Cowpea is grown in semiarid regions of Brazil. However, the occurrence of diseases, such as charcoal rot, is one of the main limiting factors to production. Disease is caused by the fungus Macrophomina spp., one of the most important plant pathogens in semiarid conditions. The use of resistant cultivars is the most effective method to control this disease. The objective of this study was to evaluate cowpea lines inoculated with different Macrophomina phaseolina isolates to determine the aggressiveness of the pathogen isolates and the predominant type of resistance in the host. The experiment was carried out in a completely randomized design, using a 5 × 10 factorial scheme with five replications (two plants per pot) in two independent crops. Partial diallel analysis was used to assess the reaction of host genotypes (horizontal and vertical resistance) and the aggressiveness of the isolates. Host reaction and pathogen aggressiveness were analysed by lesion length. Horizontal resistance was observed, corresponding to 56.69% of the variation. The lines L19, L29, L48, and L95 were the most resistant based on estimates of general responsiveness. Among the M. phaseolina isolates evaluated, N105 and ISO16 were the most aggressive based on general aggressiveness ability. By diallel analysis, we identified the most promising genotypes, as well as the most aggressive isolates.

中文翻译：

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通过双列分析鉴定抗性豇豆基因型和菜豆大孔菌分离株的攻击性

豇豆生长于巴西半干旱地区。然而，炭腐病等病害的发生是生产的主要限制因素之一。疾病是由真菌Macrophhomina spp.引起的，它是半干旱条件下最重要的植物病原体之一。使用抗病品种是控制该病害最有效的方法。本研究的目的是评估接种不同Macrophhomina Phaseolina分离株的豇豆品系，以确定病原体分离株的侵袭性和宿主的主要抗性类型。该实验采用完全随机设计，采用 5 × 10 因子方案，在两种独立作物中进行五次重复（每盆两株植物）。部分双列分析用于评估宿主基因型的反应（水平和垂直抗性）和分离株的攻击性。通过病变长度分析宿主反应和病原体侵袭性。观察到水平阻力，对应于变异的 56.69%。根据对一般反应性的估计，L19、L29、L48 和 L95 品系的抵抗力最强。在评估的M. Phaseolina分离株中，根据一般攻击能力，N105 和 ISO16 最具攻击性。通过双列分析，我们确定了最有希望的基因型，以及最具攻击性的分离株。