KARAKTERISTIK FISIOLOGIS ISOLAT Sclerotium sp. ASAL TANAMAN SAMBILOTO

Abstract

ABSTRAK Sclerotium sp. merupakan jamur patogen baru pada tanaman sambiloto (Andrographis paniculata Ness.) yang dapat mengakibatkan kematian. Penyebaran jamur ini masih terbatas di KP Cimanggu, Bogor dan KP Cicurug, Sukabumi, Jawa Barat. Tujuan penelitian adalah untuk mengetahui  pengaruh  beberapa  faktor  lingkungan  seperti  suhu, kelembaban udara (RH), pH, dan cahaya terhadap pertumbuhan isolat Sclerotium sp. asal sambiloto pada media PDA serta kisaran inangnya. Penelitian dilakukan di laboratorium dan rumah kaca Balai Penelitian Tanaman Obat dan Aromatik (Balittro), Tahun 2005. Faktor lingkungan yang diuji yaitu suhu ruangan (20, 28, 35 dan 40) o C, kelembaban udara (RH 55, 75, 85, dan 100)%, pH (4, 5, 6, 7, dan 8) dan kondisi cahaya (terang, gelap, dan terang dan gelap selang 12 jam secara bergantian). Uji kisaran inang dilakukan terhadap 3 varietas jagung (ketan, pematung, dan sokong) dan 3 varietas kacang tanah (jerapah, kelinci, dan simpai) serta tanaman sambiloto sebagai pembanding. Inokulasi dilakukan dengan cara menempelkan sclerotia jamur di bagian pangkal batang tanaman uji dekat permukaan tanah. Pengamatan pertumbuhan jamur pada media agar yang diperlakukan dan pengamatan intensitas serangan penyakit dilakukan setiap hari. Hasil penelitian menunjukkan bahwa isolat Sclerotium sp. asal tanaman sambiloto tumbuh baik pada suhu (20-35) 0 C, RH (55-100)%, dan pada kisaran pH 4-8 serta pada kondisi terang atau gelap secara terus menerus maupun bergantian selang 12 jam. Hasil uji kisaran inang menunjukkan bahwa Sclerotium sp. dapat menyebabkan kematian tidak hanya pada tanaman sambiloto, tetapi juga pada dua varietas kacang tanah (simpai dan jerapah), sedangkan pada jagung tidak menyebabkan kematian (tahan). Hasil penelitian mengindikasikan bahwa isolat Sclerotium sp. yang berasal dari tanaman sambiloto mempunyai kemampuan bertahan hidup dan berkembang pada kondisi lingkungan yang luas (broad spectrum). Ketidakmampuan jamur tersebut menginfeksi tanaman jagung varietas ketan, pematung, dan sokong dapat digunanakan sebagai salah satu cara pengendalian patogen dengan sistem tumpangsari dan rotasi. Kata kunci : Sambiloto, Andrographis paniculata Ness, Sclerotium sp., karakteristik, fisiologis, Jawa Barat ABSTRACT Physiological Characteristics of Sclerotium sp. Isolated from Sambiloto Sclerotium sp. is a new destructive fungal patogen on sambiloto (Andrographis paniculata Ness.). The distribution of the patogen was still limited in Cicurug, Sukabumi and Cimanggu, Bogor, West Java. The aim of this experiment was to observe the growth of Sclerotium sp from sambiloto under different environmental factors such as temperature, relative humidity, light condition, and pH on PDA medium as well as its host range. The experiment was conducted in Indonesian Medicinal and Aromatic Crops Research Institute (IMACRI) in 2005. The environmental factors tested were temperature (20, 28, 35, and 40) o C; relative humidity (55, 75, 85, and 100)%; pH (4-8); and light condition (continuosly on or off and 12 hours on and off alternatively). The pathogenicity of the Sclerotium sp. was tested against 3 varieties of corn (ketan, pematung, and sokong) and 3 varieties of peanut (jerapah, kelinci, and simpai) as well as sambiloto as a comparison. Sclerotia of the fungus were inoculated on the stem base of the plant tested. Observation of the growth of the fungus under different environmental factors and disease intensity on inoculated plants was conducted everyday. The results showed that the growth of Sclerotium sp. isolate from sambiloto was affected by different environmental factors. The isolate grew well at (20-35) 0 C, relative humidity ranged from (55-100)%, pH ranged from 4-8, and light condition of both continuosly on or off as well as 12 hours on and off alternativelly. The isolate was pathogenic against sambiloto as well as against 2 varieties of peanut (simpai and jerapah), however, it was not pathogenic against all the corn varieties tested. The result indicated that the isolate of Sclerotium sp. from sambiloto was a broad spectrum fungal pathogen. The resistency of the corn varieties would be of value for controlling the disease through mixed cropping or rotation systems. Key words: Sambiloto, Andrographis paniculata Ness, Sclerotium sp., physiological characteristics, West Java