Effects of Different Population Densities of Root-Knot Nematode Meloidogyne luci on Growth of Tomato and Nematode Reproduction

The pot experiment was conducted to determine the effects of four initial population (Pi) densities (101, 102, 103 and104 eggs/plant) of root-knot nematode Meloidogyne luci on plant growth of susceptible tomato and nematode reproduction. Initial values of shoot length and stem diameter as a plant growth criteria were determined prior to nematode inoculation. Additionally, chlorophyll contents of leaf were weekly recorded from nematode inoculation to end of the experiment to assess their differences. The experiment was terminated sixty days after nematode inoculation to determine shoot length, shoot weight, stem diameter, and root weight. Galls of root were evaluated according to 0-10 scale, and nematode final population (Pf) and reproduction factor (Rf) were determined. The increase in Pi densities caused reduction of plant growth parameters except for root weight. Significant reductions were found stem diameter at 101 of Pi and shoot length and weight at 103 of Pi in comparison to control (Pi=0) (P？0.05). a lower chlorophyll content was determined during the experiment period in nematode-inoculated plants compared to non-inoculated plants, but not significantly. Significant increases in the value of gall scale were found with an increase in Pi (P？0.05). Similarly, Pf increased with an increase in Pi but egg numbers of gram root had no significant differences between 103 and 104 at Pi. Maximum Rf values were recorded at low Pi values but statistically significant reduction was determined at higher Pi level than 103. Regression analyses were performed to detect the relationship between nematode and plant growth resulting in a positive correlation between Pi levels and the percentage decrease in shoot length and stem diameters in relation to the actual growth in control. Similar positive relations were also determined between values of gall scale and percentage reduction shoot length and weight over control. In conclusion, considerable reductions in the growth of tomato were at 103 of Pi when plant growth parameters, galling rates, and nematode reproduction were evaluated together