Effects of entomopathogenic fungi on growth and nutrition in wheat grown on two calcareous soils: Influence of the fungus application method

Abstract

Entomopathogenic fungi (EF) have so far aroused little interest as plant growth promoters or nutritional enhancers. In this work, we examined the performance of Triticum durum and Triticum aestivum inoculated with Beauveria bassiana or Metarhizium brunneum by application to soil or seed dressing. Both species were pot-grown on two unsterilized Zn-poor calcareous Vertisols. The effects of fungal inoculation were found to depend on crop species, soil type, sampling time and fungus application method. Both fungi exhibited significant detrimental effects at early and intermediate growth stages with some combinations of crop, soil and fungal treatment. In T. durum, direct application of B. bassiana to the soil significantly decreased grain yield (6.6%) and aerial dry matter (ADM) at harvest (5.3%), whereas direct application of M. brunneum decreased grain yield significantly (5.5%), and seed dressing with either fungus had an overall positive but not significant effect on ADM or grain yield. 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. Gains in grain Zn concentration were mostly related to losses in grain yield resulting from the fungal treatments. These results support seed dressing with EF as a promising green technology for sustainable agriculture with no adverse effects on plant performance.