The Effects of Naturally Occurring Phenolic Compounds on Seed Germination

Abstract

Caffeic acid, chlorogenic acid, coumarin,p-coumaric acid, ferulic acid, fumaric acid, gallic acid, hydrocinnamic acid,p-hydroxybenzoic acid, juglone, and pyrocatechol were examined for effects on germination of nine crop and weed species: cotton (Gossypium hirsutumL.), cantaloupe (Cucumis meloL.), corn (Zea maysL.), sorghum [Sorghum bicolor(L.) Moench], hemp sesbania [Sesbania exaltata(Raf.) Cary], sicklepod (Cassia obtusifoliaL.), velvetleaf (Abutilon theophrastiMedic), prickly sida (Sida spinosaL.), and redroot pigweed (Amaranthus retroflexusL.). Germination tests with 10-3and 10-5M solutions were conducted under controlled conditions in petri dishes at 25 C in the dark. At 10-3M, coumarin, hydrocinnamic acid, juglone and pyrocatechol inhibited germination, butp-hydroxybenzaldehyde andp-hydroxybenzoic acid were not effective and others had intermediate effects. There was little effect by any compound at 10-5M. Chlorogenic acid,p-hydroxybenzaldehyde, and pyrocatechol, each combined with coumarin, inhibited germination. The combination of coumarin plusp-hydroxybenzaldehyde had an additive effect on hemp sesbania and prickly sida, inhibiting germination to a greater extent than either compound alone. The lack of inhibitory action at the higher concentration of some of these chemicals suggests they may not exhibit a high allelopathic potential.