固氮菌的應用及發展

Abstract

肥料三要素氮、磷、鉀中，唯一能來自大氣中的是氮，但此種氮氣不能直接被植物利用，需要將氮氣轉化成氨才能被植物利用，將氮氣轉化為氨的過程謂之「固氮作用」。生物固氮是自然界的固氮微生物的作用，氮氣經由固氮細菌、放線菌或藍綠藻之固氮酵素轉化成為氨態氮，其中農業上最多的是屬於根瘤菌。根瘤菌的應用上可以減少施用氮肥，減少環境中氮的污染及土壤酸化，可提高豆科的產量及品質，並增進土壤肥力及健康。固氮菌的應用上以篩選優良菌種為首要工作。在台灣大豆根瘤菌之生理生化的研究已有相當之報導。 田間試驗中，接種根瘤菌，結果發現對大豆、毛豆、花生、銀合歡產量較未接種的處理均有增加。接種根瘤菌及菌根真菌到台灣的六個試驗地，結果顯示單獨接種根瘤菌的處理明顯增加大豆根瘤生成、瘤重及固氮酵素之活性，而對大豆產量有高達134％之增產；而雙重接種根瘤菌及菌根菌，對大豆產量之影響範圍有達145％之增產。固氮菌在台灣研究發展已邁向多功效及多作物應用之菌種，除具固氮作用外，已篩選出固氮溶磷之菌種，並已初步完成非豆科與根瘤菌形成根瘤之研究發展，將使固氮菌成為多目標用途之菌種。 In N, P, K fertilizers only N source are obtained from the air. N2 in the air is not utilized by plants. It need to be transformed to ammonia by nitrogen fixation. Biological nitrogen fixation is a process to fix nitrogen in bacteria, acety-nomycetes, or blue-green algae. Rhizobia is a most usefull inoculant in the agriculture. The application of rhizobia inoculant can decrease the N application fertilizer pollutions and soil acidification, and can increase the production and quality of legumes. The selection of superior microorganisms are main work for the successful inoculation. The physiological and biological studies for Taiwan rhizobia of soybean were reported in many papers. In field experiments results showed that productions of soybean, vegetable soybean, peanut, and Ieucaena were increased by rhizobial inoculation. Treatments inoculated with rhizobia in field experiments increased nodules, and nitrogenase activity and increased soybean production up to 134%. Treatments inoculated with both rhizobia and VA mycorrhiza increased soybean productions up to 145%. Development in N2-fixing microorganisms was studied for multi-function and multi-crops, such as P-solubilizing ability in N2-fixing bacteria. The nodulation of non-legumes was studied primarily for rhizobial multi- inoculation.