Effect of different phytoregulators on the hardening of zonal geranium.
Zonal geraniums (Pelargonium hortorum) adapted as a pot flower with red flowers, and acquired on 20 April 2007 from a commercial nursery in Murcia (Spain) in 14-cm plastic pots with peat as substrate, were placed in an unheated greenhouse under an automatic irrigation system, and treated with insecticides to control Cacyreus marshalli (Confidor 20 LS, 20% imidacloprid) and Frankliniella occidentalis (Dicofol 48 Le Cag, 48% dicofol). Hardening treatments involved the application of three phytoregulators, on 24 May: two were triazole compounds (which have both growth retardant and fungicidal activity) - Cultar (25% paclobutrazol, a growth retardant) at 60 ppm, and Vectra (10% bromuconazole) at 50 ppm; the third was Gerasol (a geranium antistress detergent) at 0.5 ml/litre (500 ppm); a control non-treatment was included. The plants were assessed on 26 June for development, leaf and flower colour, petal fall, mechanical resistance of the stems and stalks. Cultar reduced plant growth, while the other treatments did not, but it maintained leaf colour, as did Gerasol (though to a lesser degree), and enhanced the mechanical resistance of the plant. However, apart from the effect of Cultar in reducing plant growth, the overall differences between treatments and the control were not large.