Judul: In Vitro Antagonistic Assay of Endophytic Fungi Isolated from Pilea microphylla (L.) Liebm against Fusarium oxysporum f. sp. cubense (Foc)
Abstrak: ISHMAH AFIAH. In Vitro Antagonistic Assay of Endophytic Fungi Isolated from Pilea microphylla (L.) Liebm against Fusarium oxysporum f. sp. cubense (Foc). Supervised by SRI LISTIYOWATI and TRIADIATI. Endophytic fungi are reported capable of effectively inhibit the growth of plant pathogenic fungi. Utilization of endophytic fungi as an environmentally friendly biological control agent still needs to be done. This study aimed to test the in vitro antagonism ability of the endophytic fungi from Pilea microphylla (L.) Liebm against the pathogenic fungi Fusarium oxysporum f. sp. cubense (Foc) and analyzed the types of interactions and their inhibitory mechanisms. Antagonism test was performed by pairing the endophytic fungi and Foc using dual culture methods. The control was made without the addition of endophytic fungi as the antagonisms. Analysis of percentage inhibition (DH) and growth rate of radial mycelia Foc was performed using a completely randomized design (CRD). The results showed that the isolate PM 1A2.4 has a moderate inhibitory ability (DH 41.58%), with slight inhibition type of interaction exhibited and probably perform antibiosis mechanism. The isolate PM 2A2.3 has a very weak inhibitory ability (DH 10.76%), indicated by the Foc mycelia grew through (overgrowing) the mycelia of endophytic fungi. Similarly, with the isolate PM 2A2.4 against the Foc (DH 19.68%), the Foc mycelia grew around part of the mycelia of endophytic fungi. The interaction of the two endophytic fungi against Foc was competitive. The Foc hyphae paired with the isolate PM 1A2.4 and PM 2A2.3 showed vacuolization, whereas with the isolate PM 2A2.4 there was no difference with control. The endophytic fungi of P. microphylla had various antagonistic activity against Foc. Keywords: antibiosis, competition, dual culture, inhibition, vacuolization, Cendawan endofit dilaporkan mampu menghambat pertumbuhan cendawan patogen tanaman secara efektif. Pemanfaatan cendawan endofit sebagai agen pengendalian hayati yang ramah lingkungan di bidang pertanian masih perlu dilakukan. Penelitian ini bertujuan menguji kemampuan antagonisme cendawan endofit asal tumbuhan Pilea microphylla (L.) Liebm terhadap cendawan patogen Fusarium oxysporum f. sp. cubense (Foc) secara in vitro dan menganalisis tipe interaksi serta mekanisme penghambatannya. Uji antagonisme dilakukan dengan memasangkan cendawan endofit dan Foc menggunakan metode kultur ganda. Kontrol dibuat tanpa penambahan cendawan endofit sebagai antagonisnya. Analisis persentase daya hambat (DH) dan rata-rata pertumbuhan miselia radial Foc dilakukan menggunakan rancangan acak lengkap (RAL). Hasil penelitian menunjukkan isolat PM 1A2.4 memiliki kemampuan hambat sedang (DH 41,58%), dengan tipe interaksi slight inhibition yang diduga melalui mekanisme antibiosis. Isolat PM 2A2.3 memiliki kemampuan hambat sangat lemah (DH 10,76%), sehingga tampak miselium Foc tumbuh melewati (overgrowing) miselium cendawan endofit. Demikian juga isolat PM 2A2.4 terhadap Foc (DH 19,68%), miselium Foc tumbuh mengelilingi (growth around) sebagian sisi miselium cendawan endofit. Interaksi kedua cendawan endofit tersebut terhadap Foc bersifat kompetisi. Hifa Foc yang dipasangkan dengan isolat PM 1A2.4 dan PM 2A2.3 mengalami vakuolisasi, sedangkan isolat PM 2A2.4 tidak ada perbedaan dengan kontrol. Cendawan endofit asal tumbuhan P. microphylla memiliki kemampuan antagonisme yang bervariasi terhadap Foc. Kata kunci: antibiosis, daya hambat, kompetisi, kultur ganda, vakuolisasi, Endophytic fungi are reported capable of effectively inhibit the growth of plant pathogenic fungi. Utilization of endophytic fungi as an environmentally friendly biological
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Judul: The Ability of Endophytic Fungi from Pilea microphylla (L.) Leibm In Indole Acetic Acid Production
Abstrak: Pilea microphylla (L.) Liebm. merupakan herba sukulen yang memiliki kemampuan toleran cekaman kekeringan. Kemampuan tersebut mungkin terkait dengan keberadaan cendawan endofit dalam jaringan P. microphylla dan dapat menghasilkan metabolit sekunder di antaranya asam indol asetat (IAA) atau auksin. Namun, kemampuan dan waktu optimum cendawan endofit asal P. microphylla dalam menghasilkan IAA belum diteliti. Penelitian ini bertujuan mengukur konsentrasi auksin yang dihasilkan oleh isolat cendawan endofit PM 2A2.3 dan PM 2A2.4 asal P. microphylla pada berbagai waktu inkubasi. Hasil penelitian menunjukkan bahwa morfologi koloni dua kultur pada medium PDA berwarna putih dengan tekstur miselium berupa cottony. Namun dua kultur memiliki tipe pertumbuhan miselium berbeda yaitu miselium PM 2A2.3 tumbuh ke atas substrat (aerial), sedangkan miselium PM 2A2.4 merata (non aerial). Dua kultur menghasilkan konsentrasi IAA paling banyak pada masa inkubasi 2 minggu, yaitu 27,61 ppm oleh PM 2A2.4 dan 19,68 ppm oleh PM 2A2., Pilea microphylla (L.) Liebm is a succulent herb which tolerates drought stress. This fitness may be related to endophytic fungi in P. microphylla tissue and could produce secondary metabolites, including indole acetic acid (IAA). However, the ability and optimum time of endophytic fungi from P. microphylla to produce IAA have not yet been studied. This study aimed to measure the concentration of IAA produced by isolates of endophytic fungi PM 2A2.3 and PM 2A2.4 from P. microphylla at various incubation times. The colony morphology on the PDA medium from both isolates was white with a cottony mycelium texture. Both cultures had different types of mycelium growth, that was PM 2A2.3 had aerial mycelium, while PM 2A2.4 was evenly distributed (non-aerial). The isolates of PM 2A2.4 and PM 2A2.3 produced the highest concentrations of IAA at two weeks of incubation, that is 27.61 and 19.68 ppm, respectively.
Keyword: drought stress, IAA, potato dextrose broth, succulent herb

Judul: Approximation of the Median of Poisson Distribution Using the Relation of Poisson-Gamma Distribution
Abstrak: A major drawback of median is that median cannot usually be defined in closed form, even in the cases where their distribution functions are known. This study gives an approximation of the closed form for the median of the Poisson distribution by using the relation of Poisson-Gamma distribution. The approximation uses elementary techniques based on the monotonicity of certain sequences involving tail probabilities of the Poisson distribution and the Central Limit Theorem. Furthermore, a closed form expression for the mean absolute deviation 􀜧|􀜰􀰒 􀵆 􀜯􀝁􀝀􁈺􀜰􀰒􁈻| is also studied. The median is relevant because of the fact that it minimizes the mean absolute deviation of a Poisson random variable (􀜰􀰒􁈻 by considering median as central tendency.
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