Kemampuan Bakteri Kitinolitik Asal Rizosfer Tanaman Karet dalam Mengendalikan Jamur Akar Putih pada Bibit Karet

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.