Manejo nutricional da Atriplex nummularia para uso em programas de recuperação de solos afetados por sais no estado de Pernambuco

Abstract

The halophyte Atriplex nummularia is often used in phytoremediation programs is salt-affected soils. However, the recovery process is slower than the conventional correction, being dependent on the production of biomass and consequent extraction of salts, which requires management that stimulates the production of biomass and accelerates the recovery process. Thus, the work was carried out with the objective of evaluating the productive capacity of biomass and extraction of salts by Atriplex nummularia in different scenarios of nutritional management with Nitrogen (N) and Phosphorus (P) under irrigation with saline water. The experiment was designed in randomized blocks in a double factorial arrangement 4 (nutritional management) x 5 (electrical conductivity levels of irrigation water) with four replications totaling 80 experimental units. For nutritional management, doses for nitrogen (N1 = 80 kg ha-1) and phosphorus (P1 = 60 kg ha-1) were used to form: 1) no dose of nitrogen and phosphorus (N0P0) (control treatment), 2) nitrogen dose without phosphorus dose (N1P0); 3) without nitrogen dose with phosphorus dose (N0P1) and 4) nitrogen dose with phosphorus dose (N1P1). The levels of electrical conductivity in irrigation water were 0.08; 1.7; 4.8; 8.6 and 12.5 dS m-1. The experiment was carried out for 93 days and evaluated parameters of biometry, fresh and dry biomass of leaves, stems and roots, leaf and osmotic water potential, osmotic adjustment, in addition to the nutritional composition in plant tissues. The sodium contents in leaves, stems and roots demonstrate that in Atriplex nummularia irrigated with water of 8.6 dS m-1, nitrogen fertilization has a beneficial effect on the phytoextraction of sodium and potassium contents. Nitrogen application under saline conditions reduces the adverse effects of salinity on water potential, osmotic potential and osmotic adjustment in Atriplex nummularia plants. Given the results obtained, nitrogen fertilization can be an alternative to mitigate the negative effect of saline stress in the soil. Chlorophyll fluorescence parameters showed the importance of providing nitrogen sources as a strategy to reduce the damage caused by saline stress. Thus, it is suggested to cultivate Atriplex nummularia irrigated with waters of up to 4.8 dS m-1 with nitrogen fertilizer management at a rate of 80 kg ha-1 for greater yield.