Nitrate and nitrite reductase activities in soybean plants raised with saline water

Nitrate reductase (NR) and nitrite reductase (Nir) activities were substantially declined in leaves and roots of two soybean genotypes grown under a range of NaCl and Na₂CO₃ salts (0–12 dSnr⁻¹). Na₂CO₃ proved more inhibitory than NaCl to both enzymes and leaves showed higher levels of NR and NiR activity than roots. However, the salt induced inhibition was also higher in leaves. Plants exhibited higher activity of NiR than NR in both plant parts and genotype PK-472 proved relatively resistant to salts as compared to Alankar.