Manejo de produção do girassol anão de jardim

Abstract

The Sunflower (Helianthus annuus L) is an ornamental cut and vase flower that has great expression in the market, because it has an expressive beauty, shape and different color. Sunflower harvesting point is an important factor for growers, which is characterized by its stem length over 50 cm. On the other hand, there is the demand of consumers, who prefer compact plants and inflorescence that has 10 to 15 cm in diameter. Studies on the breakdown of apical dominance, through the management known as pinch in sunflower crop, are carried out so that the lateral stems reach the largest size. However, the use of phytoregulators may increase or decrease both the main and lateral stems. Given this, the work evaluated whether sunflower flowering depends on the conditions of different types of harvest management. For that, a randomized design with four treatments and five repetitions was used. The treatments were: removal of the main chapter, removal of the main chapter and application of the gibberellin growth hormone, removal of lateral shoots and spontaneous development of the plant (control). To evaluate the effect of management on plant growth were analyzed: plant height (AP), stem diameter (DH), stem length (CH), number of leaves (NF), chapter outer diameter ( DE) and beginning of flowering (IF). The evaluations of fresh and dry mass were performed before the management application with the removal of one plant in the vegetative phase and the second in the reproductive phase. At 58 days after planting (DAP), the number of lateral shoots in the treatment with main chapter removal and gibberellin application was higher than the other treatments. Plant height, leaf number and diameter did not differ significantly between treatments. The removal of the side buttons did not influence the outer diameter of the chapter. Therefore, the different types of management applied at 44 days were not sufficient to verify their influence on the flowering of the plant.