Effect of NAA and Homobrassinolide on Growth, Yield and Quality of Beetroot (Beta vulgaris L.)
Abstract
Beetroot (Beta vulgaris L.) is an important root vegetable valued for its nutritional and economic importance. Its growth, yield and quality are influenced by plant growth regulators; however, information on the comparative effects of naphthalene acetic acid (NAA) and homobrassinolide (HBL) on beetroot under the semi-arid agro-climatic conditions of Rajasthan remains limited. The present investigation entitled was conducted during the Rabi season of 2025 at the Agronomy Research Farm, School of Agriculture, Suresh Gyan Vihar University, Jaipur, Rajasthan. The experiment was laid out in a Randomised Block Design (RBD) comprising seven treatments with three replications to evaluate the influence of different concentrations of Naphthalene Acetic Acid (NAA) and Homobrassinolide (HBL) on the growth, yield, quality and economics of beetroot. The results revealed that Homobrassinolide @ 1 ppm (T₆) proved to be the most effective treatment, recording the maximum plant height (42.19 cm at 75 DAS), number of leaves per plant (19.4 at 75 DAS), root length (16.11 cm), root diameter (8.22 cm) and total root yield (479.70 q ha⁻¹), compared with 28.43 cm, 12.9, 10.90 cm, 5.20 cm and 284.10 q ha⁻¹, respectively, under the control (T₁). Among the NAA treatments, NAA @ 200 ppm (T₃) recorded a plant height of 36.62 cm at 75 DAS, 16.2 leaves per plant at 75 DAS, a root length of 13.76 cm, a root diameter of 6.91 cm and a total root yield of 411.50 q ha⁻¹. In terms of quality, T₆ recorded the highest carotenoid content (3.27 mg 100 g⁻¹), total chlorophyll content (1.83 mg 100 g⁻¹) and anthocyanin content (55.88 mg 100 g⁻¹), compared with 2.13, 0.85 and 37.56 mg 100 g⁻¹, respectively, under the control. Among the NAA treatments, NAA @ 200 ppm (T₃) recorded 2.76 mg 100 g⁻¹ carotenoids, 1.28 mg 100 g⁻¹ total chlorophyll and 46.87 mg 100 g⁻¹ anthocyanin, indicating better performance than NAA @ 100 ppm. Economically, Homobrassinolide @ 1 ppm (T₆) recorded the highest gross return (₹3,83,760 ha⁻¹), net return (₹2,92,760 ha⁻¹) and benefit ratio (3.22), compared with ₹1,70,460 ha⁻¹, ₹88,460 ha⁻¹ and 1.08, respectively, under the control. Among the NAA treatments, NAA @ 200 ppm (T₃) recorded a gross return of ₹3,29,200 ha⁻¹, which was higher than the ₹2,68,293 ha⁻¹ recorded under NAA @ 100 ppm. Overall, Homobrassinolide @ 1 ppm was found to be the most effective treatment for improving growth, yield, quality and economic returns of beetroot, while NAA @ 200 ppm was the most effective treatment among the NAA concentrations.