Growth enhancing effects of banana homogenate on a glucomannan-rich orchid species: <em>Serapias vomeracea</em> (Burm.f.) Briq.

Abstract

Glucomannan is a plant-sourced polymer used mainly in the food, pharmaceutical, and cosmetic industries. The increasing demand for the polymer makes researchers put effort into finding agriculturally sustainable and eco-friendly production methods for the source plants. The root systems of terrestrial orchids are rich sources of glucomannan. The objective of this research was to evaluate the concentration-dependent (10, 30, and 50 g L^–1) effects of banana homogenate (BAN) on in vitro development of a glucomannan-rich orchid species, Serapias vomeracea. The control medium gave the highest seed germination rate. In contrast, the addition of 10 g L^–1 BAN into the medium either in the presence or absence of sucrose gave statistically the same germination results with the control. However, all the BAN concentrations tested triggered protocorm formation significantly better in the absence of sucrose in the medium. The maximum mean shoot and root lengths, and root number were recorded after BAN treatments at 30 g L^–1 concentration. The tuber formation and development were shown to be enhanced gradually due to BAN treatments. The successful tuberization in S. vomeracea roots was achieved after 50 g L^–1 BAN, which gave more tubers in numbers with larger diameters. This study suggested that BAN could be used for tuber production for industrial demand. In the large-scale sustainable cultivation of tuberous orchids, synthetic plant growth regulators might be replaced by this natural additive. Also, BAN should be evaluated in in vitro propagation studies on Mediterranean terrestrial orchids as a substitute for sucrose.