Foliar application of sodium molybdate enhanced nitrogen uptake and translocation in soybean plants by improving nodulation process under salt stress

Abstract

Soil salinity with different harmful effects on plant growth and productivity is one of the main reasons in diminishing biological nitrogen fixation and nitrogen assimilation in legume plants. Molybdate has a key role on nitrogen metabolism of plants and can be has a beneficial effect on it. Thus, this experiment was conducted to evaluate the effects of sodium molybdate spraying (0.2 and 0.4% solutions in water) on nodulation, nitrogen uptake and translocation in soybean plants under different levels of salt stress (0, 5 and 10 dS m-1 NaCl, respectively). Salinity reduced the nodulation, root and shoot growth and special flavonoids content in roots, which are have a key role in nodulation includes, daidzein, genistein, coumestrol and glycitein, also diminished nitrogenase, glutamine synthetase (GS), glutamate dehydrogenase (GDH), glutamine oxoglutarate aminotransferase (GOGAT) and nitrate reductase (NR) activities in nodes, nitrogen content of nodes, roots and leaves, nitrogen uptake and translocation by soybean plants. Under salt stress and nonsaline condition, sodium molybdate treatments improved the nodulation by increasing flavonoids content of roots, also these treatments enhanced the plant growth and nitrogenase, GS, GDH, GOGAT and NR activities of nodes. Furthermore, nitrogen content of nodes, roots and leaves, nitrogen uptake and translocation by soybean plants improved by sodium molybdate applications. Both of the sodium molybdate doses, exposed the similar effects on improving nodulation and nitrogen metabolism of soybean.