Potencial fitotóxico do biofertilizante da casca de pequi (Caryocar brasiliense Comb.)

Abstract

The pequi fruit peel represents 80% of its total content. This part is generally discarded. The use of this residue for the biofertilizer production appears as an alternative for its use in agriculture. However, pequi fruit peel is rich in allelopathic compounds, which may restrict the use of this residue in agricultural fields. Thus, the objective of this study was to evaluate whether the biofertilizer of pequi fruit peel can cause phytotoxic effects and, or interfere with the growth of cucumber plants (Cucumis sativus L.). We utilized a completely randomized design in 5 x 2 (levels x pH) factorial scheme with four replications. The treatments consisted of biofertilizer levels per liter of substrate: 0 (control), 10, 20, 40 and 80 mL, with and without adjustment of pH of the effluent. The biofertilizer doses did not influence the growth and production of shoot fresh and dry matter and root fresh matter of cucumber. However, the biofertilizer led to a linear increase of root dry matter for this plant. The pH correction of the biofertilizer favored only the initial growth in cucumber height. The acidity of the biofertilizer did not influence this plant fresh and dry matter production. The biofertilizer from pequi fruit peel did not cause phytotoxicity to cucumber plants, regardless of the dose. Possibly, the fermentation process to obtain the biofertilizer is sufficient to degrade or make possible toxic compounds of unavailable pequi peel. This suggests that this biofertilizer can be used in commercial crops. However, due the low nutrient availability, the biofertilizer of pequi fruit peel has a poor contribution to plant growth.