Nodulation pattern in groundnut (Arachis hypogaea Linn.) as influenced by varying levels of plant density nitrogen and phosphorus

Nodulation in groundnut was initiated at flowering, profuse at pod formation and continued upto 85 days. Nodules started degenerating after 85 days. Highest plant density treatment (2,00,000 plants/ha) was found to produce signifiicantly less number and small sized nodules per plant, only at latter stages of nodulation in both the seasons. The medium (1,50,000 plants/ha) and low (1,00,000 plants/ha) densities were found at par. The retarding effect of nitrogen, on nodulation applied either at 20 or 40 kg. N/ha over the control was observed at active growth phase in both the seasons. However, in the initial stage, of nodulation, and at 85 days, the effect of nitrogen was not significant. The positive effect of phosphorus in increasing the volume of nodules was evident in the initial stage of nodulation. The dose of 60 kg P2O5/ha was found effective over 20 and 40 kg P2O5/ha, especially under low population. The lower doses of phosphorus were not effective.