Determining the Optimal Meloidogyne Incognita Inoculum Level, Inoculation Time, Pathogencity and Gall Development on Tomato Roots for Resistance Experiments in Breeding Programs

Root knot nematodes (RKN) cause a significant damage to many cultivated crops and present study was conducted to determine the most appropriate inoculum levels of a ubiquitous RKN nematode in warm climate, Meloidogyne incognita, inoculation time and plant age for the screening of nematode resistance studies on plant breeding programs under controlled conditions. The inoculum level experiment was conducted to investigate the effect of four M. incognita inoculum levels (1000, 1500, 2000, 2500 juveniles/1000 gram soil mix) on three different age of susceptible tomato plants. Gall development was observed at 3 different ages of susceptible tomato plants with 7 different time points. The highest gall numbers were observed on nematode infected 3 day old plant roots and the least number of galls were detected on the roots of 5 day old plants. First galls were observed at 1 dpi and the highest gall number was observed on the 21^st gall counting day on three day old tomato roots. Thus the inoculation of 2000–2500 second stage juveniles/1000 gram soil mix to 3 days old tomato plants was the best to reach high gall numbers which are suitable for screening of nematode resistance studies on plant breeding programs.