Application of fulvic acid to seedlings influencing root growth and productivity of iceberg lettuce

Abstract

Humic substances are used in agriculture as promoters of plant growth, especially of the root system. The objective
of the work was to evaluate the effect of the application of different doses of fulvic acid on the growth and productivity
of American lettuce, Raider Plus cultivar. The experimental design used was entirely randomized, with five treatments
of fulvic acid 0, 1, 2, 4, 8 mL·L
-1
and four repetitions, applied at the time of transplanting. Two experiments were conducted simultaneously: one in the greenhouse, where fresh and dry mass of the aboveground and root parts, length and
volume of the roots were evaluated; and the other in the field, where, at the end of the cycle, fresh and dry mass of the
aboveground parts, number of leaves, stem length and average head circumference were evaluated. The application of
different doses of fulvic acid promoted the growth of lettuce plants, especially the root system. The emission of roots,
with predominance, of those of smaller diameter, was found in the higher concentrations of fulvic acid. The number of
leaves and the average circumference of the head expressed responses in the concentrations of fulvic acid.
Keywords: Organic System; Humic Substances; Lactuca sativa L.