Reaction of common bean genotypes to the reproduction of Meloidogyne javanica and Meloidogyne incognita

ABSTRACT The production of common bean (Phaseolus vulgaris L.) may be compromised by a variety of pests and diseases, with root-knot nematodes standing out among the soil-borne pathogens that cause significant losses. It was assessed the reaction of common bean genotypes to the reproduction of these nematodes, with emphasis on the two species most frequently found parasitizing the crop: Meloidogyne javanica and Meloidogne incognita. The experiments were conducted in a greenhouse, using a completely randomized design, with 26 treatments (genotypes), ten replications and plot consisting of a pot containing one plant. Each plot was inoculated with 1,000 eggs and second-stage juveniles and assessed at 62 days after the inoculation, when the final populations were estimated. The genotypic resistance was determined based on two criteria: reproduction factor and index. All the genotypes were susceptible to M. incognita according to both assessment criteria. The IAC Alvorada, IAC Imperador, BRS Esplendor and BRS Esteio cultivars, although may be classified as resistant to M. javanica by the reproduction factor, are classified only as moderately resistant if the assessment criterion is the reproduction index.

摘要 普通菜豆（Phaseolus vulgaris L.）的生产可能遭受多种病虫害的危害，其中作为引发严重产量损失的土传病原菌，根结线虫（root-knot nematodes）尤为突出。本研究针对普通菜豆基因型对这类线虫繁殖的响应展开评估，重点关注了两种最常寄生该作物的线虫种类：爪哇根结线虫（Meloidogyne javanica）和南方根结线虫（Meloidogyne incognita）。试验于温室中开展，采用完全随机设计（completely randomized design），共设置26个处理（菜豆基因型）、10次重复，每小区为1盆种植1株菜豆的栽培单元。每小区接种1000枚线虫卵及二期幼虫，并于接种后62天开展调查，此时可估算线虫的最终种群数量。基因型抗性基于两项判定指标：繁殖系数（reproduction factor）与繁殖指数（reproduction index）。依据两项评估标准，所有供试基因型均对南方根结线虫表现为感病。IAC Alvorada、IAC Imperador、BRS Esplendor以及BRS Esteio这几个栽培品种，若以繁殖系数为判定标准可归类为抗爪哇根结线虫品种，但以繁殖指数为评估准则时，仅能被划为中抗品种。