Empirical model for prediction of Motihari tobacco (Nicotiana rustica) leaf quality based on leaf nutrients and soil fertility

The tobacco cured leaf yield as well as leaf quality are important factor which determined market price and net return. The yield and leaf quality of tobacco influenced by a numbers of factors such as varieties, soil, irrigation water and management practices. The nutrient composition and quality constituents like nicotine and reducing sugars in the leaf are influenced by the availability of nutrients in the soil. The permanent manorial trial has been started in 1961-62 and till now continuing at CTRI Research Station, Dinhata. Database is being maintained for this trial and the data for last 10 years (2004-05 to 2014-15) was collected on first grade leaf yields was collected along with Leaf composition i.e. Nitrogen, Phosphorus, Potassium, Chloride, Nicotine and reducing Sugar contents and soil nutrients data including OC (g kg-1), available P2O5 (kg ha-1), Available K2O (kg ha-1) and Chloride (ppm) content. Relationship among the quality constituents and composition of leaf and soil fertility was developed using regression analysis. Nitrogen fertilization played crucial role for leaf yield, quality and nicotine content in leaf and recorded positive relationship with them. The nicotine and nitrogen content showed significant (P<0.01) positive relationship with linear regression equation was Y=79.041x-1412.2. However, reducing sugar content in leaf showed negative relation with phosphate in leaf with regression equation Y=-2.610x+16.94. The soil content of K2O showed significant positive relationship with leaf Potassium content. The result showed that nitrogen and phosphate fertilization may regulate nicotine and reducing content of leaf.