Allelochemicals released in soil following incorporation of rapeseed (Brassica napus) green manures.
Plant-derived allelochemicals such as those produced by glucosinolate hydrolysis in Brassica napus, or rapeseed, are viable alternatives to synthetic compounds for the control of soil-borne plant pests. However, allelochemical production and residence times in field soils have not been determined. Soil samples were taken at 0-7.5 and 7.5-15 cm during a period of 3 weeks following plow-down of two winter rapeseed cultivars (Humus and Dwarf Essex). Soil samples were extracted with dichloromethane and analyzed using gas chromatography. Nine glucosinolate degradation products were identified-five isothiocyanates, three nitriles, and one oxazolidinethione. Maximum concentrations were observed 30 h after plow-down. Compounds derived from 2-phenylethyl glucosinolate, the principal glucosinolate in rapeseed roots, dominated the profile of degradation products. Shoot glucosinolates left few traces. This indicates that rapeseed roots may be a more important source of toxic fumigants than above-ground parts of the plant.
Gardiner
J B
JB
Soil Science Division, University of Idaho, Moscow, Idaho 83844-2339, USA.
Morra
M J
MJ
Eberlein
C V
CV
Brown
P D
PD
Borek
V
V
D001937:Brassica; D002849:Chromatography, Gas; D017879:Isothiocyanates / Q000032:analysis*; D008372:Manure; D012987:Soil / Q000032:analysis*; D013863:Thioglucosides / Q000032:analysis*
D017879:Isothiocyanates; D008372:Manure; D012987:Soil; D013863:Thioglucosides