Preliminary studies on the influence of boron on the foliar biomass and quality of tobacco leaves subjected to NO₃⁻ fertilisation

The aim of the present work was to determine the influence of different B dosages on foliar biomass and quality in tobacco plants (Nicotiana tabacum L var Tennesse 86). Tobacco plants were grown under controlled conditions and submitted to regular fertilisation with macro‐ and micronutrients. The B was applied to the nutrient solution in the form of H3BO3 at 5 µM (B1), 10 µM (B2) and 20 µM (B3). The results indicated that under the experimental conditions of this work the increased application of B favoured the growth and development of the leaves, this leading to improved biomass production in tobacco leaves. The increase in foliar biomass in treatment B3 is due largely to the stimulation of NO₃⁻ assimilation. However, this situation has negative consequences for tobacco quality, given that the B3 treatment augmented the NO₃⁻ concentration as well as the foliar concentration of nicotine, both effects being harmful for human consumption. Finally, a close and directly proportional relationship was found in our experiment between the parameters foliar biomass production, total N concentration, chlorophyll concentration and decline in quality.