Comparative Pathogenicity of Meloidogyne enterolobii and Meloidogyne incognita in Cotton Cultivars

Meloidogyne enterolobii (Me) is a nematode that has recently been observed in cotton. Initial observations indicate that cotton cultivars resistant to Meloidogyne incognita (Mi) are susceptible to Me, but the reproductive capacity and ability to cause damage by Me compared to Mi is unknown. The objective of this study was to assess the reproductive capacity and ability to cause damage by Mi and Me at different population densities in two cotton cultivars. The study included two greenhouse experiments in which two cotton cultivars, resistant and susceptible to Mi, were inoculated with six increasing population densities of Me and Mi. The genetic resistance of cotton to Mi given by quantitative trait loci of the q-Mi11 and q-Mi14 genes is ineffective against Me. The Mi-resistant cotton cultivar showed a similar gall index to the Mi-susceptible cultivar when inoculated with Me. The mean gall index with Me was significantly higher than that with Mi on the Mi-resistant cotton cultivar. Based on the number of nematodes per root mass and the reproductive factor, Me showed a higher reproductive capacity than Mi on cotton. Increasing Me population densities linearly reduced the height and dry matter production of aboveground biomass in the Mi-resistant cotton cultivar. However, neither Meloidogyne species affected leaf chlorophyll content and photosynthetic rate of the cotton plants.