Ecophysiological requirements on growth and survival of the biocontrol agent Penicillium oxalicum 212 in different sterile soils

• A study of the influence of the physical environment on PO212 survival and growth.
• PO212 was able to survive and grow under different conditions in sterile soil.
• Development of models to predict the combined effects of environmental factors on PO212.
• The growth rate was positively correlated with the survival rate.
• Prediction of risk of PO212 failure to grow and survive in different sterile soils.

In order to optimize the practical application of Penicillium oxalicum strain 212 (PO212) as a biological soil treatment, and to achieve optimal biocontrol efficacy, it is essential to understand how the physical environment influences on its survival and growth. The combined effects of temperature, water potential and soil type on the survival and growth of PO212 were monitored for 30 days in microcosms. Three levels of water potential (dry, intermediate, and wet), two temperatures (15 and 25 °C), and three soils with different physical–chemical properties were used to examine the temporal survival and growth of two PO212 conidial formulations (F1, dried conidia without additives and F2, dried conidia with additives). Traditional serial dilution (CFU) on potato dextrose agar (PDA) and quantitative real-time PCR (qPCR) were used to track the PO212 treatments in the different soils. The survival (CFU) of the F1 was greater than that of the F2. PO212 was able to grow (qPCR) and survive (CFU) at all temperatures and water potentials in the three soils tested. The highest growth and survival rate was observed under some drought stress and in more acidic soils. Regression models were developed for the combined effect of temperature, water stress and soil organic matter content related to the survival and growth of PO212 in soil microcosms. Finally, the growth rate was positively correlated with the survival rate. The results could be successfully employed as an empirical approach in the development and prediction of risk of PO212 failure to grow and survive in different environments.