Arbuscular mycorrhizal fungi improve biomass, nutritive value, and digestibility of Opuntia ficus-indica (L.) Miller under different water levels by inducing resistances against cochineal infestation

Background: Opuntia ficus-indica (L.) Miller is dominantly growing in arid and semi-arid areas with low nutrient contents. Plants that grow with low-nutrient conditions are more attacked by herbivore insects and develop a strong association with arbuscular mycorrhizal fungi (AMF) to adapt to nutrient, drought, and herbivore insect stress. The objective of this study was to investigate the effects of AMF inoculations and variable soil water levels (SWA) on the biomass, nutrient concentration, nutritional composition, and nutrient digestibility of the spiny and spineless O. ficus-indica by inducing resistance to cochineal stress. Results: AMF was inoculated to O. ficus-indica plants to improve nutrient value and digestibility by inducing to resist cochineal and drought stresses. Second instar crawlers were exposed to the AMF treated and controlled O. ficus-indica plants. Drought stress reduced the below and above-ground biomass, cladode nutrient content, nutritional composition, and in vitro dry matter digestibility (IVDMD) and in vitro organic matter digestibility (IVOMD). AMF colonization significantly increased biomass production with significant changes in the macro and micro-nutrient concentrations of O. ficus-indica . AMF inoculation significantly increased the IVDMD and IVOMD of both O. ficus-indica types by improving the biomass, organic matter (OM), crude protein (CP), and reduced fiber and ash contents. AMF-inoculated cladodes improved the nutrient concentrations of the cladodes. AMF caused an increase in biomass production, increased tolerance to cochineal stress, and improved nutrient concentration, nutritional composition, and nutrient digestibility performance of O. ficus-indica . Conclusions: Our study concludes that the role of AMF on the O. ficus-indica plant is not only to resist drought and cochineal stress but also to improve biomass, nutrient concentration, nutritional composition, and nutrient digestibility. The potential of O. ficus-indica to adapt to cochineal stress is controlled by the micro and micro-nutrient concentration performance related to the AMF association.