Aislamiento y caracterización de Trichoderma spp. asociada con el cultivo de cebolla en suelos de la provincia Tungurahua

Abstract

With the method of inclusion of roots and bait with coconut fragments, Trichoderma could not be isolated. Through the use of containers with rice substrate, molasses and fish meal, an isolate of Trichoderma (P10M2) was obtained, while direct isolation from serial dilutions of soil samples three isolates of Trichoderma (P4M2, P5M1 and P6M3) were obtained. Young colonies of Trichoderma were white and light green colors at anverse of the colonies and the presence of yellow pigmentation in the P5M1 isolate were observed. Colonies were circular, some with concentric rings and irregular edges. Predominant texture of the colonies was cottony. Morphologically the isolates were similar with respect to the diameter of the hyphae, the diameter of the conidia and the length of the phyalides. Branched conidiophores with the main branches producing lateral branches. No strain was able to show significant antagonistic capacity in the dual culture test since none was able to grow on the colony of the phytopathogenic agent or sporulate on it. None of the four Trichoderma isolates were able to inhibit the mycelial growth of S. cepivora as they were not producers of volatile antifungal compounds. The main hyphal interactions observed in dual microcultures were: hyphal coiling, hyphal adhesion and hyphal lysis. The isolation and characterization of native strains of Trichoderma spp. associated with onion cultivation as a starting point to develop future biological control measures for onion white rot.