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Not AvailableInterplay of nitrogen and carbohydrate metabolism, which influenced by nitrogen nutrient management determines the quality and chemical composition of cured tobacco leaf. Tobacco variety Kanchan is grown in Northern light soils of Andhra Pradesh and is a high yielding variety showing response to higher levels of nitrogen. Effect of nitrogen (0, 40, 80, 120, 160 and 200 kg N ha-1) on nitrate reductase, nitrate accumulation and starch content in different leaf position of variety Kanchan was studied in pot (150 kg) culturewithNorthern light soil of Andhra Pradesh. The starch content decreased significantly with increase in application of nitrogen in three growth stages. But the maximumdecrease in starch content was observed with increase in application of nitrogen from 120 to 160 kg N ha-1 in all leaf positions except in the top position. The in vivo nitrate reductase (NR) activity increased significantly with increase in leaf position frombottomto top and decreasedwith age of the plant from50 to 70 days. Nitrate–N content increased from 0.14 mg g-1 dry wt. in the bottomleaves of control plants to 8.615 mg g-1 dry wt in the leaves of plants treated with 200 kg N ha-1. The nitrate content increased from bottom to top position in all treatments with increase in nitrogen application. Increased application of nitrogen increased the NR activity and accumulation of nitrate–N, thus a positive relationship was observed between NR activity and nitrate–N accumulation whereas starch content decreased with increased application of nitrogen. The negative relationship was observed between NRactivity and starch accumulation and also between nitrate– N and starch. The recommendation of 120 kg N ha-1 for the variety Kanchan grown in northern light soils of Andhra Pradesh was found to be optimum as NR activity was at a par between 120 and 200 kg Nha-1 application at 60 and 70 days of growth. Thus NR activity may be taken as one of the indicators to thematurity of leaf and availability of nitrogen to the plants.Not Availabl