Nanoscale molybdenum oxide improves plant growth and increases nitrate utilisation in rice (<i>Oryza sativa</i> L.)
Haipeng Zhang, Rui Wang, Zhiqing Chen, Jialing Pu, Juanjuan Wang, Hongcheng Zhang, Yanju Yang
Abstract
Abstract Nanoscale molybdenum oxide (nano‐MoO 3 ) is widely used in industrial and environmental fields and its release to the environment is increasing. However, the potential effect of nano‐MoO 3 on rice ( Oryza sativa L.) seedling growth is unclear. Herein, the different impacts of vaired concentrations (0, 50, 100, 200 and 300 μg Mo L –1 ) of Na 2 MoO 4 and nano‐MoO 3 on the growth and nitrate (NO 3 – ) utilisation of rice were investigated using hydroponics. The Mo concentration in roots and shoots, N metabolism enzyme activity, root morphology, root redox ability and root exudates were then analysed to understand the potential mechanisms of the growth impacts. Results showed that the Mo concentration in rice roots increased incrementally as the amount of Mo application increased, whereas different Mo sources did not affect the Mo concentration in shoots. Both Na 2 MoO 4 and nano‐MoO 3 promoted the growth and NO 3 – utilisation of rice. The promotion effects of higher nano‐MoO 3 dosages were better than those of Na 2 MoO 4 . Nano‐MoO 3 application significantly affected the activity of nitrate reductase (NR), glutamine synthetase (GS) and glutamate synthase (NADH‐GOGAT), which in turn promoted NO 3 – assimilation. Additionally, rice seedlings treated with nano‐MoO 3 had a relatively high rice root volume, surface area, total absorption area, active absorption area, low‐molecular‐weight organic acids, root oxidation and reduction capacities. Based on these results, it is proposed that nano‐MoO 3 facilitates rice growth and NO 3 – assimilation via the enhancement of nitrogen metabolism enzyme activity and the promotion of good root morphological and physiological characters with high root secretion concentration and redox ability. This study provides insights regarding the further application of nano‐MoO 3 in agriculture enhancing N use efficiency and rice productivity.