Viabilidade no uso do P4TREE® para suprimento de fósforo na produção de mudas de espécies florestais nativas

Abstract

Alternative phosphate fertilizers have been gaining prominence in scientific research due to the need for sustainable nutrient utilization. P4TREE®

is a novel phosphorus (P) adsorption technology derived from modified serpentinite interacting with human urine, with potential application as a fertilizer for forest seedlings aimed at restoring degraded areas. Our objectives were: (i) to assess the development of native species from the Atlantic Forest, Parapiptadenia rigida (Bentham) Brenan and Peltophorum dubium (spreng.) Taub, under different P doses; (ii) to determine the optimal method of P4TREE® application and evaluate its ecotoxicity; (iii) to evaluate the feasibility of P4TREE®

in supplying P and improving the nutritional status of native Atlantic Forest tree species. In the first greenhouse experiment, seedlings of tree species were fertilized with different P doses (no added P - MAP 0%; MAP 25%; MAP 50%; and MAP 100%). Following desorption tests, an ecotoxicological assay was conducted to assess potential toxicity and determine the best P4TREE®

application method. Based on these results, a subsequent experiment was conducted using solid P4TREE® incorporated into the substrate. Both species exhibited low nutritional requirements. P doses did not influence morphofunctional aspects, P concentration in plant tissues, gas exchange, or chlorophyll a fluorescence as evaluated. Desorption of P4TREE®

in NaOH solution released

10 mg P L-1

of solution. However, P4TREE®

in NaOH solution inhibited seed germination and led to death of native seedlings when applied via fertigation. Solid P4TREE® incorporated into the substrate was found to be the optimal application method. However, both species exhibited compromised growth when P4TREE® was the P source, contrasting with serpentinite. P. dubium showed higher sensitivity to P4TREE®

than P. rigida, resulting in reduced height, leaf area, diameter, photosynthetic rate, and maximum quantum yield of photosystem II. We concluded that P4TREE®

negatively affected P. dubium growth but did not affect leaf area, height, diameter, leaf dry mass, and stem dry mass of P. rigida. However, when serpentinite was used, P. dubium exhibited better morphofunctional characteristics, suggesting that components in urine and/or the P4TREE®

formation process may cause

phytotoxicity. Our findings suggest that further investigations into P4TREE®

as a P source

should consider urine exposure time and control of alkaline pH.