Nitrogen metabolism enzymes activity in flag leaf and roots of pearl millet during grain development stage

Nitrate reductase (NR), Glutamine synthatase (GS), Glutamate dehydrogenase (GDH) and Aspartate aminotransaminase (AspAT) were assayed in flag leaves and roots of four pearl millet genotypes, started from ear emergence till grain maturity at four days intervals. All enzymes showed higher activities in flag leaf than that of roots irrespective of growth stage and genotypes. A slight increase in flag leaf NR, GS and AspAT activity till anthesis started decreasing while GDH increased till 12 days after anthesis (DAA) and almost constant till 18 DAA and then started decreasing. While in roots a steep declining trend was observed in NR, GS and AspAT and reached to almost non-detectable level till maturity while GDH increased up to 6 DAA and then decreased sharply irrespective of the genotypes. The almost stable GDH activity and decreasing trend in NR, GS and AspAT suggested that re-assimilation of amino nitrogen takes place in flag leaf instead of direct assimilation from the roots for nitrogen deposition in pearl millet developing grains