Effects of Phosphate-Solubilizing Bacteria and N2-fixing Bacteria on Nutrient Uptake, Plant Growth, and Bioactive Compound Accumulation in Cyclocarya paliurus (Batal.) Iljinskaja

Abstract

Research Highlights: We firstly interpreted nutritional mechanisms involved in growth regulation and phytochemical accumulation in Cyclocarya paliurus (Batal.) Iljinskaja under three inoculant types, and selected bacterial inoculations for multiple purposes of C. paliurus plantation. Co-inoculation with phosphate-solubilizing bacteria (PSB) and N2-fixing bacteria (NFB) performed better in growth promotion and nutrient uptake than single bacterial inoculation. Background and Objectives: C. paliurus is a well-known medicinal plant as it accumulates bioactive compounds (BC) such as flavonoids, triterpenoids, and polysaccharides, in its leaves. However, the effects of plant growth-promoting rhizobacteria (PGPR) on the growth and BC yields in C. paliurus are not known. To fill this gap, the effects of different inoculants should be examined. Materials and Methods: A pot experiment was conducted and two-year-old C. paliurus seedlings were inoculated with three inoculant types (PSB, NFB, PSB + NFB). After four rounds of inoculation, the growth characteristics and concentrations of flavonoids, triterpenoids, and polysaccharides, as well as the nutrients in soil and leaves, were measured. Results: The inoculations resulted in the elevation of soil available nutrients, with improvements in plant growth, BC yield, and N and P uptake in leaves. However, the changes in BC yields were mainly a result of elevated leaf biomass rather than BC concentrations, and leaf biomass was regulated by C:N:P stoichiometry. Co-inoculation with PSB and NFB was applicable for leaf production, while inocula related to NFB resulted in higher BC yields than PSB and control. Conclusions: Our results implied that bacterial inoculants improved plant growth and BC yield by altering the nutrients in soil and leaves, while three inoculant types showed a different pattern in which co-inoculation with four strains presented a greater performance than single bacterial addition.

Isolation and screening of multifunctional phosphate solubilizing bacteria and its growth-promoting effect on Chinese fir seedlings

“…This study found that the effect of PSBs on soil nutrient content was significantly different. Compared to the control, the content of TN, TP, TK, AP and AK increased significantly, demonstrating that PSB elevated the amounts of available N, P, and K in the soil and subsequently provided better nutrition for plant growth 60 , 61 , which is consistent with the results of Matsumura et al 62 and Wang et al 63 found that inoculation with PSBs significantly increased the accumulation of available phosphorus and nitrogen in the soil, and effectively promoted the growth of Willow seedlings.…”

Succession of the Resident Soil Microbial Community in Response to Periodic Inoculations

“…In addition, the decrease in soil nutrient content at last time points may also be due to seasonal variation and nutrient uptake by plants. Our previous study confirmed that these microbial inoculants enhanced nutrient uptake and stimulated plant growth and biomass accumulation after whole inoculation procedures (32). (29).…”

“…Although this work provided the detailed information about how inoculation period and type affect the resident microbes, the future study should consider to set a unique control which receives only one dose at first and sampled at the end of experiment, to further compare the influences of repeated inoculation compared to one-off inoculation. Furthermore, insignificant (46) (32). However, it cannot be ruled out that other factors, not assessed in this study, might be driving this seasonal variation.…”

“…The influences of different microbial inoculants on soil properties under controlled conditions and the practical effects on plant nutrient uptake under natural conditions have been thoroughly evaluated ( 31 – 33 ). In this study, we sought to investigate the dynamics of soil nutrients, plant growth, and the soil-resident bacterial community in response to successive microbial inoculations over the course of a growing season.…”

Multiple Potential Plant Growth Promotion Activities of Endemic Streptomyces spp. from Moroccan Sugar Beet Fields with Their Inhibitory Activities against Fusarium spp.

“…In contrast to the well-documented action of phosphate-solubilizing and nitrogen-fixing microorganisms in plant P and N nutrition [ 13 , 14 ], the importance of microbial activity on plant K nutrition is less well understood. It has been shown that bacteria and mycorrhizal fungi do solubilize mineral K by various mechanisms such as production of alkaline substances including ammonia and other metabolites upon death of microbial cells and subsequent proteolysis [ 15 , 16 ].…”