EFFECTS OF PACLOBUTRAZOL ON GROWTH AND FRUITING CHARACTERISTICS OF ´PITANGA´ ORNAMENTAL PEPPER

Abstract

Two experiments using container-grown ornamental pepper (Capsicum chinense ‘Pitanga’), were conduced to determine effects of paclobutrazol on growth and fruiting responses. In experiment 1, paclobutrazol was sprayed on the canopy at concentrations of 0; 30; 60; 90; 120 and 150 mg ai⋅L. In experiment 2, paclobutrazol drenches were applied at 0, 5, 10, 15, 30 and 60 mg ai⋅L. Increasing paclobutrazol concentration decreased plant height, plant diameter and plant dry mass but increased leaf chlorophyll content in both experiments. Severe height retardation of plants was evident at 30 and 60 mg ai⋅L in the second experiment, also exhibiting phytotoxicity symptoms. Paclobutrazol treated plants exhibited greener leaves compared to untreated plants. Increasing paclobutrazol foliar application concentrations, the fruit diameter was increased and the fruit weight was unaffected. Considerations of growth and fruiting response should be balanced when using paclobutrazol in ‘Pitanga’ ornamental pepper pot production. INTRODUCTION Brazil has a large genetic diversity of wild peppers but more scientific research is needed to undertanding the growth cycles and cultural requirements of those plants. The use of peppers as ornamental potted plants exhibit advantages like easy seed propagation, short cycle production, heat and drought tolerance, fruit production and excellent postharvest performance (Harbaugh and Waters, 1979). A new genetic access ‘Pitanga’ pepper (Capsicum chinense), catalogued in Germoplasm Bank of Federal University of Vicosa, has potential as an ornamental pot plant, if the growth can be controlled. Application of growth retardants is a common practice for commercial growers to achieve attractive compact pot-grown plants. Researchers have reported that paclobutrazol, a triazole plant growth regulator, is effective in controlling vegetative growth and promoting compactness in the production of a number of ornamental plants including Chrysanthemum morifolium (Barret, 1982; Zalewska, 1989), Lilium longiflorum (Jiao et al. 1986), Euphorbia pulcherrima (Goulston and Shearing, 1985) and Tulips (McDaniel, 1990). Starman (1993) investigated the effects of different concentrations of uniconazole, another triazole plant growth regulator, on controlling growth and fruiting of ‘Holiday Cheer’ Capsicum annuum. Concentrations ranging from 5.0 to 15.0 mg•L gave adequade height control. Triazoles are generally more effective in retarding growth when applied to the soil or directly to stems compared to foliar applications (Davis et al., 1988). However, foliar and drench paclobutrazol applications have been studied on growth control of ornamental plant production (Anderson and Hartley, 1990; Banon et al., 2002). Despite the use of paclobutrazol in the industry of potted plants, few studies have been published concerning paclobutrazol efficacy for ornamental peppers. Also, evaluation of the effect of paclobutrazol on growth and fruiting characteristics of ‘Pitanga’ ornamental pepper has not been reported. The objective of this study was to investigate the effects of paclobutrazol on growth and fruiting characteristics of ‘Pitanga’ ornamental pepper. Proc. V IS on New Flor. Crops Eds.: A.F.C. Tombolato and G.M. Dias-Tagliacozzo Acta Hort. 683, ISHS 2005