Trichoderma harzianum T-22 and BOL-12QD inhibit lateral root development of Chenopodium quinoa in axenic co-culture

To investigate the symbiotic interaction of Trichoderma harzianum Rifai on Chenopodium quinoa Willd. in isolation, we studied axenic co-culture of the T. harzianum isolates T-22 and BOL-12QD and the C. quinoa cultivars Kurmi and Maniqueña real. Neither T-22 nor BOL-12QD affected seedling growth during two days of co-culture in the early growth phase of rapid primary root extension. However, after longer axenic co-culture, T-22 and BOL-12 were found to significantly inhibit the overall growth of C. quinoa cv. Kurmi and Real, affecting also vitality parameters as seen for chlorophyll and betalains. Lateral root development was strongly inhibited in all plant−fungal combinations, leaving stunted lateral roots. These results suggest that T. harzianum has a general capacity to inhibit the growth of C. quinoa plants with a main effect on the lateral root development.