The interaction between rhizosphere microbial community structure and metabolites significantly affects the growth and development of hydroponically cultivated chives

Abstract

This study investigated hydroponic cultivation as a recent method for chive production to elucidate the mutual feedback mechanism between the rhizosphere microbial community and metabolites, as well as the quality formation of the aboveground parts. High-throughput microbial sequencing and LC-MS untargeted metabolomics were employed to determine the composition and diversity of the rhizosphere microbial community under both hydroponic and soil cultivation, using soil-cultivated chives as a control. The rhizosphere microecological succession mechanism of chives was explored in conjunction with metabolite change analysis. Additionally, the impact of the rhizosphere microecological environment on chive quality formation in hydroponically cultivated chives was preliminarily investigated by integrating aboveground quality indicators. The results indicated that hydroponic cultivation enhances the growth and yield of chives, with the plant height, stem thickness, and yield per unit area being nearly double those of soil cultivation. Moreover, the hydroponically cultivated chives had higher levels of water-soluble carbohydrates and ascorbic acid but lower levels of dry matter and cellulose. Microbial analysis revealed that hydroponic cultivation exhibited lower microbial diversity compared to soil cultivation. Specific bacterial markers in hydroponic cultivation included Rhodanobacter, Chujaibacter, and Thermomonas, which were involved in various substance transformations, including nitrification, denitrification, and detoxification of plant toxins in the nutrient solution. Metabolomic analysis showed that carbohydrates and amino acids were the main down-regulated metabolites in hydroponic cultivation, whereas phenols, ketones, and amines were up-regulated, indicating that hydroponic cultivation promotes nutrient absorption by chives and enhances their resistance. Correlation analysis revealed that microbial markers regulate carbohydrates and amino acids, enhancing chive's absorption of these substances, which in turn promotes chive growth, increases yield, and facilitates substance accumulation. Moreover, metabolic activities like nitrification and denitrification produce phenols, ketones, and amines, enhancing chive resistance and nitrogen storage. These findings elucidate the rhizosphere microecological activities of hydroponically cultivated chives and offer practical insights for enhancing the quality and production of high-quality chives in hydroponic cultivation in the future.