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KEMAPUAN BAKTERI KITINOLITIK ASAL RIZOSFER TANAMAN KARET DALAM MENGENDALIKAN JAMUR AKAR PUTIH PADA
BIBIT KARET
ABSTRAK
Pembudidayaan tanaman karet dapat dihambat oleh adanya serangan penyakit. Penyakit tanaman karet disebabkan oleh Rigidoporus lignosus yang menyerang akar tanaman karet sedangkan Colletortrichum dan Corynespora menyerang daun tanaman karet. Penelitian ini bertujuan untuk menguji kemampuan bakteri kitinolitik dari peneltian sebelumnya yang diisolasi dari rizosfer tanaman karet dalam menghambat pertumbuhan R. lignosus Corynespora dan Colletrotrichum secara in vitro serta melihat kemampuannya dalam menurunkan serangan R.lignosus pada bibit tanaman karet secara in vivo. Isolat bakteri kitinolitik dengan kode isolat FS 4 dan FS 7 digunakan dalam penelitian ini. Hasil penelitian menunjukkan bahwa kedua isolat mampu menghambat pertumbuhan jamur patogen. Isolat FS 7 merupakan isolat dengan diameter zona hambat yang lebih tinggi. Diameter zona hambat pada R. lignosus 21.35 mm, Corynespora 17 mm dan Colletotrichum 21.5. Sedangakan isolat bakteri kitinolitik kode FS 4 terhadap R. lignosus, Corynespora dan Colletotrichum diameter zona hambat masing-masing 14.5 mm, 14.5 mm dan 20.15. Pada uji in vivo dilakukan dengan dua perlakuan. Perlakuan I adalah pemberian bakteri kitinolitik satu hari setelah inokulasi jamur patogen pada akar tanaman karet sedangkan perlakuan II aplikasi bakteri kitinolitik 30 hari setelah inokulasi jamur patogen. Kontrol positif inokulasi jamur patogen tanpa pemberian bakteri kitinolitik sedangkan kontrol negatif tidak diberikan bakteri kitinolitik ataupun jamur patogen. Hasil penelitian menunjukkan bakteri kitinolitik mampu menurunkan serangan R. lignosus pada bibit tanaman karet. Perlakuan I intensitas serangan dengan pemberian bakteri FS 4 sebesar 0% dan FS 7 sebesar 5 %. Pada perlakuan II dengan pemberian bakteri FS 4 intensitas serangan awal 40% dan intensitas serangan akhir 30 sedangakan FS 7 intensitas serangan awal 30% dan intensitas serangan akhir 30%. Kontrol negatif tidak menunjukkan adanya serangan penyakit sedangkan kontrol positif intensitas serangan sebsar 65 %. Penurunan intensitas serangan pada isolat bakteri FS 4 sebesar 83.33 % dan FS 7 33.33 %.
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THE ABILITY OF CHITINOLYTIC BACTERIA FROM RUBBER PLANT RHIZOSPHERE TO CONTROL WHITE ROOT DISEASE IN RUBBER
SEEDLINGS
ABSTRACT
Cultivation of rubber plant is inhibited by diseases. The diseases attacks rubber plants caused by Rigidiporus lignosus which damages rubber roots while Colletotrichum and Corynespora cause leaf diseases. The purpose of this study was to examine the ability of chitiniolytic bacteria which was isolated from rhizosphere of rubber plants in previous study to inhibit R. lignosus, Corynespora and Colletotrichum growth by in vitro study. In vivo study was to examine its ability to control white root disease caused by R. lignosus in rubber seedlings. Rhizospere chitinolytic bacterial isolates which had FS 4 and FS 7 code were used in this study. The result showed that both of isolates had abilities in inhibiting pathogenic fungal growth which FS 7 isolate showed higher inhibition zone. Inhibition zone of R. lignosus, Colletotrichum, Corynespora were 21.35 mm 17 mm, and 21. 5 mm, while inhibition zone of rhizospehere chitinolytic bacteria FS 4 code were 14.5 mm, 14.5 mm and 20.15 mm respectively. The study of in vivo was conducted using two treatments. The first treatment was application of chitinolytic bacteria one day after pathogenic fungi had been inoculated while second treatment was applied by chitinolytic bacterial 30 days after pathogenic fungi had been inoculated. Positive control was inoculation of pathogenic fungi without application of chitinolytic bacterial, while negative control was not applied by neither chitinolytic bacteria nor pathogenic fungi. The result showed a decline of disease intensity in rubber seedlings. The first treatment exhibited that the diseases intensity of R. lignosus was 0% for FS 4 and 5% for FS 7 while second treatment reduced from 40% to 15% for FS 4 and 30% to 20% for FS 7. Negative control did not show diseases while diseases intensity of positive control was 65%. Decreasing of disease intensity was 83.33% for FS 4 and 33.33% for FS 7 isolate.
