High Rates Of Ethylene Production Research Articles

Effects of cinnamic acid on the root growth of cucumber (cucumis sativus l.) and figleaf ground (cucurbita ficifolia bouché) seedlings

Effect of cinnamic acid (CA) on growth and endogenous hormone content in the roots of cucumber and figleaf gourd seedlings were studied and explained the reason why figleaf gourd was better in resisting CA stress than cucumber using their seedlings as experimental materials. The effect of CA at different concentrations (0, 0.05, 0.10, 0.15, 0.20 and 0.25 mmol/l) was analysed on primary root elongation, total root elongation, average diameter of total roots, total root volume, and total root tips as well as the effects of 0 and 0.25 mmol/l CA on root growth, root density, root hair growth rate, indole acetic acid (IAA) content and ethylene (ET) production rate. The results showed that CA stress decreased the primary root elongation, total root elongation, total root tips, Grade III root and root hair growth rates of both plants. The inhibiting effect of CA was stronger on cucumber than figleaf gourd. Besides, CA stress increased their average diameters of total roots and root hair densities. The increase in the average diameter of total roots of cucumber was larger than that of figleaf gourd while its increase in root hair density was far lower. Apart from that, 0.25 mmol/l CA stress increased the IAA contents and ET production rates in both kinds of roots. The increase in IAA content in cucumber root was 16% higher than in figleaf gourd. However, the increase in the ET production rate of cucumber root was 51% lower than figleaf gourd root. In conclusion, higher concentration IAA could inhibit root growth. Under CA stress, the increase in the IAA content in figleaf gourd root was lower than that in cucumber root, indicating that CA exerted a weaker inhibiting influence on figleaf gourd. Besides, higher ET production rate contributed to the increase in root hair density. Under CA stress, figleaf gourd root had a higher ET production rate than cucumber root, thus having more root hairs. Bangladesh J. Bot. 53(3): 703-710, 2024 (September) Special

The Shelf Life of Yellow Passion Fruit with an Edible Biocomposite Coating Based on Chitosan, Graphene Oxide Nanoparticles, and Beeswax

Yellow or sour passion fruit is a climacteric fruit with a high rate of respiration and ethylene production, and postharvest technology is needed to extend its shelf life. This study investigated the properties of a biocomposite film with chitosan (CH) incorporated with beeswax (BW) and graphene oxide (GO) nanoparticles for use as an edible coating to extend the shelf life of yellow passion fruit at 22 °C and 70% RH for eight days. CH films associated with BW showed lower water vapor permeability (WVP) than films with CH alone. However, adding GO to the CH + BW biopolymer matrix improved the WVP, decreased the solubility (12.8%), and increased the opacity of the film by 9% compared to those of the CH film. Fruits coated with CH + BW or CH + BW + GO exhibited a reduction in respiration rate, a slower ripening process by approximately 3 days, and a significant decrease in weight loss. This also resulted in a higher soluble solids content and increased antioxidative capacity of the pulp. The incorporation of GO into the CH + BW matrix resulted in a more pronounced delay of fruit ripening, as evidenced by the lower depigmentation of the peel at eight days, with a lightness approximately 10.7% lower at 54.92, a chroma value 16.5% lower at 49.33, a hue angle 7.2% higher at 92.56, a soluble solid (SS) content 16.7% higher at 11.32°Brix, and an acidity 31.9% higher at 4.18% compared to the control. Furthermore, the biopolymer packaging led to a higher consumer acceptance score for the fruit.

Biochemical dynamics during postharvest: Highlighting the interplay of stress during storage and maturation of fresh produce.

The lifecycle of fresh produce involves a sequence of biochemical events during their ontology, and these events are particularly significant for climacteric fruits. A high demand during ripening is observed in these plant products, which is reflected in a high rate of respiration and ethylene production. Increased respiratory demand triggers the activation of secondary pathways such as alternate oxidase, which do not experience critical increases in energy consumption in non-climacteric fruit. In addition, biochemical events produced by external factors lead to compensatory responses in fresh produce to counteract the oxidative stress caused by the former. The dynamics of these responses are accompanied by signaling, where reactive oxygen species play a pivotal role in fresh product cell perception. This review aims to describe the protection mechanisms of fresh produce against environmental challenges and how controlled doses of abiotic stressors can be used to improve quality and prolong their shelf-life through the interaction of stress and defense mechanisms.

Enhanced Preservation of Climacteric Fruit with a Cellulose Nanofiber-Based Film Coating.

Bananas are a typical climacteric fruit with high respiration and ethylene production rates after harvest, and they show rapid ripening-senescence phenotypes. Here, we demonstrate that carboxymethylcellulose nanofibers (CM-CNFs) and red cabbage extracts (RCE) can be used as a unique film coating formulation for enhancement of the shelf-life of fruit. A CM-CNF suspension solution is created through a process involving chemical modification, followed by mechanical grinding. It has a high aspect ratio that allows for the creation of a thin and transparent film on the surface of bananas. The cross-linked CM-CNF hydrogel forms a dense film layer on the banana surface during dehydration and prevents respiration and weight loss. RCE contains polyphenols acting as antioxidants, which prevent the appearance of black dots on the banana peels. It serves to mitigate the browning of banana skins and also hinders the respiration process, consequently slowing the aging of bananas.

Harvest Maturity and Preharvest Aminoethoxyvinylglycine Treatment Effects on Cold-induced Ethylene Production of ‘Gala’ Apples

Cold storage is a commonly adopted technology to maintain quality and extend shelf life; however, depending on the cultivar, ethylene production can be enhanced by short-term cold treatments. In this study, index of absorbance difference (IAD) values, which reflect skin chlorophyll concentrations of cold-influenced ripening patterns, of ‘Gala’ apples were investigated. Fruit that were untreated or treated with aminoethoxyvinylglycine (AVG), which is a plant growth regulator that inhibits ethylene production of fruit, were harvested from a commercial orchard. Two IAD value categories 0.6 to 0.8 and 0.2 to 0.4 were chosen from a single harvest in 2019, whereas in 2020, the fruit in categories 0.6 to 0.8 and 0.2 to 0.4 were chosen for two harvests separated by 1 week, respectively. In 2019, only ethylene production was measured. In 2020, ethylene production, respiration, internal ethylene concentration (IEC), flesh firmness, 1-aminocyclopropane-1-carboxylate (ACC), and malonyl 1-aminocyclopropane-1-carboxylate (MACC) concentrations of fruit kept in air at 20 °C or stored at 0.5 °C for 21 days and then transferred to 20 °C were measured. The results were different from those described in the literature for cold-enhanced ethylene production of ‘Gala’ apples. Although ethylene production occurred without cold exposure of untreated fruit, exposure of fruit to 0.5 °C for 21 days resulted in more rapid and higher ethylene production rates and IEC than for fruit kept at only 20 °C. Ethylene production was suppressed by the preharvest AVG treatment, especially in 2020. The rates of respiration and softening of non-AVG treated fruit were enhanced by cold treatment. The effects of cold treatment were more significant for less mature fruit as indicated by higher IAD values.

Ethylene Signal Is Involved in the Regulation of Anthocyanin Accumulation in Flesh of Postharvest Plums (Prunus salicina Lindl.)

Ethylene is positively correlated with the anthocyanin accumulation in postharvest plum fruit, but the regulation mechanism has not been fully clarified. In this work, the 'Friar' plum fruit under different storage temperatures (0, 10 and 25 °C) and treatments (100.0 μL L-1 ethylene and 1.0 μL L-1 1-MCP) were applied to study the relationship between anthocyanin accumulation and ethylene signal pathway. The fruits stored at 10 °C had higher ethylene production rate and more anthocyanin in flesh than those stored at 0 °C and 25 °C. Ten ethylene biosynthesis associated genes and forty-one ethylene signal transduction related genes were obtained from the previous transcriptome data. Among them, the expression levels of ethylene biosynthesis associated genes (PsACS1, PsACS4 and PsACO1), and ethylene signal transduction related genes (PsERS1s, PsETR2, PsERF1a, and PsERF12) were markedly higher in the fruits stored at 10 °C than those at 0 °C and 25 °C. Exogenous ethylene treatment enhanced while 1-MCP treatment inhibited the anthocyanin accumulation in the flesh under storage at 10 °C. In addition, exogenous ethylene treatment markedly increased the expression levels of PsACS1, PsACS4, PsACO1, PsETR2, PsERF1a, and PsERF12 in the flesh once it turning red, as well as the anthocyanin biosynthesis related genes (PsPAL, PsCHS, PsF3H, PsDRF, PsANS, PsUFGT and PsMYB10), whereas 1-MCP treatment manifested the contrary effects. Correlation analysis indicated that there was a significant positive correlation between genes expression related to ethylene signal pathway and anthocyanin biosynthesis, except for PsERF11. In conclusion, ethylene signal pathway is involved in the flesh reddening by up-regulating the anthocyanin biosynthesis related genes.

Effect of harvest maturity stage and ripening remediation agents on the shelf life and biochemical quality attributes of tomato (Solanum lycopersicon) fruits

Tomato fruit is highly perishable because of the characteristic high rate of ethylene production and respiration during ripening. Delayed ripening could be achieved through the use of ripening remediation agents (RRa) that either absorb or block ethylene binding to the fruit receptor. The effects of ripening remediation agents on shelf life and biochemical quality attributes were evaluated on tomato fruits harvested at three maturity stages (breaker, turning and full-ripe). In 2018 and 2019, harvested fruits were stored under seven ripening remediation treatments: 0.1 µL/L 1-MCP, 0.3 µL/L 1-MCP, 0.5 µL/L 1-MCP, 5% KMnO4, 10% KMnO4, 10 g of Zeolite and 20 g of Zeolite and an open shelf condition as the control. At the end of the storage period, fruits were assessed for shelf life as well as total soluble solids (TSS), titratable acids (TA), ascorbic acid, and lycopene contents. There was significant (p≤0.05/0.01) influence of ripening remediation treatments on fruits for all the measured parameters. Fruits stored with RRAs consistently out-performed those stored in the open shelf. RRAs 0.3 µL/L1-MCP, 0.5 µL/L1-MCP and 5% KMnO4 solution media had longer shelf life and higher values of total soluble solids, titratable acidity, lycopene and ascorbic acid contents. The use of 1-MCP and 5% KMnO4 is recommended as effective scavenger of ethylene for extending the shelf-life and maintaining some quality attributes of stored tomato fruits.

Effect of sesame protein and lotus seed starch based bioactive coatings enriched with Garcinia indica extract on sapodilla during storage

Sapodilla (Manikarazapota L.), commonly known as sapota, chiku, ciku and zapoteis a climacteric fruit and due to high rate of ethylene production, leads to senescence followed by spoilage. Different coating solutions were prepared from sesame protein isolate (SP) and lotus seed starch (LS) with the addition of Garcinia indica extract (GE). Two coats were applied on the fruit with manual drying after an interval of 20 min. Fruits were stored at 70%–75% RH and 20 ± 1°C temperature in plastic mesh trays in an environment chamber to store all coated and non-coated fruits. From each treatment three samples were taken and analyzed after the interval of 2 days till 12 days of storage. Results indicated that GE (Garninicia indica) extract with the combination of sesame protein and lotus seed starch could maintain the overall quality of sapodilla fruit and extends the shelf life up to 12 days. All coated samples exhibited reduced weight loss as compared to non-coated fruit. Sesame protein and lotus seed starch alone and with the incorporation of GE significantly maintained the firmness up to 12th day of storage. SP-GE and LS-GE coated sapodilla fruits indicated a significant (p ≤ 0.05) decrease in respiration rate as compared to SP and LS coated samples up to 12 days of storage. Also, Ascorbic acid (AA) content of SP-GE and LS-GE coated fruits was observed to be higher as compared to SP and LS coated fruits. Maximum TP (Total Phenol) content was exhibited by SP-GE (91.20%) followed by LS-GE (72.82%) coated fruits. Antioxidant potential of all coated samples was observed to be higher as compared to control samples at the end of storage period. Overall, GE in sesame protein and lotus seed starch-based coatings helps to maintain the nutritional parameters by impeding respiration rate of fruit samples during storage. Novelty impact statement Coating solutions were prepared from lotus seed starch and sesame protein and Garcinia indica was used as a natural plant extract for its antimicrobial and antioxidant properties. Combination of sesame protein and lotus seed starch could maintain the overall quality of sapodilla. Phytochemicals such as ascorbic acid, carotenoids and total phenolic was found to be retained with the application of coatings.

Microfluidics-Assisted Synthesis of Hierarchical Cu2 O Nanocrystal as C2 -Selective CO2 Reduction Electrocatalyst.

Copper-based catalysts have attracted enormous attention due to their high selectivity for C2+ products during the electrochemical reduction of CO2 (CO2 RR). In particular, grain boundaries on the catalysts contribute to the generation of various Cu coordination environments, which have been found essential for C-C coupling. However, smooth-surfaced Cu2 O nanocrystals generally lack the ability for the surface reorganization to form multiple grain boundaries and desired Cu undercoordination sites. Flow chemistry armed with the unparalleled ability to mix reaction mixture can achieve a very high concentration of unstable reaction intermediates, which in turn are used up rapidly to lead to kinetics-driven nanocrystal growth. Herein, the synthesis of a unique hierarchical structure of Cu2 O with numerous steps (h-Cu2 O ONS) via flow chemistry-assisted modulation of nanocrystal growth kinetics is reported. The surface of h-Cu2 O ONS underwent rapid surface reconstruction under CO2 RR conditions to exhibit multiple heterointerfaces between Cu2 O and Cu phases, setting the preferable condition to facilitate C-C bond formation. Notably, the h-Cu2 O ONS obtained the increased C2 H4 Faradaic efficiency from 31.9% to 43.5% during electrocatalysis concurrent with the morphological reorganization, showing the role of the stepped surface. Also, the h-Cu2 O ONS demonstrated a 3.8-fold higher ethylene production rate as compared to the Cu2 O nanocube.

Effects of Gas Diffusion Layers on a CO2 electrolysis Cell with an Anion Exchange Membrane for Ethylene Production

The concept of an electrolysis system, where CO2 is converted into hydrocarbons using renewable electricity, has been attracting much attention because it is expected to be one solution to achieve a decarbonized society. In order to realize an economical electrolysis system, it is important to produce high-value products such as ethylene with high reaction rate (i.e. the operating current density of CO2 electrolysis), and high efficiency (low operation voltage).The anion exchange membrane (AEM) CO2 electrolysis cells using gas diffusion electrodes (GDEs) are more advantageous than the traditional flow cell using a solution purged with CO2, both in terms of higher current density and lower voltage operation. This is because of the efficient CO2 reduction occurring at the three-phase interface of a GDE (i.e. CO2 is directly fed to the vicinity of the electrocatalysts though a gas diffusion layer (GDL)), increasing the current density, and of the cell electrodes being closely spaced, lowering the voltage. However, there are only several studies of the AEM CO2 electrolysis cells for high rate of ethylene production [1].Here, we investigate ethylene production performance of an AEM CO2 electrolysis cell consisting of copper and copper oxide nanoparticles coated on GDL as a cathode, iridium oxide-coated titanium support as an anode, and an AEM. Among these components, the GDL can play a crucial role in the efficient transport of CO2 and water management, therefore we focus on understanding the effects of GDL properties such as thickness, porosity and density on ethylene production. We evaluated the electroreduction characteristics of the cells under ambient condition by a constant current method in which a constant current is supplied for a period of time. The faradaic efficiency (FE) and partial current density (PCD) of gas products such as ethylene, carbon monoxide, methane and hydrogen are examined as a function of the total current densities (TCD). We found that the FEs and PCDs depended on the density and the thickness of the GDLs. The low density and thick GDL showed high FE and PCD of ethylene due to high gas diffusibility. The FE and the PCD of ethylene at the TCD of 600 mA/cm2 reached a maximum of 50 % and 300 mA/cm2, respectively.

Effects of Perforation Mediated-modified Atmospheric Packaging (MAP) on Shelf Life and Quality of Calcium Chloride Treated Bell Pepper (Capsicum annum)

Background: Capsicums having high respiration, transpiration, and ethylene production rates along with high susceptibility to microbial growth deteriorate rapidly during storage leading to higher loss. The current study was conducted to assess the effects of Perforation mediated- modified atmospheric packaging (MAP) on shelf life and quality of calcium chloride treated bell pepper (Capsicum annum). Methods: For this purposed green mature fruits capsicum annum variety Indra were pretreated with calcium chloride, weighed 1kg and packed in Low-density polyethylene with no perforation (T1), LDPE with 4 perforations(T2), LDPE with 8 perforations(T3), LDPE with 12 perforations(T4), LDPE with 16 perforation(T5) and open tray (T6) and stored at ambient room temperature of laboratory. Three replications were maintained for each treatment with CRD Design and different parameters were evaluated during the study period. Result: Capsicum stored in perforated LDPE packet exhibited less weight loss, higher shelf life and higher vitamin C content compared to capsicum kept in an open tray. With less perforations weight loss was less. Moreover, LDPE with 16 perforations can be considered the best treatment because with higher numbers of pores it exhibited comparatively higher shelf life, optimum quality of fruits and also check the spoilage of the fruits as compared to all treatments.

Packaging design proposal motivated by the identification of damages in Andean blackberry (Rubus glaucus Benth)

Andean blackberry is a fruit recognized by its health benefits associated with its high content of bioactive compounds. However, it is also one of the most perishable fruits because it does not have a protective cuticle, and it shows high respiration and ethylene production rates. Furthermore, it is susceptible to microbiological attacks. During harvest and commercialization, the highest percentage of losses is caused by factors such as the maturity stage, harvest practices and containers, and marketing packages. The current work aims at studying the effect of the package on fruit quality, for which the harvested fruits were placed in clamshells, traditional wooden and plastic crates with a capacity of 7 kg. The quality of the fruit was evaluated by counting in situ, damage by bruising, cuts, deformations, microbiological attacks, missing of the peduncle, and non-uniform pollination. Damage analysis included the evaluation of different regression models considering information criteria and significant parameters (P ≤ 0.05). The use of traditional packages led to higher damage from cuts and bruises. Although in clamshells there was a higher probability of finding healthy fruits, a proposal for its redesign is proposed to guarantee a better quality and shelf life of the Andean blackberry fruits.

Effects of 1-MCP on Quality and Storability of Cherry Tomato (Solanum lycopersicum L.)

Cherry tomato is a perishable fruit due to its high rate of ethylene production and respiration during ripening. 1-Methylcyclopropene (1-MCP) is known to control ripening and reduce decay of fruit by inhibiting ethylene action. In the present study, the influence of 1-MCP application on quality and storability of ‘Unicorn’ cherry tomato was observed. Fruit at pink and red maturity stages were put in the commercial plastic containers and sealed with 40 μm low density polyethylene (LDPE) film, treated with 1-MCP (0 µL L−1 (control), 0.035 µL L−1 and 0.1 µL L−1), and stored at 10 °C in 85 ± 5% relative humidity (RH). The results indicated that application of 1-MCP at 0.1 µL L−1 significantly affected firmness, cell wall thickness, water soluble pectin, weight loss, surface color, lycopene content and physiological parameters in both pink and red maturity stages compared to 0.035 µL L−1 and control. 1-MCP treatment at 0.1 µL L−1 kept the fruits firmer than 0.035 µL L−1 and the control throughout the storage period for both maturity stages. Cell wall degradation in the control treatment was higher compared to the 0.1 µL L−1 1-MCP treated fruits in both maturity stages throughout the storage period. Results of this study revealed the effectiveness of application of 0.1 µL L−1 1-MCP on quality and shelf life of cherry tomato.

1-Methylcyclopropene affects the shelf-life quality of controlled atmosphere stored ‘Cold Snap™’ pears

1-Methylcyclopropene (1-MCP) and a controlled atmosphere (CA; elevated CO2 and low O2 partial pressures) preserve the overall quality of ‘Cold Snap™’ pears during low temperature storage, including minimizing physiological disorders. In two separate years, we determined the impact of 1-MCP (0 or 300 nL L−1), pre-storage conditioning (0, 3, or 7 d at 3 °C), and CA (18 or 2.5 kPa O2, and 2 kPa CO2) on the shelf-life quality of ‘Cold Snap™’ pears following their removal from storage at 0 °C. In both years, 1-MCP effectively reduced rates of ethylene production and limited peel yellowing and fruit softening following the transfer of stored ‘Cold Snap™’ pears to ambient conditions for up to 14 d, regardless of pre-storage conditioning and CA regimen. Moreover, 1-MCP-treated fruit stored under 2.5 kPa O2/2 kPa CO2 developed lower incidences of senescent scald, regardless of the pre-storage conditioning period. In year one, this treatment combination also limited internal breakdown and internal cavity development, whereas the incidence of internal cavities was highest in 1-MCP-treated fruit in year two, regardless of pre-storage conditioning period, O2 partial pressure in the storage atmosphere, and shelf-life duration. Principal component analysis revealed that the occurrence of senescent scald and internal breakdown in ‘Cold Snap™’ pears were associated with high rates of ethylene production, peel yellowing, and softening. Similarly, internal cavity development was correlated with most ripening attributes, although the link with fruit softening was inconsistent across both years of the study.

Assessment of Ripening Degree of Avocado by Electrical Impedance Spectroscopy and Support Vector Machine

Avocado, a climacteric fruit, exerts high rate of respiration and ethylene production and thereby subject to ripening during storage. Therefore, its ripening is a significant factor to impart optimum quality in postharvest storage. To understand the dynamics of ripening and to assess the degree of ripening in the avocado, electrical sensing technique is utilized in this study. In particular, electrical impedance spectroscopy (EIS) is found to uncover the physiological and structural characteristics in plants and vegetables and to follow physiological progressions due to environmental impacts. In this work, we present an approach that will integrate EIS and machine learning technique that allows us to monitor the ripening degree of the avocado. It is evident from our study that the impedance absolute magnitude of the avocado gradually decreases as the ripening stages (firm, breaking, ripe, and overripe) proceed at a particular frequency. In addition, principal component analysis shows that impedance magnitude (two principal components combined explain 99.95% variation) has better discrimination capabilities for ripening degrees compared to impedance phase angle, impedance real part, and impedance imaginary part. Our classifier utilizes two principal component features over 100 EIS responses and demonstrates classification over firm, breaking, ripe, and overripe stages with an accuracy of 90%, precision of 93%, recall of 90%, f1-score of 90%, and auc of 88%. The study offers plant scientists a low cost and nondestructive approach to monitor postharvest ripening process for quality control during storage.

Different Preclimacteric Events in Apple Cultivars with Modified Ripening Physiology

“Anna” is an early season apple cultivar exhibiting a fast softening and juiciness loss during storage, in comparison to two mid-late season cultivars “Galaxy” and “GD.” The poor storage capacity of “Anna” was correlated with high lipid oxidation-related autoluminescence, high respiration and ethylene production rates, associated with high expression of MdACO1, 2, 4, 7, and MdACS1. All cultivars at harvest responded to exogenous ethylene by enhancing ethylene production, typical of system-II. The contribution of pre-climacteric events to the poor storage capacity of “Anna” was examined by comparing respiration and ethylene production rates, response to exogenous ethylene, expression of genes responsible for ethylene biosynthesis and response, and developmental regulators in the three cultivars throughout fruit development. In contrast to the “Galaxy” and “GD,” “Anna” showed higher ethylene production and respiration rates during fruit development, and exhibited auto-stimulatory (system II-like) effect in response to exogenous ethylene. The higher ethylene production rate in “Anna” was correlated with higher expression of ethylene biosynthesis genes, MdACS3a MdACO2, 4, and 7 during early fruit development. The expression of negative regulators of ripening (AP2/ERF) and ethylene response pathway, (MdETR1,2 and MdCTR1) was lower in “Anna” in comparison to the other two cultivars throughout development and ripening. Similar pattern of gene expression was found for SQUAMOSA promoter binding protein (SBP)-box genes, including MdCNR and for MdFUL. Taken together, this study provides new understanding on pre-climacteric events in “Anna” that might affect its ripening behavior and physiology following storage.

The Role of Auxin-Ethylene Crosstalk in Orchestrating Primary Root Elongation in Sugar Beet.

It is well-established in Arabidopsis and other species that ethylene inhibits root elongation through the action of auxin. In sugar beet (Beta vulgaris L.) ethylene promotes root elongation in a concentration dependent manner. However, the crosstalk between ethylene and auxin remains unknown during sugar beet seedling development. Our experiments have shown that exogenously applied auxin (indole-3-acetic acid; IAA) also stimulates root elongation. We also show that auxin promotes ethylene biosynthesis leading to longer roots. We have further demonstrated that the auxin treatment stimulates ethylene production by redirecting the pool of available 1-aminocyclopropane-1-carboxylic acid (ACC) toward ethylene instead of malonyl-ACC (MACC) resulting in a prolonged period of high rates of ethylene production and subsequently a longer root. On the other hand we have also shown that endogenous IAA levels were not affected by an ACC treatment during germination. All together our findings suggest that the general model for auxin-ethylene crosstalk during early root development, where ethylene controls auxin biosynthesis and transport, does not occur in sugar beet. On the contrary, we have shown that the opposite, where auxin stimulates ethylene biosynthesis, is true for sugar beet root development.

English

Tomato ( Lycopersicon esculentum Mill) is the leading vegetable in terms of production in Kenya. The Kenyan local market has a wide variety of tomato cultivars with a wide range of morphological and sensorial characteristics. However, information on the nutritional and postharvest quality of these varieties is lacking. The aim of this research was to investigate and identify tomato varieties of superior postharvest quality and recommend them to small and medium scale farmers. In this study, six tomato varieties were grown in a greenhouse and analyzed at three maturity stages (mature green, turning and red ripe). The tomatoes were analyzed at specific days after harvest and storage at room temperature (25 o C). Percentage weight loss, color, respiration and ethylene production rates were analyzed to assess the postharvest quality of the tomatoes. The color was measured using a Minolta Chromameter while the respiration rate and ethylene production rates were determined using the static system approach. Color, weight loss, respiration and ethylene production rates were positively affected by storage time when harvested at the three maturity stages. The percentage weight loss of the tomato fruits was higher in the determinate varieties, and at the turning stage of maturity (3.8 %). Minor color changes were observed after storage of the tomatoes harvested at red stage for six days. Both rates of respiration and ethylene production were low, with the respiration rate ranging between 56-10 ml CO 2 Kg -1 h -1 . The Chonto F1 variety had the highest rate of ethylene production (5.4 μL C 2 H 4 Kg -1 h -1 ) on the 4 th day of storage after harvest at the red ripe stage. Overall, the indeterminate tomato varieties displayed better postharvest quality that can prolong the fruits shelf life for marketing. In turn, the turning stage of maturity proved to be a better stage to harvest tomatoes as the color development was more uniform. Keywords: Tomato, varieties, postharvest quality, respiration rate, ethylene, color

Climacteric pattern of mangaba fruit (Hancornia speciosa Gomes) and its responses to temperature

The present study used three experiments to investigate the respiratory and ethylene production patterns of mangaba fruit and the physical and chemical changes that occur during ripening, as well as the temperature coefficient of the fruit. In the first experiment, 12 mature fruits were used to assess the patterns of respiration and ethylene production at 25°C. In the second experiment, mature fruits were kept at 25°C and left to ripen. They were analyzed, in ten replicates, at maturation, at the beginning of ripening and when totally ripe. In the third experiment, mature fruits were stored at different temperatures (5, 10, 20 and 25°C) to determine the Q10, in five replicates. The following analyses were performed: weight (fresh mass), circumference, respiration rate, ethylene production, firmness, soluble solids, pH, titratable acidity and external color (L*, a*, b*, C* and hue angle). Mangaba fruit shows respiratory and ethylene production patterns typical of climacteric fruits, with high rates of respiration and ethylene production. The ripening of mangaba fruit is characterized by softening and an increase in soluble solids, as well as by the reddening of the peel. Q10 of mangaba fruit is dependent on the temperature range, increasing as the temperature lowers.

The addition of rosehip oil improves the beneficial effect of Aloe vera gel on delaying ripening and maintaining postharvest quality of several stonefruit

In this work Aloe vera gel (AV) alone or with the addition of 10 or 2% rosehip oil was used as fruit edible coatings in a wide range of Prunus species and cultivars: peaches (‘Roma’ and ‘B-424-16’ flat type), plums (‘Red Beauty’ and ‘Songria’), nectarine (‘Garofa’) and sweet cherry (‘Brooks’). Following treatments, fruit were stored at 20°C for 6 days and analysed for the effect of treatments on fruit ripening and quality parameters compared with uncoated fruit (control). The addition of the rosehip oil to AV gel reduced respiration rate in all fruit, and ethylene production in the climacteric ones (peaches, plums and nectarine). In addition, all the parameters related with fruit ripening and quality, such as weight loss, softening, colour change and ripening index, were also delayed in treated compared with control fruit, the effect being generally higher when rosehip oil was added to AV, and especially in those fruit that exhibited the highest ethylene production rates (‘Roma’ and flat type peaches). Although the highest effect was obtained with AV+rosehip oil at 10%, the sensory panel detected an excess of gloss and oiliness on the fruit surface, which was considered as a negative attribute. Thus, 2% rosehip oil added to AV could be used as an innovative postharvest tool to increase the beneficial effect of AV as an edible coating, especially in climacteric fruit showing high ethylene production rates.