Effects of transplanting mode and nitrogen application rate on growth, development and yield of flue-cured tobacco

Objectives Suitable transplanting methods and the combination of nitrogen application rates in tobacco planting areas of Shaanxi were compared, which provided a theoretical basis for the production of high quality flue-cured tobacco in Shaanxi tobacco-growing areas.

Methods A split-plot experiment was conducted using tobacco cultivar of Qinyan 96 as materials in Baoji City, Shaanxi Province. The main plots were transplanting methods, including conventional transplanting, transplanted seedlings beneath the plastic film and transplanted seedlings uncovered inside cellular wells.The subplots were five levels of nitrogen, 52.5, 60, 67.5, 75 and 82.5 kg/hm². Tobacco samples were collected to determine the activities of nitrate reductase and amylase at growing stages, and the contents of carbon and nitrogen metabolites and the yield and quality of tobacco were investigated at the maturity stage.

Results The activities of nitrate reductase and amylase showed trends of increasing first and then decreasing in the whole growth period of flue-cured tobacco. In the conventional transplanting mode, the high nitrogen rate was suitable for high contents of carbon and nitrogen metabolites, agronomic and economic characters of flue-cured tobacco. In the membrane transplanting and well pit-type membrane transplanting, the nitrate reductase and amylase activities under the medium nitrogen rate were beneficial to the growth of flue-cured tobacco seedlings. Under the same nitrogen application rate, the growth, yield and quality of tobacco in well pit-type membrane transplanting were better than in the others. When the nitrogen application rate was 67.5 kg/hm², the activities of nitrate reductase and amylase were the highest, the carbon and nitrogen metabolites and the agronomic and economic characters were high and stable.

Conclusions The feasible transplanting mode in Weibei tobacco production area is the well pit-type membrane transplanting and the nitrogen rate is 67.5 kg/hm². This combination could improve the carbon and nitrogen metabolism of flue-cured tobacco and promote its growth and development, and improve the economic benefit.