Study of the antagonistic effects of Trichoderma harzianum and Bacillus subtilis along with low current of magnetic field on Bacterial wilt of tomato by Ralstonia solanacearum

Abstract

Given the importance of (RS), using biological control is an effective and low-risk solution to reduce the damage of this disease. In this study, antagonists of Trichoderma harzianum and Bacillus subtilis, magnetic field and irrigation with magnetized water were used simultaneously and individually, in order to biologically control this disease in order to increase the inhibition percentage of tomato plants. In this way, 15 g of Trichoderma inoculum (10⁶ CFU) and 15 ml of Bacillus suspension (10¹⁰ CFU) were poured separately in each pot, and then the seedlings were cultivated there. After the seedlings reached the stage of four to five leaves, the crown of the plant was wounded under the soil and a drop of Ralstonia solanacearum (10⁶ CFU) suspension was placed on the wound, a 0.7 mT magnetic field was used to magnetize the seed and irrigation water. This experiment was performed in ten treatments with five replications in a completely randomized design. The results of analysis of variance showed that the inhibition percentage and fresh weight of the treatments were significant at the probability level of 1% and the root length and stem length of the treatments were significant at the probability level of 5%. The best result was obtained when the tomato plant impregnated with T. harzianum and B. subtilis antagonists was simultaneously exposed to a magnetic field of 0.7 mT and irrigated with magnetized water of 0.7 mT, and finally caused 75% inhibition of tomato seedlings. While the simultaneous use of T. harzianum and B. subtilis antagonists, without exposure to a magnetic field and irrigation with non-magnetized water, caused 65% inhibition of tomato seedlings. The reason is the increase in the vegetative growth indicators of the tomato plant exposed to the magnetic field. The magnetic field increases the number and length of plant roots, which provides more surface in the root for the activity of Trichoderma and finally increases the percentage of inhibition.