Formulasi pil-benih tembakau dengan Pseudomonas putida Strain Pf-20 untuk pengendalian biologi penyakit layu bakteri (Ralstonia solanacearum)
WURYANDARI, Yenny, Promotor Prof.Dr. Bambang Hadisutrisno, D.A.A
2004 | Disertasi | S3 Ilmu PertanianPemanfaatan Pseudomonas putida strain Pf-20, bakteri antagonis yang diisolasi dari rizosfer Mimosa invisa di Medan, menunjukkan kemampuan menekan penyakit layu bakteri paling tinggi. Namun, usaha yang masih menggunakan metode pencelupan ini mengalami kesulitan dan tidak praktis dalam skala lapangan. Oleh karena itu perlu dilakukan penelitian untuk mencari suatu formula yang paling tepat untuk aplikasi pengendalian skala lapangan. Penelitian ini bertujuan untuk: (1) mengetahui pengaruh beberapa formula dengan teknik penyalutan benih terhadap viabilitas P. putida strain Pf-20 dan perkembangan penyakit layu (2) mengetahui pengaruh formula terhadap viabilitas benih dan pertumbuhan tembakau, dan (3) mendapat formula yang paling tepat untuk pengendalian penyakit layu pada tembakau secara efektif tanpa menghambat perkecambahan benih dan pertumbuhan tembakau. Formula dibuat dengan menggunakan teknik penyalutan benih dengan mengkombinasikan bahan pembawa (gambut ditambah talk dan kaolin ditambah talk), bahan aditif (1% Carboxy Methyl Cellulose (CMC) ditambah 1% arginin dan 1% CMC), serta konsentrasi P. putida strain Pf-20 (108, 109, 1010 CFU/ml). Dari kombinasi tersebut diperoleh 12 formula. Bakteri antagonis P. putida strain Pf-20 dalam uraian selanjutnya disebut Pf-20, sedangkan bakteri patogen Ralstonia solanacearum strain Rs-47 disebut Rs-47. Uji viabilitas Pf-20 dalam pil-benih dilakukan dengan menghitung populasinya dalam medium King’s B dengan interval waktu 1 minggu. Untuk mengetahui pengaruh formula terhadap perkembangan penyakit layu, dengan cara menanam bibit dari formula di rumah kaca yang telah diinfestasi dengan Rs-47 dan dihitung indeks penyakitnya. Dinamika populasi mikroorganisme rizosfer dilakukan dengan menghitung populasi patogen, antagonis, bakteri total dan jamur total pada medium selektif masing-masing. Uji viabilitas benih dalam formula diamati setiap bulan dengan menghitung persentase pil-benih yang berkecambah, daya isi dan persentase pil-benih berisi satu. Untuk mengetahui pengaruh formula terhadap pertumbuhan tanaman tembakau yaitu dengan cara menanam bibit dari formula di rumah kaca selama 2,5 bulan, selanjutnya diamati jumlah daun total, jumlah daun produktif, panjang daun, tinggi tanaman dan berat kering daun. Hasil uji viabilitas Pf-20 pada pil-benih menunjukkan bahwa populasi Pf-20 menurun seiring dengan lamanya penyimpanan pada semua formula. Pada minggu ke-0 (saat awal), populasi tertinggi diperoleh pada formula nomor 7 yaitu pil-benih dari formula dengan kombinasi bahan pembawa gambut ditambah talk, bahan aditif 1% CMC ditambah 1% arginin dan konsentrasi Pf-20 1010 CFU/ml. Populasi pada formula nomor 7 dapat mencapai 7´106 CFU/pil-benih dan dapat bertahan hidup sampai 3 bulan. Adapun hasil uji viabilitas Pf-20 dalam pil-benih berkecambah menunjukkan bahwa populasi Pf-20 pada semua formula mengalami peningkatan 2 ordo pada saat awal berkecambah dan tetap naik setelah 7 hari berikutnya. Gejala awal penyakit layu di rumah kaca terlama pada formula nomor 7 dan 1 yaitu lebih dari 14 hari, apabila dibandingkan dengan kontrol, kedua formula tersebut dapat menunda waktu inkubasi selama 5 hari. Indeks penyakit dari 12 formula yang diuji, formula nomor 7 menunjukkan indeks penyakit terkecil sampai akhir pengamatan dan kecepatan perkembangan penyakitnya ada kecenderungan rendah dibandingkan formula lain maupun kontrol. Dari hasil perhitungan populasi mikroorganisme rizosfer terlihat bahwa populasi Pf-20 cenderung turun seiring dengan waktu, sedangkan Rs-47 pada awalnya naik selanjutnya menurun setelah hari ke-20. Populasi bakteri lain dan jamur menunjukkan keadaan yang stabil sampai akhir pengamatan yaitu 1 bulan. Dari uji viabilitas benih dalam pil-benih, menunjukkan bahwa dari ke- 12 formula, persentase perkecambahan tertinggi terjadi pada formula nomor 12 kemudian diikuti formula nomor 10, 4, 8, 6, dan 2. Tampak bahwa formula bernomor genap, yaitu formula dengan bahan pembawa kaolin ditambah talk menunjukkan persentase perkecambahan yang lebih tinggi dibanding dengan formula bernomor gasal, yaitu formula dengan bahan pembawa gambut ditambah talk. Berdasarkan hasil pengamatan pada parameter agronomi di rumah kaca ada kecenderungan bahwa formula nomor 7 yaitu formula dengan kombinasi bahan pembawa gambut+talk, bahan aditif CMC+arginin, dan konsentrasi Pf-20 1010 CFU/ml, adalah yang paling baik.
Pseudomonas putida strain Pf-20, an antagonistic bacterium isolated from the rhizosphere of Mimosa invisa in Medan, showed the highest disease suppression capability when applied by using root immersion method. However, this technique is difficult and impractical to apply on a large scale. Therefore, it is important to do a research to find out the best formula suitable for disease control on a large scale. The objectives of this research were to (1) examine effect of several formulas of seed coating material on the viability of P. putida strain Pf-20 and the progress of wilt disease, (2) determine influence of the formula on the viability of seed and tobacco growth, and (3) obtain the best formula for controlling wilt disease of tobacco, without preventing seed germination and tobacco growth. The tested formula for seed coating were made by combining the carrier material (peat+talc and kaolin+talc), additive substances (1% Carboxy Methyl Cellulose (CMC)+1% arginine and 1% CMC), and the concentration of P. putida strain Pf-20 (108, 109, 1010 CFU/ml). The combination resulted in 12 formulas or 12 kinds of coated seed. In the following text, the antagonistic bacterium P. putida strain Pf-20 was referred as Pf-20, meanwhile the pathogenic bacterium R. solanacearum strain Rs -47, was referred as Rs-47. Viability test of Pf-20 in the coated seed was conducted by counting the bacterial population on the medium of King’s B every week. To determine the influence of the formula on the development of wilt disease, seedlings from the coated seeds were planted in the green house on soil that were already inoculated with Rs-47 and the disease index was then calculated. The population dynamics of microorganisms in the rhizosphere such as pathogens, antagonist, total bacteria, and total fungi was determined by counting their colonies grown on selective medium. Seed viability test in coated seed was conducted each month by calculating percentage of the germinating coated seed. Effect of the formulas on tobacco growth was determined by planting tobacco seedling originated from the coated seed in greenhouse. Total number of leaf, number of productive leaves, leaf length, plant height and dry weight of leaf were observed. The result of the viability test of Pf-20 in the coated seed showed that the population of Pf-20 decreased with the storage time in all of the formulas. In week 0, the highest population was the formula number 7, viz. the coated seed, coated with combination of peat+talc as carrier, CMC+arginine as additives and at the Pf-20 concentration of 1010 CFU/ml. The bacterial population in formula 7 can reach 7´106 CFU/coated seed and survived up to 3 months. The result of the viability test of Pf-20 in the germinating coated seed showed that the population of Pf-20 in the coated seed increased two levels in all of formula on the 5th day and increased one level on the 12th day . The longest incubation period of the wilt disease in the green house were found in the formula 7 and 1, viz. more than 14 days. Compared to the control, the incubation period of the formula 1 and 7 were 5 days slower. Based on the disease index of the formula, it was observed that the formula number 7 had the lowest disease index and its rate of disease development was lower than that of other formulas and control. It was clearly observed from the result of the counting of the rhizosphere microorganisms that the population of Pf-20 tends to decrease with the time. Meanwhile, the population of Rs-47 increased at the beginning and then decreased on the 20th day . The population of other bacteria and the fungus were stable till the end of the observation. The result of the seed viability test in the coated seed showed that the highest percentage of germination was found on the formula number 12, followed by the formula number 10, 4, 8, 6, and 2. It seemed that the even number formulas kaolin + talc as the carrier agent showed higher percentage than those of odd numbers peat + talc as the carrier agent. Based on the results of observation on agronomic parameter in the green house there was a tendency that the formula number 7 viz. the coated seed, coated with combination of peat + talc as carrier, CMC + Arginine as additives, and the PF-20 concentration of 1010 CFU/ml was the best.
Kata Kunci : Hama dan Penyakit Tumbuhan,Layu Bakteri,Formula Pengendalian,Pseudomonas Putida Strain Pf,20
