Effects of organic acids on the germination of seeds and growth of seedlings

Abstract A range of aliphatic, aromatic and amino acids at a concentration of 5 mol m^-3 inhibited the extension of roots of barley seedlings. Acetic acid is one of the least toxic but its action has the greatest ecological significance because it can be formed in phytotoxic concentrations by micro-organisms in soil. Its uptake and toxicity were greatest at low pH. Of the plant species which were examined, those most affected were barley, wheat and maize, followed by rape and clover. In aerobic conditions, microbial breakdown of the acid decreased its activity, but in atmospheres containing small concentrations of oxygen the acid prevented the germination of seeds. The toxicity could be partially alleviated by calcium carbonate applied as ground chalk to seeds.