PLANT INTERFERENCE AND CHEMICAL TOXINS IN UPLAND PASTURES

Supernatants derived from desiccated plant material gathered from Agro stis/Festuca vegetation had an inhibitory effect on the germination an d early development of seedlings of Trifolium repens cv. S184. Two com pounds, o-hydroxyphenylpropionic acid and benzoic acid, were identifie d chromatographically and their structures confirmed by mass spectrome try. Commercial preparations of the two compounds were effective inhib itors at a concentration of 10(-2) and 10(-3) M respectively when T re pens was used as the phytometer species. Benzoic acid lost its inhibit ory effect when the pH of the two solutions was adjusted to pH 5.5. Th e roots of seedlings of white clover were severely distorted by o-hydr oxyphenylpropionic acid at 10(-3) M. It is likely that phenolic acids, produced from the surface trash created by slot seeding procedures, i nterfere with the establishment of white clover in upland pastures.