Influence of method and time of application of selected plant growth retardants on growth of ivy geranium (Pelargonium peltatum)

Pelargonium Key Words: Alar, Bonzi, CCC, Method of application, Time of application, peltatum, commonly grouped as Ivy geranium, shows stretching growth habit with little number of lateral branches due to these characteristics of the species it is difficult to produce more-compact, attractive, and salable cuttings. When cultivated in containers for cuttings production, this species grows up quickly and fall-over the pots. To manage the problem growers regularly use plant growth retardants (PGRs) like Alar, CCC, Bonzi, and Florel. However, the main limitations with the use of these chemicals are misapplication related to defining the right type of chemicals, method and time applications of them for the crop. Therefore, this experiment was initiated to assess the Influence of Method and Time of Application of Selected PGRs on Growth of Ivy Geranium. The study was conducted at Jimma University College of Agriculture and Veterinary Medicine under greenhouse condition. It was laid out with 3 x 2 x 2 factorial arrangement with three replications in Randomized Complete Block Design (RCBD). The application of plant growth retardants on the tested plant brought changes on Number of Leaves per plant, Leaf Area, Number of Branches per plant, Plant Height, Inter-node Length, Main Stem Diameter, Root Length and Root Volume but not on Root Number. Number of Leaves per Plant, Number of Branches per Plant, Main Stem Diameter and Root Volume of the test plant significantly (p<0.05) increased with the application of plant growth retardants. Conversely, Leaf Area, Plant Height, Inter-node Length and Root Length showed notable reduction. Number of branches per plant was increased by 53.66% from the control in response to two way interaction effects of plant growth retardants and their method of applications (p< 0.01). The increase in number of branches is associated with the reduction of plant height (56.74%) in response to three way interaction effects of plant growth retardants, their method and time of application (p< 0.01) and inter-node length (32.18%) in response to two way interaction effect of plant growth retardants and their method of applications (p< 0.05). Bonzi plant growth retardant was found to be the most strong, while Alar was the weakest to suppress the stretching habit of the plant under investigation. The two way interaction effect of plant growth retardants and drench form of application was found more effective than spray application of plant growth retardants under investigation. Moreover, the three way interaction effect of plant growth retardants, drench application and early stage application was found very effective to restrict