本試驗以逢機增殖多型性DNA (random amplified polymorphic DNA,RAPD)，探討台灣地區收集之74 個綠天竺草(Panicum maximum var. trichoglume)和41 個天竺草(P. maximum)之遺傳歧異度。結果RAPD 分子標誌顯示，僅有18個引子具有多型性及再現性良好，在綠天竺草可擴增出117 條帶，其中有89 條具有多型性DNA 條帶，多型性比例佔73.2％，遺傳分化指數(Gst)為0.4625，基因流(Nm)為0.5811，遺傳距離矩陣介於0.0302-0.2205 間，以遺傳相似度0.10 為截點可分為4 群，第一群：台北、桃園、新竹、苗栗、台中及彰化地區；第二群：雲林、嘉義及台南地區；第三群：台東、花蓮及宜蘭地區；第四群：高雄和屏東地區。天竺草可擴增出105 條條帶，其中有72 條具有多型性DNA 條帶，多型性比例佔66.5％，遺傳分化指數(Gst)為0.5229，基因流(Nm)為0.4563，遺傳距離矩陣介於0.0401-0.2342 間，以遺傳相似度0.11 為截點可分為4 群，第一群：台中、雲林、南投及嘉義地區；第二群：台南和高雄地區；第三群：屏東地區；第四群：台東和花蓮地區。綠天竺草和天竺草族群的遺傳距離與地理距離分別為r=0.5230(p=0.00001*)和r=0.6912 (p=0.00001*)，顯示二者皆有顯著的相關性，符合距離隔離模式。因此， RAPD 於族群之歸群分析中具有高的靈敏度。

In this study, the genetic diversity of 74 green panicgrass (Panicum maximum var.trichoglume) and 41 guineagrass (Panicum maximum) in Taiwan were determined byusing random amplified polymorphic DNA (RAPD). The results showed that in theRAPD analysis, 18 out of 40 random primers were positive. In green panicgrass, total of117 bands were amplified, and there were 89 bands to possess the polymorphic typing,the percentage of polymorphic is 73.2％. The values of genetic differentiation (Gst) is0.4625, the gene flow (Nm) is 0.5811, the genetic diatance matrix located from 0.0302to 0.2205. They could be divided into 4 groups based on the genetic similarity of 0.10 asthe critical point. The first group included Taipei, Taoyuan, Hsinchu, Miaoli, Taichungand Changhua, the second group included Yunlin, Chiayi and Tainan, the third groupincluded Taitung, Hualine and Yilan, and fourth group included Kaohsiung andPingtung. For guineagrass, total of 105 bands were amplified, and there were 72 bandsto possess the polymorphic typing, the percentage of polymorphic is 66.5％. The valuesof genetic differentiation (Gst) is 0.5229, the gene flow (Nm) is 0.4563, the geneticdiatance matrix located from 0.0401 to 0.2342. They could be divided into 4 groupsbased on the genetic similarity of 0.11 as the critical point. The first group includedTaichung, Yunlin, Nantou and Chiayi, the second group included Tainan and Kaohsiung,the third group included Pingtung, the fourth group included Taitung and Hualien. Forthese two species, the values of genetic distance and geographic distance are r = 0.5230(p=0.00001*) and r=0.6912 (p=0.00001*), respectively. These results revealed that theyshowed significant relationship between them, and was consistent with the model ofdistant isolation. In this test, we have collected green ganicgrass and guineagrass from14 and 9 locations, respectively. According to the results, it showed that the speciesinvolved in one group was selected according to the nearly geographical distance byRAPD analysis. It was concluded that RAPD methods was precise for cluster analysis.