Judul: Formulasi Aktinomiset Menggunakan Beberapa Jenis Tanah sebagai Agens Hayati Penyakit Kresek (Xanthomonas oryzae pv. oryzae) pada Padi
Abstrak: Biological control is one of the techniques for controlling plant diseases using antagonistic microorganisms. Actinomycetes are bacteria that have high potential as biological agents to control plant pathogens. Actinomycetes could be formulated with a wide range of carrier in the form of flour or powder. Soil could be used as a carrier materials in a formulation because soil has a mineral content that could promote plant growth. The purpose of this research was to determine the effectiveness of actinomycetes’s formulation that used three types of soil (latosol, andosol, and podzolic) to suppress Xanthomonas oryzae pv. oryzae (Xoo). Tests that conducted in this research include antibiosis test of actinomycetes against Xoo, antibacterial formulation test of actinomycetes against Xoo, and test the effectiveness of the formulation to suppress leaf blight disease and for the growth of rice seedlings. The result of antibiosis test indicated that antibiosis of actinomycetes could suppress the growth of Xoo by means of in vitro. The result of antibacterial formulation test showed that there is a relationship between the types of formulations with concentration level. Formulation actinomycetes using andosol soil could suppress population of Xoo by 27.25%. Population of Xoo also could be suppressed by formulation actinomycetes using podzolic soil by 25.62% and formulation actinomycetes using latosol soil by 14.24%. Formulation actinomycetes using andosol soil not only could suppress population of Xoo but also could induce plant growth by increasing the average length of roots and plant height compared with the control.
Keyword: podsolic., andosol, latosol, antagonistic microorganism, rice disease

Judul: Potensi aktinomiset endofit dalam mengendalikan penyakit hawar daun bakteri pada tanaman padi (Oryza sativa)
Abstrak: Bacterial Leaf Blight (BLB) caused by Xanthomonas oryzae pv. oryzae (Xoo) is the most damaging disease in lowland rice growing areas in Indonesia. Endophytic actinomycetes provide advantages to the host plant through enhancement of plant physiological activity or through other modes of action and serve as source of agroactive compounds which can be used as biocontrol agent. The objectives of this experiments were to examine the potency of endophytic actinomycetes in controlling BLB using in planta-in vitro approaches, to characterize and identify the selected endophytic actinomycetes as well as to confirm their colonization in rice plant tissue. To obtain the objectives, the study was divided into three steps: (1) to evaluate the ability of endophytic actinomycetes in controlling BLB based on in planta (field and the greenhouse) experiments, (2) to study the biological control characters of endophytic actinomycetes using in vitro approach, (3) to characterize and identify the selected endophytic actinomycetes and their colonization in rice plant tissue. The field experiments were conducted in dry and wet seasons. The results showed that indigenous endophytic actinomycetes PS4-16 applied by seed coating and soaking techniques suppressed natural infection of BLB during dry and wet season experiments.Area under disease progress curve (AUDPC) values of PS4-16 in dry season and wet season were 1458 and 1923 respectively. Those AUDPC values were significantly different to negative control but no significantly different to the application of sinthetic bactericide. The application of endophytic actinomycetes PS4-16 under dry season could increased rice yield by 17% compared to positive control. The results of green house experiment showed that inoculation of endophytic actinomycetes AB131-1 on rice var. IR64 had a better growth than PS4-16 (21,8%). Endophytic actinomycetes AB131-1 inhibited the BLB better than PS4-16. Based on an in vitro mechanism study, all of the actinomycetes examined showed antibiosis activity against Xoo patotype IV and had a broad antimicrobial spectrum against several Gram positive and negative bacteria as well as inhibited fungal pathogens. Based on their different colony morphology observation, which produced aerial myselia and had spiral spore forming observed under both light and Scanning Electron Microscope, the selected endophytic actinomycetes AB131-1, AB131-2, PS4-16 and LBR02 belonged to the genus Streptomyces spp. The 16S rDNA sequence of AB131-1 showed 89% closed relationship with Streptomyces sp. The AB131-1, AB131-2, PS4-16 and LBR02 were able to colonize rice plant tissue which confirming them as endophytes.
Keyword: 

Judul: Cycle Hamilton pada Graf Lengkap, Graf Regular, dan Graf 2-Connected 4-Regular Berorder Kurang dari Sepuluh.
Abstrak: Suatu graf disebut graf Hamilton apabila graf tersebut memuat cycle Hamilton, yaitu cycle yang melewati setiap vertex tepat satu kali. Menentukan keberadaan cycle Hamilton pada suatu graf dapat menggunakan syarat cukup yang berupa teorema-teorema yang telah diperkenalkan sejak tahun 1950-an. Beberapa syarat cukup yang dibahas dalam karya ilmiah ini adalah syarat cukup yang berhubungan dengan graf lengkap dan graf regular. ,,,
Keyword: graf Hamilton, graf regular, graf lengkap, graf 2-connected 4-regular.