Application Of Aminoethoxyvinylglycine Research Articles

Exploring the impact of aminoethoxyvinylglycine (AVG) on the ripening behaviour and quality of bananas under different storage conditions

ABSTRACT Bananas rapidly undergo physiological deterioration after harvest owing to their climacteric and perishable nature causing significant economic yield loss. Thus, the adoption of postharvest loss mitigation strategies becomes imperative for enhancing fruit longevity. This study aimed to assess the effect of postharvest treatment with different concentrations of aminoethoxyvinylglycine (AVG) on shelf life extension and quality sustainability of bananas, such as Grand Naine, Poovan and Ney Poovan, kept under ambient (27°C ± 2°C) and cool (17°C) conditions. The findings revealed that AVG-treated bananas reduced weight loss of banana hands (0.655–2.559 kg hand−1) and higher peel thickness (0.86–2.73 mm) and firmness (6.54–12.01 N) over untreated control at ambient storage condition, whereas under cool storage, weight loss of banana hands reduced from 0.761 to 2.579 kg hand−1, while both peel thickness (1.24–2.84 mm) and firmness (7.75–11.45 N) were retained for varieties. The physio-chemical traits of fruit, such as total chlorophyll and starch content, were improved due to AVG treatment under both storage conditions. Among the treatments, postharvest application of AVG at 700 ppm showed better performance in the morphological, physiological and quality characters irrespective of the varieties.

Exogenous Spermidine and Amino-Ethoxyvinylglycine Improve Nutritional Quality via Increasing Amino Acids in Rice Grains.

Polyamines and ethylene are key regulators of the growth and development, quality formation, and stress response of cereal crops such as rice. However, it remains unclear whether the application of these regulators could improve the nutritional quality via increasing amino acids in rice grains. This study examined the role of exogenous polyamines and ethylene in regulating amino acid levels in the milled rice of earlier-flowered superior grain (SG) and later-flowered inferior grain (IG). Two rice varieties were field grown, and either 1 mmol L-1 spermidine (Spd) or 50 μmol L-1 amino-ethoxyvinylglycine (AVG) was applied to panicles at the early grain-filling stage. The control check (CK) was applied with deionized water. The results showed that the Spd or AVG applications significantly increased polyamine (spermine (Spm) and Spd) contents and decreased ethylene levels in both SG and IG and significantly increased amino acid levels in the milled rice of SG and IG relative to the CK. Collectively, the application of Spd or AVG can increase amino acid-based nutritional quality and grain yield via increasing polyamine (Spm and Spd) contents and reducing ethylene levels in both SG and IG of rice.

Aminoethoxyvinylglycine Reduces Preharvest Fruit Drop and Fruit Ethylene Evolution in ‘Red Delicious’ Apple but Affects Fruit Size and Quality Inconsistently

Aminoethoxyvinylglycine (AVG) is widely used in commercial apple (Malus ×domestica Borkh.) production to reduce preharvest fruit drop (PFD) and delay ripening for harvest management. Recently, the maximum allowable concentration of AVG was doubled (up to 264 mg⋅L−1). Reports of the relationship between the AVG concentration and fruit growth, size, and quality have been contradictory. We evaluated the relationship between the AVG concentration and PFD, fruit size, fruit quality, and expression of ethylene signaling-related and cell wall modification-related genes. Experiments were conducted in 2019 and 2020 using mature ‘Red Delicious’ in western North Carolina. The AVG treatments [0 and 132 (AVG-1x) and 264 mg⋅L−1 (AVG-2x)] were applied 3 weeks before the expected harvest. The AVG treatments reduced fruit drop and internal ethylene concentration relative to the control in both years. There was no difference in drop between AVG-1x and AVG-2x applications. Only in 2020 did AVG treatments delay fruit softening and starch hydrolysis and reduce soluble solids concentration. There were no effects on red fruit color development. Fruit size was unaffected by AVG in 2019, but it was reduced in 2020 with the AVG-2x application. AVG reduced ethylene synthesis and altered signaling, evidenced by decreased relative expression of genes related to ethylene signaling (ARGOS1, ARGOS2). AVG applications also reduced the expression of EXPA8;1, suggesting that reduced cell wall disassembly was associated with a reduction in fruit softening. These results indicate that preharvest applications of 132 mg⋅L−1 AVG effectively reduced PFD via altering ethylene evolution and signaling. Use of a higher AVG concentration was of limited benefit.

The local and systemic accumulation of ethylene determines the rapid defence responses induced by flg22 in tomato (Solanum lycopersicum L.)

Plant defence responses induced by the bacterial elicitor flg22 are highly dependent on phytohormones, including gaseous ethylene (ET). While the regulatory role of ET in local defence responses to flg22 exposure has been demonstrated, its contribution to the induction of systemic responses is not clearly understood. For this consideration, we examined the effects of different ET modulators on the flg22-induced local and systemic defence progression. In our experiments, ET biosynthesis inhibitor aminoethoxyvinyl glycine (AVG) or ET receptor blocker silver thiosulphate (STS) were applied 1 h before flg22 treatments and 1 h later the rapid local and systemic responses were detected in the leaves of intact tomato plants (Solanum lycopersicum L.). Based on our results, AVG not only diminished the flg22-induced ET accumulation locally, but also in the younger leaves confirming the role of ET in the whole-plant expanding defence progression. This increase in ET emission was accompanied by increased local expression of SlACO1, which was reduced by AVG and STS. Local ET biosynthesis upon flg22 treatment was shown to positively regulate local and systemic superoxide (O2.-) and hydrogen peroxide (H2O2) production, which in turn could contribute to ET accumulation in younger leaves. Confirming the role of ET in flg22-induced rapid defence responses, application of AVG reduced local and systemic ET, O2.- and H2O2 production, whereas STS reduced it primarily in the younger leaves. Interestingly, in addition to flg22, AVG and STS induced stomatal closure alone at whole-plant level, however in the case of combined treatments together with flg22 both ET modulators reduced the rate of stomatal closure in the older- and younger leaves as well. These results demonstrate that both local and systemic ET production in sufficient amounts and active ET signalling are essential for the development of flg22-induced rapid local and systemic defence responses.

Effects of Preharvest Aminoethoxyvinylglycine (AVG) Treatment on Fruit Ripening, Core Browning and Related Gene Expression in ‘Huangguan’ Pear (Pyrus bretschneideri Rehd.)

‘Huangguan’ pear (Pyrus bretschneideri Rehd. cv. Huangguan) is a widely planted cultivar in China. However, it is susceptible to core browning after harvest. In this study, aminoethoxyvinylglycine (AVG) was applied at 200 mg L−1 one and two weeks prior to harvest, and its effects on fruit quality, ripening and core browning were investigated during fruit storage at ambient temperature (25 ± 1 °C). The results showed that there was higher firmness, soluble solids content (SSC) and titratable acid (TA) content, but a lower ethylene production rate and core browning index in AVG-treated fruit than in control (water). Compared with the control fruit, AVG treatment decreased the malondialdehyde (MDA) content and polyphenol oxidase (PPO) activity, delayed the peak of chlorogenic acid (CGA) content in the core tissue, and significantly inhibited the expression of genes such as ACC synthase (PbACS2, PbACS3a, PbACS5a and PbASC5b), ACC oxidase (PbACO1 and PbACO2), ethylene receptors (PbETR2 and PbERS1), ethylene response factor (PbERF1), phenylalanine ammonia lyase (PbPAL1), cinnamate 4-hydroxylase (PbC4H4), 4-hydroxycinnamoyl- CoA ligase (Pb4CL2), hydroxycinnamoyl- CoA shikimate hydroxycinnamoyl transferase (PbHCT1 and PbHCT3), and polyphenol oxidase (PbPPO1 and PbPPO5), as well as phospholipase D (PbPLD) and lipoxygenase (PbLOX1 and PbLOX5). Thus, these results suggested that the reduction in core browning by preharvest application of AVG might be due to an inhibitory effect on the expression of genes associated with ethylene biosynthesis and signaling pathways, CGA biosynthesis, PPO and cell membrane degradation in ‘Huangguan’ pear.

Effects of Aminoethoxyvinylglycine (AVG) and 1-Methylcyclopropene (1-MCP) on the Pre-Harvest Drop Rate, Fruit Quality, and Stem-End Splitting in ‘Gala’ Apples

Preharvest fruit drop is a significant physiological problem that affects numerous commercially significant apple varieties, including ‘Gala.’ AVG and 1-MCP are two plant growth regulators commonly used to reduce fruit drop by reducing ethylene synthesis and perception, respectively. To optimize yield and market acceptance, a complete investigation of AVG and 1-MCP impacts on fruit drop and fruit quality of ‘Gala’ apples is required. In this study, four trials were conducted over the course of three years to determine the effects of AVG and 1-MCP on fruit drop and quality at harvest and after cold storage. Our results indicated that applications of AVG at the full-rate (130 mgL−1) three weeks before harvest (WBAH) were more effective at minimizing fruit drop than applications at the half-rate (65 mgL−1) and did not differ significantly from the double rate (260 mgL−1). Additionally, a single application of AVG was as effective in preventing fruit drop as two applications of 1-MCP. We also demonstrated that AVG decreased fruit skin pigmentation when used alone or in conjunction with GA4+7 or 1-MCP, while 1-MCP applications had no negative effect on fruit color. Finally, our data showed that when compared to 1-MCP and GA4+7, AVG alone was more effective in preventing stem-end splitting in Gala apples.

Cytokinin or ethylene regulation of heat-induced leaf senescence involving transcriptional modulation of WRKY in perennial ryegrass.

Heat stress is a major abiotic stress for temperate plant species with characteristic symptoms of premature leaf senescence. The objectives of this study were to evaluate the physiological effects of cytokinins (CK) and an ethylene inhibitor, aminoethoxyvinylglycine (AVG) on heat-induced leaf senescence in the temperate perennial grass species, perennial ryegrass (Lolium perenne), and to investigate whether WRKY transcription factors (TFs) could be associated with CK- or ethylene-mediated regulation of heat-induced leaf senescence by exogenously applying CK or AVG to perennial ryegrass. Perennial ryegrass plants foliar-sprayed with 6-benzylaminopurine (6-BA), and AVG exhibited prolonged stay-green phenotypes and a lesser degree of leaf senescence under heat stress (35/30°C), as shown by a decline in electrolyte leakage, malondialdehyde content, hydrogen peroxide, and superoxide content, and increased chlorophyll (Chl) content along with reduced activities of Chl-degrading enzymes (pheophytinase and chlorophyllase) and increased activity of Chl-synthesizing enzyme (porphobilinogen deaminase) due to 6-BA or AVG application. The suppression of heat-induced leaf senescence by 6-BA or AVG treatment corresponded with the upregulation of LpWRKY69 and LpWRKY70. The LpWRKY69 and LpWRKY70 promoters were predicted to share conserved cis-elements potentially recognized by TFs in the CK or ethylene pathways. These results indicate that LpWRKY69 and LpWRKY70 may negatively regulate heat-induced leaf senescence through CK or ethylene pathways, conferring heat tolerance in perennial ryegrass.

Reducing plant-derived ethylene concentrations increases the resistance of temperate grassland to drought

Model predictions indicate that extreme drought events will occur more frequently by the end of this century, with major implications for terrestrial ecosystem functions such as plant productivity and soil respiration. Previous studies have shown that drought-induced ethylene produced by plants is a key factor affecting plant growth and development, but the impact of drought-induced ethylene on ecosystem functions in natural settings has not yet been tested. Here, we reduced the amount of plant-derived ethylene concentrations by adding the ethylene inhibitor aminoethoxyvinylglycine (AVG), and investigated in situ plant productivity, soil respiration and ethylene concentrations for two years in a semi-arid temperate grassland in Inner Mongolia, China. Drought significantly reduced plant productivity and soil respiration, but the application of AVG reduced ethylene concentrations and significantly increased aboveground plant productivity and soil respiration, effectively enhancing resistance to drought. The reason for this could be that AVG application increased the activity of 1-aminocyclopropane-1-carboxylic acid (ACC) deaminase and abundance of the acdS gene (the key gene for ACC deaminase), facilitating reduced ACC concentrations in the plant tissue and reduced in planta ethylene synthesis. In addition, there was a significant correlation between soil ACC deaminase activity and plant productivity. Given the global distribution of arid and semi-arid areas, and the expected increases in the frequency and intensity of drought stress, this is a significant concern. These results provide novel evidence of the impact of drought-induced plant ethylene production on ecosystem functions in semi-arid temperate grassland ecosystems.

Quality of ‘Baigent’ apples as a function of pre-harvest application of aminoethoxyvinylglycine and ethephon stored in controlled atmosphere

– The objective of this work was to evaluate the effects of pre-harvest application on ‘Baigent’ apple trees cultivated under black anti-hail nets with aminoethoxyvinylglycine (AVG), in a single or split dose, combined or not with ethephon, on the quality, the antioxidant activity, and the content of phenolic compounds of the fruits after storage in controlled atmosphere (CA). The pre-harvest applications of AVG alone, both at a dose of 0.125 g L−1, as well as in split dose and at a dose of 0.0625 g L−1, reduced the rate of ethylene production, showed less yellowing fruits and a lower incidence of cracks, maintaining high flesh firmness, texture attributes, and fruit acidity, without causing negative effects on the incidence of mealiness and decay. The pre-harvest applications of AVG at a dose of 0.125 g L−1 and in split dose combined with ethephon also contributed to the reduction of the ethylene production rate and yellowing, showed high flesh firmness and texture, however, it showed a high incidence of decay and cracking when ethephon was combined with AVG at a dose of 0.125 g L−1. In the skin, application of AVG only at a dose of 0.125 g L−1 reduced the total phenolic compounds values, however, total antioxidant activity was reduced with any form of AVG application. In the flesh, there was no effect of pre-harvest application of AVG. Regardless of the dose and form of application, AVG reduced the contents of chlorogenic acid, phloridizin, and epicatechin in the skin of fruits harvested at commercial harvest.

Effect of aminoethoxyvinylglycine (AVG) on quality, berry set and coloration of ‘Alphonse Lavallée’ table grapes

AbstractThe effect of different concentrations of aminoethoxyvinylglycine (AVG; 0 (control), 250, 500, 750 and 1000 mg/l), an ethylene biosynthesis inhibitor, on grape berry set and fruit quality was evaluated under vineyard conditions. Treatments were performed on ‘Alphonse Lavallée’ grape cultivar at full bloom stage for two years. Cluster and berry growth (length, width and weight), firmness, soluble solids content, yield, berry set, anthocyanin content and colour parameters were determined on treated and untreated (control) fruits. As a result of the study, the effects of AVG concentrations on firmness were not significant. When AVG applications were compared with control, it is determined that some quality properties were statistically affected, the others were not. Fruit set was increased by lower concentrations of AVG (250 mg/l) and anthocyanin content was increased by higher concentrations of AVG (750 mg/l).

Evaluation of aminoethoxyvinylglycine (AVG) for control of vector-borne diseases in solanaceous crops

Every year, solanaceous crops, such as potato (Solanum tuberosum) and tomato (Solanum lycopersicum), suffer important economic loss due to insect pests and the diseases they transmit. While pesticides can be used to control insects directly, they can exacerbate some vector-borne diseases by increasing insect movement among plants and thus increase disease transmission. The purpose of this study was to evaluate the use of aminoethoxyvinylglycine (AVG), an inhibitor of ethylene biosynthesis, as a potential control strategy for insect vectors and vector-borne disease of tomato and potato. AVG application (0.5 g/L) was evaluated in field plots and insect populations were monitored. Two field applications of AVG reduced total insect and leafhopper populations in tomato and potato plots, however, AVG increased thrips populations in tomato fields later in the growing season. Dual-choice bioassays were performed to examine the effect of AVG on insect preference toward virus-infected plants. AVG application reduced aphid preference to Potato leafroll virus infected potato plants but did not affect leafhopper preference to Beet curly top virus infected tomato plants. Taken together, these results suggest that AVG has the potential to be used as a component of integrated management practices, but additional studies will be required.

Maturation of 'Baigent' apples protected by anti-hail nets and sprayed with aminoethoxyvinylglycine and ethephon

Abstract The objective of this work was to evaluate the effect of pre-harvest spraying with aminoethoxyvinylglycine (AVG) and ethephon on fruit maturation of 'Baigent' apple (Malus domestica) trees grown under black anti-hail nets. The treatments were: control; 125 mg L-1 AVG, sprayed 30 days before anticipated harvest time (DBAH); 120 mg L-1 ethephon 7 DBAH; 62.5 mg L-1 + 62.5 mg L-1 AVG 30 and 20 DBAH; and 62.5 mg L-1 + 62.5 mg L-1 AVG 30 and 20 DBAH + 120 mg L-1 ethephon 7 DBAH. Fruit were harvested in the commercial harvest of the control treatment (harvest 1) and 14 days later (harvest 2). Yellowing and loss of firmness were delayed by the treatments with AVG and accelerated by that with ethephon. AVG application in a single rate of 125 mg L-1 30 DBAH or in two split rates of 62.5 mg L-1 30 and 20 DBAH delays fruit maturation. The pre-harvest application of AVG in a single rate reduces the red color of the fruits, which is not affected by application in split rates, combined or not with ethephon, regardless of the date of harvest.

The effect of Aminoethoxyvinylglycine (AVG) applications on mineral contents of grape leaves

Plant growth regulators may have different physiological effects depending on the application stage and concentration when applied externally. In this study, it was aimed to determine the effects of pre-harvest aminoethoxyvinylglycine applications on the mineral contents of Vitis vinifera L. cv. Alphonse Lavallée leaves. AVG was applied to vines at five different concentrations (0, 250, 500, 750 and 1000 mg L-1) and two application stages (at full bloom and fruit set). As a result, the effects on macro elements content of the grapevine of AVG applications were significant except P. In terms of microelement contents, generally, microelement contents were increased with the AVG applications, only the amount of Fe decreased with the AVG applications. For this reason, AVG plant growth regulator is thought to have both increasing and decreasing effects on the mineral element contents of Alphonse Lavallée leaves.

Einfluss der Nacherntebehandlung mit Aminoethoxyvinylglycin (AVG) auf die Fruchtqualität von Asiatischen-Birnen (Nashi) (Pyrus pyrifolia cv. Hosui) während der Kühllagerung

The study conducted in order to assess the effect of the physiological regulator aminoethoxyvinylglycine (AVG) as a post-harvest treatment on ‘Hosui’ Asian pear fruits during storage period. Fruits were dipped in AVG aqueous solutions (0, 100 and 200 ppm) for 120 s, allowed to dry, and stored at 0–1 oC and 90 ± 5% relative humidity for 120 days. Assessment of pear quality was carried out at 30 day intervals by evaluating the following quality parameters: weight loss, flesh firmness, soluble solids content, titratable acidity, ascorbic acid content, total phenolic content, antioxidant capacity, respiration rate and internal browning rate. AVG treatment delayed ripening and prolonged storage life as indicated by prevented weight loss and delayed loss of acidity, soluble solids content and flesh firmness. At the end of the storage, both doses of AVG application reduced respiration rate and maintained a level of greater bioactive compounds than control fruits. Results indicated that internal browning in 100 ppm AVG treated fruit was significantly less than control after 120 days of storage. It can be concluded that ‘Hosui’ pear treated with AVG can be stored commercially up to 120 days at 0–1 oC and 90 ± 5% relative humidity.

Preharvest treatment with 1-aminoethoxyvinylglycine and gibberellin on the quality and physiology of cashew peduncles

Abstract: The objective of this work was to evaluate the effects of the preharvest treatment with gibberellic acid (GA3) and aminoethoxyvinylglycine (AVG) on the quality and physiological attributes of ripe 'CCP 76' cashew (Anacardium occidentale) peduncles at different developmental stages. Sprays of 180 mg L-1 GA3 and 180 mg L-1 AVG were applied, combined and isolated, at 34, 40, and 44 days after anthesis (DAA), and peduncles were harvested ripe at 46 DAA and evaluated for physical and physiological variables. The treatment with GA3 resulted in firmer peduncles with a greater apical diameter, but did not affect the physiological variables activity of the pectin methylesterase and polygalacturonase cell wall enzymes and degree of lipid peroxidation of the biological membranes, nor the physical attributes total mass (peduncles and nut) and nut size. At early developmental stages (34 DAA), GA3 increased the activity of the antioxidant enzymes superoxide dismutase and catalase, and, at later stages (40 DAA), promoted polyphenol and carotenoid accumulation. The application of AVG at the final stages (44 DAA) provided greater total antioxidant activity, despite the lower ascorbate peroxidase activity. The application of GA3 pre-harvest increases the firmness and diameter of the cashew peduncles, and the treatment with AVG increases the total antioxidant activity of the peduncles.

Effects of preharvest aminoethoxyvinylglycine (AVG) treatment on storage life and quality of ‘Golden Delicious’ apple

The aim of this study was to determine the effects of preharvest aminoethoxyvinylglycine (AVG) treatment on storage life and quality of 'Golden Delicious' apples stored in normal (air) atmosphere (NA) and controlled atmosphere (CA) conditions. For this purpose, ReTain (a commercial product containing 15% (w/w) AVG) was applied to trees of 'Golden Delicious' apple. 125 ppm dose of AVG was sprayed on the apple fruits 7 days before commercial harvest. Harvested fruits were transported to the Postharvest Physiology Laboratory of Horticulture Department immediately. AVG treated and non-treated (control groups) fruits were stored at 0°C and 90±5% relative humidity during 6 months in NA and 10 months in CA conditions (1% O2-3% CO2). The weight loss of fruits was decreased by AVG treatment compared to the control groups in both storage conditions. AVG treatment maintained the flesh firmness of apples during the storage period, especially in CA. AVG also suppressed ethylene production of fruits. Titratable acidity of the treated and non-treated fruits decreased, and soluble solid contents increased during the storage period in NA and CA conditions. According to sensorial evaluation, AVG treated fruits preserved their external appearance and taste for 6 (in NA) and 10 months (in CA). Non-treated fruits lost their marketable quality after 5 (in NA) and 8 (in CA) months of storage. As a result, preharvest AVG application (125 ppm) to 'Golden Delicious' apples 7 days before commercial harvest was effective in delaying softening, ethylene production, respiration rate and weight loss of fruits. These effects were more evident in CA condition compared to NA.

Endogenous Ethylene Concentration Is Not a Major Determinant of Fruit Abscission in Heat-Stressed Cotton (Gossypium hirsutum L.).

We investigated the role of ethylene in the response of cotton to high temperature using cotton genotypes with genetically interrupted ethylene metabolism. In the first experiment, Sicot 71BRF and 5B (a lintless variant with compromised ethylene metabolism) were exposed to 45°C, either by instantaneous heat shock or by ramping temperatures by 3°C daily for 1 week. One day prior to the start of heat treatment, half the plants were sprayed with 0.8 mM of the ethylene synthesis inhibitor, aminoethoxyvinylglycine (AVG). In a subsequent experiment, Sicot 71BRF and a putatively heat-tolerant line, CIM 448, were exposed to 36 or 45°C for 1 week, and half the plants were sprayed with 20 μM of the ethylene precursor, 1-aminocyclopropane-1-carboxylic acid, (ACC). High temperature exposure of plants in both experiments was performed at the peak reproductive phase (65–68 days after sowing). Elevated temperature (heat shock or ramping to 45°C) significantly reduced production and retention of fruits in all cotton lines used in this study. At the termination of heat treatment, cotton plants exposed to 45°C had at least 50% fewer fruits than plants under optimum temperature in all three genotypes, while plants at 36°C remained unaffected. Heat-stressed plants continued producing new squares (fruiting buds) after termination of heat stress but these squares did not turn into cotton bolls due to pollen infertility. In vitro inhibition of pollen germination by high temperatures supported this observation. Leaf photosynthesis (Pn) of heat-stressed plants (45°C) measured at the end of heat treatments remained significantly inhibited, despite an increased leaf stomatal conductance (gs), suggesting that high temperature impairs Pn independently of stomatal behavior. Metabolic injury was supported by high relative cellular injury and low photosystem II yield of the heat-stressed plants, indicating that high temperature impaired photosynthetic electron transport. Both heat shock and ramping of heat significantly reduced ethylene release from cotton leaf tissues measured at the end of heat treatment but modulating ethylene production via AVG or ACC application had no significant effect on fruit production or retention in heat-stressed cotton plants. Instead, high temperature accelerated fruit abortion by impairing pollen development and/or restricting leaf photosynthesis.

Combined Applications of Aminoethoxyvinylglycine with Salicylic Acid or Nitric Oxide Reduce Oxidative Stress in Peach During Ripening and Cold Storage

The effects of pre-harvest application of aminoethoxyvinylglycine (AVG) alone or in combination with nitric oxide (NO) or salicylic acid (SA) on the oxidative stress and fruit quality during ripening and cold storage were investigated in peach Prunus persica L. Batsch. cv. ‘Oz Delight’. Trees were sprayed with 830 g ha−1 AVG 10 days before anticipated harvest, or post-harvest fumigated with 10 μL L−1 NO or dipped in 2 mM aqueous solution of SA for 5 min in the following treatments (untreated control, pre-harvest AVG, post-harvest NO, post-harvest SA, pre-harvest AVG + post-harvest SA and pre-harvest AVG + post-harvest NO). Combined application of pre-harvest AVG and post-harvest SA resulted in reduced ethylene production, respiration rate, fruit weight loss, SSC and SSC:TA with higher fruit firmness, CIE L *, b * and h o values and TA during ripening and cold storage, as compared with control. There was no consistent trend in the activities of antioxidant enzymes in any treatment. The activities of SOD, CAT, and POD were reduced, whereas PPO enzymes increased with advancement in fruit ripening and cold storage periods. Fruit treated with combined application of pre-harvest AVG and post-harvest SA exhibited reduced oxidative stress with higher activities of POD and PPO enzymes, as compared with control during ripening and cold storage. Fruit fumigated with NO alone or in combination with AVG showed higher radical scavenging activity during ripening as well as storage, as compared with all other treatments. In conclusions, pre-harvest application of AVG in combination with post-harvest SA treatment exhibited synergistic effect in the reduction of ethylene production, respiration rate, fruit softening, changes in fruit quality (colour, SSC, TA and SSC:TA ratio) and consequently reduced oxidative stress during peach fruit ripening and cold storage.

Application of GA3, AVG and choline chloride to peach trees: Effects on nutritional status of fruit

ABSTRACTThis research was aimed to determine the effects of plant regulators such as gibberellic acid (GA3), aminoethoxyvinylglycine (AVG), and choline chloride (CC) on the nutrient components in the fruit of ‘Monroe’ peach under Isparta in Turkey ecological condition. AVG at doses of 0, 100, 150 and 200 ppm, GA3 at doses of 0, 100, 200, 300 ppm and CC at doses of 0, 1000, 2000, 3000 pmm was sprayed on the peaches 7, 21 and 30 days before commercial harvests. All concentrations of AVG treatments were found to increase the amount of nitrogen in fruits. In general, it was observed that CC and GA3 applications reduced the amount of calcium in fruits, however, AVG applications were found to not be effective. In the first year, the statistically significant of AVG treatments was seen on magnesium content only. It was determined in our study that AVG and CC treatments reduced copper content in peach fruits, all applications decreased the amount of manganese, 100 ppm AVG application increased the element zinc, and all of CC applications minimized the amount of that element.

Effects of preharvest application of aminoethoxyvinylglycine (AVG) on harvest maturity and storage life of ‘Unique’ feijoa

ABSTRACTIn a previous study, feijoa harvested earlier than ‘touch-picked’ maturity appeared visually acceptable after 6 weeks of storage but had low soluble solids content (SSC) and high titratable acidity (TA). Given that feijoa display climacteric-like behaviour, manipulation of ethylene physiology prior to harvest may have the potential to alter this outcome. Subsequently, the aim of this work was to investigate the impact of preharvest aminoethoxyvinylglycine (AVG) application on feijoa quality at harvest and during subsequent storage. The experiment comprised of three preharvest AVG treatments and two harvest occasions. AVG treatment dramatically reduced preharvest fruit drop. AVG treatment at 4 weeks before current commercial harvest timing was effective in delaying maturity. AVG treatment suppressed ethylene production rates during storage. However, AVG treatment did not alter quality (firmness, SSC, TA and flesh colour) after storage. This result adds to the evidence that postharvest ripening in feijoa may be regulated independent of ethylene despite the typical climacteric increase in ethylene observed. The results also confirmed that fruit harvested early were storable for 6 weeks without exhibiting internal browning, but having a high TA and low SSC that may affect their taste acceptability.