Abstract: Different type aqueous extracts from the above-ground part of Ageratina adenophora Sprengel were prepared under the treatments of whole plant, clipped plant and air-dried plant for 6, 24 and 48 hours, aimed to evaluate their allelopathic potential to the seed germination and seedling growth of upland rice (Oryza sativa L.), and examine the interference effect of their osmotic pressure on the allelopathic potential. It was found that these aqueous extracts had significant allelopathic inhibitory potential, with the sequence of the treatment air-dried plant>clipped plant>whole plant, and of the treating time 48 h>24 h>6 h. The osmotic pressure of the aqueous extracts was also in the sequence of the treatment air-dried plant>clipped plant>whole plant, and increased with increasing concentration and treating time. The interference effect of the osmotic pressure was increased with increasing osmotic pressure, suggesting that osmotic pressure could be an important factor which interfered in the evaluation of the allelopathic potential of aqueous extracts from A. adenophora, especially from its air-dried and clipped plants. It was proposed that whole-plant treatment should be preferred in the preparation of A. adenophora aqueous extracts.

Key words: Microsatellite DNA, Isolation, Enrichment