Phosphate Uptake is Correlated with the Root Length of Celery Plants Following the Association between Arbuscular Mycorrhizal Fungi, Pseudomonas sp. and Biochar with Different Phosphate Fertilization Levels

The interaction between arbuscular mycorrhizal fungi (AM fungi) and Pseudomonas sp. has received considerable attention. The presence of biochar may affect these microorganisms, with subsequent modification of the phosphorus uptake and root morphology, and plant biomass accumulation. This research sought to identify, in the presence or absence of biochar, the effects of the interactions of mycorrhizal fungi and Pseudomonas sp. on the responses of phosphorus (P) and nitrogen (N) uptake and the root length, surface area, and volume of celery plants with low and high P fertilization under different substrate and soil conditions. The results indicate that strong growth responses of celery plants were observed due to the combination of AM fungi, Pseudomonas sp., and biochar with low P fertilization. A strong linear relationship was found between the plant root length and P accumulation in the shoot fraction in the present study. Increased P and N uptake occurred in treatments combining these microorganisms rather than alone, and this increase especially occurred in the presence of biochar. The low availability of P was substantially recovered by the association of these three aspects. The root morphology was greatly influenced by the biochar additives and in combination with AM fungi and Pseudomonas sp. The root colonization rate of AM fungi was increased by the combination of the inoculation of Pseudomonas sp. and biochar rather than AM fungi and/or Pseudomonas sp. These results indicate an accumulating effect of AM fungi, Pseudomonas sp., and biochar exists on the plant growth response and nutrient uptake because of the increasing root length, surface area, and volume, rather than root biomass.