Effects of initial nematode population density and water regime on resistance and tolerance to the rice root-knot nematode Meloidogyne graminicola in African and Asian rice genotypes

ABSTRACT

The rice root-knot nematode (RKN), Meloidogyne graminicola, is an important pathogen affecting rice production in South and Southeast Asia. Efficacy of resistance and tolerance in selected M. graminicola-resistant African rice genotypes TOG5674, TOG5675 and CG14 and -susceptible Asian rice genotypes IR64 and UPLRi-5 were examined under a range of initial population densities (Pi) and water regimes. Resistance to M. graminicola in resistant rice genotypes was not broken with increasing pathogen pressure (Pi = 15,000 to 60,000 J2/plant). Resistant rice genotypes were even tolerant to the damage and yield loss caused by high pathogen pressure. On the other hand, increasing Pi levels caused more damage on susceptible rice genotypes. Final nematode population densities in the root systems of resistant and susceptible rice genotypes were significantly lower under flooded conditions than under upland and drought conditions. TOG5674, TOG5675 and CG14 were more tolerant to M. graminicola infection even when grown under upland and drought conditions while IR64 and UPLRi-5 were highly sensitive.

KEYWORDS:

• Damage potential
• oryza glaberrima
• oryza sativa
• plant growth and yield-contributing traits
• reproductive potential
• yield loss

Acknowledgments

This study was supported by a Flemish Interuniversity Council (VLIR-UOS) Ph.D. scholarship to MTNC. The authors would like to thank the International Rice Research Institute (IRRI) for the seeds, equipment, and facilities; and Luzviminda Fernandez, Sergio Velasco, and Juan Reyes for their technical assistance.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Flemish Interuniversity Council (VLIR-UOS) [grant number 2009].