Nitrate assimilation and mobilization of reduced nitrogen from upper three leaf blades to the developing wheat (Triticum aestivum L.) grains^*

Nitrate assimilation and mobilization of reduced nitrogen from the upper three leaf blades, on the main shoot, to the wheat grains was investigated. It was observed that 350, 534 and 484, and 809, 804 and 645 NO^-₃ μmoles were reduced by the irst (flag), second and third leaf blades at N₉₀ and N₁₈₀, respectively. Protease activity was slightly higher at N₉₀ as compared to at N₁₈₀. Flag leaf blade had higher protease activity both at pH 4 and 7. Out of the total grain nitrogen per ear at harvest, 32.4 and 48.7 percent was assimilated by the upper leaf blades at N₉₀ and N₁₈₀, respectively. All the nitrogen assimilated at N₁₈₀ was not mobilized to the grains.