Cytokinin-Regulated Physiological Parameters Affected by an Exogenous Dopamine Spray in Brussels Sprout (Brassica oleracea var. gemmifera)

Root restriction on the first stage of seedling growth decreases post-transplant biomass accumulation. Several studies in different vegetables and ornamental plants have suggested that this restriction would be overcome by means of a single 6-benzylaminopurine (BAP) spray. Based on this, the aim of this work was to evaluate the effects of both pre-transplant single BAP and dopamine (a cytokinin antagonist) sprays on the growth of Brussels sprout (Brassica oleracea var. gemmifera) plants grown in 200 plug cells tray-1, during different times of the annual cropping period. The responses of dopamine-sprayed plants were not completely similar to those previously reported. The different physiological processes studied in dopamine-sprayed plants through some growth parameters showed that dopamine affected mainly the rate of leaf appearance, which in turn positively affected both individual and total leaf area expansion. Dopamine-sprayed plants showed a higher leaf source, which allowed them to accumulate a higher biomass on both a fresh and dry weight basis during the initial vegetative growth stages. The effects of both BAP and dopamine were partially related to the environmental conditions during the experiments.