Introduction: Strawberry (Fragaria × ananassa Duch.) is one of the most valuable and widely cultivated berry crops in the world due to its high nutritional value, appealing flavor, and economic importance. In hydroponic systems, where nutrient solution is the sole source of mineral supply, precise management of micronutrients is essential for optimal plant growth and fruit quality. Among these micronutrients, copper (Cu) and zinc (Zn) play key roles in photosynthesis, enzyme activation, protein synthesis, and antioxidant defense. However, conventional mineral salts often show limited availability and may cause imbalances, whereas Amino-chelated (AC) forms can improve nutrient uptake and reduce toxicity. Therefore, this study aims to evaluate the combined foliar application of copper and zinc amino-chelates on the vegetative and reproductive traits of two strawberry cultivars, Sabrina and Camarosa, under hydroponic conditions.
Materials and Methods: To evaluate and compare the effects of Zn and Cu amino-chelates on the morphological characteristics of strawberry, a factorial experiment based on a completely randomized design with three replications was conducted in the greenhouse of the Faculty of Agriculture at Shahid Chamran University of Ahvaz. In January 2025, strawberry runners of ‘Camarosa’ and ‘Sabrina’ cultivars were obtained from a nursery in Kordestan province and transferred to the greenhouse. The plants were disinfected with Mancozeb fungicide and planted in growing beds (130 cm long, 25 cm wide, and 10 cm deep) containing a 70:30 mixture of coco-peat and perlite. The Rash nutrient solution was used for plant nutrition, and treatments commenced one month after plant establishment. The experimental treatments included foliar application of Cu AC at two levels (0 and 4 ml/L) and Zn AC at three levels (0, 2, and 4 ml/L) on both ‘Sabrina’ and ‘Camarosa’ cultivars. Foliar spraying was repeated monthly. Measured parameters included vegetative and reproductive characteristics, as well as photosynthetic pigments.
Results and Discussion: The study revealed that foliar application of Zn and Cu amino-chelates significantly improved vegetative growth, reproductive yield, and photosynthetic pigments in both 'Sabrina' and 'Camarosa' strawberry cultivars. Optimal responses were generally observed at 2-4 mL/L concentrations, highlighting enhanced biomass, fruit quality, and gas exchange efficiency. The highest shoot fresh weight (26 g) and dry weight (6.36 g), as well as the highest root fresh weight (16.33 g) and dry weight (3.79 g), were obtained in the Sabrina cultivar under the treatment of 2 mL L⁻¹ Zn amino chelate without the application of Cu amino chelate. The treatment consisting of 4 mL/L Cu amino-chelate combined with 2 mL/L Zn amino-chelate resulted in the highest levels of chlorophyll b (0.240 mg/gfw) and photosynthetic rate (8.57 µmol/m²/s). Zn and Cu amino-chelates improved vegetative growth, reproductive performance, and physiological traits in strawberry by enhancing nutrient uptake, chlorophyll synthesis, gas exchange, and growth-related metabolic processes. Zn likely promoted growth through its role in auxin biosynthesis, enzyme activation, and reproductive development, while Cu contributed to structural stability and root dry matter through lignin synthesis.
Conclusion: Overall, the results indicated that foliar application of Zn and Cu amino-chelates positively affected the vegetative, reproductive, and photosynthetic pigment indices in both ‘Sabrina’ and ‘Camarosa’ cultivars, with the treatments showing a greater increase in morphological traits for ‘Sabrina’ compared to ‘Camarosa