Interactive effects of irrigation levels, fulvic acid, and shading intensity on the growth, physiological, and biochemical traits of soilless-grown rocket (Eruca sativa Mill.)

Document Type : Research Paper

Authors

1 Department of Horticultural Sciences and Engineering, Faculty of Agriculture, University of Kurdistan, P.O. Box 66177-15175, Sanandaj, Kurdistan, Iran; Protected Agriculture Department, Bakrajo Technical Institute, Sulaimani Polytechnic University, Sulaymaniyah, Kurdistan, Iraq.

2 Department of Horticultural Sciences and Engineering, Faculty of Agriculture, University of Kurdistan, P.O. Box 66177-15175, Sanandaj, Kurdistan, Iran; Research Center of Medicinal Plants Breeding and Development, University of Kurdistan, Sanandaj, Kurdistan, Iran.

10.22034/jppb.2025.68975.1378

Abstract

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: A factorial experiment was conducted, using a completely randomized design with three replications. The first factor consisted of three different irrigation levels, 100%, 75%, and 50% of the plants' water requirements, referred to as IL100, IL75, and IL50, respectively. The second and third factors 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%, respectively. 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 to determine the significance of the main effects and their interaction for the measured traits.
Results: Most of the Main effects of the factors and their interactions were significant for most of the measured characteristics. 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 ranged from 86.36% to 87.78%, and the membrane stability index varied from 76.46% to 78.59%, both reaching their highest values under full irrigation, moderate shading, and high FA conditions. Malondialdehyde concentration, which indicates oxidative stress, was lowest under conditions of full irrigation, high shading, and the application of FA. Also, 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 such as rocket in greenhouse environments.

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Main Subjects

References

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Journal of Plant Physiology and Breeding
Volume 15, Issue 2
December 2025
Pages 217-242

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