Nitrate Application Improves Plant Growth and Nitrate Reductase Activity in Maize Under Saline Conditions

A study was conducted to examine the effect of nitrate and some inorganic nutrients on growth and nitrate reductase activity in maize grown with or without salinity. Salinity (100 mM NaCl) caused reduction in biomass and total N content of root and shoot and nitrate content and nitrate reductase activity in root and leaves in two week old maize plants raised with 0, and 6 mM nitrate as sole nitrogen source. Similarly, the inclusion of some inorganic ions Ca²⁺, K⁺, Mn²⁺, Mg²⁺ and Zn²⁺ in assay medium resulted in a rise in NR levels in roots as well leaves. It is concluded that inhibition of nitrate acquisition and assimilation of nitrate is an important contributory factor in reduced biomass accumulation.