Purpose To explore the effects of different magnesium levels on the growth and development of flue-cured tobacco.
Methods Two flue-cured tobacco cultivars, Yunyan 87 and K326, were selected as experimental materials. Hydroponic and pot experiments were conducted to compare the effects of varying magnesium levels on the agronomic traits, antioxidant enzyme activities, chlorophyll index (SPAD value) and chemical composition of cured tobacco leaves.
Results Under hydroponic conditions, when the magnesium ion mass concentration was 36 mg/L, the dry matter accumulation of stem, leaf, and whole plant of flue-cured tobacco reached the peak; when the mass concentration increased to 48 mg/L, the agronomic traits and chlorophyll content reached the peak, and the magnesium content in roots was significantly increased, indicating that magnesium ion treatment within the range of 36-48 mg/L was conducive to promot the growth and development of flue-cured tobacco, enhancing leaf photosynthesis, and improving the utilization efficiency of nutrient elements. Under the treatment of 48 mg/L magnesium ion, peroxidase and superoxide dismutase activities and malondialdehyde content were relatively low, while catalase activity reached the highest level, suggesting that 48 mg/L magnesium ion treatment could enhance the stress resistance of tobacco. In the pot experiment, when 43.2 g of magnesium fertilizer was applied per plant, nitrogen, phosphorus, and potassium contents in tobacco leaves significantly increased, while chloride content decreased, and the chemical composition of the cured leaves remained within an appropriate range.
Conclusion Both treatment with 36-48 mg/L magnesium ions for Yunyan 87 and application of 43.2 g of magnesium fertilizer per K326 plant can effectively promote the growth and development of flue-cured tobacco, improve the photosynthetic rate and the absorption and utilization efficiency of nutrients in leaves, optimize the chemical composition of cured tobacco leaves, and improve tobacco quality.
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