EFFECT OF ROOT-KNOT NEMATODES MELOIDOGYNE INCOGNITA AND M. JAVANICA ON THE GROWTH OF COFFEE (COFFEA ARABICA L.) IN POTS
AbstractThe relationship between initial population densities (Pi) of two Italian root-knot nematode species (Meloidogyne incognita race 1 and M. javanica) and growth of coffee (Coffea arabica) seedlings was studied in a glasshouse experiment. Initial population density of both nematode species consisted of (O, 0.25, 0.5, 1,2, 4, 8, 16, 32,64, 128 or 256) eggs and second stage juveniles/cm³ of soil. The response of the coffee plants to the initial population density was fitted to the model y = m + (1-m)z[supPû[supT]. The tolerance limit (1) of coffee seedlings to M. incognita race 1 was 2.09 eggs and juveniIes/cm3 soil and to M. javanica 1.9 and 1.34 eggs and juveniles/cm³ soil far total and fresh top weight, respectively. A minimum relative yield (m) of coffee was 0.4 at Pi = 128 eggs/cm soil of M. incognita and 0.4 and 0.5 far total and fresh top weight, respectively at the same levels of inoculum far M. javanica. Cross sections of M. incognita infected roots showed several moderately sized giant cells arranged around the nematode head, compared with the well developed large multinucleate giant cells induced by M. exigua.