Lettuce (Lactuca sativa L.) is the main leafy vegetable grown in Brazil. Its productivity and quality are limited by the growing season, the nearby environment and the type of cultivar adopted. The objective of this work was to verify at different times of the year the best planting environment for lettuce cultivation in a semi-humid tropical climate. For this purpose, an experiment was set up in three different seasons (October–November 2014, January–March, May–July 2015). The experimental design was randomized blocks, in a 3 × 3 × 2 factorial arrangement, consisting of three seasons, three cultivars (cvs. Vera^®, Tainá^® and Rafaela^®) and two growing environments (low tunnel with beds protected with mulching consisting of soil protection with plastic fabric covering, and beds without protection or conventional cultivation) and four replicates per treatment. Plant biomass, stem length, head diameter, number of leaves per head and crop productivity were evaluated as response parameters. The results showed that the May–July period favored biomass production, head diameter and productivity. Despite the similarity between varieties, the variety Vera^® is more productive in biomass, number of leaves per head, stem length and productivity. The low tunnel planting system with mulching is adequate under the conditions evaluated for lettuce cultivation. This system in the May–July period favors a superior development in the characteristics biomass, head diameter and productivity, if compared to conventional cultivation during the October–November period.

The agronomic use of mushroom post-harvest substrates (SPCHs) in horticultural seedbeds could be an interesting alternative for the reuse of these wastes in line with the European circular economy strategy. This work evaluates the potential use of four treatments with different SPCHs, mushroom (-Ch), mushroom (-St), mushroom compost (-CO), and a mixture (SPCH-Ch and SPCH-St) as substrates for lettuce and chili pepper seed germination. The trial was carried out in a germination chamber using commercial compost as a control treatment. The evaluation was based on its chemical (salinity, N and C content), physical (bulk and real density, porosity and water retention) and plant effect (germination and biomass) characteristics. Of the chemical properties studied, the high salinity in SPCH-Ch and SPCH-CO was a limiting factor for the development of the horticultural species evaluated (electrical conductivity 1:2.5; p/v; ~11 dS m^-1), and low germination percentages were observed. Regarding physical properties, porosity and water retention, the SPCH-CO, SPCH-St and mixture treatments presented some values outside the optimal range established for germination substrates. In the case of SPCH-St, its high C/N ratio could be a limitation for supplying N to the crop. In relation to biomass production (aerial and root) of lettuce and chili pepper, all the treatments evaluated obtained similar values to the control treatment. The mixed treatment presented the highest biomass values, significantly higher in the lettuce crop. In general, the mixed treatment proved to be the best alternative for use in the seedbed.