YIELD AND NUTRITIONAL STATUS OF KALE (Brassica oleracea) cv. DWARF BLUE CURLED SCOTCH AS A FUNCTION OF THE ELECTRICAL CONDUCTIVITY OF THE NUTRIENT SOLUTION

Abstract

Kale (Brassica oleracea) cv. Dwarf Blue Curled Scotch is a recently introduced vegetable in Mexico. Its nutritional requirements for greenhouse and hydroponics production are unknown. The first aspect to investigate to carry out a successful production in controlled environments is to elucidate the response of the crop to the electrical conductivity (EC) of the nutrient solution in its development and commercial quality, under the hypothesis that the higher the EC of the nutrient solution the higher the yield and the nutritional concentration. To verify the hypothesis, an experiment was established in hydroponics with EC of 0.5, 1.0, 1.5 and 2.0 dS m^-1 in the Steiner nutrient solution, in a greenhouse at Campus Montecillo of the Colegio de Postgraduados, Mexico. The experimental design used was completely randomized with 10 replications. Peat was used for seed germination, and the transplant was carried out 23 days after sowing. Seedlings were transplanted into 6 L pots with perlite. The four EC treatments were applied from the transplant and the harvest was carried out 54 days after transplant. Results indicated that the higher the EC, the SPAD readings and the total nitrogen concentration in the leaf increased. Plant height, leaf width, stem diameter, length and root volume, as well as fresh weight of the whole plant increased from 23 to 75 % in the solutions of 1.5 and 2.0 dS m^-1, respectively. It is concluded that a higher EC (2.0 dS m^-1) improves kale yield; likewise, the concentration of total nitrogen, nitrates and SPAD readings are increased and the concentration of Ca decreases in the petiole cell extract and in leaf tissue.