Vegetative Propagation of Two Endemic and Endangered Tree species (Humboldtia bourdillonii Prain. and Hydnocarpus macrocarpa) Warb. From Southern Western Ghats
Humboldtia bourdillonii and Hydnocarpus macrocarpa are evergreen endangered trees with huge medicinal properties, belonging to the families Fabaceae
and Flacourtiaceae, respectively. They grow very well in low to medium elevations of the Southern Western Ghats. Seeds of both H. bourdillonii and H. macrocarpa are rich in chaulmoogra oil, which is used to treat leprosy, wounds, ulcers and skin diseases. In the present study, we aimed to evaluate rooting capability of the tip cuttings of H. bourdillonii and H. macrocarpa in response to different growth hormones, under an intermittent mist propagation chamber system in a controlled environment. The effect of different concentrations (Control (0), 500, 1000, 1500 and 2000 ppm) of growth regulators (IAA, GA3, NAA and IBA) on vegetative propagation was assessed. The effect on shoot and rooting response of tip cuttings of H. bourdillonii and H. macrocarpa to various growth hormones at different concentrations were studied using an intermittent mist propagation system in a shaded tunnel. The rooting growth media
used in the present study were garden (red soil), cow dung, neem oil cake, river sand at a ratio of 1:1:1:1. Exogenous supply of IAA had a positive effect on vegetative growth of both H. bourdillonii and H. macrocarpa in terms of root development, increase in shoot and root length, number of leaves and leaf area. It is evident from the present study that the addition of IAA at an early growth stage of shoot tip cuttings under the shade tunnel method is an economically viable and rapid multiplication technique for ex vitro propagation of both the tree species in general and H. bourdillonii and H. macrocarpa in particular. However, air layering method was found very successful in this species and the percentage success achieved was 80-90%. In H. bourdillonii and H. macrocarpa, the
percentage success during May- June months was only 40%, whereas it was 90% during August- September. Overall, the result revealed that growth hormone treated tip cutting produced abundant and early rooting with higher survival percentage.