Efeitos da aplicação do extrato bruto da alga vermelha Gracilaria birdiae em cultura de alface (Lactuca sativa)

Abstract

The agribusiness is responsible for a major part of Brazil’s GDP, but to achieve its high annual productivity, Brazil needs to utilize fertilizers and stimulants, which are mostly imported. The use of organic fertilizers (biofertilizers) is an option to overcome the high costs of this input, being manure of animal rejects the most used option. These, however, cannot be used in some vegetables consumed rawly, such as lettuce, due to possible contamination of pathogenic microorganisms. Lettuce is the most consumed leafy vegetable in Brazil and, in this case, extracts from marine seaweeds are a good option thanks to their biodegradable character and because they are atoxic to both environment and living beings. The present work aimed to obtain an aqueous extract with potential of being biostimulating and/or biofertilizer to plants from the red macro algae Gracilaria birdiae. For that, an aqueous extraction was performed and the biochemical composition as well as the yield of this extract, named EB-Gb, were determined. The effect of different concentrations of EB-Gb (0.1, 0.2, 0.3 and 0.4 g.L-1) on percentage, time, speed and synchronization index of germination of seeds were determined for iceberg and baby lettuce in two distinct temperature conditions (20 and 28 °C). The effect of different concentrations of EB-Gb on the development of iceberg lettuce sprouts in liquid medium in vitro was evaluated upon biomass of shoot and root, number of leaves, length of leaf and primary root. The results suggest biofertilizer and biostimulating potential of EB-Gb, once it has showed positive effects on germination synchronization on both crops used in the study, percentage of baby lettuce germination in stress conditions, growth of shoot and primary root, number of leaves and secondary roots and percentage of shoot dry biomass of these plants.