A Influência da concentração de nutrientes no crescimento da alface crespa (Lactuca sativa L. Var. caipira) em Manaus

Abstract

With the growing demand for healthy products due to changes in the population's eating habits, lettuce is evidenced in hydroponic cultivation because it has a low caloric content, a short reproductive cycle and is usually served in nature, in the form of a salad, in the consumption of the various Social classes. The Nutrient Film Technique (NFT) was used, where the system consists of a bench whereby the root system is irrigated by slides of nutrient solution in the culture channels from a reservoir tank by the action of pumping and return with scheduled intervals. The objective of this study was to analyze the best concentration of nutrients in the growth of lettuce (Lactuca sativa) crisp in Manaus, Brazil, in order to obtain better products at commercial levels, under two conditions (winter and summer). The results of the analyzes indicated that the EC of 1.0 mS / cm achieved better results than the other treatments for CPA and CR, with averages of 21,6 cm (winter) and 17,2 cm (summer). These values are probably indicated by the lower osmotic pressure acting on the root system, in which they facilitate the absorption of water and nutrients. In relation to MSPA (summer) and MSPA (winter) with averages of 12,2 and 15,6 g respectively, they indicated that, in the summer, there was lower nutrient gain and dry phytomass accumulation by the EC of 1.0 mS / cm and that this result may have been influenced by the increase of the temperature in the leaves with influence to the photosynthetic processes. On the other hand, the MFPA and MFR (summer) in CE¹ had a 13,7% reduction in fresh mass accumulation and tabulated results in relation to those observed in winter and this may have been caused by the difference in temperature averages, had a gain of 3.4 ° C and higher concentrations of nutrients. Summer indicated that it is a not ideal time for hydroponic cultivation in the Manaus region due to the observed deficit of the results, whereas this activity becomes viable through the protected cultivation in which they promote microclimate changes inside the greenhouse, providing a better plant development.