Determining the impact of initial population densities of Meloidogyne paranaensis on phenotyping coffee genotypes to nematode resistance: a meta-analysis of studies from 2008 to 2019

Meloidogyne paranaensis is one of the highly aggressive nematode species that infect coffee crops in Brazil, causing extensive yield losses. The main management strategy is the use of resistant cultivars. However, until this moment no pattern protocols to phenotyping coffee genotypes are available regarding to (i) the more appropriate initial population density to be used in the phenotyping of genotypes, (ii) what is the plant age to inoculate the nematode, and (iii) the evaluation time. The objective of this study was to investigate and clarify the inconsistence between these parameters using a meta-analysis approach. The search was performed in Scielo and Scopus databases using the combination of words “Coffea” and “Meloidogyne”. Thirteen scientific papers published between 2008 and 2019 were selected, a total of 331 studies. The treatment group was constituted by the evaluated cultivars to be classified as resistant or susceptible and the check group was established by the standard susceptible cultivars. The analyzed variables were the reproduction factor of M. paranaensis, the fresh root weight, and the number of nematodes per gram of roots. The effect measurement was calculated by the ln of the ratio between the treatment and the check groups. Results suggested that the initial population density of 1000 eggs per plant, inoculated in plants with four leaf pairs, could be used to inoculate coffee genotypes in phenotyping tests to M. paranaensis evaluated between 80 and 90 days after the inoculation.