Abstract

BRITO, Carmem L.L. et al. Effect of paclobutrazol in the development of ornamental sunflower. Rev. de Ciências Agrárias [online]. 2016, vol.39, n.1, pp.153-160. ISSN 0871-018X.  https://doi.org/10.19084/RCA15044.

In order to evaluate the effects of paclobutrazol growth regulator on the development of ornamental sunflower studies were carried out in plants grown in greenhouse. The experimental design consisted of randomized blocks with five treatments (paclobutrazol rates) and four replications, so, 20 experimental units. Paclobutrazol was applied directly on the substrate, at 0; 75; 150; 300 and 600 mg L^-1. The cultivar 'Multissol', with an average height of 1.80 m, erect and average diameter of the flower head (capitulum) 22 cm. Plant height, stem diameter, number of leaves and internodes, leaf area, Spad index, biomass fresh weight and shoot dry, roots and capitulum were evaluated. There was a significant effect of paclobutrazol on plant growth. The application of paclobutrazol at 300 and 600 mg L^-1, 30 days after, reduces the height of sunflower plants by 50% without affecting biomass of fresh weight and dry shoots, roots and capitulum. Increasing rates of paclobutrazol changed the morphology of the shoots of sunflower plants and raised the SPAD index.

Keywords : growth inhibitor; Helianthus annuus L; plant growth regulator.

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