Effect of Pinching and Paclobutrazol (Pbz) on Vegetative Growth of Russelia equisetiformis for Using as a Pot Plant

 THE PRESENT experiment was performed at the nursery of Horticulture Research Institute, Agriculture Research centre, Giza, Egypt during two successive seasons 2013 and 2014. It intended to dwarf vegetative growth of Russelia equisetiformis for using as a pot plant. Thus, the individual and the combined effects of different pinching treatments (after either one or two months from planting) and various levels of paclobutrazol (0, 100, 150 and 200 mg/l) were applied as a foliar spray, commencing from one month of planting and then at weekly intervals till the experiment termination in (September15th) in both seasons. The results emphasized that using pinching treatment for only one time produced the highest number of secondary shoots/plant and increased fresh and dry weight of shoots/plant as well as flower number/plant. Meanwhile, treating plants with pinching treatment for two times proved its superiority in reducing plant height with increasing number of main shoots, root length and number of roots/plant. Additionally, negligible and insignificant differences were observed for fresh and dry weights of roots due to using pinching treatments in both seasons.
Plant height was gradually decreased by increasing paclobutrazol levels in both seasons, whereas number of roots/plant was progressively increased by increasing paclobutrazol level in the same seasons. Applying paclobutrazol at 100 mg/l revealed a clear increment in either fresh or dry weight of shoots/plant. Moreover, root length was increased due to using the same paclobutrazol level (100 mg/l). Supplying plants with paclobutrazol at 150 mg/l proved its mastery in raising number of main and second shoots/plant. Also, the same treatment proved its superiority for raising fresh and dry weight of roots. Meanwhile, paclobutrazol treatment at 200 mg/g gave rise to the utmost high values of flower number/plant.
Referring to chemical constituents of vegetative growth parts, pinching treatment for two times proved its mastery in raising chlorophyll (a) and carotenoids contents, whereas it slightly increased chlorophyll (b). Meanwhile, the same treatment caused a slight increment in phenols content, but decreased indoles content in the