ABSTRACT
Humic substances are used in agriculture to promote plant growth, especially of the root system. The aim of this work was to evaluate the effect of applying different doses of fulvic acid on growth and productivity in the Raider Plus cultivar of the lettuce. The experimental design was completely randomised, with five treatments of fulvic acid 0, 1, 2, 4 and 8 ml L-1 and four replications, applied when transplanting. Two experiments were conducted simultaneously; one carried out in a greenhouse, where the fresh and dry weights of the shoots and roots, and the length and volume of the roots were evaluated. The other experiment was carried out in the field, where the fresh and dry weight of the shoots, the number of leaves, length of the stem and average head circumference were evaluated at the end of the cycle. The application of different doses of fulvic acid promoted growth in the lettuce plants, especially in the root system. The emission of roots, mainly of smaller diameter, was found at the higher concentrations of fulvic acid. The number of leaves and average head circumference expressed a response to the concentrations of fulvic acid.
Key words:
Organic system; Humic substances; Lactuca sativa L.
