Effect of Paclobutrazol on Some Morphological and Physiological Characteristics of Petunia under Drought Stress

Document Type: Original Article


1 Department of Horticultural Science, Shiraz Branch, Islamic Azad University, Shiraz, Iran

2 Department of Horticultural Science, Estahban Branch, Islamic Azad University, Estahban, Iran


This experiment was conducted to investigate the effect of paclobutrazol as an anti-gibberellin on some morpho-physiological characteristics of Petunia × grandiflora ‘Bravo Blue’, and determine the optimum concentration of paclobutrazol for drought resistance in this plant. The experiment was carried out as factorial based on completely randomized design with three replications in greenhouse. The studied factors were included paclobutrazol in four levels (0, 25, 50 and 75 mg a.i. l-1) and drought stress in three levels (irrigation when soil moisture reached 90 %, 75 % and 50 % of field capacity). Results showed that the application of paclobutrazol had increased the number of flowers, aerial part dry weight and number of lateral branches, and the application of this substance decreased the plant height, root dry weight and amount of carotenoids. While, paclobutrazol did not have significant effect on the electrolyte leakage, main branch number and leaf area of petunia. Also, the results showed that drought stress increased the number of flowers per plant, and reduced the content of chlorophyll, carotenoids, flower diameter, shoot and root dry weight and leaf area of petunia. Application of 75 mg a.i.­ l-1 paclobutrazol had the greatest effect on height controlling of petunia plant under drought stress. Carotenoids and chlorophyll content was increased by increasing the paclobutrazol concentration under 50% of field capacity. Generally, the results indicated that the application of paclobutrazol under severe drought stress could prevent chlorophyll and carotenoids decline, and had partially been effective in overcoming adverse effects of drought stress.

Graphical Abstract

Effect of Paclobutrazol on Some Morphological and Physiological Characteristics of Petunia under Drought Stress


The results indicated that the application of paclobutrazol under severe drought stress could prevent of chlorophyll and carotenoids decline, and had partially been effective in overcoming adverse effects of drought stress.


Abraham, S.S., Abdul Jaleel, C., Chang-Xing, Z., Somasundaram, R., Azooz, M.M., Manivannan, P. and Panneerselvam, R. 2008. Regulation of growth and metabolism by paclobutrazol and ABA in Sesamum indicum L. under drought condition. Global Journal of Molecular Sciences, 3 (2): 57- 66.

Ahmadi, M.A., Manuchehri, K. and Torkzadeh, M. 2005. Effects of 24-epibrassinolide on lipid peroxidation, prolin, sugar and photosynthesis pigments content of colza (Brassica napus L.) under water stress. Iranian Journal of Biology, 18 (4): 295-306.

Ahmad-Nazarudin, M.R., Mohd-Fauzi, R. and Tsan, F.Y. 2007. Effects of paclobutrazol on the growth and anatomy of stems and leaves of Syzygium campanulatum. Journal of Tropical Forest Science, 19(2): 86 - 91.

Al-Khassawneh, N.M., Karam, N.S. and Shibli, A.R. 2006. Growth and flowering of black iris (Iris nigricans Dinsm) following treatment with plant growth regulators. Scientia Horticulturae, 107: 187 - 193.

Amina, A.A. and Hanan, H.L. 2011. Differential effects of paclobutrazol on water stress alleviation through electrolyte leakage, phytohormones, reduced glutathione and lipid peroxidation in some wheat genotypes (Triticum aestivum L.) grown in vitro. Romanian Biotechnological Letters, 6: 6710 - 6721.

Arnon, D.T. 1949. Copper enzymes in isolation chloroplast phenoloxidase in Beta vulgaris. Plant Physiology, 24: 1-15.

Arteca, R.N. 1996. Plant growth substances: Principles and application. Chapman and Hall. Inc. NY. 332 pp.

Asamoah, T.E.O. and Atkinson, D. 1985. The effects of (2RS, 3RS)-1-(4-chlorophenyl)-4,4-dimethyl-2-(1H-1,2,4 triazol-1-yl) pentan-3-ol (paclobutrazol: PP333) and root pruning on the growth, water use and response to drought of Colt Cherry rootstocks. Plant Growth Regulation, 3(1): 37 - 45.

Barrett, J. 2001. Section 5: mechanisms of action, p.32-41. In: M. Gaston (ed). Tips on regulating growth of floriculture crops. OFA service Inc, Columbus, OH.

Barrett, J.E. and Bartuska, C.A. 1982. PP333 effects on stem elongation dependent on site of application. HortScience, 17: 737 - 738.

Bayat, S. and Sepehri, A. 2012. Paclobutrazol and salicylic acid application ameliorates the negative effect of water stress on growth and yield of maize plants. Journal of Research in Agricultural Science, 8 (2): 127- 139.

Bian, S. and Jiang, Y. 2009. Reactive oxygen species, antioxidant enzyme activities and gene expression patterns in leaves and roots of Kentucky bluegrass in response to drought stress and recovery. Scientia Horticulturae, 120­ (2): 264 - 270.

Bray, A.E. 1997. Plant responses to water deficit. Trends in Plant Science, 2 (2): 54 - 45.

Chegah, S., Chehrazi, M. and Albaji, M. 2013. Effects of drought stress on growth and development frankenia plant (Frankenia leavis). Bulgarian Journal of Agricultural Science, 19 (4): 659 - 666.

Cox, D.A. 1991. Gibberellic acid reverses effects of excess paclobutrazol on geranium. HortScience, 26 (1): 39 - 40.

Cramer, C.S. and Bridgen M.P. 1998. Growth regulator effects on plant height of potted mussaenda ‘Queen Sirikit’. HortScience, 33: 78-81.

Denek, C.F. and Keever, G.J. 1992. Comparison of application methods of paclobutrazol for height control of potted tulips. HortScience, 27 (12): 13-29.

Desclaux, D. and Roumet, P. 1996. Impact of drought stress on the phenology of two soybean (Glycine max L. Merr) cultivars. Field Crops Research, 46: 61–70.

Fletcher, R.A. 1985. Plant growth regulating properties of sterol inhibiting fungicides. In: Hormonal regulation of plant growth and development. Agro Botanical Publishers, Bikaner. India. 103 - 113.

Fletcher, R.A., Gilley, A., Sankhla, N. and Davis, T.M. 2000. Triazoles as plant growth regulators and stress protectants. Horticultural Reviews, 24: 56 - 138.

Francescangeli, N. and Zagabria, A. 2008. Paclobutrazol for height control of petunias. Chilean Journal of Agricultural Research, 68 (3): 309 - 314.

Gianfagna, T.J. and Wulster, G.J. 1986. Growth retardants as an aid to adapting freesia to pot culture. HortScience, 21: 463 - 464.

Gilbertsz, D.A. 1992. Chrysanthemum response to timing of paclobutrazol and uniconazol sprays. HortScience, 27: 322 - 323.

Gopi, R., Sridharon, R., Somasundaram, R., Alagulakshmanan, G.M. and Panneerselvam, R. 2005. Growth and photosynthetic characteristics as affected by triazols in Amorphophallus campanulatus. General and Applied Plant Physiology, 31 (3-4): 171 - 180.

Hua, S., Zhang, Y., Yu, H., Lin, B., Ding, H., Zhang, D., Ren, Y. and Zhigen, F. 2014. Paclobutrazol application effects on plant height, seed yield and carbohydrate metabolism in canola. International Journal of Agriculture and Biology, 16(3): 471– 479.

Jaleel, C.A., Gopi, R., Manivannan, P., Kishorekumar, A., Sankar, B. and Panneerselvam, R. 2006. Paclobutrazol influences vegetative growth and floral characteristics of Catharanthus roseus (L.) G. Don. Indian Journal of Applied and Pure Biology, 21: 369 - 372.

Jaleel, C.A., Manivannan, P., Wahid, A., Farooq, M., Somasundaram, R. and Panneerselvam, R. 2009. Drought stress in plants: a review on morphological characteristics and pigments composition. International Journal of Agriculture and Biology, 11: 100 - 105.

Javadi, T. 2012. Effect of water stress on growth characteristics and gas exchange in paclobutrazol treated pear (Pyrus communis cv. Bairouty). Iranian journal of Horticultral Science, 43(3): 345 - 355.

Kalil, I.A. and Rahman, H. 1995. Effects of paclobutrazol on growth, chloroplast pigments and sterol biosynthesis of maize (Zea mays L.). Plant Science, 105: 15-21.

Kramer, P.J. and Boyer, J.S. 1995. Water relations of plants and soils. Academic Press, SanDiego, CA. 495 p.

 Kumar, S.,  Ghatty, S.,  Satyanarayana, J.,  Guha, A.,  Chaitanya, B.S.K. and Reddy, A.R. 2012. Paclobutrazol treatment as a potential strategy for higher seed and oil yield in field-grown Camelina sativa L. Crantz. BMC Research Notes, 5: 137.

Latimer, J.G. 1991. Growth retardants affect landscape performance of zinnia, impatiens, and marigold. HortScience, 26: 557 - 560.

Lever, B.G. 1986. 'Cultar'-A technical overview. Acta Horticulturae, 179: 459 - 466.

Lin, M. and Zhang, G. 1999.  Effects of paclobutrazol on the morphology, structure and chlorophyll content of regenerated plantlets of maize. Plant Sciences, 49: 85 - 88.

Lutts, S., Kinet, J. M. and Bouharmont, J. 1996. Nacl-induced senescence in leaves of rice (Oryza sativa L.) cultivars differing in salinity resistance. Annual Botany, 78: 389 - 398.

Mafakheri, A., Siosemardeh, A., Bahramnejad, A., Struik, P.C. and Sohrabi, Y. 2011. Effect of drought stress and subsequent recovery on protein, carbohydrate contents, catalase and per-oxidase activities in three chickpeas (Cicer arietinum) cultivars. Australian Journal of Crop Science, 5­(10): 1255 - 1260.

Magnitskiy, S.V., Pasian, C.C., Bennett, M.A. and Metzger, J.D. 2006. Controlling plug height of verbena, celosia and pansy by treating seeds with paclobutrazol. Horticultural Science, 41: 158 - 161.

Olsen, W.W. and Andersen, A.S. 1995. The influence of five growth retardants on growth and postproduction qualities of Osteospermum ecklonis cv. ‘Calypso’. Scientia Horticulturae, 62: 263 - 270.

Pinto, A.C.R., Rodrigues, T.J.D., Leite, I.C.  and  Barbosa, J.C. 2005. Growth retardants on development and ornamental quality of potted ‘Lilliput’ Zinnia elegans JACQ. Scientia Agricola, 62(4): 337 - 345.

Rademacher, W. 2000. Growth retardants: Effects on gibberellin biosynthesis and other metabolic pathways. Annual Review of Plant Physiology and Plant Molecular Biology, 51: 501 – 531.

Ramina, A., Toutti, P. and Tosi, T. 1985. The effect of paclobutrazol on strawberry growth and fruiting. Journal of Horticultural Science, 60: 501 - 506.

Ribeiro, D.M., Muller, C., Bedin, J., Rocha, G.B. and Barros, R.S. 2011. Effects of autoclaving on the physiological action of paclobutrazol. Agricultural Science, 2(3): 191 - 197.

Safarnejad, A. 2004. Characterization of somaclones of alfalfa (Medicago sativa) for drought tolerance. Journal of Agriculturral Science and Technology, 6: 121-127.

Stang, E.S. and Weis, G.G. 1984. Influence of paclobutrazol plant growth regulator on strawberry plant growth, fruiting and runner suppression. HortScience, 19: 643-645.

Steadman, K.J., Ellery, A.J., Chapman, R., Moore, A. and Turner, N.C. 2004.  Maturation Temperature and rainfall influence seed dormancy characteristics of annual rye- grass (Lolium rigidum). Australian Journal of Agricultural Research, 55(10): 1047 - 1057.

Tatari, M., Fotouhi Ghazvini, R., Etemadi, N., Ahadi A.M. and Mousavi. A. 2013. Study of some physiological responses in three species of turfgrass in drought stress conditions. Journal of Plant Production, 20(1): 63 - 87.

Wample, R.L. and Culver, E.B. 1983. The influence of paclobutrazol, a new growth regulator on sunflowers. Journal of the American Society for Horticultural Science, 198: 122 - 125.

Wang, Y.T. and Gregg, L.L. 1991. Modification of hibiscus growth by treating unrooted cuttings and potted plants with uniconazole or paclobutrazol. Journal of Plant Growth Regulation, 10(1): 47 - 51.

Watson, G. and Jacobs, K. 2012. Control of apple scab and cytospora canker with paclobutrazol. Arboriculture and Urban Forestry, 38(3): 112 – 116.

Werner, H. 1993. Influence of paclobutrazol on growth and leaf content of sweet cherry cultivars. Horticultural Science, 65: 519 - 527.

Whipker, B.E. 2013. Growth regulators for floricultural crops in greenhouses. In: Plant growth regulator guide. GrowerTalks Magazine, C. Beytes, ed. (West Chicago, IL: Ball Publishing), pp. 8 – 37.

Wieland, W.F. and Wample, R.L. 1985. Effects of paclobutrazol on growth, photosynthesis and carbohydrate content of ‘Delicious’ apples. Scientia Horticulturae, 26: 138 - 147.

Williamson, J.G., Coston, D.C. and Grimrs, L.W. 1986. Growth responses of peach roots and shoots to soil and foliar applied paclobutrazol. HortScience, 21: 1001-1003.