EFFECT OF PINCHING AND PACLOBUTRAZOL ON HIBISCUS ROSA-SINENSIS, L. cv. “Yellow” PLANT

A pot experiment was carried out during two successive seasons 2014/2015 and 2015/2016 at the experimental nursery of Ornamental Plants and Landscape Gardening Department, Hort. Res. Inst. to study the effect of pinching and paclobutrazol (PP333) on growth, flowering and chemical composition of Hibiscus rosa-sinensis, L. cv. “Yellow”to produce dwarfed plants. Plants were pinched before treating with paclobutrazol (0.0, 3 and 4 ppm as a drench at 250 cm3/pot, or 0.0, 30 and 40 ppm as a foliar spray). The plants received 6 doses at one month interval during the growing season. Data revealed that pinching decreased fresh and dry weight of flowers. It also increased the content of total carbohydrates, indoles and phenols in the leaves. Pinching and spraying the plants with PP333 at 40 ppm decreased the height of plant, while spraying PP333 at 40 ppm without pinching increased number of leaves, length of roots and fresh and dry weight of roots. Plants sprayed with PP333 at 40 ppm with or without pinching had higher contents of total carbohydrate, indoles and phenols. Treating plants with paclobutrazol as a drench at 4 ppm increased chlorophyll a and b contents. It was recommended spraying pinched plants with PP333 at 40 ppm to produce dwarfed plants.