**4. AMF as biofertilizers on Saffron**

Regarding the biological activity, as biofertilizers, AMF offers a way to replace, at least partially, the use of chemical fertilizers and pesticides seeing their fatal effects on the environment and health. In low soil fertility of saffron cultivation areas [43, 44], they can serve as an AMF inoculum which may be part of the solution for sustainable agriculture. Cases in point showed successful application on saffron production under controlled conditions.

*Saffron Endomycorrhizae: Diversity and Effect on Plant Growth and Corm Formation DOI: http://dx.doi.org/10.5772/intechopen.106881*

#### **4.1 Corm production**

In addition to the spice yield, another economically important attribute of saffron is the number of replacement corms. Corms inoculation by composite AMF inoculum significantly initiated and stimulated the production of new corms (**Figure 5**) [30].

Such promoting effect of AMF on initiating the new underground stem propagules was observed previously too [18, 45–47]. Considering that tuber initiation in potato is hormonally mediated [48], it may be that in the present study too AMF affected hormone balance in the saffron plant, leading to earlier initiation and production of corms. Inoculation of corms with spores has enhanced the growth of corms and the number of spores per 10 g soil and results recorded as 13–52 with the highest occurrence in December–January [49]. Caser et al. [50] approved the fact that AMF symbiosis enhanced the production of replacement corms and reduced the occurrence of fungal diseases.

#### **4.2 Growth response**

Although AMF increased the number of corms produced, it increased also shoot fresh weight and root dry weight [51]. A significant increment of the overall growth parameters such as length of aerial and below ground of saffron plants occurred too after AMF colonization [30].

The use of arbuscular mycorrhizal symbionts as biostimulants positively affected saffron cultivation, improving the crop performances and the content of important nutraceutical compounds. In particular, the inoculum composed by *R. intraradices* and *F. mosseae* increased flower production and saffron yield [52]. Such compatibility between AMF fungi and host plant was previously observed in other plants also such as onion [47] and Potato [18] cultivars.

Van der Heijden et al. [53], found that in the grassland ecosystem, inoculation of 14 AM fungal species increased plant diversity by 105% and plant productivity by 42% compared to that in the ecosystem inoculated with only 1 AM fungal species. A study has also revealed that different AM fungi can absorb P at different distances from the

**Figure 5.** *New bulbs production; M: Inoculated plant; C: Control.*

root of the plant, making the host plants inoculated with mixed AM fungal species grow better than those inoculated with AM fungal species.

Variations in the growth of saffron plants are possibly observed as a function of the age of saffron plantation as seen below (**Figure 6**).

#### **Figure 6.**

*Performance of* Crocus sativus *plants as affected by the presence of AMF and age of saffron plantations.*

#### **Figure 7.**

*Different structures of endomycorrhizal fungi colonizing the roots of Saffron plants 4 months after corms inoculation: Arbuscules (a), Spores (s) and intra-radicular hyphae (h) (G 400).*

*Saffron Endomycorrhizae: Diversity and Effect on Plant Growth and Corm Formation DOI: http://dx.doi.org/10.5772/intechopen.106881*

**Figure 8.**

*Quelques morphotypes de spores rencontrés au niveau de la rhizosphère des plants du safran provenant des cormes traitées avec un inoculum endomycorhiziens (S4), après quatre mois de culture. 1:* Rhizophagus intraradices*, 2:* Glomus lamellosum, 3: Funneliformis geosporum, 4: Densicitata nigra, 5: Glomus microcarpum:, 6: Glomus deserticola.

#### **4.3 Root colonization with AMF after corms inoculation**

The positive influence of AMF on plant is otherwise viewed in roots, at this level, mycorrhized plants are shown if they have been able to establish a strong mutualistic relationship with composite AMF inoculum. Four months after inoculation in potted culture, the roots of the plants from the inoculated corms are richly mycorrhized and showed numerous arbuscules and vesicles with extended hyphal colonizing groots. Arbuscules and spores were the most dominant structures (**Figures 7** and **8**).

### **5. Conclusion**

The growing interest in knowing and safeguarding the biological diversity associated with certain arid environments may contribute to improving ecologically the yields of agricultural crops. In the case of saffron, the rhizospheric soil harbored a diversified AMF community and its application as composite inoculum in substrate culture pertains a potential performance on growth and plant succession. As a perspective, future studies should be focused to know the influence of AMF on the growth of the saffron plant in open field conditions.

### **Acknowledgements**

This study was conducted under the research project of the 2nd PMA 2020/11, entitled 'Effect of endomycorrhizal fungi inoculum on agro morphological behavior and productivity of saffron (*C. sativus*) under water and salinity stress' financed by 'Agence Nationale des Plantes Médicinales et Aromatique' et l'Université Ibn Tofail, Kénitra, Morocco'.
