ROLE OF PHENOLIC-COMPOUNDS IN THE ANTIALGAL ACTIVITY OF BARLEY STRAW

Barley straw decomposing in well-aerated water releases a substance(s) that inhibits algal growth. Phenolic compounds are toxic to algae but are unlikely to be present in sufficient quantities to account for th e extended antialgal action of straw. However, straw is antialgal unde r conditions that may promote oxidation of phenolic hydroxyl groups to quinones; tannins are antialgal under similar conditions. The toxicit y of authentic quinones towards Microcystis is confirmed; the quinones are some 10(3) times more antialgal than phenolic acids. The possibil ity that oxidized lignin derivatives may be involved in straw toxicity towards algae is discussed.