Influence of Preharvest Spray of Calcium Chlorideand Salicylic Acid on Physicochemical and Quality Properties of Fresh Seedless Barberry Fruit

Seedless barberry (Berberis vulgaris L. var. asperma) is one of the most important horticultural and medicinal crops and also valuable fruit in South Khorasan province. Fresh barberry fruit has a very short shelf life, due to the sensitive juicy fruit tissue in the ripening stage and decay during storage. Hence, most of the harvested fruits are dried traditionally or processed as juice, jam, and other products. However, the quality of both fresh and dried fruit is low due to different environmental stresses such as drought and salt stress and consequently deficiency of minerals during growth and development and also at harvest and during storage. It has been reported that pre-harvest foliar spray of calcium salts and salicylic acid can improve resistance to pathogens before harvest and reduce physiological disorders during handling and storage in many fruits. However, there is no information regarding the effect of calcium and salicylic acid spray as well as storage duration on fresh seedless barberry fruit. The objective of the current study, therefore, was to investigate the effects of the preharvest application of calcium chloride and salicylic acid on physiological attributes and postharvest quality of barberry fruits during long-term cold storage. The experiment was conducted as split-plot in time and in a randomized complete block design with five treatments and in three replicates in the Research Orchard of Agricultural Faculty of the University of Birjand during 2014. Fifteen similar and 25-years old trees were used for the experiment. Pre-harvest treatments of foliar spraying were salicylic acid (1 and 3 mM) and calcium chloride (1 and 2%) and distilled water as control. Sprays were applied at 30 and 15 days before harvest. Fruits were harvested at commercial ripening stage, packed in plastic boxes and stored at cold room at 4±0.5 °C and 85±5 RH. Physicochemical and quality evaluations including fruit fresh weight and volume, and juice volumes of 100 berries, pH, total soluble solids (TSS), titrable acidity (TA), ascorbic acid, weight loss, electrolyte leakage of fruit and calcium content of leave and fruit were measured at harvest and after 30, 60 and 90 days of storage. Analysis of data was performed using Gen Stat program (ver 12) and comparison of means was done by LSD test at 5% probability. The analysis of variance showed that the main effects of foliar spray with calcium chloride, salicylic acid and interaction of treatments were significant in storage time. The results showed that 1 mM of salicylic acid increased the fruit fresh weight, fruit volume and fruit juice, pH, total soluble solids, ascorbic acid and titrable acidity compared to other treatments. It has been reported that salicylic acid increases cell division and growth resulting in greater yield. It was also observed that application of salicylic acid at 3mM reduced electrolyte leakage significantly that can be useful to reduce chilling injury. The lowest weight loss was obtained in sprayed fruit with calcium chloride (2%) during cold storage, in agreement with the previouswork on plum. Foliar application of calcium chloride increased the calcium content of leave and fruit, although calcium application was not a significant effect in fruit tissue. Generally, using of chemical treatments increased the physicochemical characteristics of the fruit in seedless barberry, among them calcium chloride 2% and salicylic acid at 1 mM were most effective. It can be concluded that pre-harvest spraying of seedless barberry shrub with salicylic acid and calcium chloride can improve the quality of fruit as well as extend the storage life. This is because a foliar application with salicylic acid and calcium chloride significantly affected fresh fruit weight, weight loss, fruit volume, electrolyte leakage, pH, TSS, TA and ascorbic acid in treated fruit compared to the control. Salicylic acid at 3 mM significantly decreased electrolyte leakage, which can be used as a useful tool for increasing resistance to chilling injury during long-term storage. However, further studies are needed as the effect of chemical sprays on fruit quality and quantity properties depend on different factors such as tree age and types, environmental conditions during and after the spray and also chemical concentration.