The relationship of initial population densities of Meloidogyne javanica and damage level on okra (Abelmoschus esculentus)

A field experiment was conducted in the 2 × 3 m plots to determine the effect of different initial population densities of Meloidogyne javanica on growth parameters and yield of okra (Abelmoschus esculentus; cv. Soltani) in 2013. This research was carried out based on completely randomized design (CRD) with five replications using a geometric series of 14 nematode population densities (0 to 512 eggs or second stage juveniles (J2) / cm3 soil). The plants died at high levels of nematode population (> 256). The relative shoot fresh and dry weight and relative yield fitted the Seinhorst damage model and the tolerance limit for those traits was 0.34, 0.33 and 0.28 eggs or J2 / cm3 soil, respectively. The maximum multiplication rate was 749 and the equilibrium density was 159 eggs or J2 / cm3 soil. Nematode reproduction factor was negatively correlated with the initial populations as the highest multiplication was occurred at the lowest initial population densities. Damage threshold (10% yield loss) of okra to M. javanica was estimated as 0.85 eggs or J2 / cm3 soil which represented the susceptibility of okra plant to M. javanica.