本研究觀察不同pH值土壤和不同接種處理對4個月大銀合歡(K28)苗木之影響，結果顯示：雙重接種，接種菌根菌之銀合歡苗木的高生長，地際直徑，乾重均比單獨接種根瘤和不接種者爲佳。土壤pH值也影響苗木之生長，各種生長均隨pH值增加而增加，但pH7.0以後則生長下降，銀合歡最適生長之pH值爲6.0-7.0，雙重接種之生長比未接種之銀合歡在酸性土壤之生長優良。接種處理亦影響養分之吸取量，其中N與Ca之吸取量以變重接種者最高，單獨接種菌根菌者次之，接種根瘤和完全不接種者最少。P，K，Mg，Mn，Zn之吸取量則雙重接種和接觸菌根菌者差異不顯著，唯高於接種根瘤菌和不接種者。土壤pH值亦影響苗木養分吸取，N，P，K，Mg，Mn，Zn之吸取隨pH值遞昇而增加，至pH6-7達到最高點，超過pH7.0則吸取量下降。Mn吸取量隨土壤pH值之昇高而下降，Ca則隨土壤值提高而增加。銀合歡苗木生長量和養分吸取量都受到銀合歡pH值和不同接種處理之交感效應。苗木之葉面積雙重接種者爲不接種對照之17倍；菌根感染率則在pH5.0-6.0時最高。
A pot culture experiment was conducted to study the effect of soil pH value and different inoculation treatments on growth of 4-month old seedlings in Leucaena Leucocephala (K28).
The results are showed as follows: Dual inoculation and mycorrhiza inoculaiton alone increased height growth, root collar and dry weight in leucaean seedlings. The increase was highly significant over the treatment of rhizobium inoculation alone and control. Soil pH value also affected seedling growth. Every growth component was increased accordantly with the increasing soil pH to 7. The most suitable pH values for leucaena growth were 6 to 7. Leucaena seedlings with dual inoculation were observed to adapt acid soils. Inoculation treatments also influened nutrient uptake in leucaena seedlings Dual inoculated seedlings had highest N and Ca uptake. The content of P, K, Mg, Mn and Zn in dual inoculated and mycorrhiza-alone seedlings had so significant difference, but both were higher than the rhizobium alone and control ones. The effect of soil pH values on the nutrient uptake was also prominent. There was a pronounced increase in tissue concentrations of N, P, K, Mg, Zn and Ca with increasing soil pH (4.2 to 7).On the contrary, Mn reduced in correlation with gradients in soil pH. Interaction between soil pH value and inoculation treatment was observed in both growth and nutrient uptake of leucaena seedlings. Leaf area of dual inoculated seedlings was obsearved to be 17 time of the control ones. Seedlings in pH 5.0-6.0 soil had highest root infection.
