Phosphorus-Rhizobium interaction studies on biological nitrogen fixation and yield of lentil

Abstract

SummaryField experiments were conducted at the Punjab Agricultural University, Ludhiana from 1980–1 to 1984–5 to study the response of lentil genotypes to phosphorus application and Rhizobium inoculation. The number and dry weight of nodules increased consistently with increasing rates of application of phosphorus from 0 to 60 kg P2O5/ha. Nitrogenase activity of intact root nodules increased from 17 530 to 22 390 nmol/h per g dry weight of nodules with 20 kg P2O6/ha and to 27391 and 29170 nmol/h per g with 40 and 60 kg P2O5/ha, respectively. Rhizobium inoculation also increased nodulation, nitrogenase activity and grain yield. Interaction between phosphorus and Rhizobium inoculation was significant in 3 out of 5 years, indicating that the combination of Rhizobium and 20 kg P2O6/ha gave yield equivalent to 40 kg P2O6/ha without Rhizobium.