氰氮化鈣防治豌豆萎凋病之機制

Abstract

溫室試驗結果顯示，施用氰氮化鈣（CaCN2）可有效降低土壤中豌豆萎凋病菌的數目和抑制豌豆萎凋病的發生。取含有病原菌之新社土壤混合氰氮化鈣（0.5、1.0及5.0％，w/w）後，可提高土壤pH值與鈣離子濃度，並降低土壤中病原菌及微生物的數量；尤其對真菌羣之數量影響最大，並隨著氰氮化鈣濃度的增加而降低。另試驗顯示僅以石灰提高土壤pH值及鈣離子濃度並無法控制豌豆萎凋病，但氰氮化鈣與尿素（氰氮化鈣分解時的中間產物）則皆可抑制病原菌之厚膜胞子發芽、菌絲生長及產胞量。由氰氮化鈣（0.5及1.0％處理者）之抑制曲線在不同的詩間出現兩個抑制區，而尿素則僅有一個，及氰氮化鈣對萎凋病菌菌絲生長及產胞的影響遠較尿素為甚，顯示氰氮化鈣之所以能有效抑制萎凋病的主要因子，或許是來自其中間產物，包括尿素及氰酸的殺菌作用。 Fusarium wilt of peas and its causal organism, Fusarium oxysporum f. sp. pisi, could be effectively suppressed by amending the soil with calcium cyanamide (CaCN2) in greenhouse. When the cultivated soil was amended with CaCN2 at 0.5, 1.0, or 5.0% (w/w), its soil pH value and calcium ion were enhanced but the total numbers of the soil microbes, especially the fungi, were decreased. The more CaCN2 added to the soil, the less disease was obtained. However, the experiments showed that the high soil pH value and calcium ion in the soil, adjusted by calcium carbonate, had no significant effect on the disease control. Both CaCN2 and urea inhibited the chlamydospore germination, mycelial growth and sporulation of the pathogea, but CaCN2 by using at the rates of 0.5 and 1.0% (w/w), had two inhibition zones for chiamydospore germination with time while urea had only one. Calcium cyanamide was also more effective on reducing mycelial growth and sporulation of the pathogen than urea did. Therefore, the suppression of pea wilt might be due to fungicidal effect of the intermediate products including hydrogen cyanamide and urea from calcium cyanamide.