**4. Role of AMF as a bio-fertilizer**

Biofertilizer is a combination of naturally existing substances utilized to enhance nutrient status of soil. These fertilizers are of remarkable significance to soil microflora and fauna as well as the efficient growth of plants [15]. Nearly from two decades, research investigations have focused on their multiple benefits to soil microflora and fauna and productivity. As a result, it is extensively assumed that AMF will be investigated as a substitute for inorganic fertilizers in the coming years, because mycorrhizal treatment can cause an efficient reduction in the quantity of chemical fertilizer input used, primarily phosphorus [16]. Constant use of inorganic fertilizers, herbicides, and fungicides has generated several difficulties for soil, plant, and human health, owing to their negative impact on food quality, soil micro biota, and air and water environment [17]. For excellent agricultural production, AMF is believed to have the tendency to decrease the need of chemical fertilizers by 50%, however it alters with the type of species and existing stress conditions. AM escalates the absorption efficiency of host plant roots 10 fold [18] and the effectiveness of immobile nutrients by 60 fold owing to penetration in to the nutrient depleted areas of soil. It has been reported that maize plants growing in loamy sand texture soil under water stress absorbed more phosphorus when inoculated with *Glomus etunicatum* compared to non-mycorrhizal plants [19]. Moreover Mycorrhiza has the potential alter the concentration of organic matter thereby plays a tremendous role in storage of carbon in soil [20] and changes the kinetic characteristics of roots resulting in nutrient uptake, thus it is clear indication the mycorrhiza has great role in enhancing productivity and cycling of nutrients [21, 22].

#### **4.1 AMF and mineral nutrition**

AMF colonization is widely thought to promote plant nutrient absorption. It is well known fact that inoculation with AMF can result in adequate escalation in accumulation of various macro- and micronutrients, leading to increase in production of photosynthates and thus enhanced biomass accumulation [23]. AMF have the capacity to escalate the absorption of inorganic substances, notably phosphate, in practically all plants [24]. AMF are also particularly productive at assisting plants in absorbing nutrients from mineral deficient soils. Apart from macronutrients, the association of AMF has been described to inflate the phyto-availability of microelements viz. Zinc and Copper [21, 22]. AMF increases the surface absorbency of the roots of host plant. Inflation in photosynthetic activity and other foliage activities are clearly related to an increase in the occurrence of AMF inoculation, which is clearly related to absorption of carbon, nitrogen and phosphorus, which approaches towards roots and increase tuber enlargement. AMF has been found to balance the absorption of nitrogen and phosphorus, thereby aiding plant enlargement at both high and low concentrations of P under diverse irrigation regimes.

The enhancement of growth in plants by fungi is more remarkable in tropical soils than temperate areas because of inherently low fertility in tropical areas. The phosphatic fertilizers added to the soil are fixed and became unavailable for plants, under low pH phosphorus gets fixed with Fe and Al and under high pH it gets fixed with Ca [25]. AM fungi has the ability to improve P- nutrition in plants through the enlargement of hyphae far off the root system, which permits investigation of fixed minerals [26]. The most significant function of AM is to improve Uptake of P in plants from low P concentrated areas owing to the greater surface area of hyphae and uptake mechanism. The mycorrhizal associated plants show rapid movement of P from roots to above ground parts because of steep gradient between the two. The steepness is due to rapid conversion of inorganic P in the above-ground parts compared to roots. AM also acts on phytate minerals (source of organic P) through the production of acid phosphatize to liberate the H2PO4 ions [27].

#### **4.2 AMF and plant yield**

Useful root zone microflora besides improving the nutrient content of crop, improve crop standard as well. For example, reports have revealed that colonization *AM Fungi as a Potential Biofertilizer for Abiotic Stress Management DOI: http://dx.doi.org/10.5772/intechopen.108537*

**Figure 1.**

*A diagrammatic illustration of mycorrhizal roles in regulating numerous ecosystem processes and promoting plant development under abiotic stress conditions.*

of strawberry with AMF escalated the concentration of secondary metabolites, leading to better antioxidant activity [28]. AMF has the potential to enhance nutritional standard by influencing the synthesis of carotenoids and other volatile chemicals. Further research [29] found that *Glomus versiforme* had higher levels of sugars, organic acids, vitamin C, flavonoids, and minerals, resulting in higher standard of citrus fruits. Mycorrhizal symbiosis increases anthocyanins, chlorophyll, cartenoids, total soluble phenolics, tocopherols, and a variety of mineral nutrients. Rouphael et al. [30] revealed that AMF might mitigate inanimate pressue by regulating soil pH and so preserving its horticultural value (**Figure 1**).
