**3. Contribution of AMF to plant productivity and agroecosystems**

Sustainability of agricultural ecosystems can be restored by stimulating soil life and internally regulated ecosystem processes [31]. The real significance of mycorrhizal fungi is that they connect the primary producers of ecosystems and enable the flow of energy-rich compounds required for nutrient mobilization [32]. Mycorrhizal fungi are one of the commonly occurring living organisms in soil providing many ecosystem services, including N-fixation, soil carbon cycling, plant nutrition, soil erosion control by soil binding capacity [13], soil pollutants remediation, biodiversity, plant water economy [42], and enhanced C-sequestration [22]. AMF and rhizobia can act synergistically and stimulate plant productivity by supplying different limiting nutrients to the plant (e.g., N by rhizobia and P by AM fungi) [43].

Enhanced nutrient uptake and stress resistance are some of the mechanisms by which AM fungi can enhance plant productivity. AMF symbiosis is probably more favorable in conservative and sustainable agriculture to having the potentiality of major beneficial functions such as: (1) increased productivity in the range of 16–78% by gaining more N, P, and other less mobile nutrients increased [24, 43]; (2) increased water uptake and water holding capacity that initiate drought tolerance; (3) increased tolerance to other abiotic stresses such as soil salinity, heavy metal toxicity, etc.; (4) overcoming biotic stresses and offering bio-protection against pathogen; (5) improved soil quality; (6) enhanced plant vigor and yield, thus leading to the production of safe and high-quality foods, able to promote human health (**Figure 2**) [16, 44]. This is determined by fungal the strain, climate, soil type, and cultural practices (fertilization level) in which the soil type is the

*Arbuscular Mycorrhizal Fungi (AMF) in Optimizing Nutrient Bioavailability and Reducing… DOI: http://dx.doi.org/10.5772/intechopen.106995*

**Figure 2.** *Schematic representation of brief function of arbuscular mycorrhizal fungi (AMF) (source: [44]).*

fundamental criterion to determine effective AMF symbiosis strains or species [24]. It is also to improve soil fertility, as they produce glomalin upon accumulation in soil that aids soil in soil stabilization [42, 45]. Furthermore, AMF prevent leaching losses, phosphorus (60%), and ammonium (7.5%) from grassland microcosms during periods of heavy rainfall that cause top environmental threats to ecosystems worldwide [46].

AMF fungi receive 100% of their carbon from the plant, and this increase in carbon flow to the roots, estimated at up to 20% of the plant's photosynthate, translates to a huge amount of carbon worldwide that plays a significant role in carbon cycling between the atmosphere and biosphere [34]. Bender et al. [47] have demonstrated that AMF contribute to reducing emissions of N2O by increasing N immobilization into microbial or plant biomass, which results in the reduction of soluble N in the soil and, consequently, in a limitation of denitrification. Thus, AMF could have an indirect influence on potent greenhouse gas (GHG) emissions through change of the physical conditions of soil that influence the production and transport of GHG in soil [26].

The AMF symbiosis can reduce nutrient loss from ecosystems in three main ways: (1) by improving crop nutrient extraction capacity [43] allowing the production of good yield at lower levels of soil fertility; (2) by increasing soil aggregation via physical particle enmeshment and cementing with "sticky" exudates, which results in better soil nutrient storage and retention [48]; and (3) by promoting growth of host crops, thus increasing the size of this desirable nutrient sink [46]. On average, plants inoculated with *G. mosseae* yielded 13% more biomass relative to non-mycorrhizal plants [49]. Therefore, AMF are vital endosymbionts playing an effective role in plant productivity and the functioning of the ecosystem service.
