Effect of rhizobium isolates and nitrogen on nodulation, growth and yield in lentil

The Experiments were setup in three locations, Magura (23°3´ N 89°2´ E), Rangpur (25°7´ N 89°3´ E) and Mymensingh (24°8´ N 90°0´ E), Bangladesh to know the effect of two bacterial strains and 3 nitrogen doses on nodulation, yield and biomass production. The experimental material consists of one lentil popular variety viz., Binamasur-5 which was inoculated with two promising rhizobial starins/isolates namely LB-21 and LB-40 and three levels of nitrogen viz., 25, 50 and 75 kg N ha-1. The inoculant treatments were un-inoculated control (I0), LB-21 (I1), LB-40 (I2) and mixture of LB-21 and LB-40 (I1+I2). Results indicated that nodule number, nodule weight, straw yield and seed yield at the three locations were greater in bacterial isolates treated plants than in control plants. Results further indicated that mixture of two bacterial isolates had no superior effect against any single bacterial isolate. The two isolates (LB-21 and LB-40) had almost similar greater effect on nodule number, nodule weight, physiological parameters and seed yield with being the highest in LB-40. Application of 25 kg N ha-1 under both bacterial isolates performed the best in seed yield. Application of nitrogen at the rate of 75 kg ha-1 had adverse effect on nodulation, growth and seed yield in lentil. Therefore, for getting higher seed yield in lentil, should apply N as basal dose at the rate of 25 kg N ha-1 and the bacterial isolate, LB-40 may be registered as biofertilizer after few more trials in the different lentil growing areas of Bangladesh.