Morfofisiologia e produção de alface hidropônico sob salinidade e adubação foliar com silícato de potássio.

Abstract

Based on the current global scenario of water demand to maintain intense and successive crops, it is necessary to search for alternatives for the correct management of water in order to reduce waste. Hydroponics, for example, has become a viable alternative for vegetable production using lower quality water, especially in semi-arid regions, where they are predominant. The search for alternatives includes biological or synthetic substances that generate physiological and biochemical responses that promote plant adaptation to adverse environmental conditions, such as the nutrient silicon. Thus, the objective was to study the growth, physiology and production of hydroponic lettuce cultivars subjected to salinity and silicon-based foliar fertilization. The experiment, in turn, took place between the months of September and October 2021, at the Vale dos Ipês Rural Property, located in the Municipality of São Mamede, PB. The experimental design was completely randomized in a 4 × 2 × 2 factorial scheme, the first factor is related to four electrical conductivities of the nutrient solution (1.4; 2.0; 2.6 and 3.2 dS m-1) with two concentrations of Si (potassium silicate) (0.0 and 0.6 mM) and two curly lettuce cultivars, Leila and Isabel, totaling eight replications. The experiment was carried out in a greenhouse with four hydroponic planting benches in the NFT system (nutrient film technique), spaced 0.50 m apart and profiles spaced 0.14 m apart and a slope of 5%. The number of leaves, stem diameter, dry mass of the stem and leaves, gas exchange, photosynthetic pigments and production were evaluated. It was found that salinity reduced the growth of lettuce plants 15 days after transplanting from an EC of 2.4 dS m-1. The use of nutrient solutions with EC up to 2.4 dS m-1 is recommended for lettuce production. Increases in the electrical conductivity of the nutrient solution above 2.4 dS m-1 increase the photosynthetic pigments of lettuce plants.