Effects of mycorrhiza and plant growth promoting rhizobacteria on yield and quality of artichoke

In the last two decades, increased interest in sustainable agricultural practices has seen the growing development and use of commercial microbial inoculants for increasing crop productivity and resource use efficiency. Microbial inoculants mainly include free-living bacteria, fungi and arbuscular mycorrhizal fungi (AMF). The aim of the current experiment was to assess the effect of two commercial inoculants containing AMF alone or AMF in combination with plant growth promoting bacteria (PGPR) on yield components and quality of artichoke (Cynara cardunculus subsp. scolymus (L.) Hegi). The micropropagated plants of Romanesco globe artichoke cultivar 'C3' were inoculated at transplanting with a commercial inoculum containing 700 spores g(-1) of Rhizophagus intraradices and 700 spores g(-1) of Funneliformis mossae at a dose of 2 kg ha(-1), whereas another part of the plants was inoculated with a commercial inoculum containing 132 spores g(-1) of Rhizophagus intraradices and 2x109 CFU g(-1) of beneficial bacteria (Azospirillum brasilense, Azotobacter chroococcum, Bacillus megaterium, and Pseudomonas fluorescens). The highest yield was recorded in both inoculation treatments, whereas the highest number of buds per plant and fresh weight of globe artichoke were recorded in plants inoculated with AMF and AMF+ PGPR, respectively. The P concentration in artichoke head was higher by 17.4% in both inoculation treatments compared to the control. When averaged over the microbial inoculants, higher lipophilic antioxidant activity and total phenolic content were observed in the internal than in the external bracts. The highest nitrate concentration was recorded in plants treated with AMF (774 mg kg(-1)). Both microbial inoculants did not affect the hydrophilic antioxidant activity (0.63 mmol ascorbic ac. eq. 100 g(-1) f.w.) and total phenolic content (626.2 mg gallic acid eq. 100 g(-1) d.w.). Overall, inoculation of AMF or dual inoculation AMF and PGPR could be considered an effective and sustainable tool to improve yield components with less pronounced positive effects on quality of artichoke.