EFFECT OF INITIAL POPULATION-DENSITY OF MELOIDOGYNE-INCOGNITA RACE-3 ON THE GROWTH OF KENAF (HIBISCUS-CANNABINUS L)

In a greenhouse experiment, seedlings of kenaf (Hibiscus cannabinus) cv. Tainung I were inoculated with Meloidogyne incognita race 3 at initial population densities (Pi) of 0, 100, 500, 1 000, 2 500, and 5 000 eggs + second-stage juveniles/500 cm3 soil. After 60 days, plant height, stalk diameter, and root and stem weights were significantly reduced at Pi = 5 000 but not at lower Pi's. Shoot dry weights were reduced 46% compared with the untreated control. The total nematode population (eggs and second-stage juveniles recovered from roots and soil) increased with increasing inoculum levels and the reproductive factor (R = final population/initial population) decreased as the initial inoculum level increased.