[Relationship between SO2 exposure mode and Chinese pine growth].

Area of Science:

• Environmental Science
• Plant Physiology
• Atmospheric Chemistry

Context:

• Chinese pine seedlings (87 days old) were subjected to controlled sulfur dioxide (SO2) exposure for 60 days.
• Three SO2 treatment levels were applied: 0.1 mg/m³, 0.2 mg/m³, and an intermittent high concentration (0.5 mg/m³ for 6 hours, 0.1 mg/m³ for 18 hours).

Purpose:

• To investigate the physiological and biochemical responses of Chinese pine seedlings to varying concentrations of sulfur dioxide (SO2).
• To assess the impact of SO2 on leaf characteristics, nutrient content, and growth parameters.

Summary:

• Low SO2 concentration (0.1 mg/m³) increased leaf sulfur content by 17% and potassium ion leaching by 22% without visible damage or significant changes in growth metrics.
• Moderate SO2 (0.2 mg/m³) led to a 5% decrease in carotenoids, a 92% increase in leaf sulfur, a 67% increase in potassium leaching, and a 4.5% reduction in dry weight.
• High intermittent SO2 (0.5 mg/m³ for 6 hours) caused visible leaf abnormalities, a 21% decrease in carotenoids, a 104% increase in leaf sulfur, an 89% increase in potassium leaching, a 5% decrease in photosynthetic rate, an 8% increase in transpiration rate, and a 7.6% reduction in dry weight.

Impact:

• Even low levels of SO2 can induce significant physiological changes in sensitive plant species, such as Chinese pine.
• Elevated SO2 concentrations negatively affect plant health by reducing photosynthetic efficiency, nutrient balance, and overall biomass accumulation.
• Findings highlight the potential for SO2 air pollution to impact forest ecosystems and agricultural productivity.