Purpose Plant microbial biostimulants, such as arbuscular mycorrhizal fungi (AMF), enhance nutrient concentration in fruits, including tomato. However, field studies on tomato AMF inoculation are scarce. AMF species belonging to Gigasporaceae and Glomeraceae families known to vary in life-history strategies may determine differential effects on plant nutrient benefits and residue decomposition. Despite this, the effect of different life-history strategies on nutrient acquisition of tomato fruits has not been investigated yet. Methods We studied the effect of inoculation of two tomato varieties with four AMF species belonging to Glomeraceae and Gigasporaceae. Fungal colonization, yield, fruit nutrient concentration, litter decomposition, and bacterial and fungal abundances in soil were assessed in the field under organic agriculture. Results Overall Gigasporaceae promoted the concentration of nutrients in tomato fruits compared to Glomeraceae. A variability in AM fungal colonization and fruit nutrient concentration was detected within Glomeraceae. Scutellospora pellucida increased the yield (+ 27%) of var. Rio Grande with respect to Gigaspora gigantea. In var. Rio Grande, inoculation with Funneliformis mosseae did not change litter decomposition as compared to non-inoculated controls, whereas it was lower than in Sclerocystis sinuosa and Gigasporaceae species, which showed the highest decomposition rates. AMF inoculation promoted soil total bacterial and fungal abundance and fungal:bacterial (F:B) ratio compared to controls, and members of Gigasporaceae had the highest F:B ratio. Conclusion These findings pointed at the inclusion of AM fungal life-history strategy within the selection criteria for the development of biofertilizers able to enhance the nutritional value of vegetables under organic farming systems.

This study is the first approach to in vitro asymbiotic germination of two species of Sicilian threatened terrestrial orchids, Anacamptis longicornu and Ophrys panormitana. Seeds were collected in the wild and cultured in two different media—Orchimax medium (OM) and Murashige and Skoog (MS)—and exposed to different photoperiods and temperatures to evaluate the best conditions for the specific stages of development. The germination of A. longicornu was very high on OM (95.5%) and lower on MS medium (21.4%), whereas O. panormitana germinated only on OM medium, with significantly lower percentages (12.0%), compared with A. longicornu. This difference is caused by variation in quality and quantity of nutrients used, primarily by nitrogen source. The results show that temperature and photoperiod widely affect seed germination and development. Although further investigations on asymbiotic and symbiotic germination are needed for the improvement of conservation of Mediterranean terrestrial orchids, our results contribute to the conservation of this group of plants.

<p>Agricultural production in regions such as sub-Saharan Africa (SSA) is very low as compared to other regions such as the Mediterranean area (MED). Differences are mainly due to agricultural input use which is generally lower in SSA. Indeed, in both regions, where unsustainable agricultural practices are largely applied although varying in intensification, soil organic carbon degradation and soil biodiversity decline are widespread issues. However, whether changes of soil microbial diversity have consequences on agroecosystem services, like crop productivity, in such agro-ecological zones is still scarcely investigated at field level. This long-term field study aimed to understand how different agricultural practices, such as conservation agriculture (CA)-based systems, affect soil microbiome (i.e., arbuscular mycorrhizal fungi (AMF) and bacteria) and their implications on crop productivity. We selected two contrasting soils and agro-ecological zones, in Italy (Centre of Agro-Environmental Research “Enrico Avanzi” – CiRAA – in Pisa) and in Zambia (Msekera Research Station – MRS – in Chipata), to investigate the responses of AMF and bacterial community to CA practices. The experiment at CiRAA was started in 1993 on a silt loam soil and was set up as a split plot design to test tillage regime as the main plot factor and nitrogen (N) fertilization rate as the sub-plot factor. Tillage regimes were conventional tillage (CT) and minimum tillage (MT), while the N fertilization rates were no fertilization (N0) and fertilized with 200 kg N ha<sup>-1</sup> split into three applications (N200). For all treatments, wheat (<em>Triticum</em> <em>aestivum</em> L.) was rotated with soybean (<em>Glycine max</em> L.) in one-year rotations. The experiment at MRS was started in 2012 on a sandy clay loam soil and tested three treatments: CT and maize (<em>Zea mays</em> L.) as sole crop, no-tillage plus mulch (NT+M), and no-tillage plus mulch and rotation (NT+M+R) with maize in rotation with soybean. The climate is cold humid Mediterranean (Csa) at CiRAA and warm temperate with dry winters and hot summers (Cwa) at MRS. DNA was extracted from soil: for AMF PCRs were carried out amplifying part of the SSU, ITS1, 5.8S, ITS2 and part of the LSU of the 18S rRNA region, while for bacteria PCRs were carried out amplifying the V3 and V4 regions of the 16S rRNA region. AMF were characterized by a cloning and Sanger sequencing approach (ca. 1700 bp), whereas bacteria by an Illumina sequencing approach (ca. 630 bp). In both zones, AMF and bacterial composition was similar among CA systems, whereas the long-term implementation of the CA systems resulted in more diverse microbial communities across the agro-ecological zones. CA systems led to positive interactions between AMF and bacterial communities and more complex soil microbial networks. This ultimately led to an improved crop yield. At MRS, soybean as a rotational crop enriched bacterial diversity and within the AMF communities, members of the family <em>Gigasporaceae</em> were more dominant. We finally identified the microbial taxa highly related to crop productivity, providing cause-effect relationships for the involvement of microbes in crop productivity.</p>

Purpose: In the scenario of an increased atmospheric CO2 concentration, nutrients are reduced in all vegetables. In this context, arbuscular mycorrhizal fungi (AMF) could enhance nutrient concentration in edible portions of plants, including tomato. However, field studies on tomato AMF inoculation are scarse. AMF species belonging to Gigasporaceae and Glomeraceae families known to vary in life-history strategies may determine differential effects on plant nutrient benefits and residue decomposition. Despite this, the effect of different life-history strategies on nutrient acquisition of tomato fruits has not yet been investigated. Methods: We studied the effect of inoculation of two tomato varieties with AMF belonging to Glomeraceae and Gigasporaceae. Fungal establishment, yield, fruit nutrient concentration, litter decomposition, and bacterial and fungal abundances in soil were assessed in a two-year field trial under organic agriculture. Results: Overall Gigasporaceae promoted the concentration of nutrients in tomato fruits compared to Glomeraceae. A variability in AM fungal colonization and fruit nutrient concentration occurred within Glomeraceae. Scutellospora pellucida increased the yield (+27%) of var. Rio Grande respect to Gigaspora gigantea. In var. Rio Grande, Funneliformis mosseae determined a litter degradation similar to controls and lower than Sclerocystis sinuosa and Gigasporaceae species, which showed the highest decomposition rates. AMF inoculation promoted soil total bacterial and fungal abundance and fungal:bacterial (F:B) ratio compared to controls, and members of Gigasporaceae had the highest F:B ratio. Conclusion: These findings strongly support that AM fungal life-history strategy should be considered in biofertilizer development to enhance the nutritional value of vegetables under organic farming systems.