do these results support the conclusion from other experiments that c3 plants what hypothesis were the researchers testing in this study? what hypothesis were the researchers testing in this study? sugar beet seedlings have a higher rate of fungal infection in heated soils. the disease-suppressive properties of soils are due to the activities of soil microorganisms. 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. a better growth response than c4 plants under increased co2 concentration? why or why not?