Influence of Plant Growth Regulators and Cutting Types on Sprouting and Growth of Henna (Lawsonia inermis L.) in Arid and Semi-Arid Regions of Western Rajasthan

The experiment was carried out to observe the effects of plant growth regulators (PGRs) viz., indole-3-acetic acid (IAA), indole-3-butyric acid (IBA), and naphthalene acetic acid (NAA) on the vegetative propagation of henna (Lawsonia inermis L.) on hardwood, semi-hardwood, softwood, and twigs cuttings. Significant variations were observed in sprouting percentage (%), shoot and leaf growth, root development, and biomass across cutting types and PGR treatments. Hardwood cuttings recorded the highest mean sprouting rate (81.63%), with maximum sprouting (98.14%) achieved under IAA at 1500 and 2000 ppm, followed by IBA 1000 ppm and IAA at 500 and 1000 ppm. Semi-hardwood cuttings showed moderate sprouting (66.79%), best under IAA 1000 ppm (88.33%), while high IAA (2000 ppm) showed reduced sprouting. Softwood and twig cuttings showed relatively lower sprouting rates (48.58 and 46.40%, respectively), with IAA at 500–1000 ppm yielding the best results. In hardwood cuttings, IAA at 500 ppm showed the maximum shoot length (38.33 cm) and leaf number (6.00), while IBA at 1500 and 1000 ppm also enhanced growth significantly. IBA 500-1500 ppm consistently enhanced root number and biomass, especially in hardwood (29.6) and semi-hardwood cuttings (15.6), whereas IAA was more effective in promoting root elongation. NAA generally resulted in lower sprouting and root formation, particularly at higher concentrations. The study highlights the superior effectiveness of IBA and IAA for rooting and growth in henna cuttings, emphasizing the importance of cutting type and auxin concentration for optimizing propagation. These findings provide a valuable basis for developing efficient, sustainable propagation protocols to support large-scale cultivation of henna in arid and semi-arid regions.