title: Quantification of allelopathic potential of sorghum residues by novel indexing of richards' function fitted to cumulative cress seed germination curves.
abstract: The inhibitory activity of aqueous extracts of field-grown sorghum (Sorghum bicolor cv. Bird-a-boo) herbage and roots was quantitatively indexed by three aspects of cumulative cress (Lepidium sativum cv. Curlycress) seed germination: the germination onset; weighted mean rate; and final germination percentage. Extract potency was greatest for herbage collected four weeks after planting but declined sharply thereafter as the plants matured. About 91% of the inhibitory activity obtained from four-week-old herbage was in a low molecular weight fraction. Differential effects of herbage and root extracts on cress seed germination suggest that the nature and/or proportion of biologically active substances extractable from these plant parts is dissimilar.
authors: Department of Horticulture, Pesticide Research Center, Michigan State University, East Lansing, Michigan 48824.
authors: F R
authors: FR
authors: Lehle
authors: A R
authors: AR
authors: Putnam