Jayasinghe, C.K.Parker, C.A.Kulasooriya, S.A.2012-06-252012-06-251989Journal of the Rubber Research Institute of Sri Lanka69pp.49-58https://dl.nsf.gov.lk/handle/1/8959A wide range of incubation time from a few minutes to severl hours have been used with defferent plant systems in investigations on acetylene reduction assays. However, the duration of incubation period is of utmost importance in obtaining nitrogen fixation estimates using this technology. Time course experiment showed that acwtylene reduction by nodules of P. phaseoloides and D. ovalifolium started without a lag but rate of the nitrogenasse activity was reduced 4 hours after incubation while M. invisa showed a considerable activity even at the 8th hour of incubation. In the second experiment which was conducted to observe the relationship between acetylene reduction activity and incubation time upto one our, there was a linear relationship for both P. phaseoloides (r = +0.9832) and D. ovalifolium (r = + 0.99961)AgriculturePuerariaDesmodiumMimosaNitrogen fixationCover cropsArticle