What is the appropriate content of [formula omitted] irrigated into tomato cultivation soil for enhancing its carbon fixation?

Abstract

To improve the carbon fixation capacity of crops, HCO3− is applied to the rhizosphere under a suitable pH value, which can enhance the utilization of CO2 by crops. This study aimed to clarify the maximum fixation capacity of HCO3− in tomato plants by exploring the optimal concentration of HCO3− in their cultivation environment. The results showed that the tomato could maintain both the net increase of HCO3− fixation and normal growth, when the maximum concentration of HCO3− in the cultivation surroundings was discovered during the growth period: 25 mmol/L NaHCO3-solution in seed germination, 14 g-NaHCO3/kg-soil in the cotyledon development, 8 to 10 g-NaHCO3/kg-soil during the seedling, 6 g-NaHCO3/kg-soil in the flowering, and 9 g-NaHCO3/kg-soil in the fruiting. However, excessive HCO3− could impair the development of tomato plants, especially the vegetative growth at seedling/flowering stages and the root growth at fruiting stage due to the increased soil pH and EC by HCO3−. On the other hand, H2O produced by the decomposition of HCO3− by tomato plants could alleviate physiological stress under severe conditions. Therefore, HCO3− became the main inorganic carbon source of tomato assimilation under extreme stress. This study provides a data basis for selecting and optimizing the appropriate HCO3− application amount when CO2 is used for agricultural eco-fixation in the form of HCO3− in the future.