Growth-promoting activity of indigenous trichoderma isolates on wheat seed germination, seedling growth and yield

Abstract

Apart from their biocontrol potential, Trichoderma rhizosphere-competent strains stimulate plants growth via several direct mechanisms that affect various growth parameters. In this study, effect of five indigenous isolates (T. harzianum T 969, T. harzianum T 447, T. hamatum T 614, Trichoderma sp. isolate T and Gliocladium virens G525.) on wheat (variety Moghan 3) seed germination, seedling vigor and plant growth was examined through seeds treatment by the conidia and culture filtrate of the isolates. In the field experiments various growth parameters including rootlet and shoot length, stem height and weight, root length and weight, total leaf area, head and tiller number and 1000 grain weight as well as the plant total chlorophyll content and stomata conductance response were evaluated. In overall, seed germination rate was increased. The highest seed germination rate (95.8%) was observed for T. harzianum T969 non-sterilized cultural filtrate treatment and after 96 hours. The isolate G. virens G525 spore treatment decreased the rate by 54.5%. Although all isolates colonized on rootlets but no significant effect on the seedlings growth was observed. Isolate T. hamatum T614 caused necrotic reaction on rootlets, revealing its parasitic rather than symbiotic activity. In the field experiments, the isolates had significant effect on parameters such as stomata conductance, 1000 grain weight, ear fresh and dry weights, ear length and stem and root dry weight but they showed no significant effect on other evaluated parameters. Some isolates improved the affected parameters and some had negative effects which are discussed.