Substrate with coffee powder residue and its influence on tomato germination and seedling growth

Abstract

Strained coffee powder is an organic residue available in large quantities that could be used as a source of nutrients, improving substrate quality. However, little is known about its application in transplant production. This study aimed at evaluating the influence of this residue, in mixtures with soil (Ferralsol) and cow's manure, on seed germination and transplants growth of F1 hybrid tomato cultivar 'Giovanna'. The experiment, performed in a greenhouse at the Agua Limpa Farm, University of Brasilia, had seven treatments, with respective mass proportions of 0-90-10, 20-70-10, 40-50-10, 60-30-10, 80-10-10 and 100-0-0, coffee residue, soil and manure, including 100% sand as control. The plots, with nine seeds each, were sown in 3.5×3.5×5.0 cm polypropylene trays, on an entirely randomized plot design. Plant height, root length, stem diameter, fresh and dry weight of shoots and roots and germination rate were evaluated. Soil and manure, followed by sand, had best results for germination and growth. Treatments containing coffee residue produced negative effect on germination, except the ones containing 20 to 40% coffee powder residue affecting emergence and growth. These findings support the possible allelopathic effect of coffee as secondary metabolites in plants as measured here by tomato germination, emergence and transplant growth. Still, further studies on the nature of inhibitory compounds and their subsequent elimination before use in substrate are suggested.