Effects of Paclobutrazol and Pinching on Ornamental Pepper

Abstract

Pinching, manual removal of shoot apices, and/or plant growth regulators (PGRs) are used to create commercially preferred compact and well-branched ornamental plants. The influence of paclobutrazol (PB) with and without pinching on the growth and fruit characteristics of a tall ornamental pepper (Capsicum annuum) was assessed 2, 4, 6, and 8 weeks after the initial treatment. PB was sprayed on pinched or nonpinched whole plants at 5, 10, or 15 ppm a.i. Pinching and PB reduced the plant height between 25% and 50% and the canopy diameter up to 8% and 17%, respectively. Height/diameter ratio (H/D) ranged from 1.0 for 10 and 15 ppm PB applied to pinched plants to 2.3 for control plants. Paclobutrazol increased the SPAD chlorophyll value and total fruit number, delayed fruit set, and decreased fruit diameter and dry weight. The relationship between PB and plant height and diameter, SPAD chlorophyll value, dry weight, and fruit number was best explained by a third-order polynomial (r2 = 0.83–0.99). Paclobutrazol may substitute costly pinching treatment for height control and may offer an economic advantage for commercial greenhouse operators.