COMPARISON OF TWO POPULATIONS OF MELOIDOGYNE JAVANICA BASED ON MORPHOLOGY, BIOLOGY AND PATHOGENICITY TO GROUNDNUT

Abstract

Two populations of Meloidogyne javanica race 3 were isolated from groundnut plants collected from Pallipalem (Prakasan district) and Tirupati (Chittoor district) areas of Andhra Pradesh, India. The populations were characterized on the basis of morphology and morphometrics of females, males, and second-stage juveniles, morphology, life cycle, egg-hatch, and pathogenicity on two groundnut cultivars, JL 24 and Robut 33-1. Differences in morphology and morphometrics between the two populations were minor and it was not easy to differentiate them. Both populations had three esterase bands typical of M. javanica. The life cycles of both the populations were completed in 24 days at an average ambient temperature of 26.5 ºC. Thermal optimum for egg-hatch was 25-27 ºC for the Pallipalem populations, and 25-30 ºC for the Tirupati population. The Pallipalem population density reduced the dry shoot mass and shoot length of JL 24 at initial population densities of 1 and 10 eggs/cm³ soil, respectively. The Tirupati population reduced the dry shoot mass of JL 24 only at an initial population density of 10 eggs/cm³ soil and it did not cause any reduction in shoot length. The Pallipalem population produced greater number of galls and eggsacs on both the cultivars when compared with the Tirupati population and it was more virulent than the Tirupati population particularly on JL24.