Nitrogen metabolism of the upper three leaf blades of wheat at different soil nitrogen levels

Abstract

Some aspects of nitrogen metabolism, during grain development, of the upper three leaf blades on the mainshoot of wheat (Triticum aestivum L.) cv. Pusa Lerma, grown under three soil nitrogen levels (0, 30 and 120 kg ha^-1), were investigated. It was observed that these leaf blades were active in NO^-₃ assimilation. Of the leaf blades, the flag lead blade had significantly higher nitrate reductase activity, higher amount of free amino acid and soluble protein content, whereas the content of NO^-₃ was significantly lower than in the other two leaf blades. Application of soil nitrogen significantly enhanced the nitrate reductase activity (N₃₀ over N₀ and N₁₂₀ over N₃₀), free amino acid (N₃₀ over N₀ and N₁₂₀ over N₃₀), soluble protein (N₁₂₀ over N₀) and NO^-₃ content (N₃₀ and N₁₂₀ over N₀) in all three leaf blades. During the 35-day period, viz. from 7 days prior to anthesis to 28 days after anthesis, the three leaf blades together reduced 280, 608 and 1397 NO^-₃ µmol under N₀, N₃₀ and N₁₂₀, respectively.