Bacillus subtilis Promotes Cucumber Growth and Quality under Higher Nutrient Solution by Altering the Rhizospheric Microbial Community

Abstract

Bacillus subtilis was applied in peat-based soilless cultivation systems containing a mixed substrate (peat:vermiculite:perlite = 2:1:1, v/v/v) and irrigated by one-strength or four-strength Hoagland’s nutrient solution to explore whether it can alleviate inhibition by higher-nutrient solutions (four-strength) and bring benefits to improvements of quality. The results showed that higher-nutrient solutions improved the flavor quality of cucumber fruit; especially, the contents of (E,Z)-2,6-nonadienal and (E)-2-Nonenal were effectively increased, which are the special flavor substances of cucumber. B. subtilis K424 effectively improved growth performance, photosynthetic capacity, vitamin C content, soluble sugars, soluble protein, and total pectin in cucumber under higher nutrition solution conditions. Compared with the higher solution treatment, the bacterial diversity significantly increased, whereas the presence of fungi had no significant difference following the B. subtilis K424 application. Moreover, B. subtilis K424 reduced the relative abundance of Actinomadura and promoted that of the Rhodanobacter, Bacillus, Pseudomonas, Devosiaceae, and Blastobotrys genera. Redundancy analysis showed that Bacillus, Rhodanobacter, and Blastobotrys were positively correlated with the substrate enzyme of sucrase, catalase, and urease. This study provides insight that B. subtilis K424 mitigated the deleterious effects of high levels of nutrition solution on cucumber growth and quality by improving the substrate enzyme, regulating the microbial community structure, and enhancing the photosynthetic capacity.

Effect of Cucumber Continuous Monocropping on Traditional Chinese Medicine Residue through Analysis of Physicochemical Characteristics and Microbial Diversity

“…Previous studies have demonstrated that as the duration of continuous monocropping increased, the presence of beneficial bacteria decreased, but the abundance of pathogenic fungi increased. To alleviate and resolve the obstacles in continuous monocropping of cucumber plants, methods such as cucumber-green garlic intercropping/crop rotation [19,66] or the application of Bacillus subtilis as a soilless substrate [67] have been extensively studied, the results of which indicate that the growth and quality of cucumber plants have improved to some extent with such methods. In the soilless cultivation system of cucumber, garlic [68] and corn straw [23] were added to produce highquality cultivation substrates.…”

Radical-induced rapid humification of waste milk and the performance of derived slow release fulvic-like fertilizer

“…6G shows that the relative abundances of plant growth-promoting bacteria (PGPB) (Bacillus, Sinomonas and Ammoniphilus) in SRNFF-treated soil increased from 4.3, 1.4 and 0.12 to 5.1, 2.3 and 1.3% respectively. Therein, Bacillus could increase nutrients in soil 51 , and…”