Promotion of seed germination and seedling growth of Zea mays by magnesium hydroxide nanoparticles synthesized by the filtrate from Aspergillus niger

Abstract

An approach for green synthesis of magnesium hydroxide nanoparticles [Mg(OH)2NPs] has been developed and its efficacy in seed germination, in vitro and in vivo plant growth promotion was studied on Zea mays at different concentrations. Mg(OH)2NPs at 500 ppm showed improved seed germination (100%) and growth. The effect of Mg(OH)2NPs was analyzed by measurement of plants height and chlorophyll a fluorescence using plant efficiency analyzer. The seedlings grown in MS medium supplemented with Mg(OH)2NPs showed significant increase in shoot height (11.96 ± 0.4 cm) and root length (3.92 ± 0.4 cm). Similarly, for in vivo studies, the enhanced shoot height (44.2 ± 1.6 cm) and root length (29.2 ± 1.3 cm) was recorded as compared to plants treated with their bulk counterpart. However, 500 ppm bulk Mg showed comparatively lower shoot height (38 ± 1.5 cm) and root length (21.6 ± 2.3 cm). The chlorophyll a fluorescence measurements revealed that plants treated with Mg(OH)2NPs showed maximum performance index and minimum dissipation as compared to control and plants treated with bulk Mg.In addition, atomic absorption spectrophotometric analysis performed for both in vitro and in vivo grown plants, revealed that leaves and roots of the plants treated with Mg(OH)2NPs demonstrated higher Mg contents. It was found that Mg content in leaves and roots for in vitro plants were 131.45 and 103.52 mg/kg, respectively; whereas for in vivo grown plants it was 132.58 and 114.58 mg/kg, respectively. Therefore, Mg(OH)2NPs can be potentially used for enhancement of seed germination and seedling growth promotion. Keywords: Magnesium hydroxide nanoparticles, Aspergillus niger, Zea mays, Seedling growth promotion, Seed germination