اثر چند ترکیب شیمیایی و عوامل مهار زیستی در مهار نماتد ریشه‌گرهی Meloidogyne incognita در گوجه‌فرنگی

Reducing the damage of plant parasitic nematodes can be achieved by inducing the host plant's defenses. In this study, the capability of various biological agents, including Trichoderma virens and Piriformospora indica, as well as chemical compounds including pyridoxine, folic acid, thiamine, humic acid, boric acid, zinc sulfate, and manganese sulfate on inducing resistance in tomato plants against root-knot nematode Meloidogyne incognita was examined. The experiments were conducted in sand absorbent polymer (SAP) tubes under growth chamber condition (25-26°C). Twenty-one days after inoculating the plants with second-stage juveniles (J2s), the plant growth indices including plant height, root length, and dry weight of aerial parts and roots, were measured. Then, the infected roots were stained with acid-fuchsin, and the number of galls, J3s, J4s, and females was counted. The experiment was conducted twice, with ten replications each time. Infected plants treated with 0.05 % (v/v) tween 20 served as positive control and untreated/uninfected plants were served as negative control. Analysis of variance (ANOVA) was performed by Minitab version 17 in a completely randomized design and means were compared using LSD test (P≤5%). The analysis of galls per root system revealed that thiamine and boric acid treatments yielded in fewer galls compared to the untreated controls, whereas the biological control agents T. virens strain T6, T. virens strain T-65, and P. indica showed a higher number of galls compared to the control plants. The analysis of the number of J3/J4 showed that all treatments, except for manganese sulfate, yielded in significant increase compared to the control, indicating that they interfered with the nematode development. These findings revealed that thiamine, boric acid, pyridoxine, manganese sulfate, and zinc sulfate were effective in significantly decreasing the nematode population (based on the total number of J3s, J4s, and females) within each root system. In other words, the thiamine treatment led to increase in the dry weight of aerial part, while the boric acid, zinc sulfate, and pyridoxine resulted in a reduction of the dry weight. Based on dry weight of root, the thiamine treatment yielded in the highest amount, while pyridoxine, boric acid, folic acid, and zinc sulfate yielded in the lowest amount of dry weight. The highest plant height belonged to the humic acid, and the lowest belonged to pyridoxine and T. virens strain T6 treatments. The results showed that humic acid, thiamine, manganese sulfate, and boric acid treatments increased the root length significantly, and other treatments did not show significant effect on root length compared to control. Overall, the results showed that thiamine, as the most effective treatment, caused a reduction in number of galls (82.83%) and nematode population (44%), delay in nematode development (34.22%), and increase in plant growth parameters, compared to the control.