A Sustainable Intercropping System for Organically Produced Lettuce and Green Onion with the Use of Arbuscular Mycorrhizal Inocula

Arbuscular mycorrhizal fungi (AMF) are efficient for improving crop production and quality in organic farming systems. Our objective was to examine the effects of two AMF inocula, Rhizophagus intraradices and Diversispora spp., against a non-inoculated control on lettuce and green onion grown organically in an intercropping cropping system. At time of harvest, colonization levels were very low, and not different compared to the control that was colonized by the native mycorrhizal community. The yield of inoculated lettuce and green onion was unchanged, as also observed in the root system architecture analysis parameters. In both crops, color was not affected, limiting the possibility for consumers to reject the product. Nitrate accumulation was well below the limits set by European Commission in all treatments. Sugar, chlorophyll, K, Na and P contents were also quantified, showing no particular variations. In AMF-treated lettuce, important phytochemical characteristics, such as phenol content and ascorbic acid, showed a tendency for reduced values, while antioxidant capacity was significantly reduced by both AMF treatments. The study provides a description about the effect of AMF on two important co-cultivated crops. Research should be continued in order to determine best matches between plant material and AMF inocula that could result in enhanced production and nutritional quality.

Automated summary

The effects of two types of arbuscular mycorrhizal fungi (AMF) inocula on lettuce and green onion were examined. The AMF inoculation did not significantly affect the yield and root system architecture of the crops. Nitrate accumulation was within the limits set by the European Commission. However, important phytochemical characteristics and antioxidant capacity showed a tendency for reduced values in the AMF-treated lettuce.