Effect of Biochar on Tomato Growth and Soil Microecology Under Phenolic Acid Stress

Objective The study was conducted to clarify the regulation effects of biochar on"tomato-soil-microbial community"system under phenolic acid stress.

Method Pot experiments were conducted to compare the effects of biochar addition on tomato growth, physiological indices, tomato yield and quality, soil physicochemical properties and soil microbial diversity under phenolic acid stress. Redundancy analysis was used to reveal the interaction mechanism among the above factors.

Result Compared with the treatment under exogenous phenolic acid stress, the application of 5% biochar could effectively alleviate the stress effect of phenolic acid on tomato plant growth, increase root activity and root-shoot ratio, the single plant yield and average weight of single fruit were increased by 15.2% and 4.3%, and ratio of sugar to acid was increased by 32.0%. Compared with the phenolic acid stress treatment, the application of biochar increased soil pH by 0.59 units, decreased EC value by 21.9%, and the total phenolic acid content was reduced by 25.3% at harvest time. Redundancy analysis results showed that biochar changed the four main soil environmental factors: pH, alkaline nitrogen, total nitrogen, and total phenolic acid contents, then promoted the abundance of microorganisms positively related to tomato yield and quality, and inhibited the abundance of those negatively related to tomato yield and quality.

Conclusion Generally, biochar addition can selectively promote or inhibit soil microbial community abundance related to tomato yield and quality by changing the soil pH, nitrogen, total phenolic acid content and other physicochemical properties. Through the change of microecological environment of rhizosphere soil, the stress effects of phenolic acid allelochemicals on tomato plants can be alleviated, hence achieving the effects of promoting growth, increasing production and improving quality.