Lactuca sativa L., Paspalum Notatum L., organic fertilizer, sustainable agriculture, agroecology, substrate

Greenponics is a technique that encompasses the cultivation of plants using biomass of organic plant origin, not composted. Within the current Brazilian scenario and the global context, which demands solutions for the production of seedlings, with economic and social viability, in a sustainable way, scientific research seeks alternatives. This organic system acts as a substrate and source of nutrients for plants. Based on previous work carried out on this system, it was found that it has agronomic potential for the cultivation of peppers, tomatoes and lettuce. The production of seedlings in this system is a recent aspect, and its efficiency would be an alternative to the difficulty in obtaining substrates rich in nutrients. Therefore, the objective of the present study was to evaluate the interaction and viability of seedling production using potato grass clippings as a substrate. Chopped and dried grass clippings were used, and this material was purchased within the UFRRJ campus, in Seropédica, RJ. Two experiments were carried out to produce seedlings in trays, the last being the investigation of the influence of grass components on seed germination. The first experiment was organized in 6 polystyrene trays with 128 cells in each, arranged randomly, in which their locations were rotated on the bench. There were 7 treatments, the Carolina Soil® commercial substrate control and with different proportions of grass and soil (100%, 80%, 60%, 40%, 20% and 0%). The variables analyzed were: aerial part dry mass (MSPA), root dry mass (MSR), and seedling height, in addition to measuring electrical conductivity and pH. The cells of the trays were completely filled with the chopped grass and its dilution proportions with soil. In each cell, 4 seeds and sifted sand were used over all treatments, thinning was carried out, leaving one seedling in each, with average characteristics compared to the others. The second experiment was using mixtures of grass clippings with soil, at different times of incubation of the grass with water, the treatments were, T1: Carolina Soil®; T2: 100% grass without incubation; T3: 100% with 18 days of incubation; T4: 100% grass with 28 days of incubation; T5: planosol with 5% grass without incubation; T6: flat soil. It was verified that there is viability of using grass clippings as an alternative substrate for the production of lettuce seedlings, based on the mineralization of the grass, treatments with 100% grass obtained standards equivalent to those of commercial seedling production crops.