In vitro interaction between Trichoderma harzianum and plant growth promoter rhizosphere bacteria

Resumen

In order to assess the interaction between a strain of Trichoderma harzianum, TH-382, with different strains belonging to Azospirillum and Sinorhizobium, an in vitro experiment was conducted. The growth and culture of the strains were conducted according to the preestablished methodology. A completely randomized design was applied with five treatments: as control, Trichoderma in solid pure medium; Trichoderma vs. A2, Trichoderma vs. NRG34, Trichoderma vs. N7 and Trichoderma vs. DS2 and ten repetitions. The variables colonies diameter and morphology were assessed. It was proved that Trichoderma may grow in a solid medium specific for rhizobia. Although there was no inhibitor halo, lower diameter of the Trichoderma colony was proved in two treatments cultured with the strains A2 and NRG34 (Sinorhizobium meliloti). This was evident at 72 h and 96 h of culturing. The strains N7 (Azospirillum zeae) and DS2 (A. canadense) were colonized by that of Trichoderma. It is concluded that there was negative interaction between Trichoderma and Azospirillum, predominating Trichoderma, and neutral interaction between Trichoderma and Sinorhizobium, where Sinorhizobium inhibited partially the fungi growth. The results of the interaction of Trichoderma with the strains A2 and NRG34 may be considered as promising for agricultural practice. These results are suggested to be considered for the combined inoculations of Trichoderma and rhizosphere bacteria in further experiments with useful crops for cattle feeding.
Key words: Azospirillum, Sinorhizobium, fungi, compatibility, antagonism.