Thermal requirements and population dynamics of root-knot nematodes on cucumber and yield losses under protected cultivation

Several studies were carried out to determine (i) thermal requirements for development, egg production and emergence of juveniles, and completion of the life cycle of Meloidogyne incognita and Meloidogyne javanica on cucumber, (ii) the maximum multiplication rate and the equilibrium density of root-knot nematodes on cucumber and yield losses in pot and plastic greenhouse experiments, and (iii) the relationships between relative leaf chlorophyll content (RLCC) and relative cucumber dry top weight biomass (RDTWB) in relation to increasing nematode densities at planting (P-i) in pot experiments. Thermal requirements of M.incognita and M.javanica on cucumber did not differ, irrespective of the biological stage. In the pot experiments, M.javanica completed one generation. The maximum multiplication rate (a) was 833, and the equilibrium density (E) varied according to the effective inoculum densities. The relationship between RDTWB and P-i fitted the Seinhorst damage function model. The RLCC value at 40 or 50days post-inoculation also fitted the damage model and was related to RDTWB. In greenhouse experiments, conducted from 2009 to 2012, M.incognita completed three generations. The values for a and E were 1147 and 625second stage juveniles (J2) per 250cm(3) soil, respectively. The tolerance limit was below zero, and the minimum relative yield ranged from 012 to 034.