Uso de tela plástica fotosseletiva e de paclobutrazol no cultivo de girassol ornamental em ambiente protegido, em Ilha Solteira –SP.

Abstract

The objective of the research was to evaluate the use of photoselective plastic shadenet and effect of plant growth regulator paclobutrazol drench concentrations (0; 0,25; 0,50; 0,75 e 1,0 mg.L-1 of substrate) on pot plants of sunflower grown under protected environment, as well as the microclimatic changes resulting from the use of the referred plastic net. Two greenhouses were covered with transparent polyethylene film, 100 μm thick, and at one of them, the plastic film was applied over a blue photoselective plastic shadenet (30% of shading). Microclimatic and agronomic parameters were evaluated. The results showed that radiant density flux was reduced by 27,5 %, in average, when the shadenet was used, what had influenced poorly the air temperature and humidity in the shelter. Further, the use of the shadenet did not reduced plant height and did not influenced inflorescence diameter, the number of leaves per plant and the interval from transplant to flowering. Nevertheless, paclobutrazol substrate drench decreased plant height, leading to more compact plants that can be grown and commercialized in pots, without any loss to plant quality, since the inflorescence diameter and the number of leaves per plant were not commercially affected by the use of the growth retardant, and the flowering was delayed according to the paclobutrazol concentration, but not exceeding one week.