Spraying plant growth regulators alters morphological yield attributes, productivity and root withanolides in Withania somnifera (L.) Dunal

Abstract

Ashwagandha (Withania somnifera (L.) Dunal), is a one of the most important medicinal plants of India and is widely used in Ayurveda for its adaptogenic, neuroprotective, and memory-enhancing properties. Its therapeutic value is attributed to active compounds such as alkaloids and withanolides. A field experiment was conducted during the winter season of 2022-2023 at the Herbal Garden, Department of Plant Physiology, JNKVV, Jabalpur, to assess the effect of foliar-applied plant growth regulators (PGRs) on crop morphology, biomass, and withanolide content. Results indicated that the leaf area index (LAI) was the highest when no growth regulator sprayed (only plain water spray). The maximum leaf biomass yield was found with spraying of IBA @ 50 ppm. The maximum stem, fruit, seed, and total biomass were observed under IBA @ 100 ppm. Root length as well as secondary root formation were also highest at IBA @ 100 ppm. Both IBA @ 100 ppm and NAA @ 100 ppm individually effective in enhances root yield. The maximum root yield 739.73 kg ha-1 was found with either of 100 ppm IBA or 100 ppm NAA. The highest harvest index (19.98%) was achieved with IBA @ 100 ppm and NAA @ 50 ppm (when root is used as economic yield), while 25% HI was recorded with IBA @ 50 ppm (when seed as economic yield). The maximum Withanolide A (0.067%) and Withanolide B (0.005%) contents were recorded under NAA @ 50 ppm and NAA @ 100 ppm, respectively. Corresponding yields were 40.65 kg ha⁻¹ for Withanolide A and 3.48 kg ha⁻¹ for Withanolide B. The study confirms that optimized PGR application improves biomass and bioactive content in ashwagandha, enhancing its therapeutic and cognitive value