The ciliate protozoan Colpoda cucullus can improve maize growth by transporting soil phosphates

Little is known regarding the ability of protozoans to transfer phosphates and improve maize growth. The objective of this study was to determine whether Colpoda cucullus could improve the maize phosphorus (P) level by transferring phosphate. In this three-compartment root box study, the soil in the outer compartment was inoculated with the common ciliate, C. cucullus, together with the addition of either KH232PO4, rock phosphate (RP), super phosphate (SP) or ammonium phosphate (AP), and then maize was grown in the inner compartment. The results showed that the maize plants grown in the soil inoculated with C. cucullus had much higher 32P radioactivity than the control. Colpoda cucullus inoculation resulted in significant increases in dry matter by up to 25.07%, and nitrogen (N), P and potassium (K) absorption by 1-36% (P<0.05). Soil available P in the inner compartment of the root box was also enhanced by at least 30% due to the ciliate inoculation (P<0.05). It was therefore suggested that phosphates might be transported from the outer to inner compartments by the inoculated C. cucullus and then absorbed by the maize plant.