KARAKTERISASI MORFOLOGI JAMUR BLAS (Pyricularia oryzae) DI TIGA KABUPATEN DI SUMATRA UTARA DAN TINGKAT VIRULENSINYA TERHADAP BEBERAPA KULTIVAR PADI

Abstrak

Pyricularia oryzae is the fungal pathogen responsible for rice blast disease, which significantly impacts the decline of agricultural productivity. This study conducted an analysis of the macroscopic and microscopic morphological characteristics of the fungus, as well as its virulence levels across three rice cultivars. The research was conducted from May to July 2025 across three regencies (Toba Samosir, Simalungun, and Karo), UPTD Health Laboratory of North Sumatra Province, and the Biology Greenhouse of the Faculty of Mathematics and Natural Sciences at Universitas Negeri Medan. Leaf samples exhibiting blast symptoms were cultured on PDA media to obtain isolates, which were subsequently characterized macroscopically and microscopically before being inoculated onto 21 day old rice seedlings. Symptoms were observed on days 14 and 24, while the virulence level was determined using the SES blast test standard (IRRI, 2014). A total of 10 isolates were successfully identified, exhibiting three macroscopic morphological variations: colonies with smooth margins (TS01, TS02, SI03, SI04), wavy margins (TS04, SI02, KA04), and concentric rings (TS03, KA02). Microscopic characterization revealed variations in conidial shapes, including pyriform, elliptical, and obclavate forms. Virulence testing indicated that isolate TS04 (PO1) was avirulent on Inpari 32, moderately virulent on Ciherang, and virulent on IR64. Isolate SI03 (PO2) demonstrated moderate virulence on Inpari 32, virulent on Ciherang, and moderate virulence on IR64. Similarly, isolate KA02 (PO3) was moderately virulent on Inpari 32, virulent on Ciherang, and moderately virulent on IR64. Overall, Inpari 32 exhibited better resistance compared to the other two cultivars.