Effects of ferulic acid onGlomus fasciculatum and associated effects on phosphorus uptake and growth of asparagus (Asparagus officinalis L.).

The effect of ferulic acid, an allelochemical produced by asparagus, on hyphal elongation and colonization of asparagus byG. fasciculatum was studied. Spore germination in vitro was not affected, but hyphal elongation decreased significantly with increasing ferulic acid concentration. In the greenhouse, mycorrhizal colonization of roots and growth of mycorrhizal asparagus decreased significantly with increasing ferulic acid concentration, while growth of nonmycorrhizal plants was not affected by ferulic acid. Although plant tissue phosphorus levels were not affected by ferulic acid or mycorrhizal status, ferulic acid inhibition of hyphal elongation in vitro and fungal root colonization in vivo suggests that production of ferulic acid by asparagus reduces the symbiotic effectiveness of the fungus and subsequently reduces plant growth.