Mycorrhizal Inoculation Improves Plant Growth and Yield of Micropropagated Early Globe Artichoke under Field Conditions

The micropropagation appears to be a valid alternative method for the production of large-scale, phenotypically homogeneous, and disease-free plants, particularly for spring globe artichoke genotypes. Nevertheless, micropropagated plants have some problems during the acclimatization in field environments. The inoculation with arbuscular mycorrhizal fungi appeared to overcome the transplanting stress. Therefore, a comparison was drawn between the field performances of different vegetative propagation techniques (micropropagated/mycorrhized and offshoots cultivation) of early globe artichoke clones over two growing seasons. The micropropagation/mycorrhization appeared to deliver a better field performance in terms of both plant growth and productivity traits as compared with offshoots cultivated. In particular, the micropopagated/mycorrhized plants exhibited the highest vegetative growth values than the offshoots of the cultivated ones, such as the plant height and the main floral stem length. The micropopagated/mycorrhized plants were also more productive, exceeding the head yield of offshoots cultivated ones by about 63%. However, the micropopagated/mycorrhized plants accumulated almost a month late on the first harvest respect to offshoots cultivated ones. Our data also showed that the effects of the new proposed propagation method were genotype- and season-dependent. Accordingly, some plant growth and productivity traits showed significant ‘propagation method × genotype’ and ‘propagation method × growing season’ interaction. This study revealed that the micropropagation, as well as the mycorrhization, could represent an efficient and sustainable cropping system to reintroduce and increase the productivity of autochthons landraces.

First Report of Meloidogyne javanica on Globe Artichoke in Florida, USA

Globe artichoke (Cynara cardunculus var. scolymus L.) is native to the Mediterranean region and cultivated worldwide for its edible flower buds and the medicinal value of its leaves (Pignone and Sonnante 2004). In 2019, artichokes were planted on 29 km2 predominantly in California, with a yield of over 100 million kg (USDA 2020). It has been grown as a specialty crop in Florida since 2017 (Agehara 2017a). Meloidogyne spp. (root-knot nematodes/RKNs) can lead to yield losses to artichoke (Greco et al. 2005). In June 2020, artichokes (cv. Imperial Star) with stunting, wilting, and galled-root symptoms were observed in a research field with sandy soil located at the University of Florida Gulf Coast Research and Education Center (UF/GCREC), Wimauma, Florida. The goal of this report was to identify the RKN species collected from two symptomatic artichoke roots. Morphological measurements (mean, standard deviation and range) of 15 second-stage juveniles (J2s) included body length = 409.1 ± 31.6 (360.3 - 471.3) µm, body width = 15.4 ± 1.6 (12.4 - 18.8) µm, and stylet length = 14.7 ± 0.7 (13.9 -16.1) µm. Perineal patterns of five matured females had a high dorsal arch and double lateral lines. Morphological characteristics of the RKN cultures were consistent with the description of M. javanica (Eisenback and Triantaphyllou 1991). DNA was extracted respectively from two RKN females isolated from the diseased artichoke roots. The nematode species was confirmed with primers Fjav/Rjav and resulted in ≈ 670 bp fragment (Zijlstra et al. 2000). The COXII region of mtDNA was amplified by C2F3/1108 (Powers and Harris 1993), and the sequencing results were submitted to the NCBI with GeneBank Accession No. MZ397905. The molecular sequences had 100% identity with M. javanica in COXII (MK033440 and MK033439). The pathogenicity test was conducted in the greenhouse at UF/GCREC from May to August 2021 (temperature = 26.7 ± 4.1°C, relative humidity = 83.9 ± 14.6 %). Each of the ten 6.5-in-diameter plastic pots containing 3.8-L pasteurized soil was seeded with one artichoke seed. Five pots were inoculated with 5000 eggs of the field RKN cultures 4-week after planting, and five pots served as the untreated control. Two months after inoculation, galled symptoms were only observed in inoculated plants with an average gall index (Bridge and Page 1980) of 6.2 ± 2.2; 99,240 ± 72,250 eggs were extracted from each root system, and the nematode reproduction factor was 19.9 ± 14.4. Meloidogyne spp. has been reported on artichoke in Europe, Asia, and South America (Greco et al. 2005). This is the first report of RKN on artichoke in the United States. Meloidogyne javanica caused severe root gall symptoms and visible aboveground damage in the form of chlorosis, stunting, and wilting of artichoke planted at the UF/GCREC research farm. Meloidogyne javanica is the predominant RKN species at the UF/GCREC research farm and one of the most common RKNs in Florida (Gu and Desaeger 2021). Artichoke is a new crop in Florida, and RKNs is likely to be one of the main soilborne problems for its production in the state. Its long growing season (October - May) (Agehara 2017b) allows for high nematode reproduction rates. Several new growers have already reported RKN as a problem in their fields. For artichoke to become a commodity in Florida, managing RKNs will be critical. This report provides new information on the risk that RKNs pose to artichoke, a newly established specialty crop in Florida.

Evaluation of Autonomous Mowers Weed Control Effect in Globe Artichoke Field

The development of a fully automated robotic weeder is currently hindered by the lack of a reliable technique for weed-crop detection. Autonomous mower moving with random trajectories rely on simplified computational resources and have shown potential when applied for agricultural purposes. This study aimed to evaluate the applicability of these autonomous mowers for weed control in globe artichoke. A first trial consisting of the comparison of the performances of three different autonomous mowers (AM1, AM2 and AM3) was carried out evaluating percentage of area mowed and primary energy consumption. The most suitable autonomous mower was tested for its weed control effect and compared with a conventional weed management system. Average weeds height, weed cover percentage, above-ground weed biomass, artichoke yield, primary energy consumption and cost were assessed. All the autonomous mowers achieved a percentage of area mowed around the 80% after 180 min. AM2 was chosen as the best compromise for weed control in the artichoke field (83.83% of area mowed after 180 min of mowing, and a consumption of 430.50 kWh⋅ha−1⋅year−1). The autonomous mower weed management achieved a higher weed control effect (weed biomass of 71.76 vs. 143.67 g d.m.⋅m−2), a lower energy consumption (430.5 vs. 1135.13 kWh⋅ha−1⋅year−1), and a lower cost (EUR 2601.84 vs. EUR 3661.80 ha−1·year−1) compared to the conventional system.