Abstract

In this paper, the roles of some environment factors and plant growth regulators on the change in nicotine levels in Nicotiana tabacum L. leaves were studied. Nicotine levels increased during leaf growth. The nicotine accumulation in tobacco leaves was inhibited by 12:12 hours light:dark photoperiod and low NO3-/NH4+ ratio. GA3 (10-mg/l) treatment was required for decreasing nicotine levels in leaves, but increasing plant growth. The roles of plant growth regulators: auxins, cytokinins, gibberellins and ere discussed in relation to the root and leaf growth on leaf nicotine levels.