Pomology
Abdollah Ehteshamnia; 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.
Yahya Selahvarzi; Zabihollah Zamani; Ali Reza Talaie; Mohammadreza Fattahi
Abstract
Introduction: Pomegranate (Punica granatum L.) belonging to the family Punicaceae, native to subtropical regions of Iran and adapted to arid or semi arid climates with mild winters. Pomegranate is fairly drought tolerant but requires regular irrigation to produce high yield and fruit weight. Large ...
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Introduction: Pomegranate (Punica granatum L.) belonging to the family Punicaceae, native to subtropical regions of Iran and adapted to arid or semi arid climates with mild winters. Pomegranate is fairly drought tolerant but requires regular irrigation to produce high yield and fruit weight. Large parts of Iran within the boundaries of central deserts (Dasht-e-kavir and Kavir-e-Loot) have arid or semi-arid conditions which make them suitable for pomegranate production. However drought crisis and water resources restriction are very serious in these areas.
Materials and Methods: This experiment was conducted on 7-year old pomegranate cv. Shahvar trees from 2013 to 2014 in Torbat-e-Heydarieh, Razavi Khorasan, Iran. Irrigation treatments and Gibberellic acid application were used in Completely Randomized Split-Plot Design with four replications. Irrigation treatments included [1-control: 100% of estimated crop evapotranspiration (Etc) 2-Sustained deficit irrigation (SDI): watering was constantly used at 50%Etc, and 3-Regulated deficit irrigation (RDI): not watering was imposed until fruit set and then irrigation was applied same as control]. Foliar application of Gibberellic acid was done with two concentrations (0 and 150 ppm) at early May and September. Precipitation and pan evaporation (Ep) was recorded by weather station that located at 15 km distance from the studied orchard. Daily crop reference evapotranspiration (ETo) was estimated by penman-monteith equation. Trees were drip-irrigated by two lateral lines parallel to the tree row and four emitters that each one delivers 4 liters per hour. Fruit weight and numbers, tree production (yield), peel, arils and juice percent and finally fruit cracking of each treatment were determined at ordinary harvest time in late of October. Some uniform and intact fruits per treatment transferred to cold storage (T= 5 ◦C, RH= 85-90%). After storage period the fruits transfered to shelf life condition (7 days at 20 ◦C and RH= 65-70%) to evaluate physiochemical traits at 2 different storage periods (9 and 18 weeks). Weight loss and chilling index were determined during 3 weeks intervals of storage. Weight loss was evaluated by a gravimetric method and results were expressed as percent of initial fresh weight. Chilling index was quantified by 5 point scale of fruit husk injury: (1: without disorder, 2: slight disorder signs 3: moderate signs 4: severe signs and 5: unmarketable).
Results and Discussion: In present research the effects of deficit irrigation treatments on all the measured attributes was significant at harvest time (p≤ 0.01). But Gibberellic acid spray had significant effect only on Fruit weight, juice percent and fruit cracking disorder. Likewise, deficit irrigation and Gibberellic acid interaction showed significant difference for fruit weight and cracking disorder. The results indicated that fruit weight, total yield and fruit juice in regulated deficit irrigation increased by 39.6, 17.1 and 16.6 percent in compare with control, respectively. Fruit numbers in control trees (108.3) was more than sustained (93.6) and regulated (87) deficit irrigation. It is possible that sustained (SDI) and regulated (RDI) deficit irrigation have decreased sprouting growth and consequently second or third waves of pomegranate flowers that forming on these shoots was lower by water restricting. Pomegranate peel percent in studied deficit irrigation strategies were less than control and naturally aril percent was more in these treatments. In other hand, the highest fruit cracking (9.1%) and lowest fruit weight (205.8 g) occurred in sustained deficit irrigation. However Gibberellic acid application could increase fruit weight and alleviate cracking disorder. The results of cold storage experiment showed that maturity index, antioxidant activity, total anthocyanin and chilling index improved by Sustained deficit irrigation. Variations of ripening index during cold storage occurred because of sugar conversion, not the changes of organic acids content. Indeed, rate of starch degradation to simple carbohydrates in fruits increase under drought condition. Probability drought in deficit irrigation treatments as an oxidative stress motivates antioxidant system and consequently increases chilling resistance in pomegranate fruits. Preharvest Gibberellic acid application amended weight loss and increased total anthocyanin and antioxidant activity during cold storage.
Conclusions: On the base of this study it seems that using of some deficit irrigation strategies have acceptable consequences on pomegranate fruit production at conditions of water resources restriction. Likewise Gibberellic acid application on trees that were subjected by deficit irrigations ameliorates the adverse effects of drought stress.
