با همکاری انجمن علمی منظر ایران
نوع مقاله : مقالات پژوهشی
نویسندگان
گروه ژنتیک و تولیدات گیاهی، دانشکده کشاورزی و منابع طبیعی، دانشگاه محقق اردبیلی، اردبیل، ایران
کلیدواژهها
عنوان مقاله English
نویسندگان English
Introduction
Tomato (Solanum lycopersicum) is one of the most widely grown vegetable crops in the world and is of high nutritional and economic importance. However, tomato production is severely constrained by abiotic stresses, particularly salinity, which reduces water uptake, disrupts ionic balance, damages chlorophyll, and induces oxidative stress. Nutrient management has emerged as a promising approach. Nitrogen, phosphorus, and potassium are fundamental for growth and osmotic adjustment, while micronutrients such as iron, zinc, manganese, and boron act as cofactors for enzymes, participate in antioxidant defense, and contribute to reproductive success. This research aimed to investigate the effects of NPK and micronutrient fertilization, both individually and in combination, on tomato yield, quality, and physiological parameters under varying salinity levels, with the ultimate goal of providing sustainable solutions for tomato production in salt-affected areas.
Materials and Methods
The experiment was carried out in 2024 at the greenhouse of Mohaghegh Ardabili University, Iran. The experimental design was factorial, based on a randomized complete block with three replications. Treatments included four salinity levels (0, 2, 4, and 8 dS.m⁻¹) imposed by adding NaCl to irrigation water, and four fertilizer treatments: control (no fertilizer), NPK (200 kg N, 150 kg P, and 150 kg K.ha⁻¹), micronutrients (Zn, Fe, Mn, and B applied as foliar spray), and combined NPK + micronutrients (half NPK dose plus foliar micronutrients). NPK was applied partly as basal and partly as top dressing, while micronutrients were sprayed twice during vegetative growth and once after fruit setting. The measured traits included yield components (fruit number, average fruit weight, total yield per plant), physiological parameters (chlorophyll index by SPAD, proline content, electrolyte leakage), and biochemical traits (fruit lycopene and the activity of antioxidant enzymes catalase and peroxidase). Data were analyzed by ANOVA using SAS and SPSS, and mean comparisons were conducted with Duncan's multiple range test at the 5% level.
Results and Discussion
Salinity stress markedly reduced tomato performance. Yield per plant declined from 3.5 kg in the control to 1.6 kg under 8 dS.m⁻¹, representing a 54% reduction. Similarly, fruit number decreased from 28.5 to 16.8 and average fruit weight from 125.3 g to 94.8 g. These reductions were accompanied by decreases in chlorophyll index and lycopene content, confirming the negative impact of salinity on both growth and quality. Proline content and electrolyte leakage, indicators of stress, increased significantly with higher salinity. Fertilizer treatments substantially alleviated these effects. The combined NPK + micronutrient treatment consistently produced the best results. Under this treatment, yield reached 3.25 kg per plant, almost restoring yield levels under non-saline conditions. Lycopene content, which dropped to 7.6 mg.kg⁻¹ in the unfertilized control at 8 dS.m⁻¹, increased to 15.2 mg.kg⁻¹ with combined fertilization under non-saline conditions. Similarly, chlorophyll index (SPAD) was maintained at 39.5 in the combined treatment compared with 28.3 in stressed, unfertilized plants. Physiological responses also confirmed the benefits of fertilization. Proline accumulation, which reached 8.9 μmol.g⁻¹ fresh weight in stressed unfertilized plants, was significantly reduced in fertilized ones, reflecting less need for osmotic adjustment. Electrolyte leakage was minimized under combined fertilization, suggesting better membrane stability. Antioxidant defense was strongly enhanced: catalase activity reached 30.5 units.mg⁻¹ protein in plants treated with NPK + micronutrients, compared with 15.2 in the control. Peroxidase activity increased to 9 units.mg⁻¹ protein compared with only 6.5 in the control. These results confirm that micronutrients such as Fe, Mn, and Zn act as cofactors, improving enzyme activity and enabling plants to neutralize reactive oxygen species more efficiently. Overall, the findings show that while salinity causes severe reductions in yield and fruit quality, integrated nutrient management substantially mitigates these negative effects. The superiority of the combined treatment compared to either NPK or micronutrients alone highlights the importance of balanced nutrition. It also shows that micronutrients can reduce the reliance on high chemical fertilizer inputs, thus aligning with sustainable agriculture practices. These results are consistent with previous reports on the role of balanced fertilization in enhancing salt tolerance by improving chlorophyll biosynthesis, antioxidant defense, and osmotic regulation.
Conclusion
The findings confirm that the combined application of NPK and micronutrients effectively mitigates the adverse effects of salinity on tomato growth and yield by improving chlorophyll biosynthesis, lycopene accumulation, and antioxidant enzyme activity while reducing stress indicators such as proline and electrolyte leakage. This integrated fertilization strategy enhances yield stability, fruit quality, and plant resilience, offering a sustainable solution for tomato production in saline environments. Furthermore, it reduces dependence on high chemical fertilizer inputs, supporting environmentally friendly practices and long-term agricultural sustainability.
کلیدواژهها English
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