Treated Domestic Effluents: An Option for Cultivation of Ornamental Sunflower in a Hydroponic System

Abstract

Aims: The present study aimed to evaluate the use of treated domestic effluent as complementary nutritional source for the production of ornamental sunflower (Helianthus annuus L. cv. ‘Anão de Jardim’) in a DFT hydroponic system with pyramid-type structure. Study Design: Was used completely randomized experimental design with four treatments and six replicates, totaling 24 experimental plots, each one comprising of 7 plants. Place and Duration of Study: The experiment was conducted between March to May 2017, in a greenhouse, located in the experimental area of the Agricultural Engineering Graduate Program of the Federal University of Recôncavo of Bahia, located in the municipality of Cruz das Almas-BA, Brazil. Methodology: Ornamental sunflower plants were grown in nutrient solution with different concentrations of nutrients prepared in treated domestic effluent (TDE) or public-supply water as described: T1 – Furlani’s nutrient solution at 100% concentration prepared with public-supply water (control), T2, T3 and T4 – Furlani’s nutrient solutions at 100, 75 and 50% of nutrient concentration prepared with TDE, respectively. Were evaluated plant height, stem diameter, number of leaves, leaf area, leaf and stem dry mass, the absolute and relative growth rates of height, stem diameter and dry shoot mass (leaves plus stem), internal and external diameter of the capitulum, dry mass of the capitulum, contents of the N, P, K, Ca and Mg in the leaf and stem, water consumption and water use efficiency of plant. Results: Nutrient solution with concentration reduced by 50% and prepared with TDE (T4) led to satisfactory growth until the first 20 days and, after this period, although growth and production were inferior to those obtained in the other treatments (T1, T2 and T3), but the variables evaluated in the plants of all treatments met the requirements for commercialization. The contents of N, P, K, Ca and Mg in leaf and stem of sunflower plants at harvest did not show significant differences under different treatments. Conclusion: The obtained results allow to infer on the viability of using TDE to prepare the nutrient solution and as a complementary source of nutrients up to the extent of 50% for the cultivation of ornamental sunflower, cv. ‘Anão de Jardim’ in a hydroponic system.