Evaluación de dosis creciente de nitrógeno en cultivo hidropónico de lechuga (<i>lactuca sativa</i> l.) utilizando la técnica raíz flotante

Abstract

This work has the objective to evaluate different levels or increasing doses of nitrogen in hydroponic crop of lettuce, using the technique of floating root, in an effort to determine the it influence on the readings of a clorofilómetro SPAD CCM 200 Plus fresh weight and the dry matter of the culture. The clorofilómetro provides results in SPAD units, reflecting the nutritional status of the crop by measuring the intensity of green lettuce leaves, generating an idea about the conditions of nutritional soil according to nutritional status of plants, for subsequent crop nutritional adjustment. The culture was isolated from external factors through mesh or ZARAN and set in wooden crates where lettuces are suspended in vessels white 1 ounce plastic resting on white floating on a water surface foam in such water is It incorporates oxygen through aerators equipment; Drawers were arranged in blocks form with treatments completely at random, the source of water used to form the solutions is well, completely analyzed, however, the area does not have a separate water source, all aparataje was established in the Granja Santa Inés of the Academic Unit of Agricultural Sciences at the Technical University of Machala. The experiment consists of changes in nutrient solution to maintain adequate levels of nutrients each treatment (T1 0% N, T2 100% N, T3 150% N and T4 200% N), therefore the change is made same every 4 days, every treatment with corresponding replicates are incorporated respective salts (fertilizers) as well as daily readings parameters pH, EC and daily STD performed with a computer HANNA. Samples were taken every 8 days, taking 5 samples per repeat and performing five readings per plant with equipment, then reading be taken to the laboratory of soil of the Academic Unit of Agricultural Sciences to be weighed on an analytical balance ECHO to obtain the average weight and then placed in the oven to obtain the dry matter. The T4 (200% N) obtained the highest value in the third sample, with 6,670 units SPAD, thus indicating which is the most intense green has and is also the only treatment that is significantly different to others, however, in the first two sampling this treatment has significant differences from the others it is the T1 (0% N). The study of the values of nitrogen through the intensity of green color of chlorophyll to diagnose deficiencies of this element (N), so that it can adjust the dose of salts or fertilizations, not simply in hydroponics but also in crops grown in soil or other substrate, allowing to adjust the fertilization, this technique having general applicability in crops, providing quick results and strengthening the efficient use of nutrients.