Abstract
Nitrogenase activity associated with the roots of five local grasses and cereals I. e. Zsea mays L.; Cyttoliots deregylan, Pere ; J.S'org.httm thicoor Darlyrootenittrn aegypfiwri (L.) Beauv. and Oryza aativa L. was determined using acetylene reduction assay (ARA), for pre-inen.beted and fresh erobied roots. All except 0. $42.114.161ehowed higher nitrogenase activity, both for pre-inonbated and fresh roota. Among pre•ineubsted roots, the unwashed roots showed average nitrogenase activity in the range of 4-107 nano!. g-L D.W.hr-1, washed roots allowed in the range of 4.96 nn x.,1 hr.1 and surface sterilized roots activity which w detected in two grace +a (Zea mays L. and Cynoclon daelyfon. Pers.), was in the range of 1.9 nmol DAV, Lir.% For fresh roots, activity WIS is the range of 2-29. rano] g.t D.W. hr-t.
INTRODUCTION
Nitrogen fixation sslociated. with grasses is not a new concept as Lipman and. Taylor 0923) reported this in wheat plant. Recent energy crises and disv-sloprnent of sensitive and relatively easier techniques like aoetylene reduction assay (Rudy eg al 1968) renewed the interest in this area, COMNiderabia data have been acuotanulated by using acetylene reduction assay (AR A) by different workers (Dobereiner el ca., 1972; ari Berkum and Day, 19801. Aaioeiative riat„on iiiacinn has also been reviewod by different authors (van Berkuiu and 19S0). The nitrogen fixing bacteria associated with grass roots have been isoN-ted and identified (Zafar eg 1984y
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* Department of Botany, University of Agriculture, Faisalabad. ** soil Biology Division, Nuclear institute for Agriculture and Biology (NT —4,131, Faisalabad.
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