Abstract:
An Investigation was conducted to determine the effects of varying temperatures between 20 to 30 C day and 10 to 15 C night on the Inhibitory activities of aqueous extracts of ambrosia artemisiifolia, Ambrosia trifida, Bramus Inermis and Hellanthus annus on Spring and Winter wheat germination and growth. The results showed that Winter wheat seed germination was significantly less In the presence of extracts at 24/12, 28/14 and 30/15 than under a 20/10 C (day/night) temperature regime, whereas Spring wheat showed no dramatic extract Inhibition under any of the temperature regimes. This might be due to genetic differences between Spring and Winter wheat and, thus, allowing Spring wheat to be competitive with other Spring weedy species. The dramatic significant reduction In dry weight of both Spring and Winter wheat seedlings grown for ten days In the aqueous extracts Is considered to be of tremendous economic Importance to wheat agriculturists. The striking reductions In productivity (10 65 percent) caused by the extracts would seriously reduce wheat yield If those Inhibitory species are permitted to grow on the same field as wheat. Although the exact nature of the alleopathic agents In the plants tested In this study Is not known, It Is apparent that further research Is necessary In order to Isolate the specific Inhibitory compounds. Once Isolated, further Investigations can be pursued that will allow elucidation of the mechanlsm(s) Involved In alleopathy. Isolation of the alleopathlc agents might also suggest a possible explanation as to why those agents demonstrated greater Inhibitory activities on wheat germination and growth under temperature regimes above.
