Growth Reduction effects of Paclobutrazol Applied at Different Cacao Seedling Stages.

The effects of paclobutrazol on the morphological and growth characteristics of caco (Theobroma cacao L.) seedlings were evaluated. The experiment was arranged in four randomized blocks in a split-plot lay-out. Main plots were assigned to growth stages (mature cotyledonary leaves, first, second and third flushes) and sub-plots to paclobutrazol dosages (0,30, and 60 ppm). Periodic measurements were taken of stem diameter, height and leaf number. At the end of the experiment leaf area and dry weights of root, stem and leaves were obtained. In general, paclobutrazol decreased diameter, height, leaf number and leaf area in all concentrations. The effect depended on concentration and stage of growth. Dry weight of all plant parts decreased with the application of paclobutrazol. The highest root, stem and leaf dry weight reductions, 74%, 82% and 77%, respectively, were found at the 60 ppm-cotyledonary stage treatment. The lowest reduction was at the 60 ppm-third flush combination (22%, 38% and 39% for root, stem and leaf, respectively). There was more partitioing of assimilates to roots than to shoots in most of the treatment combinations.