Endophytic entomopathogenic fungi isolates as growth promoters of the grass Urochloa brizantha

This study evaluated the growth-promoting action of 16 isolates of the entomopathogenic fungal genus Metarhizium spp., representing 14 from the native pastures and two commercial isolates, on the forage grass Urochloa brizantha, via drench application to seeds. Multivariate analysis of plant height, length of the longest leaf and root, and dry and fresh weight of leaves and roots indicated the most promising isolates, five from native pastures (CEPAF_ENT25, CEPAF_ENT26, CEPAF_ENT27, CEPAF_ENT42, and CEPAF_ENT59) and one commercial (IBCB 425), all isolates of Metarhizium anisopliae. Except for isolate CEPAF_ENT59, there was a positive correlation between growth parameters of U. brizantha with the contents of chlorophyll a and b and carotenoids and with the contents of N, P, and Zn in the leaves. Endophytic colonization tests indicated the presence of Metarhizium spp. in all plant parts, most frequently in the stems. Furthermore, the selected isolates of Metarhizium spp. were recovered from the cultivation substrate and positively affected the germination and initial growth of U. brizantha. Thus, the most promising isolates have potential for application to seeds of U. brizantha.