Six experiments were carried out during 1973 and 1974 to study the effects of some cultural practices on tobacco. In Expts 1 and 2 effects of N, topping and suckering were studied. Leaf area was increased by N and topping in both experiments. Suckering significantly decreased, and slightly increased, the area in Expts 1 and 2, respectively. The number of leaves per plant was increased by topping and suckering in Expt 1, but decreased by both in Expt 2. N decreased the number of leaves in both experiments. Yield of cured leaf was increased by all three factors in Expt 1 and by suckering only in Expt 2, whereas both N and topping slightly decreased the yield in the latter experiment. Quality was significantly lowered by the higher rate of N, while generally improved by topping and suckering.

In Expts 3 and 4, effects of plant density, N and stage of suckering were studied. The yield of cured leaf was increased by the higher plant density, by 9 and 15%, and decreased by the higher dose of N, by 15 and 7%, in Expts 3 and 4, respectively. Early suckering was beneficial in Expt 3 (16%), but harmful in Expt 4 (8%). Leaf quality was decreased by the higher rate of N, but improved by the higher plant density. Time of removal of suckers had no significant effect on yield or quality.

In Expts 5 and 6 effects of supplementary irrigation at different stages of growth were studied. Both the number of leaves per plant and yield followed very similar trends. The best yield and quality were obtained when irrigation was not limiting during all three phases of growth. However, the last phase (C) was the most critical phase regarding irrigation in Expt 5, while the first two phases were the most critical ones in Expt 6, since withholding irrigation during phase C reduced yield by 44–50%, and only 6%, in the two experiments, respectively. Leaf quality seemed to be best when irrigation was applied throughout the growth period, particularly the first two phases of growth.