or okra var. 'Smooth Green' whole fruit, its pericarp and seeds. Based on these data, the fruit's optimal stage of maturity for harvest was determined. Fruits were collected at different developmental stages starting at 3 days after anthesis (DAA) and every 3 days thereafter until th the 24 day when further growth in size was no longer evident. Morphological parameters were measured in situ using intact fruits. Fresh and dry weights were measured using destructive samples. Histological procedures were used to examine anatomical features of the pericarp. The Alkali Trapping Method was used to monitor respiratory activity of the developing fruits. The okra plants started to flower at 48 days after sowing. A tiny fruit was formed immediately the day after anthesis and continued to grow in size and weight reaching full mature size at day 24. Growth in fresh weight of the whole fruit, the pericarp and the seed followed a double sigmoidal pattern while seed growth was linear. Young fruits had high moisture but low dry matter content while older ones had low moisture and high dry matter content. Young fruits were light green in color, more rounded in diameter and more hairy while older ones were deep green in color, became increasingly ribbed and glossy or less hairy as they matured. Anatomically, young pericarp had smaller and tightly compact cells becoming larger and bulkier with increasing age. Based on the results, okra is best harvested and consumed as fresh green vegetable when it is young at 9 DAA, when it is light green and immature, when it is about 16.8 cm in length, about 1.9 cm in diameter, has high moisture content of about 92%, when its pericarp tissues and seeds are soft, translucent and spongy and has lower respiration rate which ensures longer shelf life and good eating quality