Biological characterization of isolates of the Rhizoctonia solani fungus in rice (Oryza sativa) from Karanganyar District, Indonesia

Abstract

Abstract. Itsnaini NR, Supyani, Gutomo HS. 2019. Biological characterization of isolates of the Rhizoctonia solani fungus in rice (Oryza sativa) from Karanganyar District, Indonesia. Bioteknologi 16: 74-81. This research aims to study the biological character of Rhizoctonia solani J.G.Kühn isolates, evaluate the virulence of R. solani isolates, analyze the relationship between biological characters and the virulence level of the collected R. solani isolates, and study the biological character of R. solani, which has a low virulence level. This research was conducted at the Laboratory of Plant Pests and Diseases Faculty of Agriculture, Universitas Sebelas Maret, Surakarta, Central Java, Indonesia, at an altitude of 99 m above sea level, while Rhizoctonia solani fungus in rice (Oryza sativa) was collected from Karanganyar District, Indonesia. The researchers designed this research as exploratory research in the field and conducted it in the laboratory and greenhouse. Research variables included growth rate, colony phenotypic character (including color, surface structure, and the presence or absence of air hyphae), the diameter of damage to apples, percentage of spot area, and disease intensity. Data analysis of test results on the growth rate, virulence test on apples, and percentage of spot area using the mean and standard deviation presented in graphical form while the analysis of disease intensity on the host plant using analysis of variance based on the F test at 5% level and if there was a significant difference, it was continued with Duncan's test. The results showed that the R. solani isolates from the Karanganyar area had a variety of biological characteristics (color, air mycelium, colony profile, and colony diameter) and virulence levels. Isolates that were categorized as hypovirulent were isolates K+ (P6); P28; P17; P16; and P26, each caused a spot area of 35.93%; 36.94%; 42.16%; 45.28%; 45.99% in host plants and the isolate which was considered virulent was isolate P7 which caused 56.57% of the spot area. The disease intensity in isolate K+ (P6); P28; P17; P16; and P26, respectively, were 53.33%; 46.67%; 55.55%; 59.26%; 62.96%, and the disease intensity of P7 isolate, which was virulent was 73.33%.