Nanopartículas de ZnO e de CuO : efeitos fisiológicos em plantas de feijão-caupi (Vigna unguiculata)

Abstract

Nanoparticulate zinc (ZnO-NP) and copper (CuO-NP) oxides have been widely used in several industrial sectors, with the possibility of being used as nanofertilizers. The objective of this study was to evaluate the potential of ZnO-NP and CuO-NP in supplying Zn and Cu to cowpea plants grown in nutrient solution, as well as to evaluate the ZnO-NP fertilizer potential in soil cultivation. To separate the effect of metal and nanoparticle, common metal oxides were used for comparison (ZnO and CuO). The effect of oxides on plants was evaluated in independent experiments in nutrient solution. Two sources of Zn (ZnO-NP and ZnO) were tested at doses 0, 5, 20, 80 and 400 mg L-1 and two sources of Cu (CuO-NP and CuO) at doses 0, 40, 400, 1000 and 2000 mg L-1. The dissolution capacity of the oxides in different aqueous matrices and their effects on the germination, the biomass production, the mineral composition, the pigment content and the photosynthetic apparatus of the plants were evaluated. Under the conditions of this study, the oxides did not promote inhibition of germination at the doses tested. High doses of the metals caused a reduction in biomass production, nutrient content, chlorophyll content and changes in the structure and structure of the photosynthetic apparatus. However, at lower doses of oxides there were no symptoms of phytotoxicity, biomass decrease or alteration of mineral composition. In soil, at the dose of 100 mg kg-1 ZnO-NP stimulated the production of biomass, showing potential fertilizer for this crop.