GROWTH RETARDATION OF SHAMROCK (TRIFOLIUM DUBIUM) IN HYDROPONIC CULTURE

The shamrock (Trifolium dubium) is worn by people of Irish descent internationally on St. Patrick's Day (17 March). As a contribution to the development of a production blueprint for ready-to-wear and root-intact plants, for export internationally, the influence of plant spacing and use of growth retardants in hydroponic culture was investigated.

A density of 256 plants m^-2 produced better quality plants than higher (400.m^-2) or lower (204.m^-2) densities. Such plants had a better branched, open-structure and spreading habit, resulting in a well- balanced, uniform rosette.

Chlormequat treatment (at 2.5, 7.5 and 22.5 mgl^-1) had little effect on plant form/shape, compared with paclobutrazol (at 0.3, 0.9 and 2.7 mgl^-1) or uniconizole (at 0.1, 0.3 and 0.9 mgl^-1). Paclobutrazol and uniconizole produced dose-related growth reductions, which were too severe at the higher concentrations. Plant spread and height reductions were 60 and 71% respectively at the 0.9 mgl^-1 uniconizole level.

Plant spread : height and shoot : root ratios were significantly altered by chemical treatment. The enhanced greening of treated plants was a distinct quality advantage.