<p>Salah satu kendala dalam penyimpanan jagung adalah serangan hama<br />gudang. Salah satu hama gudang jagung adalah <em>Sitophilus zeamais</em><br />Motschulsky (Coleoptera: Curculionidae). Hama ini ditemukan di<br />daerah panas maupun lembap. Hama ini bersifat polifag, dapat<br />merusak serealia seperti beras/gabah, jagung, gandum, dan sorgum,<br />namun dilaporkan sebagai hama penting pada jagung. Kehilangan<br />hasil jagung di wilayah tropis akibat <em>S. zeamais</em> berkisar antara 30-<br />100%. Biji jagung yang disimpan selama 6 bulan menunjukkan<br />kerusakan 85% dan bobot biji menyusut 17%. Telur hama tersebut<br />diletakkan di dalam biji dan dalam beberapa hari akan menetas<br />menjadi larva. Larva menyelesaikan siklus hidupnya di dalam biji.<br />Telur berwarna putih bening, berbentuk lonjong, lunak dan licin,<br />berukuran 0,7 mm x 0,3 mm. Larva berwarna putih kekuningan,<br />tidak bertungkai, kepala berwarna cokelat, terdiri atas empat instar,<br />panjang 1,5–4 mm. Periode larva berlangsung 25 hari. Imago <em>S.</em><br /><em>zeamais</em> berukuran 3-4,5 mm. Hama <em>S. zeamais</em> dapat dikendalikan<br />dengan cara: 1) menyimpan jagung dalam wadah maupun gudang<br />secara higienis, 2) menanam varietas tahan, 3) menggunakan<br />musuh alami yaitu parasit, predator, dan patogen, seperti parasitoid<br /><em>Lariophagus distinguendus</em> dan <em>Anisopteromalus calandrae</em>, serta<br />patogen <em>Beauveria bassiana</em>, 4) memanfaatkan insektisida nabati<br />yang memiliki toksisitas tinggi terhadap <em>S. zeamais</em>, yaitu <em>Ageratum</em><br /><em>connyzoides</em> (bandotan), <em>Andropogon nardus</em> (serai), <em>Allium sativum</em><br />(bawang merah), <em>Nicotiana tabacum</em> (tembakau), <em>Zingiber officinale</em><br />(jahe), dan <em>Azadirachta indica</em> (mimba), serta 5) menyemprotkan<br />insektisida sintetis metil pirimifos.</p>
Evaluation of five inner carriers and Bacillus subtilis formulation to control banded leaf and sheath blight (Rhizoctonia solani Kuhn). One alternative control method against plant pathogens is the use of antagonistic microorganisms, such as Bacillus subtilis. The use of the antagonistic bacteria on corn especially in Indonesia is still lack. The objective of this research was to evaluate some inner carrier and to make formulated antagonistic B. subtilis to be used as biological control agents on corn diseases. This research consists of laboratory and greenhouse activities. The laboratory activities consist of B. subtilis biomass production, formulation of B. subtilis, and evaluation of five types of inner carrier. In the greenhouse, testing the formulation B. subtilis with talc as an inner carrier, which is compared with the treatment solution of B. subtilis, nordox, metalaxyl fungicides. The data collected in this study were percentage of germination, damping off due to pathogen R. solani, plant height, plant fresh weight, and percentages of R. solani incidence on 14 DAP. The results showed that talc powder and corn flour were the best inner carrier to be used in sorage formulation of antagonistic Bacillus. Formulated Bacillus subtilis TM4 showed no negative affect on seed germination and able to suppress the development of R. solani in greenhouse. Key words: Bacillus subtilis, formulation, inner carrier, Rhizoctonia solani ABSTRAKEvaluasi lima jenis inner carrier dan formulasi Bacillus subtilis untuk pengendalian hawar pelepah jagung (Rhizoctonia solani Kuhn). Salah satu alternatif pengendalian patogen tanaman yaitu pemanfaatan mikroorganisme antagonis seperti Bacillus subtilis. Penggunaan bakteri antagonis tersebut pada tanaman jagung di Indonesia masih sangat kurang. Penelitian ini bertujuan mengevaluasi beberapa inner carrier dan membuat formulasi bakteri antagonis B. subtilis untuk digunakan sebagai agensia pengendali hayati penyakit pada tanaman jagung. Kegiatan penelitian ini terdiri dari kegiatan laboratorium dan rumah kaca. Di laboratorium dilakukan produksi biomass B. subtilis, pembuatan formulasi B. subtilis, dan evaluasi formulasi dari lima jenis inner carrier. Di rumah kaca, dilakukan pengujian formulasi B. subtilis dengan talc sebagai inner carrier yang dibandingkan dengan perlakuan larutan B. subtilis, fungisida nordox, dan fungisida metalaxyl. Pengamatan dilakukan terhadap daya kecambah, damping off akibat patogen R. solani, tinggi tanaman, berat segar tanaman, dan persentase serangan R. solani pada 14 HST. Hasil penelitian menunjukkan bahwa talc dan tepung jagung merupakan inner carrier yang terbaik untuk digunakan dalam pembuatan formulasi bakteri antagonis B. subtilis. Formulasi B. subtilis TM4 tidak berpengaruh negatif terhadap daya kecambah benih serta mampu menekan perkembangan R. solani di rumah kaca.
The compulsory requirement for releasing new high yielding maize varieties is resistance to downy mildew. The study aimed to determine the level of homozygosity, genetic diversity, and genetic distance of 30 S3 genotypes of maize. Number of primers to be used were 30 polymorphic SSR loci which are distributed over the entire maize genomes. The S3 genotypes used were resistant to downy mildew with homozygosity level of >80%, genetic distance between the test and tester strains >0.7, and anthesis silking interval (ASI) between inbred lines and tester lines was maximum 3 days. The results showed that 30 SSR primers used were spread evenly across the maize genomes which were manifested in the representation of SSR loci on each chromosome of a total of 10 chromosomes. The levels of polymorphism ranged from 0.13 to 0.78, an average of 0.51, and the number of alleles ranged from 2 to 8 alleles per SSR locus, an average of 4 alleles per SSR locus. The size of nucleotides in each locus also varied from 70 to 553 bp. Cophenetic correlation value (r) at 0.67 indicated that the Unweighted Pair-Group Method Using Arithmetic Averages (UPGMA) was less reliable for differentiating genotypes in five groups. Of the total of 30 genotypes analyzed, 17 genotypes had homozygosity level of >80% so it can be included in the hybrid assembly program.
ABSTRAKRhizoctonia solani penyebab penyakit hawar pelepah dan upih daun serta Bipolaris maydis penyebab penyakit hawar daun merupakan patogen penting pada tanaman jagung. Penggunaan biopestisida merupakan salah satu alternatif untuk mengendalikan penyakit ini. Penelitian dilakukan untuk menentukan efektivitas formula bakteri Bacillus subtilis dalam menghambat perkembangan penyakit hawar pelepah dan upih daun R. solani dan hawar daun B. maydis di lapangan. Pengujian formula biopestisida dilakukan dengan dua cara aplikasi, yaitu perendaman benih jagung untuk pengendalian R. solani dan penyemprotan untuk pengendalian B. maydis di lapangan. Formula bakteri antagonis B. subtilis TM4 efektif menekan perkembangan penyakit penyakit hawar pelepah dan upih daun melalui perlakuan benih tetapi tidak efektif untuk menekan perkembangan penyakit hawar daun melalui penyemprotan formula. Kata kunci: Bacillus subtilis, biopestisida, Bipolaris maydis, penyakit hawar daun,Rhizoctonia solani ABSTRACTBanded leaf and sheath blight (BLSB) and maydis leaf blight (MLB) caused by Rhizoctonia solani and Bipolaris maydis, respectively are considered as important diseases in maize. The use of biopesticides is an alternative method to control the diseases. This study was conducted to determine the effectiveness of bacterial formula Bacillus subtilis to inhibit the development of BLSB and MLB on the plant. Testing of biopesticide formula was done in two different applications, i.e. seed treatment for BLSB control and leaf spraying in the field for MLB. The results showed that the B.subtilis formula effectively suppressed the development of BLSB but it was not effectively suppressed the development of MLB .
<p>Biotic stress, especially downy mildew (Peronosclerospora philippinensis) incidence, is one of the most important constraints in the development of corn in the country, because it attack on young plant of susceptible varieties, it can cause damage up to 100%. Resistance screening of 84 of S1 maize lines to downy mildew and the formation of S2 lines resistant to downy mildew was conducted in Bajeng Experimental Farm at Gowa, South Sulawesi lasted from February to May 2013. This study aimed to screen the S1 lines resistant to downy mildew and forming S2 lines resistant to downy mildew. Four weeks before the S1 lines planted, the source of inoculum (Anoman variety) was planted in two rows around the test plot. One week after Anoman was planted, it was sprayed with a conidial suspension of the fungus P. philipinensis in the early morning. Three weeks after inoculation of Anoman, 84 of S1 lines to be screened for downy mildew were planted. In this test, resistant check MR14 and susceptible check Anoman was included, each planted in two rows along the 5 m, a spacing of 75 x 25 cm with two replications. Urea fertilizer was used at a dose of 350 kg/ha and Ponska with a dose of 300 kg/ha. Observation of the percentage of downy mildew incidence started at 30 days after planting. The results showed that only three lines and MR14 resistant showed moderately resistant to downy mildew. Percentage of disease incidence ranged from 36&ndash;100 percent. However, from this test a number of 580 S2 lines resistant to downy mildew were obtained.</p><p> </p><p><strong>Abstrak</strong></p><p>Cekaman biotik terutama serangan penyakit bulai (Peronosclerospora philippinensis) merupakan salah satu kendala dalam pengembangan jagung di tanah air, karena serangan umur muda pada varietas rentan, akan menyebabkan kerusakan tanaman sampai 100% (puso). Skrining dan reaksi ketahanan 84 galur S1 jagung tahan terhadap penyakit bulai dan pembentukan galur S2 tahan penyakit bulai dilakukan di Kebun Percobaan Bajeng Kabupaten Gowa Sulawesi Selatan pada Februari hingga Mei 2013. Penelitian ini bertujuan menyaring galur-galur S1 tahan penyakit bulai dan membentuk galur-galur S2 tahan bulai. Empat minggu sebelum penanaman galur S1, terlebih dahulu dilakukan penanaman varietas Anoman sebagai sumber inokulum dua baris di sekeliling petak pengujian. Satu minggu setelah penanaman varietas Anoman, dilakukan penyemprotan dengan suspensi konidia cendawan P. philipinensis pada pagi hari. Tiga minggu setelah inokulasi pada Anoman, 84 galur S1 yang akan diskrining terhadap penyakit bulai ditanam. Pada pengujian ini, diikutkan MR14 sebagai cek tahan dan varietas Anoman sebagai cek rentan, masingmasing ditanam dalam dua baris sepanjang 5 m, jarak tanam 75 x 25 cm dengan dua ulangan. Pupuk yang digunakan ialah urea dengan takaran 350 kg/ha dan Ponska dengan takaran 300 kg/ha. Pengamatan terhadap persentase serangan penyakit bulai dilakukan mulai pada umur 30 hari setelah tanam. Hasil pengujian menunjukkan bahwa hanya tiga galur dan cek tahan MR14 yang menunjukkan reaksi agak tahan terhadap penyakit bulai. Persentase serangan berkisar antara 36&ndash;100 persen. Namun, dari pengujian ini diperoleh 580 galur S2 tahan bulai.</p>
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