EPIDEMICS) Abstract
6. Kelimpahan Cendawan Endofit dan Keparahan Penyakit Busuk Buah Kakao
Pada saat penelitian, penyakit utama yang banyak dijumpai adalah penyakit busuk buah Phytophthora palmivora. Korelasi keberadaan penyakit tersebut dengan frekuensi kemunculan cendawan endofit disajikan pada Tabel 4.6. Nilai korelasi negatif yang tinggi, dalam kasus keparahan penyakit rendah dan cendawan endofit tinggi mengindikasikan bahwa endofit tersebut berpotensi untuk dikembangkan sebagai agens biokontrol. Cendawan endofit yang dominan pada awal pengambilan sampel, Fusarium lichenicola, ternyata tidak berkorelasi negatif dengan adanya penyakit utama. Sebaliknya, cendawan yang dominan pada pengambilan kedua, Phomopsis columnaris berkorelasi negatif dengan penyakit busuk buah kakao. Frekuensi kemunculan cendawan Phomopsis columnaris, Diaporthe angelica, Fusarium sp. T47a, Xylaria sp., Polyporaceae DIS 126a berkorelasi negatif cukup tinggi dengan keparahan penyakit (Tabel 6).
Tabel 4.6 Korelasi frekuensi kemunculan spesies cendawan endofit dengan kejadian penyakit busuk buah
Spesies Korelasi
Tanpa Atap Diatap
Fusarium lichenicola 0.7824 0.5009 Bionectria sp. -0.1342 -0.3818 Gibberella zeae 0.5691 0.5963 Phomopsis columnaris -0.6824 -0.4590 Fusarium ambrosium -0.0539 -0.3804 Glomerella cingulata 0.5932 0.3622 Diaporthe phaseolorum -0.0120 -0.3801 Schizophyllum commune -0.6365 -0.5485 Diaporthe angelica -0.7913 -0.4842 Fusarium sp. T47a -0.7190 -0.4377 Xylaria sp. DIS 125b -0.3539 -0.5395 Fungal Endo-phyte 9147 0.1923 -0.2218 Aphyllophorales DIS 296 a -0.0197 -0.2679 Colletotrichum sp. MCA 2773 0.3936 0.0932 Polyporaceae DIS 126a -0.7163 -0.4424
Uncultured ascomycetes -0.0280 -0.3167 Diaporthe eres -0.4362 -0.5232 Diplodia pinea 0.7299 0.0483 Psathyrella leucotephra -0.3054 -0.6408 Colletotrichum crassipes -0.5253 -0.5843 Laccocephalum mylittae -0.3969 -0.3298 Xylariaceae DIS 360g -0.1817 -0.0323 Ascosalsum viscidulum 0.0728 -0.5434 Aschersonia sp.WYBX-3 -0.3490 -0.5306 Giberella circinata 0.5063 -0.0529 Nigrospora oryzae -0.1687 -0.5182
Fungal endo-phyte P815A -0.1687 -0.5182
Calocybe gambosa -0.3599 -0.0316
Resinicium friabile -0.3824 -0.1679
FE 6722 (Pestalotiopsis) -0.4292 -0.1838
Nectria rigidiuscula -0.0245 -0.3002 Fusarium sp. QJC-1403 -0.5428 -0.0195 Meskipun demikian, perlu juga berhati-hati dalam mempertimbangkan calon agens biokontrol dengan memperhatikan apakah spesies tersebut pernah dilaporkan sebagai patogen tumbuhan atau mikroorganisme yang membahayakan. Di lain pihak, walaupun nilai korelasi negatifnya kecil tetapi pernah dilaporkan sebagai agens biokontrol, maka spesies tersebut layak untuk diuji kemampuannya sebagai agens biokontrol. Oleh karena itu, P. columnaris dan D. angelica tidak
akan dipilih, tetapi Aschersonia sp., C. gambosa dan Xylaria sp. dapat dipilih untuk pengujian selanjutnya.
Kesimpulan
Sebanyak 2843 isolat yang terdiri dari 37 spesies (6 Basidiomycetes, 30 Ascomycetes dan satu belum teridentifikasi) telah dieksplorasi dari 1440 sampel kulit buah kakao. Keragaman cendawan endofit meningkat pada kondisi kering Januari-April 2008 dari kondisi basah di bulan Maret-April 2007. Iklim makro berupa curah hujan lebih berpengaruh terhadap keragaman cendawan endofit daripada iklim mikro berupa pengatapan. Perubahan dominansi spesies cendawan endofit juga terjadi, Fusarium lichenicola pada bulan basah menjadi Phomopsis columnaris pada bulan kering.
Kelimpahan beberapa cendawan endofit seperti Fusarium sp. T47a, Xylaria sp., Polyporaceae DIS 126a, Aschersonia sp., C. gambosa dan Xylariaceae berkorelasi negatif dengan kejadian busuk buah Phytophthora palmivora. Cendawan endofit tersebut berpotensi sebagai agens biokontrol melalui induksi ketahanan.
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KETAHANAN TANAMAN TERHADAP PENYAKIT BUSUK BUAH