Effects of humus and shading levels in the production of Lactuca canadensis L. seedlings

The objective of this study was to verify levels of shade and doses of earthworm humus in the production of Lactuca canadensis L. seedlings.  The experimental design was completely randomized in a 4 x 5 factorial scheme (four levels of shade and five doses of humus).  The different levels were obtained using black polyethylene screen with 35, 50 and 70% shade and in full sun. The substrates were obtained by mixing commercial substrate for vegetables (Vivatto Slim ® plus), with earthworm humus in the proportions of 0, 15, 30, 45 and 60%.  There was no seedlings emergence in the full sun and, the treatment with 50% of shade allows the best development. The substrate without humus and with 60% presented superior results but the higher dose stood out for number of leaves (3.14) and chlorophyll content (32.9%), in 50% of shade. For the other variables, there was no difference between the commercial substrate and 60% of humus, so the commercial substrate can be used in the production of Lactuca canadensis L. seedlings, considering the ratio benefit/cost ratio.