Effect of Nitrogen Nutrition on Solute Accumulation and Ion Contents of Maize under Sodium Chloride Stress

Abstract

Salinity is a major abiotic stress that limits the productivity of crops, particularly cereal crops, while decreasing nutrient availability, especially of nitrogen. An experiment was conducted to study the effects of salt stress [i.e., S0, S1, and S2 (control, 1.09; 5; and 10 dS m−1)] and four different nitrogen (N) levels [i.e., N0, N1, N2, and N3 (control, 175, 225, and 275 kg N ha−1)] on two maize hybrids, Pioneer 32B33 (salt tolerant) and Dekalb 979 (salt sensitive). The experiment was conducted in a wire house. The experiment was laid out with three factors in a completely randomized design. The plant tissue was analyzed for solute and ion contents. With the increase in salt stress and N rate, solute (i.e., glycinebetaine), protein, total soluble sugar, and total free amino acids accumulated in both hybrids. Nitrate (NO3) and nitrite (NO2) reductase activity decreased sharply at 10 dS m−1 compared to lower levels of salinity but it increased significantly with the addition of N. The uptake of potassium (K+), calcium (Ca2+), magnesium (Mg2+), N, and phosphorus (P) reduced significantly in shoots with increased salinity while the sodium (Na+) and chloride (Cl) contents were increased. It is concluded from the present study that at greater salinity level, hybrid Pioneer32B33 maintained statistically greater solute and ion contents excluding Na+ and Cl ions and significantly decreased enzyme activity. However, these parameters were increased by N rate.