Effect of Silicon, Sulfates, and Bacterial Isolates on Protease Enzyme Activity and Gray Mold Resistance of Eggplant Plants

• Sarab Jalil Ghadhban¹*, Khaldoon Faris SAEED¹

  Author

Gray mold disease caused by Botrytis cinerea is an important fungal disease that can negatively affect the growth and productivity of eggplant plants. In the present study the efficacy of potassium silicate, potassium sulfate and three isolates of beneficial bacteria in individual, and their combination, was tested on the effect on gray mold disease, protease enzyme activity and growth parameters of eggplant plants. The experiment was carried out in the greenhouse with eggplant cultivar (P.K.111) and 17 treatments such as individual treatments, combined treatments, fungicide treatment and positive and negative control. The incidence and severity of disease were determined during three consecutive weeks after inoculation with B. cinerea and protease activity and root growth characteristics were also investigated.The results indicated a progressive increase in disease incidence for the positive control (65% for first week, 92% for second week, and 98% for third week) and disease severity (40% to 67.33% for second and third weeks, respectively). Of the single bacterial treatments, Bacterial Pantoea agglomerans as the most effective in reducing disease development. The combined treatment of Potassium sulfate + Potassium silicate was the most effective non-chemical treatment, as it suppressed disease incidence and severity to 18% and 8% respectively in the first week, 40% and 25% respectively in the second week and 45% and 30% respectively in the third week. In the third week, the fungicide treatment recorded the lowest disease incidence and severity with 40% and 25%, respectively, of the infected treatments.

There were also significant differences between treatments in protease enzyme activity. The latter resulted in the highest activity (1.483) followed by the same treatments with Bacterial isolates 2 and 3 with activities 1.410 and 1.387, respectively while the negative control recorded the lowest (0.637). Potassium silicate alone gave the highest root dry weight (39.366 g) and potassium sulfate + potassium silicate + Bacterial isolate 2 gave the highest root fresh weight (45.922 g).

Overall, the findings indicate that the integration of silicon, sulfate, and beneficial bacterial isolates, particularly Bacterial isolate 2, has potential as a component of an integrated management strategy for gray mold disease in eggplant. The combined treatments reduced disease development and, in some cases, improved root growth and protease activity, supporting their potential as sustainable alternatives or complementary approaches to chemical disease control.

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