DIFFERENCES IN UPTAKE KINETICS OF AMMONIUM AND NITRATE IN LEGUMES ANDCEREALS

Influx isotherms were obtained for nitrate and ammonium from three leg umes, Cajanus cajan (L.) Millsp., Cicer arietinum L. and Arachis hypog aea L. and three cereals, Sorghum bicolor (L.) Moench., Pennisetum gla ucum L. and Zea mays L. The transition in influx isotherms for both ni trogen sources was found to be within the concentration range (0.05-2. 5 mM) tested. There were significant differences in Km and Vmax for am monium between legumes and cereals. The difference in the kinetic prop erties for nitrate uptake between the two groups of plants only became apparent at the higher concentration tested. Legumes translocated abs orbed nitrate and ammonium to shoots more rapidly than cereals. Result s show that there are significant differences in uptake and translocat ion of ammonium and nitrate between legumes and cereals.