Inoculum Sources Modulate Mycorrhizal Inoculation Effect on Tamarix  articulata Development and Its Associated Rhizosphere Microbiota

Abstract

(1) Background: Soil degradation is an increasingly important problem in many parts of the world, particularly in arid and semiarid areas. Arbuscular mycorrhizal fungi (AMF) isolated from arid soils are recognized to be better adapted to these edaphoclimatic conditions than exogenous ones. Nevertheless, little is known about the importance of AMF inoculum sources on Tamarix articulata development in natural saline soils. Therefore, the current study aims at investigating the efficiency of two AMF-mixed inoculums on T. articulata growth, with consideration of its rhizosphere microbiota. (2) Methods: indigenous inoculum made of strains originating from saline soils and a commercial one were used to inoculate T. articulata in four saline soils with different salinity levels under microcosm conditions with evaluation of rhizosphere microbial biomasses. (3) Results: Our findings showed that indigenous inoculum outperforms the commercial one by 80% for the mycorrhizal rate and 40% for plant biomasses, which are correlated with increasing shoot phosphorus content. Soil microbial biomasses increased significantly with indigenous mycorrhizal inoculum in the most saline soil with 46% for AMF, 25% for saprotrophic fungi and 15% for bacterial biomasses. (4) Conclusion: Present results open the way towards the preferential use of mycorrhizal inoculum, based on native AMF, to perform revegetation and to restore the saline soil microbiota.

Keywords: ergosterol; mycorrhizal inoculation; phospholipid fatty acids; soil salinity.

Figure 1

Effect of AMF inoculum sources on T. articulata total seedling biomass in the four studied soils. NI: non-inoculated. CI: commercial inoculum. AI: Indigenous inoculum. Data are represented as mean ± standard deviation. Means are obtained from five replicates (n = 5). Different letters indicate significant differences between treatments in the four studied soils according to the Tukey HSD test (p < 0.05).

Figure 2

Impact of AMF inoculum sources on T. articulata shoots phosphorus content in the four studied soils. NI: non-inoculated. CI: commercial inoculum. AI: Indigenous inoculum. Data are represented as mean ± standard deviation. Means were obtained from five replicates. Different letters indicate significant differences between treatments according to the Tukey HSD test (p < 0.05).

Figure 3

Effect of AMF inoculum sources on C16:1ω5 soil content of T. articulata cultivated soils. (a) PLFA amount. (b) NLFA amount. (c) NLFA: PLFA C16:1w5 ratio. NI: non-inoculated. CI: commercial inoculum. AI: Indigenous inoculum. Data are represented as mean ± standard deviation. Means were obtained from five replicates. Different letters indicate significant differences between treatment and different symbols indicate significant differences between soils according to the Tukey HSD test (p < 0.05).

Figure 4

Effect of AMF inoculum sources on ergosterol levels of the soils of T. articulata in the four studied soils. NI: non-inoculated. CI: commercial inoculum. AI: Indigenous inoculum. Data are represented as mean ± standard deviation. Means were obtained from five replicates. Different letters indicate significant differences between treatments and different symbols indicate significant differences between soils according to the Tukey HSD test (p < 0.05).

Figure 5

Influence of AMF inoculum sources on PLFA bacteria Gram + and Gram - amounts of the soils of T. articulata in the four studied soils. NI: non-inoculated. CI: commercial inoculum. AI: indigenous inoculum. Data are represented as mean ± standard deviation. Means were obtained from five replicates (n = 5). Different letters indicate significant differences between treatment and different symbols indicate significant differences between soils according to the Tukey HSD test (p < 0.05).