Stimulation of weed seed germination by 1–(3‐chlorophthalirnido) cyclohexanecarboxamide (AC 94377)

Abstract

The N-substituted phthalimide, AC 94377, promoted the germination of drystored seeds of 17 out of 24 weed species in Petri-dish tests maintained at 22°C. In a further test it was able to substitute for light and/or alternating temperatures in promoting the germination of some species. AC 94377 was more active than GA, in stimulating Solanum nigrum seed to germinate. When mixed with soil in the laboratory, AC 94377 again promoted germination of S. nigrum but the level and persistence of activity differed between soils. In the glasshouse, with soil containing a natural weed seed population, more seedlings emerged from treated than from untreated soil but this number represented fewer than half of the apparently viable seeds present. Field applications of AC 94377 promoted the germination of hand-sown seeds of certain weed species but did not increase the number of seedlings emerging from the natural weed seed bank.

The Germination Stimulant AC94377 Reduces Seed Survival of Wild Mustard (Sinapis Arvensis)

“…Chemical stimulation of dormant weed seed germination by nitrogen fertilizers, herbicides, and either natural or synthetic plant growth regulators was reviewed (26). The Nsubstituted phthalimide AC-94377 enhanced dark germination of dormant seed of numerous weeds (4,8,19) both in petri dishes (4,19) and soil (4,8) in the greenhouse. These studies demonstrated that AC-94377 did not kill dormant seed.…”

“…AC-94377 has gibberellin-like activity in a range of gibberellin bioassays (24) and competitively inhibited GA4 binding in cucumber (Cucumis sativus L.) hypocotyl extracts (29). When applied to soil in the laboratory, GA3 also enhanced germination of dormant seed of numerous weeds (1,2,5,11,15,23) including many of the same species whose germination was stimulated by AC-94377 (4,8,19), such as wild mustard. Dormant wild mustard seed were chosen as a model system to study the impact of AC-94377 on seed survival in the field because of this weed's economic importance in cereal and sunflower (Helianthus annuus L.) production in the northern Great Plains of the U.S. and Canada (20).…”