Preservation of moderately resistant or tolerant genotypes: a strategy to overcome guava decline

Abstract

Originating from Tropical America, the culture of guava (Psidium guajava L.) has great relevance for Brazil. However, the emergence of the pathosystem designated as guava decline, a phytosanitary problem caused by root parasitism by nematodes of the species Meloidogyne enterolobii Yang & Eisenback in association with opportunistic fungi, decimated many orchards in all regions of Brazil and other countries. In this work, accessions of guava trees, originated from seeds, were vegetative propagated, by mini cuttings, keeping their genotypes preserved and reassessing the resistance by means of clones in order to verify or not the reactions of host plants. The results point to high virulence of the parasite, as well as high accommodation of the species P. guajava, besides the existence of great variation of the reaction between plants of the same genotype and between different genotypes, indicating that the strategy of germplasm preservation and the reassessment of the reaction in clones may be important in the search and selection of germplasm with some degree of resistance or tolerance characteristics to M. enterolobii. The commercial progeny of cv. Paluma P02R5R2 obtained the lowest mean parasite reproduction factor (RF = 22.11) among the genotypes evaluated, being classified as moderately resistant and preserved for further studies.