Field Inoculation Research Articles

Sakha108 Egyptian Rice Variety Japonica Type High Yielding and Resistant to Blast

Sakha108 was released in 2018 as a high yielding cultivar amended for enhancing rice production in Egypt. Sakha108 was developed from backcrossing between Sakha101 and HR5824-B-3-2-3 to retrieve blast resistance that was broken in wide spread variety Sakha101. The cross between Sakha101 and HR5824-B-3-2-3 was initiated in 2003, F1 then was backcrossed with Sakha101 as to produce F1BC1. This backcross was advanced up to 2008 to enrich the genetic background of the recurrent parent Sakha101 along with blast resistance and reach homozygosity up to F1BC6. Five selected promising sister lines were evaluated in preliminary yield trial (GZ8564-SP70-20-6-1-1, GZ8564-SP70-20-6-1-2, GZ8564-SP70-2-6-1-3, GZ8564-SP70-20-6-1-4 and GZ8564-SP70-20-6-1-5). The promising line GZ8564-SP70-20-6-1-1 surpassed all selected lines and was evaluated from 2010 to 2015 in multi-location yield trials, regional, final and verification yield trials. The results indicated that GZ8564-SP70-2-6-1-1 exceeded yield potential of recurrent parent Sakha101, yet with shorter growth duration and blast resistance. The selected line grain yield recorded 10.75 and 11.00 t/haduring 2015 and 2016 seasons with total duration 137 day, while Sakha101 recorded 10.32 and 10.50 t/ha, respectively with a total growth duration of 145 day. GZ8564-SP70-2-6-1-1 showed high level of blast resistance in the field and artificial inoculation under greenhouse conditions compared with Sakha101 that showed susceptible reaction to rice blast under both field and greenhouse conditions. The application of 165 kg N/ha-1 and wider space (25x20 cm) significantly increased growth, yield attributes and grain yield of the new cultivar Sakha108. The new cultivar exhibited multiple resistance to other important biotic stresses.

First Report of Fusarium armeniacum Causing Fusarium Head Blight on Soft Red Winter Wheat in Illinois.

In the summer of 2016, while surveying the diversity of the Fusarium head blight (FHB) causal agent on soft red winter wheat (Triticum aestivum) in Illinois, we identified hundreds of naturally infected plants in five locations. Samples with characteristic symptoms of FHB (bleaching, accompanied by pink/white mycelium) were collected one to three weeks after anthesis. The collected glumes and developing kernels were surface sterilized and plated on sterile media. Single conidia isolates were derived for further work. All isolates were deposited to the USDA-ARS Mycotoxin Prevention and Applied Microbiology Research Unit in Peoria, IL. Among the collection, isolate CMR105 showed characteristics of F. armeniacum growing on PDA with abundant white mycelia and pigments of orange to pink (Suppl. Figure 1B). The CMR105 macroconidia were prominently curved, long, and tapering with a distinct foot shape typical of F. armeniacum (Leslie and Summerell, 2006). CMR105 conidia were produced quickly and abundantly compared to typical isolates such as BMR001, which were rare and slow-growing. The translation elongation factor 1-alpha (EF1-α), RNA polymerase 2 (RPB2), β-tubulin, and the internal transcribed spacer (ITS) genes were sequenced from selected isolates, including CMR105. The resulting DNA sequences were trimmed and aligned using blast on the Fusarium ID database and NCBI's nr database. For all the genes, isolate CMR105 had a 99% or higher similarity to multiple F. armeniacum accessions (Suppl. Table 1). We then conducted a phylogenetic analysis using the DNA sequences of three concatenated genes (RPB2, β-tubulin, and ITS). A maximum likelihood tree supported that isolate CMR105 is F. armeniacum (Suppl. Figure 1E). Koch's postulates were carried out in greenhouse experiments on spring wheat cultivar 'Norm'. At anthesis, a spore suspension of 5 x 104 spores per ml was injected into the central spikelet of wheat heads. Three plants were inoculated per isolate and a mock control consisting of water. The inoculated plants were placed into a mist chamber for 48 hours. Symptoms consisting of premature bleaching of multiple spikelets and pink/white coloration were observed one-week post-inoculation. No symptoms were observed on the control. Two weeks post-inoculation, kernels from the wheat heads were collected, surface sterilized with 10% bleach, and plated on PDA. The recovered isolates showed similar colony morphology to the inoculum. Similar results were obtained on field inoculations on soft red winter wheat. F. armeniacum has been reported from the United States, Australia, South Africa, China, and Argentina (Kommedahl et al., 1979; Nichea et al., 2015). To date, F. armeniacum has been reported to cause seed and root rot on soybeans, has been recovered from asymptomatic corn, and more commonly found as a soil saprophyte (Ellis et al., 2012; Leslie and Summerell, 2006; Nichea et al., 2015). We have shown here for the first time that F. armeniacum also causes FHB on wheat in Illinois. In both field and greenhouse assays, our F. armeniacum strain was less aggressive than F. graminearum strains. Recently, F. armeniacum was reported to cause FHB on emmer and spring wheat in New York (Fulcher and Bergstrom, 2020). It is important to note that many species of the genus Fusarium cause FHB. In this report, we show evidence that F. armeniacum is another causal agent of FHB in Illinois and warrants further study and surveillance.

Field inoculations of nitrogen fixing endophytes on turfgrass

Turfgrass is the number one irrigated crop in the United States. Lawn care regimes require high chemical fertilizer and water inputs. Endophytes, defined as microorganisms that live within plants, have the potential to decrease the high water and high fertilizer requirements of turfgrass. This study evaluated the inoculation of multiple mutualistic endophytes on a commonly planted turfgrass mix in field trials. Previous studies, in greenhouse and lab settings, found these same endophytes increase drought tolerance and grass greenness. Nine 3 ft by 3 ft turfgrass plots were inoculated with an endophyte consortium in the spring and fall of 2017. Inoculated plots were compared with non-inoculated controls for overall chlorophyll content, overall plot greenness, and mean total height accumulation. The results of the study indicated that there was no significant effect of endophyte inoculations on the turfgrass. Additionally, endophytes were extracted, cultured and sequenced from the plots two months post inoculation. The endophytes applied were not detected, indicating that they were unable to survive the entire growing season within the turfgrass. The current research will be one of the first studies to show that endophytes, inoculated onto a novel host, were unable to survive field conditions in a perennial crop and yield the benefits that were observed in vitro and in greenhouse trials. Future research should evaluate the success of these endophytes on other plant species in the field and in non-limiting environments and run a quantitative PCR experiment using isolate specific primers to determine endophyte survival over time in the field.

Adaptation of plant‐mycorrhizal interactions to moisture availability in prairie restoration

The strength and direction of plant response to inoculation with arbuscular mycorrhizal fungi (AM fungi) is dependent on both abiotic and biotic contexts, often generating patterns of AM fungal mediation of plant adaptation. However, knowledge of plant‐community level effects of these interactions in grassland restoration is limited. We conducted a field inoculation experiment by inoculating five plant species native to a drier prairie and five plant species native to a moister prairie with mycorrhizal fungal communities from each prairie type. Species were paired by genus or family to account for phylogenetic effects. The inoculated plants were transplanted to study plots seeded with a restoration seed mix. Plots were manipulated to create either moister or drier conditions similar to environments of the plant species and mycorrhizal communities. In both transplanted and seeded plant species, we found that only drier prairie‐range species benefited from moisture‐regime matched AM fungal inoculum. Other seeded prairie plant species demonstrated a negative response to inoculation, likely due to the earlier successional stage of these species. Additionally, nonseeded plants benefited from inoculation in different ways: native nonseeded plants had highest cover with drier prairie inoculum in drier conditions, while nonnative plants had highest cover with moister prairie‐origin inoculum. These results suggest that use of local AM fungi may be particularly important in restorations at drier sites, even at relatively small differences in moisture availability. Further, specific knowledge of relative responsiveness of seeded plant species and nonseeded plant species to AM fungal inoculation will be useful in planning restorations.

Towards sustainable yield improvement: field inoculation of soybean with Bradyrhizobium and co-inoculation with Azospirillum in Mozambique.

The effects of sole inoculation of soybean (Glycine max L. Merrill) with Bradyrhizobium and co-inoculation with Bradyrhizobium and Azospirillum on nodulation, plant growth and yields were investigated in the 2013/2014 and 2014/2015 cropping seasons under field conditions in Mozambique. The treatments included (1) Control (non-inoculated control, with symbiosis depending on indigenous rhizobia), (2) Urea (non-inoculated, receiving 200kgha-1 of N), (3) Sole inoculation with B. diazoefficiens strain USDA 110, and (4) Co-inoculation with B. diazoefficiens strain USDA 110 and A. brasilense strains Ab-V5 and Ab-V6, evaluated in a randomized complete block design with five replications. Nodule number and dry weight, shoot dry weight, biological and grain yields, grain dry weight, and harvest index were evaluated. In general, both sole inoculation and co-inoculation enhanced nodulation in relation to control. Sole inoculation increased grain yield by 22% (356kgha-1), the same enhancement magnitude attained under mineral N treatment, suggesting that Bradyrhizobium inoculation provides ecological and economic sustainability to the soybean crop in Mozambique or other countries with similar agro-climatic conditions. Co-inoculation did not increase grain yields in relation to neither the control nor sole inoculation, indicating that further research with adapted and high yielding soybean varieties along with effective rhizobial strains is required in Mozambique to attune the beneficial Azospirillum-plant cultivar-rhizobia interactions that have been reported in other countries for several legumes, including soybean.

Alterations of foliar arthropod communities in a maize agroecosystem induced by the root-associated fungus Trichoderma harzianum

Plants establish multitrophic interactions above- and belowground with arthropods and microorganisms. Trichoderma spp. are common soil fungi that colonize roots and promote plant growth and health. Under controlled conditions, Trichoderma spp. have been shown to induce plant resistance against the attack of foliar herbivore insects. Here, we investigated the effect of field inoculation with Trichoderma harzianum in the rhizosphere of maize plants during the vegetative plant growth phase on the community of pest and beneficial arthropods associated with maize foliage. Independent of T. harzianum inoculation, the arthropod community was complex and harbored chewing and piercing-sucking herbivores as well as natural enemies. Inoculation with T. harzianum increased the abundance of chewing herbivores, decreased the number of piercing-sucking herbivores and increased the abundance of sampled pest regulating arthropods. In addition, we provide a biochemical basis of shoot metabolites, which may be involved in the alterations of the foliage arthropod community mediated by T. harzianum. Inoculation with T. harzianum caused substantial changes in the levels of sucrose, jasmonic acid (an activator of defense responses against herbivory) and (Z)-3-hexen-1-ol (a volatile compound that attracts natural enemies of herbivores). In conclusion, our results show that inoculation with T. harzianum can alter the arthropod community associated with maize foliage and reduce the abundance of specific pest insects under field conditions.

Field-inoculated Ailanthus altissima stands reveal the biological control potential of Verticillium nonalfalfae in the mid-Atlantic region of the United States

Ailanthus altissima, perhaps the best-known example of an entrenched invasive weed tree in North America, was introduced to the Eastern U.S. roughly 240 years ago. The biological control of A. altissima has been a topic of interest since the discovery of a destructive naturally occurring Verticillium wilt disease of A. altissima in 2002. After nearly 20 years of research, an augmentative commercial release of this disease agent, Verticillium nonalfalfae, could be initiated in the near future. However, a few questions still remain: i) does the interaction of V. nonalfalfae with the less virulent V. dahliae inhibit the biological control effectiveness of V. nonalfalfae, and ii) do climate and A. altissima stand variables affect this biological control’s efficacy? To help answer these questions, a three-year field inoculation study including 3,245 A. altissima trees in 13 sites across four hardiness zones of Pennsylvania and Virginia, U.S. was implemented. Disease progressed and spread at similar rates in A. altissima trees co-inoculated with V. nonalfalfae and V. dahliae as those inoculated with V. nonalfalfae alone, with no indication of disease progression changing in co-inoculated trees. Verticillium dahliae alone resulted in lower levels of disease, and no disease spread. Similar results were seen in a supplemental greenhouse inoculation study. Despite slight regional variation of disease progression and spread correlated to climate or stand variables, V. nonalfalfae always caused severe disease and spread rapidly to other A. altissima trees through the forested plots. Our results support the use of V. nonalfalfae as a biological control agent throughout the mid-Atlantic region of the U.S. regardless of stand and climate variables, and including sites where trees are already infected with V. dahliae.

Eastern Filbert Blight Resistance in American and Interspecific Hybrid Hazelnuts

Eastern filbert blight (EFB), caused by the fungus Anisogramma anomala, is a primary limitation to european hazelnut (Corylus avellana) cultivation in eastern North America. American hazelnut (Corylus americana) is the endemic host of A. anomala and, despite its tiny, thick-shelled nuts, is a potentially valuable source of EFB resistance and climatic adaptation. Interspecific hybrids (Corylus americana × C. avellana) have been explored for nearly a century as a means to combine EFB resistance with wider adaptability and larger nuts. Although significant progress was made in the past, the genetic diversity of the starting material was limited and additional improvements are needed for expansion of hazelnut (Corylus sp.) production outside of Oregon, where 99% of the U.S. crop is currently produced. Our objective was to determine if C. americana can be a donor of EFB resistance. We crossed 29 diverse EFB-resistant C. americana accessions to EFB-susceptible C. avellana selections (31 total progenies) to produce 2031 F1 plants. In addition, new C. americana germplasm was procured from across the native range of the species. The new collection of 1335 plants from 122 seed lots represents 72 counties and 22 states. The interspecific hybrid progenies and a subset of the American collection (616 trees from 62 seed lots) were field planted and evaluated for EFB response following field inoculations and natural disease spread over seven growing seasons. EFB was rated on a scale of 0 (no EFB) to 5 (all stems containing cankers). Results showed that progeny means of the interspecific hybrids ranged from 0.96 to 4.72. Fourteen of the 31 progenies were composed of at least one-third EFB-free or highly tolerant offspring (i.e., ratings 0–2), transmitting a significant level of resistance/tolerance. Several corresponding C. americana accessions that imparted a greater degree of resistance to their hybrid offspring were also identified. In addition, results showed that 587 (95.3%) of the 616 C. americana plants evaluated remained completely free of EFB. These findings confirm reports that the species rarely expresses signs or symptoms of the disease and should be robustly studied and exploited in breeding.

Phenotyping of F2 populations of Indian mustard for Sclerotinia rot caused by Sclerotinia sclerotiorum under artificial inoculation conditions

Sclerotinia rot incited by Sclerotinia sclerotiorum is a major threat of rapeseed- mustard worldwide. For over two decades, research on the management of this disease has been directed at various approaches, and yet available methods have not provided effective control. Host resistance offers the environmentally safe and long-term method for effective management of this disease. Therefore, F2 population of two crosses i.e. RH 1138×RH 1222-28 and RH 406× RH 1222-28 were screened for their relative resistance/tolerance to Sclerotinia rot under artificial inoculation and permanent sick plot conditions in field at Research Area of Oilseeds Section, Department of Genetics and Plant Breeding, CCS HAU, Hisar during rabi 2018-19. Results indicated that fourteen individuals of F2 population (RH 406 × RH 1222-28) and only two individuals of F2 population (RH 1138 × RH 1222-28) exhibited complete resistance to Sclerotinia rot under artificial inoculation conditions.These sources of resistant F2 plants need to be tested for confirmation for their resistance with other inoculation techniques and after that may be utilized in resistance breeding programme for development of resistant variety of Indian mustard.

Resistance in melon toMonosporascus cannonballusandM. eutypoides: Fungal pathogens associated with Monosporascus root rot and vine decline

AbstractThe fungal speciesMonosporascus cannonballusandM.eutypoideshave been described as the causal agents of Monosporascus root rot and vine decline disease (MRRVD), which mainly affects melon and watermelon crops. Resistance toM.cannonballushas been reported in some melon cultivars (ssp.melo). Moreover, melon ssp.agrestisaccessions have proven to be better resistance sources. This is the case of the Korean accession ‘Pat 81’, highly resistant under field and artificial inoculation. The objective of the work here presented was the evaluation of the resistance to MRRVD of different accessions representing the variability ofCucumis melossp.agrestis, against both,M.cannonballusandM.eutypoides, in a multiyear assay under different infection conditions. In general,M.eutypoideswas less aggressive thanM.cannonballusin the different environmental conditions. There was a strong influence of temperature on MRRVD, with more severe symptoms with higher temperatures and with variable effect of infection on plant development depending on the fungal species considered. Resistance to MRRVD has been confirmed in ‘Pat 81’ and in its derived F1 with a susceptible Piel de Sapo melon. Among the new germplasm explored, African accessions (both wildagrestisand exotic cultivated acidulus) showed good performance in artificial inoculation assays and in field conditions. These sources do not present compatibility problems with commercial melons, so they can be introduced in backcrossing programs. The accession assayed of the wild relativeCucumis metuliferus, also resistant to Fusarium wilt and to root‐knot nematode, was highly resistant to MRRVD. The interest of this accession mainly relies in its advantages as a rootstock for melon.

Native plant abundance, diversity, and richness increases in prairie restoration with field inoculation density of native mycorrhizal amendments

Ecological restoration efforts can increase the diversity and function of degraded areas. However, current restoration practices cannot typically reestablish the full diversity and species composition of remnant plant communities. Restoration quality can be improved by reintroducing key organisms from the native plant microbiome. In particular, root symbionts called arbuscular mycorrhizal (AM) fungi are critical in shaping grassland communities, but are sensitive to anthropogenic disturbance, which may pose a problem for grassland restoration. Studies of mycorrhizal amendments include inoculation densities of 2–10,000 kg of inocula per hectare. These studies report variable results that may depend on inocula volume, composition, or nativeness. Here we test eight different densities of native AM fungal amendment, ranging from 0 to 8,192 kg/ha in a newly installed prairie restoration. We found that native plant establishment benefited from native mycorrhizal inocula, resulting in improvements in native plant abundance, richness, and community diversity. Moreover, the application of very low densities of native mycorrhizal inocula, as suggested on commercial mycorrhizal products, were ineffective, and higher concentrations were required to benefit native plant abundance and community diversity. These data suggest that higher densities of mycorrhizal amendment or perhaps alternative distribution methods may be required to maximize benefits of native mycorrhizal amendments in restoration practices.

THE PATHOGENICITY AND TOXIGENIC PROPERTIES OF Fusarium crookwellense L.W. Burgess, P.E. Nelson & Toussoun DEPENDING ON WEATHER CONDITIONS

Field inoculation experiments were performed during 2015–2017, in south-eastern part of Poland. The pathogenicity of F. crookwellense was estimated based on the kernels yield reduction of 10 selected oat genotypes. Panicles of oat were inoculated with conidial suspension of F. crookwellense strain No. 72 which caused a reduction in kernels yield by 28.54% and kernels number per panicle by 28.07%, compared to the control. The lowest yield reduction, as a result of the panicle inoculation with F. crookwellense, was found in the case of the cultivar ‘Pablo’ (18.73%), while the highest in the case of breeding line POB 961-1344/13 (36.4%) and cv. ‘Kozak’ (34.3%). Statistically the highest average yield reduction was observed in year 2016, when a higher amount of rainfall, especially in July (just after inoculation) and higher temperature, compared to the long-term standard, were observed. During the period between inoculation and harvest, F. crookwellense was able to produce nivalenol, fusarenone X and zearalenone in oat kernels at the average level of 0.065 mg∙kg-1, 0.026 mg∙kg-1 and 0.015 mg∙kg-1 respectively.

Traits of the entomopathogenic nematode, Heterorhabditis bacteriophora (Hb-EG strain), for potential biocontrol in strawberry fields

Entomopathogenic nematodes (EPNs) can provide a substantial control, especially of the root feeding larval pests. The objective of the present study was to examine beneficial traits of an indigenous entomopathogenic nematode species, Heterorhabditis bacteriophora Poinar (Hb-EG strain), and to identify superior biocontrol candidates for suppression of the scarab beetle Temnorhynchus baal (Reiche & Saulcy) (Coleoptera: Scarabaeidae: Dynastinae) larvae as serious pests of strawberry in Egypt. The nematodes were applied to infect the greater wax moth, Galleria mellonella L. cadavers, to represent natural emergence from the host in laboratory and under field conditions. Its average yield was 49604 infective juveniles (IJs) per G. mellonella larva. Overall averages of nematode-induced mortality in G. mellonella larvae were (4.63, 3.12, and 1.92) at 4, 8, and 12 weeks, respectively, after continuous weekly baiting with 5 cadavers. Nematode capability for infection and reproduction ranged from 72 to 26% one to five months, respectively, after field inoculation of the infected larvae into the strawberry rhizosphere. The number of IJs, moved to the North of the rhizosphere, was significantly (P ≤ 0.05) less than that moved to the South or the East as reflected by the numbers of infected insects. The factors that may have a marked influence on EPN foraging behavior, persistence, and movement direction with implications for harnessing them as biological pest control agents were discussed.

Practices of biological soil crust rehabilitation in China: experiences and challenges

Biological soil crusts (biocrusts) are a central component of dryland ecosystems. However, they are highly vulnerable to disturbance and natural recovery may be slow. Therefore, finding ways to enhance the reestablishment of biocrusts after disturbance has been of great interest to researchers. This article provides a review of the laboratory cultivation and field inoculations of biocrust materials in China (mostly published in Chinese). Larger filamentous cyanobacteria (e.g.Microcoleus) are relatively easy, although slow, to grow in culture compared to other biocrust components. Thus, most researchers have focused their efforts on the cyanobacteria and a few species of mosses that are also easily grown but at smaller scale. For all the studies, a small amount of biocrust material was collected and its biomass enhanced under controlled conditions. However, the enhancement was done using various methods and techniques in different regions. These materials were then applied to disturbed field sites, again with various methods. Results show that keeping the inoculated soil surface wet for some time period after inoculation was crucial for restoration success. Cyanobacterial establishment was improved by installing automatic sprinkling using micro‐irrigation techniques and/or physical structures that reduced sediment moving onto the inoculated area. Experimental applications in China showed that cyanobacteria can be successfully inoculated at a large scale (hundreds of ha). Moss inoculation, on the other hand, was only accomplished at a small scale (several m2). To assess whether biocrust restoration can enhance the establishment of a self‐supporting ecosystem, further research is needed on how inoculation affects vegetation diversity and structure and ecological processes.

Crop Yield, Ferritin and Fe(II) boosted by Azospirillum brasilense (HM053) in Corn

An increasing global population of over 4.5 billion people drives increasing demand for calories—30% of which are satisfied by grain crops, such as maize. High-density farming practices have been implemented but tend to deplete the soil of essential elements resulting in lower nutritional value, notably iron, of cultivated crops. Low iron content in staple crops can contribute over time to severe, even fatal, micronutrient deficiencies. Enhancing grain iron content using post-harvest biofortification strategies can be costly. However, field inoculation using biologics like Azospirillum brasilense (HM053) can be a cost-effective alternative to improving crop nutritional value. Using ion chromatography with chemiluminescence detection, we have shown that maize seeds harvested from outdoor pot-grown plants possessed a four-fold higher iron content as ferrous iron (Fe+2) compared to non-inoculated plants. Seeds from A. brasilense HM053-inoculated plants also contained approximately 13 nmol of ferritin per ground dried weight of kernel compared to 3 nmol from non-inoculated plants. In addition, A. brasilense HM053 inoculation increased crop yield 30–50% relative to non-inoculated plants.

Controlling runoff generation and soil loss from field experimental plots through inoculating cyanobacteria

Controlling runoff generation and soil loss from hillslopes is a priority for land management. The capability of cyanobacteria as inoculants has recently been utilized in land management, and as a result various lab-scale studies have been conducted. The present study conducted a field-pilot experiment in Miandoab City, south of West Azerbaijan Province, North West Iran, to evaluate the success of cyanobacteria inoculation in runoff and sediment reduction from an abandoned and degraded land at large plot scale under natural rainfall. On 26 December 2017, the cultured native cyanobacteria (Nostoc sp. and Oscillatoria sp.) was inoculated on the 22.1 × 1.83 m2-plot in three replicates along with three control plots treated by pure water. The runoff and soil loss from the treated plots were measured for seven rainfall events that produced runoff during normal rainy season of the study area i.e., December 2017 to May 2018. Results showed that inoculation of cyanobacteria significantly (p < 0.05) decreased runoff by some 35, 25, 31, 33, 46, 47, and 57% for the recorded rainfall events (1 to 7), respectively. The beneficial reduction of sediment concentration due to the inoculation of cyanobacteria was also observed for rainfall events 1, 2, 3, and 5 at the respective tune of 16, 34, 36, and 135% compared to those of control plots. Soil cracks indicators, roughness, and aggregate stability were also improved by 5.1 to 27%, 14 to 20%, and 13 to 22%, respectively, owing to the inoculation of cyanobacteria. Although vegetation cover at the end of experiment was 2.6 times denser than that in the beginning, there was no significant difference between inoculated and control plots. By and large, field inoculation of cyanobacteria was found as an efficient technique for runoff and soil loss inhibition, particularly in degraded and abandoned drylands.

Field Inoculation of Bread Wheat with Rhizophagus irregularis under Organic Farming: Variability in Growth Response and Nutritional Uptake of Eleven Old Genotypes and A Modern Variety

Arbuscular mycorrhizal fungi (AMF) promote crop growth and yield by increasing N and P uptake and disease resistance, but the role of field AMF inoculation on the uptake of micronutrients, such as Fe and Zn, and accumulation in plant edible portions is still not clarified. Therefore, we studied the effect of field inoculation with Rhizophagus irregularis in an organic system on 11 old genotypes and a modern variety of bread wheat. Inoculation increased root colonization, root biomass and shoot Zn concentration at early stage and grain Fe concentration at harvest, while it did not modify yield. Genotypes widely varied for shoot Zn concentration at early stage, and for plant height, grain yield, Zn and protein concentration at harvest. Inoculation differentially modified root AMF community of the genotypes Autonomia B, Frassineto and Bologna. A higher abundance of Rhizophagus sp., putatively corresponding to the inoculated isolate, was only proved in Frassineto. The increase of plant growth and grain Zn content in Frassineto is likely linked to the higher R. irregularis abundance. The AMF role in increasing micronutrient uptake in grain was proved. This supports the introduction of inoculation in cereal farming, if the variable response of wheat genotypes to inoculation is considered.

In situ effects of Lathyrus sativus- PGPR to remediate and restore quality and fertility of Pb and Cd polluted soils.

Rehabilitation of heavy metals contaminated soils using association between legumes and beneficial rhizospheric microorganisms such as plant growth-promoting bacteria (PGPR) is a major challenge in agronomy. The present study focuses on assessing the impact of field inoculation with I1 (Rhizobium leguminosarum (M5)+Bacillus simplex+Luteibacter sp.+Variovorax sp.) and I5 (R. leguminosarum (M5)+Pseudomonas fluorescens (K23)+Luteibacter sp.+Variovorax sp.) on growth and phytoremediation potential of Lathyrus sativus plants as well as soil quality and fertility. The experimentation was carried out in mine tailings of northern Tunisia. Obtained Results indicated that the in situ inoculation with I1 and I5 significantly increased the shoots (47% and 22%) and roots dry weights (22% and 29%), as well as nodules number (48% and 31%), respectively, compared to uninoculated plants. The maximum Pb accumulation in the above-ground tissue was recorded in plants inoculated with I5 (1180.85mgkg-1 DW). At the same time, we noticed a reduction in total Pb and Cd in the rhizosphere of inoculated plots mainly in those inoculated with I5 reaching 46% and 61%, respectively, compared to uninoculated plots. Likewise, I5 inoculum significantly enhanced soil total nitrogen (35%) and available phosphorus (100%), as well as β-glucosidase (16%), urease (32%) and alkaline phosphatase (12%) activities. Here we demonstrate the usefulness of L. sativus inoculated with I5 inoculum formed by mixing efficient and heavy metals resistant PGPR to boost an efficient reclamation of Cd and Pb contaminated soils and, ultimately, to improve their quality and fertility.

Trichothecium roseum Enters ‘Fuji’ Apple Cores Through Stylar Fissures

Apple core rot, an economically important disease worldwide, appears both before and during harvest. Current gaps in understanding of the infection cycle impede progress toward more effective management of this disease. The fungus Trichothecium roseum is the main pathogen of core rot on apple in China. In this study, we used fluorescent labeling to trace colonization of T. roseum in floral tissues, characterizing routes of penetration to the core of 'Fuji' apples. T. roseum infected petals, anthers, filaments, stigmas and separated styles of flowers, and floral debris served as inoculum for core infection. In field inoculations, T. roseum entered styles initially through stylar fissures and colonized pluricellular hairs of these fissures during early stages of fruit development. Subsequently, hyphae grew along the extending fissures, which are continuations of stylar fissures located between stylar bases and carpel cavities. The hyphae remained in the extending fissures from mid-June to late July. When fruit developed an open sinus in late July, the sinus eventually fused with extending fissures and carpel cavities in late August, hyphae invaded carpel cavities, and ultimately fruit flesh via cracks on carpel cavity walls. Our results revealed for the first time the routes by which T. roseum penetrates apple fruit, and provided significant insights for strategic management of core rot.

Potential of a coevolved rust fungus for the management of Himalayan balsam in the British Isles: first field releases

SummaryIn 2014, the rust fungus Puccinia komarovii var. glanduliferae, native to the foothills of the Himalayas from Kashmir to Western Nepal, became the first fungal agent to be released into Europe for the classical biological control of a non‐native weed. The target, Impatiens glandulifera or Himalayan balsam, is a prolific invader of riparian habitats in Europe and North America. During the period 2015–2018, a strain of the rust from India was released at a total of 36 sites, in 17 counties in England and Wales. There was limited field infection in 2015 and inoculation experiments conducted under controlled conditions revealed significant variation in the susceptibility of plant populations to the rust, with some showing immunity. Subsequently, a second strain of the rust from Pakistan was released in 2017 and was found to infect a different cohort of Himalayan balsam populations. The rust mass production methodology, and field inoculation and monitoring protocol, are detailed, and plants were tested for susceptibility to both rust strains prior to field release. Levels of foliar infection at selected sites in 2017 and 2018 are presented, as well as seedling infection rates in the spring of 2019. The results show that the rust is able to overwinter and establish populations in stands of Himalayan balsam in England. The issues involved with measuring the impact of the biological control agent are discussed.