SUMMARY
AbstrakRendahnya produktivitas lahan pertanian di Indonesia berkaitan dengan serangan penyakit tanaman, contohnya penyakit layu Fusarium pada tanaman tomat dan busuk pangkal batang pada tanaman kelapa sawit yang disebabkan oleh Ganoderma boninense. Penelitian sebelumnya telah berhasil mengisolasi aktinomisetes dari tanah Arboretum Universitas Riau, namun belum diketahui kemampuannya dalam menghambat jamur Fusarium oxysporum f.sp lycopersici dan Ganoderma boninense. Penelitian ini bertujuan untuk menguji 32 isolat aktinomisetes terhadap jamur target dengan metode difusi agar. Aktinomisetes potensial yang terpilih, dilanjutkan untuk produksi senyawa antifungi dengan lama waktu fermentasi yang berbeda (4, 5, dan 6 hari) dan diuji dengan metode difusi kertas cakram. Hasil penelitian uji aktivitas antifungi dengan metode difusi agar menunjukkan 31 isolat aktinomisetes mampu menghambat pertumbuhan jamur F. oxysporum f.sp lycopersici dan isolat A2.01 memiliki zona hambat tertinggi yaitu sebesar 36,10 mm. Sebanyak 28 isolat aktinomisetes mampu menghambat jamur G. boninense dan isolat D2.28 memiliki zona hambat tertinggi, yaitu sebesar 45,71 mm. Isolat aktinomisetes Arboretum Universitas Riau sebagian besar dapat menghambat pertumbuhan kedua jamur target dengan metode difusi agar, namun hasil uji senyawa antifungi isolat potensial dengan metode difusi kertas cakram belum mampu membentuk zona hambat. Isolat aktinomisetes potensial dapat diaplikasikan menggunakan kultur langsung secara in vivo.Abstract The low productivity of agricultural land in Indonesia occurred because of plant diseases attack such as Wilt Fusarium in tomato plant and Basal Stem Rot disease in palm oil caused by Ganoderma boninese. Previous research had successfully isolated the actinomycetes from soil of Arboretum University of Riau However, the antifungal potency of those isolates against Fusarium oxysporum f. sp lycopersici and Ganoderma boninense had not been known. This research aimed to screening 32 actinomycetes isolates against the fungal target by using agar diffusion method. The selected actinomycetes were continued to produce crude antifungal by different duration of fermentation (4, 5 and 6 days) using disc diffusion method. The result of the antifungal activity using agar diffusion method showed that there were 31 isolates that able to inhibit the F. oxysporum f. sp lycopersici and isolate A2.01 showed the highest inhibition zone by 36.10 mm. There were 28 isolates that able to inhibit the G. boninense and isolate D2.28 showed the highest inhibition zone by 45.71 mm. Almost all of the isolate was able to inhibit both of two fungals targets with diffussion agar method, but the crude antifungal compound of the potential isolate by disc diffusion method could not inhibit both of the fungal targets. The potential actinomycetes isolate was suggested to be applied as a culture directly in vivo.