Effect of paclobutrazol in potted plants of four cultivars of Dianthus barbatus x chinensis

摘要

Dianthus barbatus x chinensis is a perennial herb derived from the interspecific cross between Sweet Williams (D. barbatus L.) and China pink (D. chinensis L.). At present cultivated as a cut flower, it could be potential as a flowering potted plant, but height control should be performed. In this study, the possibility to reduce plant height by the use of paclobutrazol (triazole; PBZ) was investigated in four cultivars. In addition, the effect of PBZ on flowering (inflorescence number and size, and flowering time) and on leaf colour was evaluated. Two experiments were carried out in different seasons (corresponding to autumn potting and summer potting, respectively) and PBZ was applied as a substrate drench at different dosages: 0.5, 1, and 2 mg per pot for autumn-potted plants; 0.25, 0.5, and 1 mg per pot for summer-potted plants. Paclobutrazol resulted to be effective in controlling plant height in all the studied cultivars without producing any toxicity symptoms. Neither effect of PBZ on number and size of inflorescences, nor on flowering time was observed. On the contrary, PBZ enhanced leaf colour.