IDENTIFIKASI MORFOLOGI JAMUR BLAS (Pyricularia oryzae) DI BEBERAPA WILAYAH SUMATERA UTARA DAN UJI KETAHANAN BEBERAPA VARIETAS PADI (Oryza sativa L.) TERHADAP INFEKSI

Abstrak

This study aims to examine the macroscopic and microscopic morphological characteristics of the Pyricularia oryzae fungus, the causative agent of rice blast disease, alongside the resistance levels of several rice (Oryza sativa L.) varieties. This descriptive and experimental research was conducted at the Regional Technical Implementation Unit of the North Sumatra Provincial Health Laboratory and the Biology Greenhouse of the Faculty of Mathematics and Natural Sciences, Universitas Negeri Medan from May to July 2025. Leaf samples exhibiting blast symptoms were collected from Deli Serdang, Serdang Bedagai, and Tebing Tinggi, then cultured on PDA media to obtain isolates. Identification relied on detailed morphological characters. Subsequently, the obtained isolates were inoculated onto three 21 day old rice varieties via spore suspension. Observations occurred on days 14 and 24 utilizing the SES blast test standard (IRRI, 2014). The results indicated seven P. oryzae isolates categorized into three macroscopic variations. The first (DS 02, SB 04) featured brownish gray colonies, black reverse, radial lines, velvety texture, irregular shape, and wavy margins. The second (DS 05, SB 02) showed blackish gray colonies, black reverse, no radial lines, cottony texture, circular shape, and smooth margins. The third (SB 03, TT 01, TT 04) displayed brownish gray colonies, black reverse, radial lines, velvety texture, circular shape, and smooth margins. Microscopically, these isolates possessed transparent hyphae, nodular surfaces, and pyriform, obclavate, or elliptical conidia containing 2 to 3 septa. Resistance testing of the three varieties demonstrated that Inpari 32 is classified as resistant, IR64 as moderately resistant, and Ciherang as susceptible.