Effect of increasing nitrogen fertilization rate on yield and quality of Burley tobacco (Nicotiana tabacum L.) grown under stressed and well-watered conditions

Non-optimal levels of N and water cause adverse effects in tobacco, particularly on the quality of cured leaves, which shows nnbalanced chemical properties or generally non-marketable characteristics. This research aimed to study the effects of N fertilisation on leaf yield and quality (mainly smoke injury) of Burley tobacco in both stressed and well-watered conditions. Two water regimes (a rainfed control, RC, irrigated only for seedling establishment and a wellwatered treatment, WW, receiving the full amount of crop evapotranspiration, ETc) and 4 N fertilisation rates (0, 120, 240 and 360 kg ha-IN) were factorially combined in a field experiment carried out in southem Italy in 1994 and 1995. Yield of cured leaves and yield components per plot were determined on the whole plant and per stalk position. Quality of cigarettes and smoke was determined. The RC yielded significantly less than the WW. The yield of cured leaves increased significantly with increasing N fertilisation ti11 the rate of 120 kg ha-', while higher doses than 120 did not produce any substantial changes. As regards quality, the higher number of aspirations per cigarette was recorded in 1995 while the tar content was higher in 1994. Water regimes significantly influenced al1 parameters. For the whole plant, yield in 1994 was lower than 1995 (-30%) although the yield reduction in 1994 was equally distributed among each layer. Nicotine and tar content as well as number of aspirations per cigarette (burning rate) were favourably affected by irrigation. The increase in N fertilisation increased nicotine content while no effect emerged in tar content due to nitrogen.