Understanding the experimental design what hypothesis were the researchers testing in this study? what hypothesis were the researchers testing in this study? the disease-suppressive properties of soils are due to the activities of soil microorganisms. sugar beet seedlings have a higher rate of fungal infection in heated soils. sugar beet seedlings have a lower rate of fungal infection in disease-suppressive soils. soils can be treated to reduce their ability to suppress fungal disease in seedlings.