Effect of source of nitrogen on nitrate reductase activity and biomass productivity in peanut mutant

The experiment was conducted under sand culture condition to know the effect of nitrogen sources on nitrate reductase activity (NRA) and its consequence on dry mass production and seed yield in peanut. The treatments were two genotypes viz., Dacca-1, a widely cultivated variety in Bangladesh and Mut-3, a promising mutant and three nitrogen sources viz., (i) O N, (ii) 5 mM KNO3 and (iii) 5 mM NH4Cl. No rhizobial inoculant was provided for O N treatment. Results showed that NRA increased with supplying nitrogen as nitrate or ammonium at early growth stage of peanut with being the highest in nitrate. But no effect was observed at reproductive growth stage. Leghaemoglobin content decreased with adding nitrogen in the form of nitrate or ammonium resulting in decreased growth and development thereby yield in peanut over control. The NR activity was greater in Mut-3 than Dacca-1 and Mut-3 also showed higher dry mass and pod yield than Dacca-1. Mut-3 was significantly affected by adding nitrogen in the form of nitrate or ammonium, whereas Dacca-1 had no significant effect indicating the variety Dacca-1 resistance to ammonia suppression.