EFFECTS OF SEASONAL VARIATION AND NITROGEN TREATMENTS ON NODULATION AND NITROGEN FIXATION BEHAVIOUR IN <em>PONGAMIA</em> <em>PINNATA</em>

Abstract

Nodulation behaviour and nitrogenase activity were studied in relation to nitrogen treatment (i.e. 0, 40,80, 100 kg N ha^-1) and seasonal variations in Pongamia pinnata seedlings. A marked increase in the nodule biomass per plant and nitrogenase activity was observed in the rainy season followed by winter and summer. Two peaks, one small in early summer and another large during the rainy season, were observed in nitrogenase (g^-1 fresh wt.h^-1 and pl^-1 h^-1 ) activity. However.no definite trend was observed due to the different nitrogen treatments on the nodule biomass and nitrogenase activity, but 40 kgN ha^-1 was observed to be more effective than the others.