Assimilatory glutamate dehydrogenase activity (L. glutamate: NAD, oxidoreductase, GDH, E.C. 1.4.1.2.-4) in roots and shoots of maize seedlings raised in dark at 25±2°C in presence of 1/2 strength Hoagland’s solution containing NH4NO, as sole source of nitrogen, increased between 3rd and 8th day and then it declined slightly on 9th day. Almost similar trend was seen in total protein content. Kjeldahl nitrogen also increased in the begining but it either levelled off or declined slightly after 5th day. The enzyme activity and total nitrogen were higher in roots than in shoots. On the other hand, protein content was higher in shoots than in roots. The experiments demonstrate that GDH is an important enzyme in ammonium assimilation in roots and that increased enzyme activity in older roots is perhaps due to changes in some kinetic parameters of the enzyme.
