SYNTHESIS AND EFFECT OF HYDROXYAPATITE NANOPARTICLES ON THE GERMINATION AND GROWTH OF COMMON BEAN

Abstract

Some fertilizers have been designed in nanometric size to improve the efficiency in the absorption of nutrients, but it is necessary to make toxicity tests before their widespread use. This study aimed to optimize the synthesis of hydroxyapatite nanoparticles (NPHA) and to evaluate its effect on seed germination and growth of bean plants (Phaseolus vulgaris L.). The hypothesis was that NPHA can supply the P necessary for the bean, without being toxic. NPHA were synthesized by the wet chemical precipitation method, and the speed of addition of reagents and agitation were varied. The characterization included particle size distribution, zeta potential, crystalline structure and particle size by X-ray diffraction, transmission electron microscopy, and Fourier Transform Infrared Spectroscopy (FTIR). The effect of NPHA was evaluated on bean germination and growth, in a completely randomized experiment. The NPHA were highly crystalline, with a size between 15.51 to 154.41 nm, and with similar morphology to leaves. The NPHA (250 to 1000 µmol P L^-1) did not affect the germination. Root growth was similar, with concentrations between 250 and 500 µmol P L^-1 but decreased 23.7 and 48% in higher doses (750 and 1000 µmol P L^-1). The NPHA are not toxic for beans (up to 31 mg L^-1 P) and can be useful to provide P to the plants; moreover in doses of 20 µmol L^-1 increased the height of the plant between 31.3 and 66.7%, compared to the plants watered with Hoagland solution. However, it is necessary to generate more information.