Document Type : Research Paper - Pomology

Authors

• Ehsan Alinezhad ¹
• Mehdi Hadadinejad ²
• Kamran Ghasemi ³
• Morteza Soleimani Aghdam ⁴

¹ Former Msc student, Department of Horticulture, Faculty of Agronomy Sciences, Sari Agricultural Sciences and Natural Resources University (SANRU), Sari, Iran

² Assistant Professor, Department of Horticulture, Faculty of Agronomy Sciences, Sari Agricultural Sciences and Natural Resources University (SANRU), Sari, Iran

³ Associate Professor, Department of Horticulture, Faculty of Agronomy Sciences, Sari Agricultural sciences and Natural Resources University (SANRU), Sari, Iran

⁴ Associate Professor, Department of Horticultural Science, Faculty of Agriculture and Natural Resources, Imam Khomeini International University, Qazvin, Iran

Abstract

Introduction
Blackberries are susceptible to post-harvest decay, weight loss, and wrinkling due to the absence of a protective cuticle layer, leading to a short life and challenging long-term storage. The present study investigates the effect of pre-harvest foliar applications of calcium and potassium compounds on the shelf life and quality of thornless blackberries.
Materials and Methods
A factorial experiment was conducted in 2020 using a completely randomized design with two factors and three replications. The first factor consisted of nutritional treatments applied at the fruit-set stage at five levels: (1) control, (2) calcium nitrate (5 g/L), (3) potassium silicate (1 g/L), (4) calcium nitrate (5 g/L) + potassium silicate (1 g/L), and (5) potassium fertilizer (51-0-0, 3.5 g/L). The second factor was storage duration in cold storage (4 ͦC) at four levels (0, 6, 12 and 18 days post harvesting). Qualitative traits (weight loss percentage and fruit firmness), sensory quality (pH, soluble solids, taste index, ascorbic acid content), nutritional value (total phenol and anthocyanin), and sensory evaluation (marketability, taste, and color) were examined.
Results and Discussion
The results recorded an increase in the weight loss over the storage period with the combined treatment of calcium nitrate and potassium silicate significantly reducing water loss by day 18. This treatment also managed to maintain the highest firmness (0.21 N) during storage, whereas firmness decreased with extended storage. Fruit length and width declined with time, with the highest values obtained in the control treatment (2.107 and 1.923 centimeters, respectively). Soluble solids and taste index peaked on day 12, with the highest amounts (9 and 4.22, respectively) obtained in the potassium silicate treatment. Also, ascorbic acid content increased in the control treatment until day 6 but decreased thereafter while potassium silicate treatment significantly (P≤ 0.05) preserved vitamin C (9% retention) by day 18. The combined calcium nitrate and potassium silicate treatment resulted in the highest phenol content (74.75 mg/g gallic acid) and anthocyanin levels (189.8 mg cyanidin 3-glucoside/L) at harvest. Finally, sensory evaluation revealed a decline in fruit quality and consumer preference with extended storage, though potassium treatments were found to be most effective in maintain sensory attributes.
Conclusion
The findings highlight the efficacy of pre-harvest foliar applications of calcium nitrate and potassium silicate in extending the shelf life of thornless blackberries. Additionally, these treatments improved fruit firmness, soluble solids, taste index, vitamin C content, phenol, and anthocyanin levels. The use of calcium nitrate and potassium silicate enhances the levels of phenols and anthocyanins in the fruit. Despite the natural decline in fruit quality during storage, these nutritional treatments offer a practical solution for farmers and fruit sellers to enhance product quality and prolong storage life.

Keywords

• Anthocyanin
• Berry
• Fruit-set
• Merton
• Post-harvest

Main Subjects

• H: Post Harvest Physiology