Productivity, leaf quality and nutrient-use efficiency of FCV tobacco (Nicotiana tabacum) genotypes to levels of N and K application under irrigated Alfisols of Andhra Pradesh

A field experiment was conducted for 3 consecutive seasons (2010–2013) at Jeelugumilli, Andhra Pradesh to assess the yield potential, leaf quality and nutrient-use efficiency of flue-cured Virginia (FCV) tobacco (Nicotiana tabacum L.) genotypes grown in irrigated Alfisols in relation to N and K management. Results showed that FCV tobacco cv. ‘Kanchan’ and hybrid ‘CH-1’ were on par with regard to yield and grade index. Graded rates of N and K application caused progressive and significant increase in green leaf, cured leaf and grade index. Recommended dose of fertilizers (RDF) produced significantly higher cured leaf yield by 13.0, 45.8 and 193.8% and grade index by 14.1, 53.7 and 224.4%, when compared to 80, 40 and 0 kg N/ha respectively. RDF produced significantly higher cured leaf yield by 2.69, 8.52 and 26.5% and grade index by 5.80, 16.8 and 43.1% when compared to 66.4, 33.2 and 0 kg K/ha respectively. The leaf chemical quality parameters viz. nicotine, reducing sugars, reducing sugars/nicotine ratio and chlorides showed changes in response to N and K rates and were within the acceptable limits. The mean total N uptake ranged from 12.9 to 73.5 and mean K uptake ranged from 30.6 to 81.5 kg/ha. Total N and K uptake was marginally higher in cv. ‘Kanchan’ (3.63%) and ‘CH-1’ (4.14%), respectively. In the total 52.2 kg/ha of N uptake, proportion of N accumulation in leaf, stem and root was 54, 25.4 and 20.7% respectively. In the total 61.5 kg/ha K uptake, proportion of K accumulated in leaf, stem and root was 73.4, 17.6 and 9.0% respectively. Agronomic-use efficiency, physiological efficiency, internal efficiency, partial factor productivity and recovery efficiency were higher at lower levels of N and K and decreased with increase in their levels. Nutrient harvest index (translocation index) for N and K almost remained same with increase in N and K level. Both cv. ‘Kanchan’ and hybrid ‘CH-1’ performed on par and would require 120-26.2–99.6kg N-P-K/ha when grown after sunnhemp in situ green manure for getting optimum productivity, better grade index with acceptable chemical quality parameters, optimum nutrient-uptake and nutrient use-efficiencies under irrigated Alfisols of Andhra Pradesh.