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Entomopathogenic fungi (EF) have so far aroused little interest as plant growth promoters or nutritional enhancers while protecting the plant against insect pests and mites. In this work, we examined the performance of Triticum durum and Triticum aestivum plants pot‐grown on two unsterilized Zn‐poor calcareous Vertisols and inoculated with Beauveria bassiana or Metarhizium brunneum by application to soil or seed dressing. The effects of fungal inoculation were found to depend on crop species, soil type, sampling time and fungus application method. While the height of the control plants tended to be significantly greater than the height of inoculated plants at early and intermediate growth stages, the trend changed at more advanced plant stage of development, 56 days after sowing (DAS). This was supported by the significant increase in aerial dry matter (ADM) in T. aestivum plants treated with B. bassiana by seed dressing (17.4%) or with M. brunneum with soil application and seed dressing (20.6 and 26.9%, respectively) 69 DAS. In T. durum, at harvest, seed dressing with B. bassiana or M. brunneum had an overall positive but not significant effect on ADM or grain yield, whereas direct application to the soil slightly decreased grain yield (6.6 and 5.5%, respectively) and ADM (5.3 and 6.1%, respectively). In T. aestivum, none of the fungus–application method combinations affected yield at harvest significantly. Fungal inoculation had little influence on nutrient uptake, whereas application to soil increased Mn uptake and grain Mn concentration in T. durum. Zinc uptake was significantly increased only in T. aestivum grown on the soil with the lowest Zn content treated with M. brunneum. Grain Zn concentration tended to be inversely related to grain yield. These results support seed dressing with EF as a promising green technology for sustainable crop protection and production with no adverse effects on plant performance. [ABSTRACT FROM AUTHOR]

Although entomopathogenic fungi (EPF) are best known for their ability to protect crops against insect pests, they may have other beneficial effects on their host plants. These effects, which include promoting plant growth and conferring resistance against abiotic stresses, have been examined in recent years to acquire a better understanding of them. The primary purposes of the present study were (i) to ascertain in vitro whether three different strains of EPF (viz., Metarhizium, Beauveria and Isaria) would increase the Fe bioavailability in calcareous or non-calcareous media containing various Fe sources (ferrihydrite, hematite and goethite) and (ii) to assess the influence of the EPF inoculation method (seed dressing, soil treatment or leaf spraying) on the extent of the endophytic colonization of sorghum and the improvement in the Fe nutrition of pot-grown sorghum plants on an artificial calcareous substrate. All the EPFs studied were found to increase the Fe availability during the in vitro assay. The most efficient EPF was M. brunneum EAMa 01/58–Su, which lowered the pH of the calcareous medium, suggesting that it used a different strategy (organic acid release) than the other two fungi that raised the pH of the non-calcareous medium. The three methods used to inoculate sorghum plants with B. bassiana and M. brunneum in the pot experiment led to differences in re-isolation from plant tissues and in the plant height. These three inoculation methods increased the leaf chlorophyll content of young leaves when the Fe deficiency symptoms were most apparent in the control plants (without fungal inoculation) as well as the Fe content of the above-ground biomass in the plants at the end of the experiment. The total root lengths and fine roots were also increased in response to fungal applications with the three inoculation methods. However, the soil treatment was the most efficient method; thus, its effect on the leaf chlorophyll content was the most persistent, and the effects on the total root length and fine roots were the most apparent. In conclusion, EPF improved the Fe nutrition of the sorghum plants, but their effects depended on the inoculation method. [ABSTRACT FROM AUTHOR]

Background and aims: Entomopathogenic mitosporic ascomycetes Beauveria, Metarhizium and Isaria sp. are commonly used for pest control but can also serve other, lesser known functions such as increasing nutrient bioavailability or promote plant growth. The objective of this work was to identify the doses of entomopathogenic fungi (EF) to be applied to soil in order to modify iron (Fe) uptake by plants and promote their growth. Methods: We used an in vitro assay to assess the ability of Beauveria bassiana, Metarhizium brunneum and Isaria farinosa to mobilize Fe from nine Fe oxides differing in composition, particle size and crystallinity, including ferrihydrite, hematite, goethite and magnetite. We also conducted an in vivo assay by applying five different doses (viz., 0, 5 × 10, 5 × 10, 5 × 10 and 5 × 10 conidia ml) of a conidial suspension of M. brunneum to the surface of a calcareous soil, which induced Fe chlorosis and a non-calcareous soil which did not induce chlorosis to explore the ability of the fungus on improving Fe nutrition and plant growth of sorghum and sunflower plants. Results: In the in vitro assay, all three EF increased Fe availability differently depending on particle size and crystallinity, and I. farinosa and B. bassiana increased the pH of the culture medium, whereas M. brunneum did not produce a great effect. In the in vivo assay, the highest dose (5 × 10 conidia ml) of M. brunneum alleviated Fe chlorosis symptoms of sorghum plants grown in the calcareous soil, and the two highest doses (5 × 10 and 5 × 10 conidia ml) increased plant height and inflorescence production of sunflower grown in both soils. Conclusions: The observed benefits of EF on plant growth and nutrition provide support for more sustainable and cost-effective use of these biocontrol agents. [ABSTRACT FROM AUTHOR]

Entomopathogenic fungi are known due to their ability to kill insects and besides they can play other roles, such as promoting plant growth or improving nutrient uptake. The main aim of this work was to assess the potential of Beauveria bassiana strain EABb 04/01-Tip for improving iron (Fe) nutrition in plants grown on calcareous substrates. Plants of a dicot (tomato) and a monocot (wheat) were pot-grown on an artificial substrate consisting of 0–240 g kg −1 Fe oxide-coated sand (FOCS), 250 g kg −1 calcium carbonate sand and quartz sand. The plants were subjected to two different treatments, namely seed dressing, which involved inoculating seeds with a conidial suspension of B. bassiana before sowing, and a control without inoculation. Leaf chlorophyll concentrations (SPAD) and Fe uptake by plants were correlated with the FOCS content of the substrate, therefore the experimental design was appropriate to see different levels of Fe chlorosis symptoms. B. bassiana was able to colonise both tomato and wheat plants without a negative effect on plant height, plant dry weight, root development in tomato or grain production in wheat. In addition, B. bassiana alleviated Fe chlorosis symptoms (described for first time) in both crops during early growing stages (<50 days after sowing) but the intensity of the effect depended on the plant species and available Fe on substrate. Nutritional alterations in K due to fungal application were detected in tomato and wheat plants. [ABSTRACT FROM AUTHOR]