Factors Influencing in vitro Germination and Seed Storage Behavior of Couroupita guianensis Aubl. – A Useful Tropical Tree Species

Abstract

Couroupita guianensis Aubl. popularly known as cannonball tree is widely distributed in the tropical regions. The tree parts are commonly used to treat wounds and tumors. Leaves, flowers, and fruits contain active phytochemicals with significant biological activity. In the recent years, destruction of natural habitats by mankind has reduced its distribution. Natural propagation of C. guianensis by seeds is greatly hindered by poor seed germination and viability. Therefore, the present study was undertaken to optimize the conditions for in vitro embryo germination and to investigate the seed storage behaviour. Mature seeds inoculated on MS basal medium germinated within 10 d with a frequency of 61.6%. Supplementation of plant growth regulators (PGRs) to MS medium improved the embryo germination frequency (100%). Seedlings with highest shoot length (8.10±0.11 cm) and root length (6.27±0.14 cm) were produced in MS medium supplemented with 1.0 mg/l kinetin and 0.1 mg/l indole-3-butyric acid. Among different strength liquid MS basal salts, quarter-strength produced a greater number of secondary roots (8.00±0.28) with average root length of 17.83±0.58 cm. Seed storage behaviour studies clearly proved the recalcitrant nature as only freshly harvested mature seeds retained the germination potential upon storage at 15 ºC for up to 45 d. Desiccation of seeds on exposure to air-dry storage resulted in rapid deterioration of germination. Pre-conditioning of germinated seedlings in liquid MS basal salts was required for their survival under field conditions. Plantlets with well-developed roots were successfully acclimatized to the field with 100% survivability. This protocol facilitates conservation, sustainable utilization and re-introduction of C. guianensis into its natural habitats.