Microbial Biofertilizer Decreases Nicotine Content by Improving Soil Nitrogen Supply

Area of Science:

• Agricultural Science
• Soil Science
• Biotechnology

Background:

• Biofertilizers are recognized for improving soil biological and physicochemical properties.
• Nicotine content in tobacco is a critical factor for quality and consumer health.
• Regulating soil nitrogen supply is a potential strategy to manage nicotine levels in tobacco plants.

Purpose of the Study:

• To investigate the efficacy of a novel microbial biofertilizer containing Phanerochaete chrysosporium and Bacillus thuringiensis in reducing nicotine content in tobacco leaves.
• To elucidate the underlying mechanisms of nicotine reduction by analyzing soil nitrogen dynamics, enzyme activities, and plant nitrogen accumulation.

Main Methods:

• Application of a microbial biofertilizer (P. chrysosporium and B. thuringiensis) to tobacco crops.
• Monitoring of soil nitrate-nitrogen (NO₃⁻-N) and ammonium-nitrogen (NH₄⁺-N) levels.
• Measurement of nitrogen supply-related enzyme activities (nitrate reductase, urease).
• Analysis of nitrogen and protein content in tobacco leaves at different growth stages.

Main Results:

• The biofertilizer application led to a significant reduction in tobacco leaf nicotine content, up to 16-18% in mature upper leaves.
• Soil NO₃⁻-N and nitrate reductase activity increased, while NH₄⁺-N and urease activity decreased in biofertilizer-amended soil.
• Total nitrogen and protein concentration in lower and middle leaves increased, but decreased in upper leaves, indicating altered nitrogen distribution.

Conclusions:

• The microbial biofertilizer effectively reduces nicotine content in tobacco by modulating soil nitrogen supply and plant nitrogen uptake.
• The observed changes in nitrogen metabolism and distribution within the plant contribute to the reduction in nicotine levels.
• This biofertilizer shows potential for improving tobacco quality and offers valuable insights for sustainable tobacco cultivation practices.