Postharvest physiology
Abdollah Ehtesham Nia; Shirin Taghipour; Sara Siahmansour
Abstract
IntroductionWhile grapes are considered as non-climacteric fruits, during the post-harvest stages, due to the softening of the tissue, it is very prone to decay, which shortens its post-harvest life. Today, due to the desire of consumers to use high quality food, the use of biodegradable films and coatings ...
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IntroductionWhile grapes are considered as non-climacteric fruits, during the post-harvest stages, due to the softening of the tissue, it is very prone to decay, which shortens its post-harvest life. Today, due to the desire of consumers to use high quality food, the use of biodegradable films and coatings with antimicrobial properties, is a suitable alternative to synthetic preservatives, in order to maintain food security and prevent wastage of significant capital. Edible coatings are edible thin layers that are used to increase the shelf life and quality of fruits. This material increases the quality and health of the product by creating a semi-permeable barrier to water vapor and oxygen and carbon dioxide gases between the product and the environment, and to prevent anaerobic respiration, it absorbs a certain amount of gases and to this Sequence increases product shelf life. One of the most important ways to increase the shelf life and maintain the quality of agricultural products, especially fruits, is the use of edible coatings on the crop surface. Chitosan is one of the most important natural derivatives of chitin, of which about 50% of its acetyl’s groups have been removed. Due to the fact that Aloe vera gel has no taste and odor, can be considered a good option as a cover for fruits after harvest and due to its elasticity and strength solution in water, as a suitable layer on the product. Located and protects the fruit from mechanical damage and moisture loss. Material and Methods In this study, 12-year-old mature grape trees of ‘Asgari’ cultivar in the scaffolding garden of Abestan region of Khorramabad city in 1398 were studied. In the pre-harvest stage, chitosan was sprayed on the tree and in the post-harvest stage, Aloe vera gel was applied by dipping the fruit in Aloe vera gel in the laboratory. After treatment, the fruits were stored in the refrigerator at a temperature of 4 ± 0.5 ° C and were examined at different time stages for quantitative and qualitative characteristics of the fruit. 20 identical grape trees (in terms of fruit size and load, with 50 to 70 annual branches in 8-14 buds) selected and grape clusters with different concentrations of chitosan (control (distilled water), 2 and 3 Percentage of chitosan) at different stages of growth (fruit set), 35 and 50 days later) were sprayed directly with 4 liters per vine, by hand sprayer (2 ml Tween 80% was added as the active surfactant). For this stage, immediately after harvesting the grapes, take them to the laboratory and immerse them in concentrations (zero, 25 and 33%) of Aloe vera gel for 10 to 20 seconds and then in the air. They dried. Then, grape fruits weighing about 360-300 g in each experimental unit were stored for 28 days at 4 ° C and examined. This study was performed as a factorial experiment (2 factors) in a completely randomized design with three replications. The first factor is the effect of the treatments studied in seven levels including: control, 2% chitosan (CTS 2%), 3% chitosan (CTS 3%), chitosan 2% + Aloe vera gel 25% (AVG 25% + CTS 2%), chitosan 3% + Aloe vera gel 25% (AVG 25% + CTS 3%), 2% chitosan + 33% Aloe vera gel (AVG 33% + CTS 2%), chitosan 3% + Aloe vera gel 33% (AVG 33% + CTS 3%) and the second factor was storage time at five levels (zero, 7, 14, 21 and 28 days after harvest). Data analysis was performed using SAS software and a significant difference between treatments for each trait with a minimum significant difference at the probability level = 0.05 α was determined. Results and Discussion The results of analysis of variance showed that the effect of treatment and storage time on the desired traits was significant at the level of one percent. Fruits treated with chitosan and Aloe vera gel had higher texture firmness, taste index, phenolic content, antioxidant activity and titratable acids and caries index and pH were lower than the control. The highest content of phenol, antioxidant, flavor index and titratable acidity in all five measurement times belonged to 2% chitosan treatments with both concentrations of Aloe vera gel (25 and 33%) and the lowest amount belonged to the control treatment. In control treatment, the percentage of caries index increased during storage and in grapes treated with chitosan and Aloe vera gel, the caries process was slower and the lowest rate of caries was observed in 2% chitosan treatment with aloe vera gel on the 14th day. In general, it was observed that pre-harvest application of chitosan and post-harvest Aloe vera gel increase the post-harvest life of ‘Asgari’ grapes and improve its quality traits. Chitosan creates a barrier with selective permeability to oxygen and carbon dioxide gases, and by placing carbon dioxide at a higher level and reducing oxygen, it creates a modified atmosphere around the fruit, which reduces respiration and ethylene production. As a result, it reduces the aging process and reduces the consumption of organic acids and sugars and prevents the increase of pH. Low pH prevents browning of the fruit due to the activity of catechins and chlorogenic acid enzymes. Aloe vera gel coating maintains and increases the antioxidant capacity of the whole fruit by reducing fruit juice loss, reducing respiration, reducing ethylene production and delaying aging. Conclusion The combined treatment of chitosan 2% and Aloe vera gel (25 and 33%) increased fruit firmness, titratable acidity, taste index, total phenol content and antioxidant activity of grapes and reduced pH and caries index. Application of these treatments increased the post-harvest life of ‘Asgari’ grapes by 14 days, so it can be stated that the use of chitosan in the pre-harvest stage and the use of Aloe vera gel in the post-harvest stage as biodegradable and natural compounds to increase Shelf life of ‘Asgari’ grape fruit is recommended.
Pomology
Sara Siahmansour; Abdollah Ehtesham Nia; Asdolhossein Rezaei Nejad
Abstract
Introduction
Reduction of water available to the plant leads to many morphological, physiological and biochemical changes in plant cell and plant organs activity will be directly disrupted. In addition to the defense systems in the plant itself, there are other ways to increase plant resistance, ...
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Introduction
Reduction of water available to the plant leads to many morphological, physiological and biochemical changes in plant cell and plant organs activity will be directly disrupted. In addition to the defense systems in the plant itself, there are other ways to increase plant resistance, including the use of plant growth regulators. Salicylic acid is known as one of the common compounds used for environmental stresses and an essential molecular signal in plant fluctuations in response to environmental stresses. This substance has a protective effect and improves the growth process of the plant. This combination stimulates the plant immune system by inducing transcription of a specific group of genes involved in the defense and development of systemic resistance. Physalis is a small fruit of the Solanaceae family that originates in tropical and subtropical regions of South America. This genus has 80 species in the world, of which the famous species Ph. minima L., Ph. angulate L., Ph. philadelphia L., Ph. alkekengi L., Ph. peruviana L., Ph. pubscens L., Ph. ixocarpa L., among these species, Peruviana species is considered due to its unique taste and high yield.
Material and Methods
An experiment was conducted at the Faculty of Agriculture research greenhouse of Lorestan University Khorramabad, Iran. (latitude 33◦ 29` N, longitude 48◦ 22` E, altitude 1125 m) in May 2018. The experimental design was factorial based on completely randomized design with three replications. The treatments consisted of 3 levels of deficit water stress (95, 85, and 75% field capacity) and four salicylic acid concentrations (0, 0.5, 1, and 2 mM). Physalis seedlings were grown into pots containing soil, sand, and manure. In this research, chlorophyll (Chl a, Chl b, total Chl) and carotenoid content, chlorophyll fluorescent parameters (F0, Fm, Fv, and Fv/Fm), fresh and dry weight of fruit, fruit diameter, fruit number, TSS and vitamin C, proline, leaf anthocyanin and shoot soluble sugar, fresh and dry weight of leaf, leaf area, root volume and plant height, were measured.
Results and Discussion
The results showed that the effect of deficit water stress and salicylic acid treatment on the measured traits including photosynthetic pigments, chlorophyll fluorescence, fresh, and dry weight of fruit, number of fruits, amount of vitamin C, proline, soluble sugar, fresh and dry weight of leaves, leaf area, plant height and root volume were significant. Foliar application of salicylic acid at a concentration of 2 mM under water stress under 75% of field capacity increases the concentration of photosynthetic pigments including chlorophyll a (25.69%), chlorophyll b (14.08%), total chlorophyll (6.70%), and carotenoid (7.26%) and increased chlorophyll fluorescence parameters including Fm (5.2%) and Fv (1.92%). Salicylic acid at a concentration of 1 mM had better results on quantitative and qualitative traits of fruit including a number of fruits (2.67%), fresh weight of fruit (10.61%), and dry weight of fruit (0.6%). Under stress conditions of 75% of field capacity, application of 2 mM salicylic acid reduced the concentration of proline (31.2%), soluble sugar (11.69%) and leaf anthocyanin (4.93%). Therefore, according to the results, the best levels of irrigation for breeding Physalis (Physalis pruviana L.) are 85 and 95% of field capacity, and the concentration of 2 mM salicylic acid as a natural modulator has an effective role in reducing the effects of dehydration stress. Stress significantly reduces the maximum efficiency of photosystem II (Fv/Fm). This adverse effect on Fv/Fm may be due to its role in inhibiting electron transfer, as well as destroying the reaction centers in PSII. Accumulation of proline under stress is because proline, as a compatible osmolyte, removes all types of active oxygen and protects the cell, and provides the necessary conditions for the plant to absorb water. Salicylic acid increases the chlorophyll synthesis and protects the chloroplast membrane from stress by removing destructive free radicals by stimulating the biosynthetic of the photosynthetic pigment pathway and reducing the chlorophyllas enzyme. It also prevents the ethylene formation by inhibiting of ACC- synthetase enzyme, which in turn prevents the degradation of chlorophyll. Salicylic acid regulates the various physiological processes such as plant growth and development.
Conclusion
According to the results, the application of salicylic acid under low irrigation stress, as a growth enhancer and stress modulator, showed good results and improved physiological traits such as increasing photosynthetic pigments (chlorophyll and carotenoids), Fm, Fv and maximum efficiency of photosystem II and improvement of biochemical traits (proline, soluble sugar and leaf anthocyanin) at a concentration of 2 mM and increase in fruit traits (fresh and dry weight, number of fruits, vitamin C and fruit diameter) at a concentration of 1 mM. Growth and morphological traits also showed an increase in fresh and dry leaf weight, leaf area, plant height at a concentration of 2 mM salicylic acid at low irrigation stress levels. Therefore, salicylic acid can be used to reduce the destructive effects of deficit water stress and increase the quantity and quality of fruit if the Physalis plant is grown in arid and semi-arid regions.
Pomology
Abdollah Ehtesham Nia; Shirin Taghipour; Sara Siahmansour
Abstract
Introduction: Table grapes (Vitis vinifera L.) is one of the most important fruits that is widely grown in the world and is the export fruit of many countries. Although edible grapes are classified as non-climacteric fruits, they are very prone to spoilage due to their softening, weight loss, and decay ...
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Introduction: Table grapes (Vitis vinifera L.) is one of the most important fruits that is widely grown in the world and is the export fruit of many countries. Although edible grapes are classified as non-climacteric fruits, they are very prone to spoilage due to their softening, weight loss, and decay caused by fungi, as a result which consequently leads to low storability. Different strategies have been postulated to maintain firmness and control decay of table grapes during storage and improve functional properties of fruit such as pre and postharvest chitosan coatin, and exogenous abscisic acid application. Table grapes have a short shelf life due to the thin pericarp and fleshy texture of the fruit. Polyamines (PAs) application also showed a significant role in extending the storage periods of several fruit species with maintenance of fruit quality. Postharvest treatments are not necessarily the best way of maintaining fruit quality during postharvest period. Such treatments are expensive, increase the risk of fruit damage through extra handling and also encourage grower to pay less attention to on-tree quality. Pre-harvest application considered as a good alternative to cope with mentioned problem. To the best of our knowledge, there is not any report in literature about the role of pre-harvest application of Pas and post-harvest table grape in Aloe vera gel (AVG) as a possible role in reducing mechanical damage of berries which leads to lower decays. Besides these, damage caused by human handling starts at harvest operation, which still occurs by hand for most fruits.
Materials and Methods: This study was done on 12-year-old mature grape varieties of ‘Yaghouti’ in two independent experiments in the scaffolding garden of Abestan region of Khorramabad city and laboratory post harvesting of horticultural sciences department of Lorestan University in 2019. Therefore, this study investigated the effect of foliar application before harvesting of putrescine (PUT) in three different concentrations (0, 2.0 and 3.0 mM) and immersion post-harvest fruit in AVG (25.0 and 33.0%) on grape fruit quality and shelf life of table grape (Vitis vinifera cv. ‘Yaghouti’) in five times (0, 9, 18, 27 and 36 day) during storage at 4° C. The study was based on a factorial experiment with two pre-harvest spraying factors with PUT and post-harvest immersion in aloe vera gel (AVG) with three replications. The parameters of soluble solids (TSS), titratable acids (TA), ascorbic acid, total anthocyanin content (TCA), total phenol content (TPC), fruit firmness, shelf life of table grape (per day) were measured.
Results and Discussion: Fruits treated with both PUT concentrations showed greater firmness, vitamin C, total anthocyanin and phenol content, TSS, and during storage retained their shelf life longer than the control. At all five measurements, the highest levels of phenol and total anthocyanin content and firmness were related to the treatment of PUT 2.0 mM with coating of 25% and 33% AVG and the lowest was related to control. Also, pre-harvest use of PUT significantly prevented the softening of the fruit during storage and kept the firmness fruit. Softening contributes to quality loss in reducing the shelf life, but PAs treatment resulted in maintenance of flesh firmness during cold storage. Therefore, Put- and Spd-treated grape have higher firmness at harvest leading to much lower mechanical injury during harvest and handling process and providing better transportability. The purple skin color of table grape was related to the presence of anthocyanin compounds, from which the anthocyanin malvidin-3-glucoside has been found as major component. Although, total anthocyanins were reduced in control and treated fruits during cold storage, but pre-harvest foliar spraying of Put delayed total anthocyanins concentration after 36 days of storage and decreased the loss of these compounds at the end of experiment. PAs have been described as anti-senescence agents and a great number of researches have been focused on the role of exogenous PAs on fruit ripening. Also it has been reported that the ripening process and senescence of table grapes is correlated with the anthocyanin concentration and profile. However, the data on pre-harvest application of polyamine on different fruit species are scant. Khan et al., (2007) showed that pre storage application of Put would retard fruit softening in ‘Angelino’ plum during cold storage by suppressing ethylene biosynthesis. In mango, Malik and Singh (2005) reported that pre-harvest application of PAs improved fruit shelf life, increased ascorbic acid content and retarded fruit skin color changes compared to control
Conclusion: Pre-harvest foliar application of Put on grapevines maintained higher firmness at harvest and postharvest periods and also improved the fruit quality in terms of phenolics, ascorbic acid, anthocyanin and also controlling weight loss during cold storage. Overall, the results showed that pre-harvest use of 2.0 mM PUT and post-harvest immersion in 25.0% and 33.0% AVG improved the shelf life of the cultivar by 16 days compared to control.
