Phyllody Malformation in Flowers of Rosa×hybrida cv. Motrea: Effects of Rootstocks, Flower Position, Growth Regulators and Season

Abstract

Phyllody, a common malformation of Rosa×hybrida cv. Motrea, is characterized by the formation of vegetative structures in place of stamens and carpels. The incidence of phyllody in this cultivar is dependent on the type of the root system. The highest proportion of malformed flowers was found in ungrafted plants, this decreased in plants grafted on R. indica major and was lowest on R. canina inermis. Flowers formed on shoots, which were located closer to the roots, were more prone to phyllody than those grown on the upper part of the plants. The incidence of phyllody was lower in winter than in summer, while shading of the plants reduced the proportion of malformed flowers regardless of their root system and the season. Application of gibberellic acid (GA₃) or benzylaminopurine (BAP) greatly promoted the incidence of phyllody, while paclobutrazol (PBZ) reduced it. The activity of endogenous cytokinins in the xylem exudates from ungrafted plants was higher than in exudates from those grafted on R. indica major, and the lowest activity was found in exudates from plants grafted on R. canina inermis. The involvement of plant hormones in the development of floral organs in rose flowers is discussed.

Cytokinins, flower malformation, gibberellic acid, homeosis, phyllody, roses