Comparative reproduction mechanisms of three species of Ocimum L. (Lamiaceae)

Matthew Oziegbe,Joshua Olumide Matthew,Temitope Olatayo Kehinde

doi:10.5586/aa.1648

Abstract

Ocimum species have a combination of reproductive system which varies with the locality and cultivar. We have studied here the reproductive mechanisms of five variants of three Ocimum species in Nigeria, namely: Ocimum canum Sims., O. basilicum L., and O. americanum L. Flowers from each variant were subjected to open and bagged pollination treatments of hand self-pollination, spontaneous self-pollination and emasculation. All open treatments of the five Ocimum variants produced more fruit and seed than the corresponding bagged treatments. The two O. canum variants and O. basilicum ‘b1’ produced high fruit and seed set in the open and bagged treatments of spontaneous self-pollination. Ocimum basilicum ‘b2’ and O. americanum produced higher fruit and seed set in the self-pollination open treatment but significantly lower fruit and seed set in the bagged treatment. Fewer fruit and seeds were produced in the emasculated open treatments but none in the emasculated bagged treatments of the five Ocimum variants. The floral foragers comprising of bees, wasps and butterflies visited the Ocimum species to collect pollen or nectar in the open treatments. The two O. canum variants and O. basilicum ‘b1’ variant reproduced mainly through autogamy but O. basilicum ‘b2’ and O. americanum showed mixed reproduction of autogamy and outcrosssing. Insect visitation to the flowers enhanced pollination resulting in higher fruit and seed set in all the Ocimum species studied.

Highlights

The genus Ocimum L. belongs to the family Lamiaceae and comprises approximately 30 species of herbs and subshrubs distributed across tropical regions of Asia, Africa, Central and South America, with Africa as the primary center of diversity of the genus [1]
In each of the Ocimum species the terminal inflorescence consist of flowers arranged in whorls and oriented horizontally to the axis
Anther dehiscence occurred before anthesis in O. canum ‘c1’ and in two variants of O. basilicum

Summary

Introduction

The genus Ocimum L. (basil) belongs to the family Lamiaceae and comprises approximately 30 species of herbs and subshrubs distributed across tropical regions of Asia, Africa, Central and South America, with Africa as the primary center of diversity of the genus [1]. Ocimum species are very important in indigenous systems of medicine [4,5,6,7,8]. In addition to these uses, Ocimum is widely cultivated as a potherb for culinary uses [9] and for the fresh herb market for which export of Ocimum from Israel alone is worth 4 million US dollars per year. The pollen and nectar of members of the genus Ocimum are known to support certain potential pollinators of several wild plants species when the latter are not in bloom [11].

Methods

Results

Conclusion