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چکیده
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Objective: This study aimed to assess the interactive effects of irrigation levels, foliar application of fulvic acid, and shading intensity on the growth, physiological performance, and biochemical traits of rocket (Eruca sativa Mill.) cultivated in soilless conditions under greenhouse environments. Methods: An experiment was conducted with three different irrigation levels—100%, 75%, and 50% of the plants' water requirements, referred to as IL100, IL75, and IL50, respectively. Furthermore, the study included three concentrations of foliar fulvic acid (FA): 0, 1, and 2 g L⁻¹, along with three shading intensities of 0%, 50%, and 80%. Rocket plants were cultivated in a controlled hydroponic system, and growth-related traits, as well as physiological and biochemical characteristics, were measured. The data were analyzed using analysis of variance (ANOVA) to determine the main and interaction effects among treatments. Results: Most of the measured parameters exhibited significant main and interaction effects. The highest shoot and root biomasses were observed under full irrigation (IL100), without shading, and with 2 g L⁻¹ of FA, while severe shading (80%) and a water deficit (IL50) significantly diminished growth. Notably, IL50 resulted in increases of up to 27% in chlorophyll a, chlorophyll b, and carotenoid contents compared to IL100, with the application of FA enhancing this effect. Relative water content (RWC) ranged from 86.36% to 87.78%, and the membrane stability index (MSI) varied from 76.46% to 78.59%, both reaching their highest values under full irrigation, moderate shading, and high FA conditions. Malondialdehyde (MDA) concentrations, which indicate oxidative stress, were lowest at 0.398–0.454 µmol g⁻¹ FW under conditions of full irrigation, high shading, and the application of FA. In contrast, plants grown under IL50 without shading and treated with 2 g L⁻¹ of FA showed the highest concentrations of soluble carbohydrates and proline. These levels were approximately 200% and 73% higher, respectively, compared to control plants that were grown under IL100 with 80% shading and no FA. Conclusion: The optimized coordination of irrigation, foliar FA application, and shading intensity significantly enhances the growth, physiological, and biochemical tolerance of rocket plants. This strategy promotes sustainable and efficient soilless cultivation of leafy vegetables in greenhouse environments.
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