Nitrate Reductase Activity in Wheat (Triticum Aestivum L.) I. Distribution Throughout the Leaves

Summary The distribution of nitrate reductase activity, as measured in vivo in the leaves of some spring wheats, was recorded. In plants grown under controlled conditions the highest activity was found in the youngest ligule emergent leaf. The acropetal part of this leaf had the highest level of activity until the leaf began to senesce. Changes in nitrate reductase activity in response to nitrate concentration in the nutrient solutions were also most pronounced in this tissue. Nitrate reductase activity in the basipetal part of the youngest ligule emergent leaf of two wheat varieties, grown at a range of nitrate levels, was followed throughout development. With a given variety the optimal nitrate concentration for development of enzyme activity was the same as that for growth, but this concentration differed between varieties.