Vegetables are not a single compatibility group. Tomatoes, peppers, onions, beans and many cucurbits can form arbuscular mycorrhizal associations. Brassicas generally do not. For compatible vegetables, transplanting provides a practical opportunity for root contact. Crop nutrition, irrigation and growing conditions remain important.
Keep the context.
Biological compatibility, successful colonisation and a measurable plant response are different questions. The growing conditions matter, and general research is not a promise of a particular result with MegaMyco.
References
Read the biology at its source. These references describe general science and study-specific findings.