Culturing conditions affect biological control activity of Trichoderma atroviride against Rhizoctonia solani in ryegrass.
OBJECTIVE
Effects of culture conditions on productivity, germinability and bioactivity of Trichoderma atroviride LU132 conidia were assessed to identify the factors affecting conidium 'fitness' (quantity and quality) and to withstand variable environmental conditions, increase conidial productivity, and perform optimum bioactivity.


RESULTS
The interaction effects of temperatures (20 or 30°C) vs hydrocarbon types (dextrose or sucrose in constant C : N 5 : 1) were assessed for bioactivity and colonization potential in pot experiments with ryegrass in the presence of pathogen, Rhizoctonia solani. Trichoderma atroviride produced in different culture conditions increased some growth parameters of ryegrass plant and also reduced the pathogenicity effects of R. solani. For example, Trichoderma colony produced at 20°C with sucrose increased all plant growth parameters and conidia produced at 20°C with dextrose gave the greatest bioactivity.


CONCLUSIONS
The bimodal population cycle in T. atroviride recurred in pot experiments in a manner similar to that previously observed in agar plates but indicating that simulated natural conditions shortened the Trichoderma life cycle. Trichoderma colonized ryegrass root system and symbiotically interacted with ryegrass and greater ryegrass colonization resulted from medium production treatment with dextrose rather than sucrose.


CONCLUSIONS
This study is the first report on the effects of inoculum production conditions on conidium quality of Trichoderma to colonize and to maintain populations in host rhizospheres, and also the ability to promote plant growth and suppress a soil-borne disease. The results of these experiments provide new knowledge on how manipulation of culture conditions of T. atroviride LU132 can influence conidium fitness, as a basis for optimizing commercial production of the fungus as a biological control agent.
Bio-Protection Research Centre, Lincoln University, Lincoln, New Zealand.|Dryland Agricultural Research Institute, Kermanshah, Iran.
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Daryaei
Faculty of Agriculture and Life Sciences, Lincoln University, Lincoln, New Zealand.
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Jones
Bio-Protection Research Centre, Lincoln University, Lincoln, New Zealand.
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Ghazalibiglar
Bio-Protection Research Centre, Lincoln University, Lincoln, New Zealand.
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TR
Glare
Bio-Protection Research Centre, Lincoln University, Lincoln, New Zealand.|New Zealand Institute for Plant and Food Research Ltd, Lincoln, New Zealand.
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Falloon
D003470:Culture Media / Q000737:chemistry / Q000378:metabolism*; D008129:Lolium / Q000254:growth & development / Q000382:microbiology*; D010935:Plant Diseases / Q000382:microbiology* / Q000517:prevention & control; D018517:Plant Roots / Q000378:metabolism / Q000382:microbiology; D012232:Rhizoctonia / Q000254:growth & development* / Q000378:metabolism; D013172:Spores, Fungal / Q000254:growth & development / Q000378:metabolism; D013696:Temperature; D014242:Trichoderma / Q000254:growth & development* / Q000378:metabolism
D003470:Culture Media
Trichoderma; bimodal population cycle; bioactivity; colonization potential; conidium fitness; germinability