Organic residues and Parachlorella microalgae favor the growth and gas exchange of cedar

ABSTRACT

Using organic residues and bioinputs is a promising and sustainable practice to produce seedlings with forest essences, such as Cedrela fissilis Vell. (cedar), a vulnerable species close to extinction due to intensive exploitation in native areas. Thus, we aimed to evaluate the effect of different substrates based on organic residues associated with or without the application of Parachlorella sp. microalgae in the emergence and morphophysiology of C. fissilis seedlings. Sowing was carried out on six substrates: Oxisol with a clayey texture; Oxisol + Parachlorella sp.; Oxisol with sheep manure (3:1, v v^–1); Oxisol with sheep manure + Parachlorella sp.; Oxisol with cattle manure (3:1, v v^–1); and Oxisol with cattle manure + Parachlorella sp. The addition of organic residues to the soil, especially cattle manure, contributes to increasing the percentage of emergence, plant height, chlorophyll index, CO₂ assimilation rate, and instantaneous carboxylation efficiency of Rubisco due to the superior chemical attributes in the substrate, which promote greater physiological efficiency. Organic residues increased the water use efficiency of seedlings. The application of Parachlorella sp. microalgae contributes to increases in the CO₂ assimilation rate and stomatal conductance when seedlings are grown only in Oxisol. C. fissilis seedlings produced in the substrate with sheep and cattle manure showed better growth and gas exchange characteristics.

Cedrela fissilis Vell.; bioinputs; sheep manure; cattle manure; stomatal limitation