Growing vegetables
Z. Khalili; F. Nekounam; T. Barzegar; Z. Ghahremani; M. Farhangpour
Abstract
IntroductionTomato (Solanum lycopersicum L.) belongs to the Solanaceae family, which is one of the most widely cultivated and economically important vegetables in the world, which is an excellent source of ascorbic acid and has high antioxidant capacity against oxidative damage caused by free radicals. ...
Read More
IntroductionTomato (Solanum lycopersicum L.) belongs to the Solanaceae family, which is one of the most widely cultivated and economically important vegetables in the world, which is an excellent source of ascorbic acid and has high antioxidant capacity against oxidative damage caused by free radicals. Ascorbic acid (AsA) is a water-soluble vitamin that plays a key physiological role in scavenging reactive oxygen species (ROS), and enzyme cofactor. Ascorbic acid is antioxidant and anti-stress agent, and also acts as a signaling molecule in some plant physiological processes and defense mechanisms. Positive roles of such antioxidants in scavenging or chelating the free radicals and activating the natural resistance against different biotic and abiotic stresses have been reported in several fruit trees. Calcium has a vital role for normal growth and development of plants due to an important role in balancing membrane structures, increasing nutrient uptakes and activates of metabolic processes. Calcium plays a vital role in maintains cell wall stability, integrity and determining the fruit quality. To our knowledge, however, little information is available regarding the interaction effect of ascorbic acid and calcium chloride on tomato. Thus, the aim of this study was to investigate the foliar application of ascorbic acid and calcium chloride on quality and antioxidant capacity of tomato fruit. Materials and MethodsTo study the effect of foliar application of calcium chloride (Ca) and Ascorbic acid (AsA) on growth, yield and fruit quality of tomato, the field experiment was carried out from June to September 2021 at Research farm of faculty of Agriculture, at the University of Zanjan, Iran. Each treatment was carried out with three replicates. Different concentrations of Ca (0, 0.3, 0.6 and 0.9 %) and AsA (0, 100, 200 and 300 mg.l-1) were sprayed three times (0, 15, 30 days after full bloom). Fruits were harvested at two harvests stage (orange and red color) and transferred to the laboratory on the same day. Flesh firmness was determined with penetrometer (model Mc Cormic FT 32), using an 8 mm penetrating tip. Results were expressed in kg cm-2. The pH values of solutions were monitored with pH meter. TSS was measured in the extract obtained from three fruit of each replicate with a digital refractometer Atago PR-101 (Atago Co., Ltd., Tokyo, Japan) at 20◦C. Total ascorbic acid content was expressed as mg per 100 g of juice. Antioxidant activity was measured using the free radical scavenging activity (DPPH) and calculated according to the following formula: RSA%= 100(Ac-As)/Ac. Statistical analyses were performed with SPSS software package v. 20.0 for Windows, and means comparison were separated by Duncan’s multiple range tests at p< 0.05. Results and DiscussionThe results showed that fruit harvested at red color stage had higher vitamin C, total soluble solid (TSS), total phenol, flavonoids contents and antioxidant capacity compared to fruit harvested at orange color stage. Foliar application of AsA and Ca had significantly improved tomato fruit quality. The highest value of TSS (4.9 °B), vitamin C (46.1 mg.100 ml-1), total phenol and flavonoids contents and antioxidant capacity (36%) was achieved with application of 300 mg.l-1 AsA and 0.9% Ca in fruit harvested at red color harvest time. The lowest value of pH and highest TA was observed in red color fruit treated with 300 mg.l-1 AsA and all Ca levels. Ca had significant effect on fruit firmness, which the highest fruit firmness was obtained from 0.9% Ca. The fresh tomato is an important source of ascorbic acid for human consumption. AsA significantly increased the amount of vitamin C in the plum and sweet pepper fruits. Increasing vitamin C content in fruits after treatment with Ca could be related to inhibiting action of calcium on the activities of ascorbic acid oxidase that use ascorbate as a substrate. The results indicated that treatment of Ca produced fruits with higher firmness compared to control and other treatments. Firmness and resistance to softening can be increased by the addition of Ca, due to interaction of calcium with pectate acid in the cell wall to form calcium pectate and retarding polygalacturonase activity. Differences in the percentage of TSS content at the time of harvest indicated the AsA and Ca effects on carbohydrate accumulation in fruits, which had different potential on respiration rates and consequently storability of plants. The antioxidant activity has positive correlation with total phenolic content, flavonoids and content of ascorbic acid. ConclusionsThe results of our research indicated that per-harvest foliar application of AsA and Ca improved fruit quality attributes including vitamin C, fruit firmness, TSS and antioxidant activity. These results suggest that AsA and Ca treatments, especially AsA 300 mg.l-1 and Ca 0.9%, may be proposed to improve fruit quality.
Postharvest physiology
K. Manda-Hakki; H. Hassanpour
Abstract
Introduction
One of the most important global challenges is food waste, about 30% of the world's agricultural land is wasted. Every year, about 9.5 million tons of food is lost in the post-harvest phase of agriculture. Therefore, storage technology is very important to increase shelf life, preserve ...
Read More
Introduction
One of the most important global challenges is food waste, about 30% of the world's agricultural land is wasted. Every year, about 9.5 million tons of food is lost in the post-harvest phase of agriculture. Therefore, storage technology is very important to increase shelf life, preserve nutrition and maintain the taste of fresh products. Storing strawberry fruits at an inappropriate temperature after harvesting significantly increases weight loss, rotting and softening. L-phenylalanine as an amino acid is used for the biosynthesis of all phenolic compounds through the phenylpropanoid pathway. In recent years, the application of exogenous phenylalanine has been considered for use as a biologically safe molecule to maintain the postharvest quality of many horticultural crops. L-phenylalanine treatment has been reported to reduce the frost damage of plum fruit during cold storage by maintaining membrane integrity and improving reactive oxygen species (ROS) scavenging capacity. The treated fruit showed a higher DPPH inhibition capacity by increasing the accumulation of phenolic compounds and antioxidant enzyme activity. Aghdam et al. (2019) also reported that application of L-phenylalanine significantly reduced cold damage, membrane lipid peroxidation and ROS accumulation in tomato fruits during cold storage.
Materials and Methods
Strawberry fruits were obtained from a commercial greenhouse located in Urmia at full maturity stage. The fruits were transported to the laboratory of the Department of Horticultural Sciences in Urmia University with necessary precautions to prevent any mechanical damage to the product. The fruits were separated in terms of size and uniformity, so that the fruits were divided into 3 groups, one group as a control group and 2 groups were treated with concentrations of L-phenylalanine (4 and 8 mM). After drying the treated fruits, they were placed in zipped nylon bags and kept in a cold room for 15 days at a temperature of 3 ± 0.5 °C and a relative humidity of 90-95%. Also, three biological replicates at each time point were included in the analysis. The samples obtained at each of these times were used to evaluate skin color, titratable acidity, soluble solids, taste index, pH, weight loss, firmness, antioxidant capacity, total phenol content, and polyphenol oxidase enzyme activity.
Results and Discussion
The results showed that the effect of post-harvest treatment, storage time, and the interaction between them were statistically significant on all of the traits. In terms of color changes, the effect of post-harvest treatment (p≤0.05) was significant only in b* index, and the highest rate was observed in the 4 Phe treatment. The effect of storage time was also significant in a* and Chroma indices (p≤0.05) and the highest level was observed in both of these indices at day 5. The effect of storage time was also significant in TA (p≤0.01), the highest value was observed in day 10. In antioxidant capacity (p≤0.05), TSS (p≤0.05) and taste index (p≤0.01), the interaction effect between storage time and Phe treatment was significant. In antioxidant capacity, the highest percentage of DPPH inhibition was observed in day 10 and 4 Phe treatment, in TSS, the highest rate was observed on day 10 and 8 Phe treatment, and in taste index, the highest rate was observed on day 15 and 4 Phe treatment. The effect of post-harvest Phe treatment and storage period on fruit weight loss was significant (p≤0.05) and (p≤0.01) respectively, and the lowest percentage of weight loss was observed in Phe 4 and day 5. In terms of firmness and total phenol content, only the effect of Phe treatment was significant (p≤0.05) and (p≤0.01), respectively, the highest level of firmness in the 4 Phe treatment and the highest amount of total phenol content in the 8 Phe treatment were observed. In the PPO enzyme, only the effect of storage time (p≤0.05) was significant.
Conclusion
According to the obtained results, the 4 Phe treatment is the best concentration of phenylalanine to increase the shelf life of harvested strawberry fruits under cold storage.
