Peranan Tanah Rhizosfer Bambu sebagai Bahan untuk Menekan Perkembangan Patogen Phytophthora palmivora dan Meningkatkan Pertumbuhan Bibit Pepaya

Abstract

Abstrak. Tanah rhizosfer bambu diduga memiliki peranan sebagai bahan penekan perkembangan penyakit tanaman yang ada di dalam tanah (disease suppressive soil). Tujuan dari penelitian ini adalah: (i) mempelajari peranan dan mekanisme tanah rhizosfer bambu dalam mengendalikan penyakit, (ii) mempelajari keragaman fungsional mikroba rhizosfer bambu, dan (iii) mempelajari peranan dari tanah rhizosfer bambu dalam meningkatkan pertumbuhan tanaman dan menekan patogen tanaman, khususnya Phytopthora palmivora. Penelitian dilaksanakan pada bulan Juli 2014 sampai April 2015 dan dibagi ke dalam dua bagian: (i) percobaan rumah kaca untuk mengetahui pengaruh tanah rhizosfer bambu terhadap pertumbuhan dan persentase kematian tanaman dan (ii) percobaan laboratorium untuk mengetahui keragaman fungsional mikroba tanah rhizosfer bambu dalam menekan P. palmivora melalui uji dual culture secara in vitro. Sampel tanah rhizosfer bambu diambil pada kedalaman 0-20 cm dari beberapa lokasi di Kabupaten Bogor Jawa Barat dengan empat spesies bambu, yaitu: Gigantochloa apus, Dendrocalamus asper, Scyzosthachyum longispiculatum, dan Bambusa vulgaris. Hasil penelitian menunjukkan bahwa mikroba asal tanah rhizosfer bambu memiliki keragaman yang tinggi dan kemampuan yang lebih baik dalam meningkatkan pertumbuhan bibit tanaman pepaya dan menekan patogen tanaman. Persentase kematian tanaman pepaya pada D. asper dan B. vulgaris sebesar 12 dan 17%, dan persentase kematian tertinggi dijumpai pada tanah non rhizosfer bambu, yaitu sekitar 54%. Mikroba rhizosfer bambu juga berpotensi dalam menekan patogen tanaman melalui fenomena antibiosis. Persentase bakteri dan cendawan antibiosis tertinggi adalah 88 dan 80% pada D. asper, dan persentase terrendah adalah 43 dan 0% pada tanah non rhizosfer bambu. Dengan demikian tanah rhizosfer bambu merupakan bahan yang baik untuk media pembibitan tanaman pepaya.

 

Abstract. Bamboo rhizosphere soil is expected to exhibit disease suppressive soil phenomena. The objectives of this research were to evaluate (i) the role and mechanisms of bamboo rhizosphere soil on disease suppression, (ii) the functional diversity of bamboo rhizosphere soil, and (iii) the benefits of bamboo rhizosphere soil in improving papaya seedling growth and suppressing soil-borne disease, especially the Phytopthtora palmivora. This research was conducted from July 2014 to April 2015, and divided in two parts; (i) bio-assay in the greenhouse to determine the influence of bamboo rhizosphere soil on plant growth and the plant mortality rate and (ii) laboratory investigation of the functional biodiversity of bamboo rhizosphere in suppressing P. palmivora in vitro with dual culture method. Bamboo rhizosphere soil samples were taken at the depth of 0-20 cm from several locations in Bogor District, West Java Province under four bamboo species, namely: Gigantochloa apus, Dendrocalamus asper, Scyzosthachyum longispicu-latum, and Bambusa vulgaris. Results showed that the microbe’s diversity under bamboo rhizosphere varied highly and they increased papaya seedling growth as well as suppressed soil-borne pathogens. The death percentages of papaya seedling under D. asper and B. vulgaris were 12 and 17%, respectively. The highest death percentage was under non bamboo rhizosphere of about 54%. Microbes of bamboo rhizosphere soil were also had a potential to reduce pathogen by antibiotic phenomena. The highest percentages of antibiotic bacteria and antibiotic fungi of about 88 and 80% were found in D. asper, and the lowest ones of about 43 and 0% were found in non bamboo rhizosphere soil. This research suggests the use of bamboo rhizosphere soil as a good medium for papaya nursery.