Production of stunted pot plants from Ruellia simplex

A pot experiment was carried out at Botanical Garden of National Gene Bank, Agricultural Research Center, Giza, Egypt during 2018 and 2019 seasons to investigate the effect of pinching treatments and foliar spraying with paclobutrazol (PBZ) on Mexican petunia (Ruellia simplex C.Wright), aiming to produce more compact plants. Three pinching treatments (non, single after 1 month from transplanting and double after 1 and 3 months from transplanting) and 4 PBZ concentrations of 0, 50, 100 and 150 ppm at one-month interval and their combined treatments laid out as a factorial RCBD was employed in this study. Best single-treatment results of dense foliage were found with single pinching or PBZ at either 50 or 100 ppm. As for combined effects, single pinching + spraying with PBZ at 100 ppm was the superior combined treatment; with a reduced plant height by 50.17 and 50.06%, increased number of branches/plant by 95.85 and 96.18%, reduced number of leaves/plant by only 10.27 and 9.26% and increased number of flowers/plant by 51.97 and 48.43% in both seasons, respectively. However, this treatment delayed flowering by 5.3 days in the first season only. The highest values regarding chlorophylls (a and b), carotenoids and total indoles were recorded by this superior combined treatment. Finally, it is recommended to treat Mexican petunia plants cultivated in 16-cm-pots filled with peat moss + perlite (1:1 by volume) with single pinch after 1 month from transplanting + 4 applications at one-month interval with PBZ at 100 ppm for optimum stunting with satisfied quality as pot plant. et al. (2015) on gaillardia, and Soliman (2011) snapdragon, Rathore and Mishra (2014) on Tagetes erecta L., Shahin et al. (2014) on Chrysanthemum carinatum, Mutlu and Agan (2015) on ornamental pepper, El-Sadek (2016) on Hibiscus rosa-sinensis and (2016) on Lagerstroemia