Resíduos orgânicos e microalga Chlorella spp. na produção de mudas de Cedrela fissilis Vell

Abstract

Cedrela fissilis Vell. is a tree species with silvicultural and medicinal interest, vulnerable to extinction due to its intensive exploitation in native areas. Therefore, attention is needed during the production of seedlings of this species aiming at its ex-situ cultivation, and in this case the substrate is a determining factor in the growth and vigor of the seedlings. In view of the above, the aim of this study was to evaluate the effect of different substrates based on organic residues, associated or not with the application of the microalgae Chlorella spp. in C. fissilis seedlings. The experiment was carried out under a nursery-type agricultural screen with top and side cover of black nylon screen with 30% shading. Sowing was carried out in black polyethylene tubes with a volume of 290 cm3 previously filled with substrates made of three materials, all combined, or not, with the application of microalgae Chlorella spp., formulating six treatments: S1) Distroferric Red Latosol – DRL (SANTOS et al., 2018) clayey texture, S2) DRL + C. spp., S3) DRL + sheep manure (3:1, v/v) – DRLSM, S4) DRLSM + C. spp., S5) DRL + cattle manure (3:1, v/v) – DRLCM and S6) DRLCM + C. spp. The experimental design used was randomized blocks, with six replications, and each experimental unit consisted of six tubes with one seed in each. C. fissilis seedlings are responsive to the use of organic residues, especially bovine manure, as it contributed to increase the percentage of emergence, height growth, chlorophyll index, and the photosynthetic rate and carboxylation efficiency of Rubisco. It is concluded that the addition of organic residues in the formulation of substrates contributes to the improvement of chemical attributes and the formation of seedlings of C. fissilis. Seedlings produced in a substrate with Dystroferric Red Latosol with sheep and cattle manure show greater growth and gas exchange, and the use of microalgae C. spp. contributed little to the production of C. fissilis seedlings.