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Application of growth retardants in hybrids of ornamental sunflower.


The cultivation of ornamental sunflower has been increased during the past few years, as cut flower and pot plants. Several management practices are used for the production of pot ornamental plants, and among them the use of growth retardants. The objective of this research was to evaluate the effect of three growth etardants on development of hybrids of ornamental sunflower (‘Sunbeam’, ‘Sunbright’ and ‘Sunbright Supreme’). The experiment was conducted under greenhouse conditions at Faculdade de Ciências Agrárias e Veterinárias - UNESP- Câmpus de Jaboticabal-SP. The plants were fertilized with Osmocote, White Kristalon, Orange Kristalon and calcium nitrate and were conducted by pinching lateral buds, leaving only the apical flower bud. The solutions of paclobutrazol (3mg/pot, in the substratum), chlormequat chloride (0.4g/pot, leaf application) and daminozide (0.5g/pot, leaf application) were applied when the plants presented 5-6 leaf pairs (25 days after sowing) and average height of 21.45 cm. The experimental design was in complete blocks and factorial arrangement of three hybrids and three retardants plus the control, with four replications. There was no significant interaction between the factors for all the characters analyzed (plant height, leaf number, head diameter and leaf area). The lowest value of plant height was obtained with the application of chlormequat chloride. The hybrid ‘Sunbright’ presented the highest height, smallest head and highest leaf area. There were no significant differences among hybrids nor among products in relation to leaf number. Daminozide induced lower head diameter and was different (P<0.05) from control plants. The final height of all plants that received the growth retardants was not enough for marketing.

ISSN: 2447-536X

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