Dwarfing effects of paclobutrazol, chlormequat and daminozide applications on potted Primula forbesii Franch

In order to control plant height, inhibit overgrowth and prevent the lodging of flower stalks, potted Primula forbesii Franch. plants were treated with PP333, CCC and B9 by spraying their leaves and irrigating the potted soil. Results showed that all three plant growth regulators had dwarfing effects on plant height. The effect from strong to weak was PP333, B9 and CCC. The effect of soil irrigation was much greater than that of spraying the leaves with PP333, while spraying the leaves with CCC was more effective than irrigating the soil. For B9, irrigating the soil was equally effective as spraying the leaves. All three treatments restrained the length of flower stalks, but various effects were noted in the number of flowers and their diameters. The optimum dwarfing treatment for P. forbesii was the application of 500 mg/L CCC on potted soils. This treatment not only dwarfed the height of plants significantly, but also improved the quality of potted flowers by making the leaves greener and maintaining similar diameters and numbers of flowers.