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Nutmeg (Myristica fragrans Houtt) is a multipurpose plantation commodity crop that almost all parts of the plant have strategic economic value to be cultivated. In Indonesia there are the largest nutmeg commodity centers, including the Maluku islands, North Sulawesi and Aceh. The biggest problem with nutmeg plants is the attack of pests and diseases. One of the most severe diseases in nutmeg is white root mushroom (Rigidoporus lignosus). This study aims to 1) determine the fungus of white root fungus antagonists (Rigodoporus lignosus) from the Aceh nutmeg rhizosphere (Myristica fragrans Houtt), 2) identify the content of antibiotic fungus JAP antagonist compounds in Aceh nutmeg plants. The study was conducted by taking soil samples from nutmeg plants at three nutmeg plantations in South Aceh. The antagonist fungus isolation activity uses a dilution method. Isolation of JAP from infected roots using direct planting method. Furthermore, it is identified macroscopically and microscopically. The antagonist test was carried out using the dual culture method with RAL. From the rhizosphere in the nutmeg area, 5 candidate antagonist isolates were obtained, having high in vitro antagonism ability to the pathogen R. lignosus. Identification results showed that isolates 1, 2 and 3 were Trichoderma spp, and isolates 4 and 5 were Gliocladium virens. Keywords: In vitro, the content of antibiotic compounds, Aceh nutmeg, Rigidoporus lignosus, antagonistic test

Yanti LA, Achmad, Khumaida N. 2018. Resistance mechanisms of white jabon seedlings (Anthocephalus cadamba) against Botryodiplodia theobromae causing dieback disease. Biodiversitas 19: 1441-1450. Anthocephalus cadamba (Roxb.) Miq. seedlings are the most preferred plant for the nursery as they serve a lot of benefits and can be used as shading trees, reforestation, plywood, pulp, paper, and traditional medicines. Further, those benefits can increase the economic value of this plant. The main problem in the nursery of forestry plants is pest and disease attacks, one of which is dieback disease. The dieback disease is caused by Botryodiplodia theobromae Pat. that may lead death of the host plant. Every plant has its resistance mechanism toward pathogen attacks. This research aimed: (1) to study B. theobromae attack through wounded and non-wounded stem infection methods on white jabon seedlings; (2) to study the resistance mechanisms of white jabon seedlings both structural and biochemical resistance against B. theobromae. This study employed a factorial treatment design laid out in a completely randomized design. The structural resistance was determined by studying the microscopic appearance of the white jabon seedlings’ stem by using a scanning electron microscope. Meanwhile, the biochemical resistance was determined by characterizing the chemical compounds of white jabon seedlings' stem using phytochemistry analysis. The result showed that the disease incidence of the control (inoculated without pathogen isolate) and the inoculated (inoculated with pathogen isolate) seedlings were, respectively, 0% and 100% (with wounded stem) and 0% and 30% (non-wounded). The disease severity of control and inoculated seedlings were 0% and 62% (with wounded stem) and 0% and 12% (non-wounded stem), respectively. The incubation period of wounded and non-wounded stems on inoculated seedlings (inoculated with pathogen isolate) was one day after inoculation with the numeric values (disease scores) of 4 and 2, respectively. White jabon seedlings had necrotic resistance as structural resistance mechanism against the pathogen attack. White jabon seedlings also contained secondary metabolites such as alkaloids, flavonoid, phenyl hydroquinone, tannin, saponin, and steroids. The biochemical resistance of white jabon seedling after pathogen attacks was shown by the increase of accumulated phenolic compounds such as flavonoid and tannin.

Peanut has high economic value because has high nutritions especially protein and fat, but the development of broad harvesting and peanut production for the last five years (2008-2012) continues to decrease. The main problem of the peanut low production are disease attacks S. rolfsii and the low broad harvesting. The drop of peanut production in Nusa Tenggara Barat causing harm caused by fungi S.rolfsii can reach 58,3 % per year. Peat is potential land to be developed to farming land. Peat has high acidity so fungi S. rolfsii would be easy to develop and resulted disease severity of peanut disease. Solution of this problem is the gift of lime. This study aims (1) to test the effect of dosages of lime to peanut resistance which was infected by rot stem S. rolfsii on peat land; (2) to study interaction of peanut varieties and dosage of lime to rot stem disease attacks S. rolfsii on peat land. This study used factorial block randomized design 2 x 3 with 3 replications. The studied factors were peanut varieties and the dosage of lime. The result showed that on the effect of varieties, the widest disease percentage was on Takar 2 variety on age 21, 28, 42, and 49 day after planting (DAP) that significant difference with Bison variety. The worth disease intensity was on Takar 2 variety that significant difference with Bison variety (on age 45 and 60 DAP). Key words: dosage of lime, peanut varieties, peat land, the sclerotia of Sclerotium rolfsii