Application of barley straw to dammed river for algal control

In 1970s, barley straw has been known to be capable of controlling algal growth. In vitro and in situ experiments were performed to investigate the effects of barley straw on algal growth inhibition substances. In addition, its ecotoxicity and the algal growth inhibition substances extracted from barley straw were examined. In the in vitro experiment, barley straw and retinaspora leaf treatment groups caused significant decreases (p value<0.05) in the number of cells in Anabaena affinis, Microcystis aeruginosa, and Scenedesmus quadricauda compared with the control group. However, the treatment group, which applied 0.2g of barley straw, showed a tendency of increasing the number of cells in S. quadricauda compared with the control group. It reveals that types of algae and proper applications of barley straw are important to inhibit algal growth. In addition, the barley straw showed almost no ecotoxicities in ecotoxicity experiments while the retinaspora leaf showed a certain degree of ecotoxicity (Toxicity unit >36). In the in situ experiment, algal growth was inhibited by barley straw. In particular, diatoms exhibited a tendency of decreasing the number of algal cells compared with blue-green algae. It shows that the barley straw does not inhibit the growth of all algae and shows different effects according to types of algae. The algal growth inhibition substances were extracted from the barley straw and tested. It was found that a ferulic acid in various phenol compounds affected the algal growth most.