Impact of bicarbonate on organic acid exudation, silicon uptake and utilization in maize roots
摘要
Global climate change has made carbon neutrality a crucial goal. The karst environment, with high bicarbonate content, challenges plant growth and carbon sequestration. Bicarbonate has both negative and positive effects on plants, and selecting suitable crops to effectively leverage the positive effects of bicarbonates is vital for karst agriculture. This study aimed to investigate how different bicarbonate concentrations affect organic acid exudation from maize roots. It also explored the impact on silicon uptake, growth, photosynthesis and cellular metabolic energy in two maize varieties (Jingke 968 and Tiannuo 182) and compared their adaptability to bicarbonate environments. The experiment was conducted in a greenhouse. Maize seedlings were cultured with Hoagland’s nutrient solution containing different concentrations of NaHCO3 (0, 5 and 10 mM). After 21 days, various indices were measured. The results show that malic and citric acids were key organic acids in maize’s response to bicarbonate stress. Jingke 968, under bicarbonate stress, exhibits reduced photosynthesis and growth, with less energy for silicon uptake and lower carbon storage in phytoliths. Tiannuo 182 adapts better to a 5 mM bicarbonate environment. It also exudes more organic acids, improving its adaptation to high bicarbonate (10 mM) conditions and enhancing carbon sequestration. Tiannuo 182 is more suitable for karst regions with complex bicarbonate environments as it can allocate more energy to growth and silicon absorption. The differential response of maize varieties to bicarbonate stress provides scientific support for variety selection and zoning in karst cultivation areas.