Characterization of soybean genotypes for Asian soybean rust reaction

Milena Moura De Araujo,Natal Antonio Vello

doi:10.1590/s1984-70332010000300003

Abstract

Our objective was to characterize soybean experimental lines for Asian soybean rust reaction. In the 2004/2005 growing season, three experiments were conducted with middle-cycle and three with late-cycle genotypes, designed in randomized blocks with four replications. Twelve experimental lines and two cultivars of each cycle were used. In each experiment the plant management differs as follows: three applications of carbendazim or three of flutriafol or without applications. The experimental lines with high yield, low notes to the symptoms and resistance to lodging, were selected and tested again in the 2005/2006 growing season. Genotypes with high severity and yield were considered tolerant to rust and the low severity and high yield ones as moderately resistant. Among the medium-cycle genotypes, there was moderate resistance to rust in one line and tolerance in five. Among the late-cycle genotypes, the six lines showed moderate resistance. The line USP 97-08135 is more tolerant to rust.

Highlights

In recent years, the Asian soybean rust (ASR), whose causal agent is the biotrophic fungus Phakopsora pachyrhizi
The main symptom in infected plants is the lesions formation, consisting of pustules reaching 2 to 5 square mm, in which occurs the formation of globular structures called uredias, which produce large numbers of urediniospores
The ASR is spread by the wind through urediniospores, and may develop rapidly, causing a reduction in leaf area and yield (Bromfield et al 1980)

Summary

Introduction

The Asian soybean rust (ASR), whose causal agent is the biotrophic fungus Phakopsora pachyrhizi Sydow) has been a disease of major importance to the soybean-producing countries, affecting even the United States of America in 2004 (Lynch et al 2006). The main symptom in infected plants is the lesions formation, consisting of pustules reaching 2 to 5 square mm, in which occurs the formation of globular structures called uredias, which produce large numbers of urediniospores. The leaf tissue around the first uredias acquires a light brown color (tan lesion type - sensitivity) to reddish brown (RB type of injury, reddish brown - resistance) (Bromfield et al 1980). The ASR is spread by the wind through urediniospores, and may develop rapidly, causing a reduction in leaf area and yield (Bromfield et al 1980)

Objectives

Methods

Results