Four allergic proteins with molecular weights of 17.9, 20.1, 26.6 and 66.5 kDa have been identified from the pollen (Rosas Alvarado et al., 2008).
The most active allelochemicals from Amaranthus palmeri (AM) were volatile compounds.
Volatiles emitted by soil containing AM residues and by dried and partially rehydrated leaf and flower residues themselves reduced carrot and tomato seed germination to < 7 %.
Freshly harvested AM inhibited only carrot seed.
Germination of AM and carrot seeds was retarded by exposure to volatiles from dried AM residues. Onion seeds were also inhibited by volatiles from AM (Bradow and Connick, 1987).
The four compounds chondrillasterol, phtol, 2,6-dimethoxybenzoquinone and vanillin, showed biological activities, to varying degrees, in seed germination bioassays (Bradow, 1985).
Laboratory seed germination bioassays of crude organic solvent extracts of Amaranthus palmeri parts indicated the presence of both promotive and inhibitory compounds.
Aqueous extracts of the leaves and thyrses (flowering parts) had no significant effect on any of the seeds tested (Bradow, 1985).