Crescimento e características funcionais de plantas jovens de Hevea brasiliensis (Willd. ex A.Juss.)Müll.Arg.) e Bertholletia excelsa (Bonpl.) submetidas à fertilização fosfatada e a bactérias solubilizadoras de fosfato

Abstract

Advances in biotechnology applied to forestry sciences are making possible sustainable and eco-efficient approaches that increase productivity in the field and reduce costs and environmental impacts through modern silvicultural practices that support sustainable and environmentally friendly production. The inoculation of microorganisms in the soil is one example, especially when it comes to the need for more efficient use of nutrients such as phosphorus, whose availability in the soil for plants can be enhanced by the action of phosphate-solubilizing bacteria (PSB). The use of beneficial bacteria in the soil is emerging as a viable alternative to contribute directly (i.e. biological fixation of N2, solubilization of P and production of phytohormones, etc.) or indirectly (biosynthesis of antimicrobial compounds and elicitation of induced systemic resistance) to the efficiency of fertilizers and, consequently, to plant performance in the field. Considering the potential application of this biotechnology, this research aimed to evaluate the effect of phosphate fertilization associated with phosphate-solubilizing bacteria on the growth and functional characteristics of young plants of Hevea brasiliensis and Bertholletia excelsa. The first chapter provides an overview of the use of phosphate-solubilizing microorganisms that stimulate plant growth, highlighting the importance of this biotechnology as a viable tool for reducing the use of chemical inputs and highlighting the lack of this method in forestry, especially in native Amazonian forest species. In the second chapter, we investigate the functional responses of two forest species, Hevea brasiliensis and Bertholletia excelsa, under different treatments: Control, Liming, Natural Phosphate (FN), Soluble Phosphate (FS), Phosphate-solubilizing Bacteria (BSF), Bacteria combined with Natural Phosphate (BSF+FN) and Bacteria plus Soluble Phosphate (BSF+FS). A combination of bacterial strains from the Bacillus genus was used: Bacillus velezensis and Lysinibasillus xylaniticus, inoculated directly into the soil of the pots. 10 ml were applied, divided into 2 applications of 5 ml each, with an interval of 15 days between them. The seedlings remained in the greenhouse throughout the experimental period. Growth variables (height, stem and leaves) were measured every month, as well as photosynthetic performance. The data collected during and at the end of the experimental period (120 days) was subjected to analysis of variance and the means were compared using the Tukey test (P<0.05). The results showed better responses in terms of growth rates for both species under the BSF treatment. Under the BSF+FN and BSF+FS treatments, the chestnut seedlings showed greater biomass accumulation in the leaf compartment. The root system of B. excelsa showed greater biomass under liming, BSF and FN and the H. brasiliensis species under the BSF, control, liming and BSF+FN treatments. The greatest accumulation of total dry mass for both species was in the BSF treatment. Both species showed better photosynthetic performance under the BSF treatment, as evidenced by the increase in stomatal conductance. The results obtained indicate superior performance of the species submitted to the BSF treatment in relation to the variables TCR-A, D; TCA-A, D; total biomass accumulation and photosynthetic performance. Our data suggests that bacterial inoculation alone favored the growth and development of the seedlings.