Biological fitness of Trichoderma atroviride during long-term storage, after production in different culture conditions

ABSTRACT

Identification of the production and storage factors that affect conidium germination and bioactivity (fitness) will assist the success of biological control agents. Effects of culturing conditions on conidium fitness of Trichoderma atroviride LU132 were examined in different storage conditions over time. Abiotic factors (temperature, nutrients, water activity and pH) during production were studied. Conidia from the culturing regimes which resulted in greatest and least bioactivity against Rhizoctonia solani in dual culture were selected to assess effects of storage conditions on conidium fitness. Fitness of the test conidia was examined after storage at 30°C and at 0% or 50% relative humidity (RH) over 6 months. Fitness declined over time, and the decline was greater for 50% RH than 0% RH, probably through reduced metabolic activity of conidia during long-term storage. Stored conidia were probably affected by dehydration, temperature and other factors such as oxidation, before and during storage, and also by rehydration after storage. The greatest number of conidia and germination percentage resulted from production at 25°C, but greatest bioactivity resulted from those produced at 30°C. No significant effects on bioactivity were detected between the conidium production treatments C : N 5 : 1 and C : N 160 : 1, indicating that C : N ratio in culture medium is not important for conidium survival of T. atroviride.

KEYWORDS:

• Biological control agent
• water activity
• culture conditions
• abiotic factors
• germination
• bioactivity
• Rhizoctonia solani

Acknowledgements

Mr D. Saville gave advice on experimental design and statistical analyses and Dr H. Ghazalibiglar assisted in data collection and interpretation.

Disclosure statement

No potential conflict of interest was reported by the authors.

Supplemental Data

Supplemental data for this article can be accessed here: http://dx.doi.org/10.1080/09583157.2015.1077929.

Additional information

Funding

This study was completed as part of research funded by the New Zealand Ministry of Business, Innovation and Employment ‘Biological control Products’ programme (C10X 0706).