IMPACT ON POT-BOUND CHARACTERISTICS TO COMMERCIALIZE NATIVE ORNAMENTAL (MUSSAENDA FRONDOSA L.) POT PLANT THROUGH PINCHING, PACLOBUTRAZOL AND HEADING BACK

Abstract

The present study was conducted over two consecutive growing seasons (2021–2023) at the Regional Horticultural Research and Training Station, Dhaulakuan, Himachal Pradesh, to evaluate the influence of pinching, heading back, and paclobutrazol on root architecture and biomass dynamics of Mussaenda frondosa L. under pot culture. The experiment followed a factorial randomized complete block design (RCBD) with three replications. During the first season, treatments included three pinching levels (no pinch, single pinch, and double pinch) and four concentrations of paclobutrazol (0, 50, 100, and 150 ppm). In the subsequent season, two heading back levels (no heading back and single heading back) were introduced, while continuing the same paclobutrazol treatments. Root and shoot parameters were assessed post-anthesis through destructive sampling. Double pinching (P3) significantly reduced the primary root length (32.58 cm) and enhanced secondary and tertiary root proliferation (144.50 and 384.42), fresh and dry root weight (49.29 and 32.81 g, respectively), and shoot biomass (178.43 g fresh). Among paclobutrazol concentrations, 150 ppm (PBZ4) consistently yielded the highest root-shoot ratio (0.36), tertiary roots (365.00), and biomass accumulation. The interaction P3 × PBZ4 exhibited synergistic effects, producing the highest tertiary root count (418.00) and root fresh weight (55.17 g). In the second year, single heading back (H2) significantly improved root-shoot attributes, particularly when combined with 150 ppm PBZ (H2 × PBZ4), resulting in maximum shoot biomass (260.13 g fresh) and root weight (78.98 g fresh at 50 ppm). Control plants consistently showed the least growth. These findings underscore the potential of integrating morphological manipulations with growth regulators to optimize pot-bound M. frondosa cultivation for ornamental use.