Glucosinolate-containing plant tissues as bioherbicides

Enzymatic hydrolysis of glucosinolates, a class of compounds found in Brassica species, results in a number of products with potential to inhibit seed germination. To investigate the impact of both volatile and water soluble allelochemicals, germination bioassays were conducted with Lactuca sativa seeds in the presence of defatted seed meal of Brassica napus. Seed meal in which glucosinolates were hydrolyzed to remove volatile glucosinolate degradation products was compared with intact seed meal and water controls. Only tissues containing glucosinolates produced volatiles that inhibited germination. Biologically active volatiles were identified by GC-MS as isothiocyanates and nitriles, products of glucosinolate hydrolysis. Water-soluble components also inhibited germination, with analysis confirming the presence of nonvolatile products of glucosinolate hydrolysis. The results suggest that allelochemical control of germination with glucosinolate-containing plants may contribute to reductions in synthetic pesticide usage if weed seeds are targeted.