Disease severity and infection rate of soybean leaf rust disease on several genotypes

Abstract

Soybean leaf rust disease caused due to Phakopsora pachyrhizi Syd so far is considered as a major disease of soybean production. The utilization of soybean genotype with high yielding and source of genetic resistances to soybean leaf rust is could be one one effort to overcome the low production problem. Resistant varieties requires a source of resistant parent. Evaluation of these variety of the disease and the rate of infection is important as an indicator to assess the viability of a genotype, as a source of resistant gen. Based on IWGSR (International Working Group Soybean Rust) rating codes, from 12 genotypes tested (four parents and 8 crosed genotypes), only one genotype resulted from crossing between Mutiara-1 and GHJ-6 was categorized resistant. These genotypes had the lightest lower of disease index (KP) with the lowest infection rate (r), become the most elegible source of gamatic resistace. The remaining 11 genotypes were moderatly resistant to disease. Genotypes GHJ-6 (parent), Mutiara-1 (parent), crossing of GHJ-7 and Mutiara-1, and the crossing of Mutiara-1 and GHJ-6 had same rate of infection (54.46) with the crossing of Mutiara-1and GHJ-6 (r=0.22) but showed lower and considered as source resistant genes. Another indicator that can be used to evaluate this eligibility of genotype as a source of resistant genes is a decrease in crop yields due to soybean leaf rust infections.