NITROGEN SUPPLY IN LISIANTHUS (Eustoma grandiflorum [Raf.] Shinn) CV. ABC2 LAVANDER

Abstract

Lisianthus is a species of high economic value due to the attractiveness of its flower, variety of colors and prolonged vase life. However, there is little information regarding its nutrient demands, especially nitrogen. Nitrogen is quantitatively the most important nutrient for the growth of plants. The objectives of the present study were to define nitrogen concentration for optimum growth and quality of lisianthus cv. ABC2 Lavender, to elaborate the curve of nutritional supply of nitrogen to determine the sufficiency concentration, and to determine the distribution of this element within the plant. Lisianthus liners were established in 10 L black polyethylene bags filled with volcanic rock of 3 mm in diameter. The treatments consisted of increasing concentrations of nitrogen: control (no nitrogen), 3, 6, 9, 12, 15 and 18 meq L^-1; the reminder nutrients were supplied based on Steiner´s nutrient solution formulation. The experiment was set up in a completely randomized design. The results indicated that for optimum leaf area, height, number of flower buds, dry weight and time to flowering, the best treatment was 6 meq L^-1 of nitrogen. Concentrations lower than 6 meq L^-1 and higher than 15 meq L^-1 caused growth reduction. According to the models for nitrogen supply, the sufficiency range was between 6.4 and 7.4 meq L^-1, which was associated with a shoot nitrogen concentration of 1.5% to 1.7%, which we proposed as nitrogen sufficiency values for this cultivar. The order of accumulation of biomass was: shoot>flowers>root; the order of accumulation of nitrogen was: flowers>shoot>root.