DOI: 10.32649/ajas.2025.159973.1678 ISSN: 1992-7479

Effectiveness of Trichoderma Secondary Metabolites on Disease Severity, Morphological Characteristics and Chlorophyll Content in Tomato Plants Infected with Alternaria Solani

S. M. Alhadethy, R. F. Hamdi
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The pots experiment was carried out in Haditha city, Anbar, Iraq, under greenhouse conditions using a random design. It aimed to investigate the impact of Trichoderma secondary metabolites on disease severity, morphological characteristics, and chlorophyll content on the tomato plant. The effect was evaluated by measuring the growth of the shoot and root systems, including the number of leaves, plant height, leaf area, fresh and dry weights, as well as chlorophyll concentration, an indicator of photosynthetic efficiency. Experimental treatments were conducted four weeks after transplanting the seedlings into pots (i.e., at two months of age). They included five treatments: control (without any addition), Trichoderma treatment only, Alternaria solani infection treatment only, preventive treatment of spraying Trichoderma at 15 days of age from germination, and infecting the plants with A. solani, and after the symptoms appeared they were treated by spraying Trichoderma filtrate. The Trichoderma treatment alone did not contribute to disease development (decreasing in disease severity) and also showed significant increase in plant height, number of leaves, number of branches, leaf area, fresh and dry weights, and leaf area (42.00 ± 2.02 cm), (12.00 ± 1.14), (6.80 ± 0.37) (40.38 ± 0.72 cm2), (13.37 ± 0.41)g, and (2.04 ± 0.30)g, respectively compared to the control (25.00 ± 0.70)cm, (8.00 ± 0.54), (5.00 ± 0.30), (20.4 ± 0.38), (7.13 ± 0.32)g, and (0.542 ± 0.02)g, respectively. The treated plants also recorded a significant increase in chlorophyll content with Trichoderma (44.15 ± 0.74 mg/100 g) compared to the control (21.25 ± 0.42 mg/100 g). Trichoderma had a significant effect on the length, with fresh and dry weights of the root at 17.78 ± 0.38 cm, 1.268 ± 0.081 g, and 0.123 ± 0.002 g, respectively. In comparison, the control’s was 7.53 ± 0.35 cm, 0.246 ± 0.018 g, and 0.043 ± 0.002 g, respectively. These results indicate that Trichoderma can be an effective bioagent for improving tomato growth and increasing its productivity

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