Abstract. Swantara IMD, Bawa IGAG, Suprapta DN, Agustina KK, Temaja IGRM. 2020. Identification Michelia alba barks extract using Gas Chromatography-Mass Spectrometry (GC-MS) and its antifungal properties to inhibit microbial growth. Biodiversitas 21: 1541-1550. Fungicides are substances that inhibit the growth or kill the pathogenic fungi. A substance can be categorized as a fungicide if it shows antifungal activity. This activity is resulting from bioactive compounds derived from the secondary metabolites. Michelia alba bark’s extract could inhibit the growth of Curvularia verruculosa, the cause of leaf spot disease on rice. The purpose of this study was to analyze chemical compounds of bark extract which inhibit the growth of C. verruculosa. The extraction of bark metabolites of M. alba was done using methanol as the solvent. The inhibitory test of the extract was carried out by the diffusion well method on Potato Dextrose Agar (PDA) medium. Analysis of chemical compounds of the M. alba extract was carried out in Gas chromatography-mass spectroscopy. The results of inhibitory test found that the M alba bark extract inhibits the C. verruculosa with the inhibition zone as wide as 36 mm in diameter. The majority of chemical compounds identified from the M. alba extract consisted of 10 compounds, namely: Hexadecanoic acid, methyl ester; 4H-tomentosine; 4H-tomentosine (compound isomer 2); 3-hydroxy pregn-4-ene-20-one; Tomentosine; 2-hydroxy tomentosine; Tert-butyl-2-aminophenylcarbamol; 2H-cyclohepta [b] furan-2-one, 3,3a, 4,7,8,8a-hexahydro-7-methyl-3-methylene-6-(2-formil-3-oxobutyl)-; Isoxanthanol and Xanthanol. To conclude, this extract is useful to treat C. verruculosa that causes leaf spot disease on rice.

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Corn productivity in Indonesia is still relatively low compared with other countries. Therefore, it is necessary to increase the productivity of corn by using rhizobacteria, which have multiple traits. This study was conducted to obtain indigenous rhizobacteria of Bali that have multiple traits, can produce indoleacetic acid (IAA), fix nitrogen from atmosphere, produce siderophores, colonize roots, increase seed germination, and promote the growth of corn. Isolation of rhizobacteria was carried out from the rhizosphere of plants belonging to the Gramineae family that grows in Bali Island, Indonesia. Six isolates, namely, Sr3, Tb9, Rg1, Rg23, Al27, and Jg8, could produce IAA, fix nitrogen from the atmosphere, produce siderophores, and increased germination rate and vigor index of corn seedling. Among them, three isolates, namely, Rg1, Sr3, and Jg8, significantly (p <0.05) increased the germination rate of corn seeds, increased vigor index, increased root dry weight and shoot dry weight of corn at the age of 7 days, and were able to colonize corn roots. Compared with the control, the rhizobacteria treatment increased the germination of corn seeds ranging from 5.04 to 13.05%. Based on the analysis of the 16S rRNA gene, it was found that these rhizobacteria species were Glutamicibacter nicotianae strain Rg1 (accession number OM349119), Brevibacillus invocatus strain Sr3 (accession number OM327515), and Micrococcus luteus strain Jg8 (accession number OM362349). Under a greenhouse condition, all the three isolates significantly (p <0.05) increased nutrient uptake, the leaf chlorophyll content, net assimilation rate, and crop growth rate of corn when compared with control. These results suggested that these isolates of rhizobacteria obviously promoted the growth of corn and can be developed as biostimulant to promote the growth and increase the corn yield in Bali, Indonesia.

ABSTRAKPenyakit layu stewart merupakan penyakit serius pada tanaman jagung manis (Zea mays). Gejala khas penyakit ini ialah garis berwarna hijau pucat sampai kekuningan yang sejajar dengan tulang daun. Gejala seperti ini ditemukan pada daun jagung manis di daerah Denpasar, Tabanan, Gianyar dan Karangasem pada tahun 2015. Deteksi patogen dengan metode polymerase chain reaction dilakukan menggunakan DNA total yang diisolasi dari daun tanaman bergejala dan pasangan primer CPSL1/ CPSR2c. Amplikon dengan ukuran ~1100 pb berhasil diperoleh dari sampel asal Denpasar. Analisis sikuen nukleotida memastikan bahwa gejala penyakit layu stewart tersebut disebabkan oleh bakteri Pantoea stewartii subsp. stewartii. Hasil analisis sikuen menunjukkan bahwa P. stewartii subsp. stewartii isolat Bali memiliki tingkat homologi yang tinggi (98.97-99.08%) dan berada dalam satu clade dengan isolat asal Kanada, Amerika Serikat, dan Jepang. Ini merupakan laporan pertama mengenai P. stewartii subsp. stewartii yang menginfeksi tanaman jagung di Provinsi Bali.Kata kunci: analisis sikuen, nukleotida, Pantoea, Zea mays ABSTRACT Stewart's wilt is a serious disease of sweet corn (Zea mays). The typical symptoms of the disease are pale-green to yellow linear streaks parallel to the veins. The symptoms were observed on sweet corn in Denpasar, Tabanan, Gianyar, and Karangasem areas during a survey in 2015. Pathogen detection based on a polymerase chain reaction was carried out using total DNA obtained from symptomatic leaf samples and the pairs of primers, CPSL1/CPSR2c. The expected sized (~1100 bp) amplicon was detected in samples from Denpasar. Sequence analysis confirmed that Stewart's wilt disease symptoms are caused by Pantoea stewartii subsp. stewartii. Nucleotide sequence and phylogenetic analysis showed that P. stewartii subsp. stewartii from Bali has high homology (98.97-99.08 %) and placed in the same clade with isolates from Canada, USA and Japan. This is the first report of P. stewarti subsp. stewartii on corn in Bali.

ABSTRAKPenyakit layu stewart telah menimbulkan masalah besar bagi negara produsen jagung. Penyakit yang disebabkan oleh bakteri Pantoea stewartii subsp. stewartii ini pertama kali dilaporkan keberadaannya pada tanaman jagung di Bali yaitu pada tahun 2017. Kejadian penyakit baru pada komoditas penting seperti jagung, sangat urgen untuk dicarikan solusi pengendaliannya. Menyusun strategi pengendalian penyakit, harus mengacu pada pertanian berkelanjutan dengan mempertimbangkan keseimbangan dan keamanan lingkungan, kesehatan petani dan konsumen. Alternatif pengendalian yang yang merupakan tujuan penelitian ini adalah pemanfaatan rhizobakteria sebagai penginduksi ketahanan tanaman terhadap penyakit layu stewart. Penelitian rumah kaca dirancang menggunakan Rancangan Acak Kelompok (RAK) dengan pola faktorial dilakukan untuk menguji potensi rizobakteri sebagai agens penginduksi ketahanan tanaman jagung. Penelitian menggunakan dua faktor yaitu isolat rizobakteri (isolat TLKC, isolat CgBd dan tanpa isolat rizobakteri yaitu menggunakan air steril sebagai kontrol) dan cara apilkasinya (perendaman kecambah, perendaman akar bibit, dan penyiraman bibit). Variabel yang diamati adalah keparahan penyakit, pertumbuhan tanaman (tinggi tanaman dan jumlah daun), hasil (panjang dan berat tongkol per tanaman), total fenol dan kandungan asam salisilat. Perlakuan isolat rizobakteri CgBd yang diaplikasikan melalui perendaman kecambah merupakan perlakuan terbaik, karena memberikan pengaruh terhadap pertumbuhan tanaman yaitu tinggi tanaman tertinggi, jumlah daun terbanyak, dan produksi yaitu panjang dan berat tongkol yang tertinggi; dan keparahan penyakit terendah. Rendahnya keparahan penyakit karena tanaman jagung memiliki ketahanan yang meningkat terhadap penyakit layu stewart. Indikator peningkatan ketahanan jagung terhadap penyakit layu stewart adalah peningkatan kandungan total fenol dan asam salisilat. Penelitian menyimpulkan bahwa rizobakteri isolat CgBd dan TLKC mampu berperan sebagai agens penginduksi ketahanan sistemik dan sekaligus sebagai pemacu pertumbuhan tanaman; dan cara aplikasi rizobakteri yang terbaik adalah melalui perendaman kecambah jagung pada suspensi rizobakteri.Kata kunci: jagung, Pantoea, rizobakteri, perendaman kecambah, keamanan lingkungan ABSTRACT Stewart wilt disease has caused major problems for corn producing countries. Disease caused by Pantoea stewartii subsp. stewartii was first reported its existence on corn plants in Bali, in 2017. The incidence of new diseases on essential commodities such as corn, it is very urgent to look for its control solutions. Devise strategies for disease control, it should refer to sustainable agriculture by considering the balance and the environmental security, the health of farmers and consumers. An alternative control which is the purpose of this research is the utilization of rhizobakteria as inducers of plant resistance to stewart wilt disease. Greenhouse studies was designed using a randomized block design (RBD) with factorial pattern was conducted to test the potential...

Monitoring Coastline changes is a very important task to assess and evaluate the condition of the coastal area. Accurate results of changes in coastline are very useful as a consideration in making decisions for coastal area management and planning for future coastal development. Therefore, coastline changes, both erosion and accretion were examined in this study. Batu Mejan Beach is selected as a study area. It is a tourism destination often visited by foreign and local tourists in North Kuta Beach. Its current condition is very poor because of the erosion that has occurred. The government has tried to build a sea wall for protection, but the structure has failed. Remote sensing is a method that can monitor shoreline changes more efficiently than taking measurements directly into the field. With the remote sensing method, changes in the shoreline at a certain period can be investigated. The remote sensing analysis method is used to extract coastlines from Landsat 7 satellite images in 2002 and Landsat 8 in 2018. Landsat was analyzed using a combination approach of threshold and band ratio methods of infrared bands and green bands. Image processing uses ENVI 5.3 software and ArcGIS 10.4.1 with the Quoted Shoreline Analysis System (DSAS) extension to make transect shoreline calculations. The results of the analysis of the rate of change in the coastline along Batu Mejan Beach showed abrasion of 0.11-5.14 m/year and accretion of 0.29-0.84 m/year.

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