• 作者： 楊秋忠; D.P. Bartholomew
• 作者服務機構： 國立中興大學土壤研究所; 夏威夷大學農藝及土壤系
• 中文摘要： 本研究利用蛭石盆栽方式，以Hoagland營養液及缺氮營養液進行探討二種林波草(Bigalta and Greenalta)根分泌物對螢多藤生長、營養吸收及固氮作用的影響。本試驗盆栽採用新設計分隔式觀察根分泌物的作用，結果顯示二種林波草的根分泌物在Hoagland營養液栽培都具有抑制螢多藤幼苗的地上部生長，而在缺氮營養液栽培則只抑制根部生長。接受根分泌物的營多藤之地上部所含氮、鉀、鎂、硫、鐵及銅量與未接受根分泌物處理之含量無顯著差異，唯磷之含量有顯著之抑制現象。二種禾草在Hoagland營養培養下根所分泌之物有抑制螢多藤的根重、根瘤重及根瘤大小，而根瘤固氮酵素的活性並未受影響。本研究指出螢多藤的生長抑制可能是與林波草的分泌物之有毒物質有密切關係。
• 英文摘要： It has been observed that the growth of Desmodium intortum (Mill.) Urb. cv. Greenleaf is inhibitedwhen grown with limpograss (Hemarthria altissima (Poir.) Stapf. and Hubb). To ascertain whether rootexudates from donor plants of cv. Bigalta and Greenalta limpograsses inhibited the growth of Greenleafdesmodium, the effects of root exudates from the two grasses on growth, nutrient uptake, nodulation, andnitrogen fixation of the legume were studied. The plants were grown in a greenhouse in a vermiculiteculture system and were watered with Hoagland's and N-free nutrient solutions. Competition between thespecies for nutrients and light were minimized by growing the plants in divided pots which kept the plantsseparated but permitted transfer of root exudates between halves of the pots. Exudates from Bigalta andGreenalta inhibited the top growth of Greenleaf seedlings in pots with dividers irrigated with Hoagland'ssolution, but not in the N-free nutrient solution. Fresh shoot yields of Greenleaf were less in the presence ofroot exudates from Bigalta as compared to those from Greenalta. The concentrations of N, K, Mg, Na, S,Fe, and Cu in the tops of Greenleaf receiving root exudates from the two grasses did not differ significantlyfrom the control, although the P concentrations of Greenleaf plants receiving root exudates from Bigaltawere significantly lower than the control. Average root weight, total nodule weight, and nodule size werevery low in the presence of root exudates from both grasses in Hoagland's culture. Under N-free regimes,nitrogenase activity as estimated by acetylene reduction was lower in nodules of Greenleaf plants that hadtheir roots intermingled with those of donor plants. These data indicate that Greenleaf growth retardationin vermiculite cultures was due to allelopathic substances in root exudates produced by Bigalta and Gre-enalta, and, especially where N is limiting, some of this effect may be due to interference with nodulationand nitrogen-fixation.
• 中文關鍵字： Allelopath; Desmodium intortum; Hemarthria altissima; Nitrogen fixation; Root ex-wdates
• 英文關鍵字： --