The Effect of 2,4-D on Germination of Pigweed Seed

Abstract

THE use of 2,4-dichlorophenoxyacetic acid (2,4-D) to control T annual weeds such as pigweed (Amaranthus retroflexus L.) is common. Abundant evidence has been published to show that 2,4-D affects germination and subsequent seedling development. Allard et al. (1) found that 2,4-D delayed germination and caused abnormalities in seedlings of 22 broadleaf and cereal species. Elongation of radicles was inhibited in mustard seedlings (7) and in both nondormant and embryo-dormant seeds (4) as well as in seeds with impermeable seed coats (4). Germination can not only be delayed but can be inhibited (4, 5, 6), although at low concentrations of 2,4-D germination may be accelerated (6). Leachates produced by rainfall coming in contact with 2,4-D in soil were deleterious to seeds of flax and corn (2). To explore further the effects of 2,4-D on seeds, germination tests were made with scarified and nonscarified seeds of pigweed and on the effect on yield and germination of seeds harvested from pigweed plants that were sprayed with sublethal doses of 2,4-D in field plots.