Acanthamoeba castellanii alone is not a growth promoter for Hordeum vulgare

Abstract

Protists are important key players in the microbial loop and influence their environment by grazing, which leads to the return of nutrients into the soil and reduces pathogen pressure of plants. Espacially protists on and around plant roots, are important for plant’s development and growth. For this study, the crop Hordeum vulgare was selected, which is the fourth most important crop in the world. Seeds of H. vulgare were inoculated with Acanthamoeba castellanii alone or with additional soil bacteria. The germination of the seedlings and the growth of the plants in pouches was monitored over three weeks, while the plants were reinoculated. No differences were found in leaf growth, root growth, root and leaf nitrogen content or ammonia content of the liquid from the pouches. In contrast, the relative increase in root and leaf dry weight showed a small difference compared to the controls. The results of this experiment demonstrated that seed inoculation with A. castellanii alone or with additional unidentified soil bacteria did not have a major effect on plant growth and development of barley. Nevertheless, small changes in the plant development were detected, indicating that A. castellanii should be considered for further investigation of co-inoculations with plant growth promoting bacteria and additional nutrients.