Growth of Zea mays in response to artificial inoculation with endophytic Beauveria bassiana compared to Trichoderma sp. 'atroviride B'

Demand for sustainable crop production is putting pressure on growers to improve yield while using environmentally friendly solutions. Recently, entomopathogenic fungi have been reported to promote plant growth under certain conditions; however, colonisation of plants as endophytes may be inconsistent or persistence within plant tissues brief. We studied the effects of inoculating three Beauveria bassiana isolates in comparison with a known plant-growth-promoting isolate of Trichoderma sp. 'atroviride B' as a positive control, on the growth of maize (Zea mays L.). We tested the plant response by measuring multiple parameters including biomass, length, chlorophyll content and root architecture following inoculation, to identify even subtle plant growth effects. Fungal isolates were inoculated by inserting hyphae through a small wound made in the stem of emerging seedlings, a technique that has not been previously used for B. bassiana. Results showed neutral effects on biomass, but plants exhibited root architecture changes because of inoculation with B. bassiana isolate (FRh2), which increased fine root length and because of T. sp. atroviride B which increased larger diameter root length. A higher chlorophyll content was observed for plants inoculated with B. bassiana isolate (J18), although this did not correlate with biomass differences. The inoculation technique enabled the comparison of systemic effects to the plants and may have affected subtle but important root-trait modifications. Changes to root architecture can impact resource acquisition in plants, therefore this study highlights the importance of measuring various physiological changes in the plant host when assessing for potential growth effects.