本研究主要目的為探討紫、白花藿香薊不同密度下對落花生生育及產量之影響，試驗結果如下：藿香薊對落花生生育及產量影響在春、秋作皆顯示，隨藿香薊密度增加落花生地上部乾重、根乾重、葉面積、分枝數皆顯著減少。對秋作落花生產量而言，每平方公尺10株之紫花藿香薊並未減少落花生種子產量，但每平方公尺40株之紫花藿香薊則減產達63%；而秋作每平方公尺10株之白花藿香薊對落花生種子產量減少達23%，但每平方公尺40株之白花藿香薊則減產82%。春作每平方公尺10株之紫花藿香薊使落花生種子產量減少13%，但每平方公尺40株之紫花藿香薊則減產58%。此外，春作每平方公尺10株白花藿香薊使落花生種子減產16%，但每平方公尺40株白花藿香薊則減產達41%。

The major goal of this study was to investigate the effects of different plant densities of A. houstonianum Mill. and A. conyzoides L. on the growth and yield of peanut. Results were summarized as following: In both spring and fall experiments, data showed that the high plant density of Ageratum resulted in the reductions of shoot dry weight, root dry weight, leaf area and branch number of the peanut. In fall experiment, the yield of peanut was not decreased under 10 plants/m^2 of A. houstonianu; however, A. houstonianum at 40 plants/m^2 decreased the yield of peanut by 63%. In fall experiment, A. conyzoides at 10 and 40 plants/m^2 resulted in 23 and 82% yield decreament of peanut, respectively. In spring experiment, A. houstonianum at 10 plants/m^2 decreased peanut yield by 13%; however, A. houstonianum at 40 plants/m^2 decreased the yield by 57%. In fall experiment, A. conyzoides at 10 and 40 plants/m^2 decreased peanut yield by 16 and 41%, respectively.