Lower Ethylene Production Rate Research Articles

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.

Physico-chemical and postharvest quality characteristics of intra and interspecific grafted tomato fruits

The objective of this study was to evaluate the physico-chemical and postharvest quality characteristics of intra- and interspecific grafted tomato fruit. Anna F1, a commercial tomato variety was interspecifically (Tomato Scion and African eggplant rootstock ( Solanum aethiopicum) ) and intraspecifically (Tomato Scion and bacterial wilt resistant hybrid tomato rootstock) grafted. The tomatoes were grown in a greenhouse and harvested at mature green, turning and ripe stages respectively. The tomatoes were analyzed for size, weight, cumulative weight loss, color changes, texture, respiration and ethylene gas production rates, vitamin C and lycopene content. Interspecific grafting on Manyire green, AB2, and intraspecific grafting on Armada, and B.B rootstocks significantly improved physical and physiological attributes of the tomato fruit. There was significant difference (p < 0.05) in size and weight of grafted tomatoes and control at all the three maturity stages. Intraspecific grafted tomato fruits on Armada rootstocks had the best quality characteristics in terms of firmness, low weight loss, respiration and ethylene production rates which are associated with extended postharvest shelf-life. Intraspecific grafting reduced respiration and ethylene gas production rates with tomatoes grafted onto Armada rootstocks attaining the least climacteric peaks of 20.20 ml CO 2 Kg -1 h -1 and 0.34 μL C 2 H 4 Kg -1 h -1 respectively at mature green stage, thus leading to extendend postharvest life of these tomatoes. Tomatoes grafted onto B.B rootstock had the highest vitamin C content (28.11 mg/100 g). In general, intraspecific grafting recorded the best quality traits over the interspecific grafting. However interspecific grafting of tomato onto African eggplant Manyire and AB2 rootstocks had lower but comparable fruit quality to intraspecific grafting. • The effect of grafting on tomato quality is dependent on scion/rootstock combination. • Tomatoes from Manyire and AB2 rootstocks grafts (interspecific), and Armada and B.B rootstocks (intraspecific) had improved physical, physiological qualities as compared to nongrafted control. • Fruits from the Armada rootstock reported the best quality characteristics in terms of firmness and low weight loss, respiration and ethylene production rates which are associated with prolonging shelf-life. • Lycopene content was not affected by grafting. • In general, intraspecific grafting had the best quality traits over the interspecific grafting. However interspecific grafting of tomato onto African eggplant Manyire and AB2 rootstocks has comparable fruit quality to intraspecific grafting especially for resource poor farmers.

Application of ethylene scavenging nanocomposite film prepared by loading potassium permanganate-impregnated halloysite nanotubes into low-density polyethylene as active packaging material for fresh produce

This study reported the development of a potassium permanganate-based ethylene scavenger using halloysite nanotubes (HNTs) as an encapsulation material. Different concentrations of the potassium permanganate-impregnated HNTs (P-HNTs) were loaded into a low-density polyethylene (LDPE) matrix. The results indicated that the loading of the P-HNTs into the LDPE matrix did not optimize the mechanical and barrier properties of the nanocomposite films. However, the loading of 1 g/100 g P-HNTs increased the thermal stability, crystallinity, and ethylene scavenging capacity (by 1700%) of the nanocomposite film. The cherry tomatoes that were wrapped with the 1% P-HNTs/LDPE nanocomposite film (P-HLNF) and stored at 20 °C for 21 d exhibited a low ethylene production rate and respiration rate; furthermore, the nanocomposite film delayed the decrease in the firmness and the color change of the cherry tomatoes.

Physiological responses and quality attributes of muscadine grape (Vitis rotundifolia Michx) to CO2-enriched atmosphere storage

Abstract Muscadine grape (Vitis rotundifolia Michx) is a non-climacteric fruit that rapidly loses quality during storage. This study aimed to assess the effect of controlled atmosphere (CA) on quality parameters and muscadine grapes decay. Berries of two muscadine grape cultivars, Triumph, and Supreme, were stored at 4 °C with 95 % relative humidity in either regular air (AIR), regular CA (RCA) (6 % O2 + 10 % CO2), or CA with extreme CO2 level (ECA; 4 % O2 + 30 % CO2) for up to 42 d. Treated berries with either RCA or ECA provided better control of weight loss. Both CA treatments reduced decay incidence, but there was no decay in ECA berries after 42 d for both cultivars and no evidence of CO2 injury. The results showed that berry softening was significantly delayed by RCA and ECA, which had a lower ethylene production rate than berries exposed to AIR. Application of RCA and ECA also retained greater total antioxidant activity, total phenolic compounds, and firmness compared to AIR. These results demonstrate that maintaining CA conditions postharvest leads to improved preservation of compositional quality and delayed softening and decay of harvested muscadine grapes compared with AIR storage.

Ethanol vapor treatment inhibits apple ripening at room temperature even with the presence of ethylene

Abstract The present study aimed to evaluate the effect of two ethanol vapor doses (250 and 500 ppm), 1-methylcyclopropene (1-MCP) (0.650 ppm) with or without ethylene application (150 ppm) on the aerobic and anaerobic metabolism and quality of ‘Elstar’, a fast ripening apple cultivar, and ‘Nicoter’, a slowly ripening apple cultivar, over 14 d of holding at room temperature (20 ± 2 °C). Fruit were subjected to treatments for 24 h and analyses performed after 0, 7 and 14 d holding at room temperature (20 ± 2 °C). For both cultivars studied, ethanol vapor treatments, especially 500 ppm, inhibited the ripening of apples even when combined with 150 ppm of ethylene, but not as much as 1-MCP treatment in ‘Nicoter’ apples. Fruit treated with ethanol vapor maintained lower electrolyte leakage, higher flesh firmness, greener color and had more healthy fruit. However, its application increased the pyruvate decarboxylase (PDC) and alcohol dehydrogenase (ADH) activity, acetaldehyde and ethyl acetate accumulation, but in concentrations below the odor threshold reported in the literature. The 1-MCP treatment increased decay incidence, reducing the healthy fruit amount in ‘Nicoter’ apples after 14 d, but maintained a very low ethylene production and respiration rate, which allowed higher acidity maintenance after 14 d holding at room temperature. There was no incidence of external and internal physiological disorders in both cultivars.

Postharvest application of potassium silicate improves keeping quality of banana

ABSTRACTGRAS (General-Regarded-As-Safe) compounds play a considerable role in food industry to secure the food safety and environmental sustainability. Soluble silicon (Si) acts as a disease control agent for many plants. Climacteric pattern of ripening and postharvest diseases limit the shelf life of banana during transportation to local and overseas destinations. The ability of banana fruit to absorb Si upon postharvest dip treatment and if so, the absorption of Si confers any effects on disease reduction and keeping quality, were investigated. Banana dipped in 1500 µg mL−1 silicon for 20 minutes showed longer shelf life among different Si concentration × dipping time treatment combinations. Si treatment resulted significantly lower rates of ethylene production, respiration and delayed time taken for fungal rot development compared to non Si-treated (control) fruit. Total soluble silicon content in peel tissues was significantly higher [0.54% dry weight (dw)] in Si-treated versus control fruit (0.13% dw). Si treatment had no effect on total Si content, total soluble solids (TSS) content, titratable acidity (TA) or antioxidant activity in banana fruit pulp. This indicates that dip-treatment allowed Si to penetrate and remain in peel without reaching fruit pulp while extending the shelf life without altering the organoleptic properties of banana fruit pulp.

Improving the storage quality of Tahitian limes (Citrus latifolia) by pre-storage UV-C irradiation.

UV-C (180-280nm) has been shown to extend the postharvest shelf-life of many horticulture crops. In this study, Tahitian limes (Citrus latifolia) were exposed to 0, 3.4, 7.2 and 10.5kJm-2UV-C then stored for 28days in air at 10°C and 80% RH. Weight loss, peel colour, calyx abscission, ethylene production, respiration rate, total soluble solids (TSS), titratable acidity (TA) and acceptability index were assessed. The results showed that UV-C treatment maintained lime peel green colour and retained calyx attachment after 28days storage. UV-C treatment also affected endogenous ethylene production and respiration rate, where the highest UV-C treatment (10.5kJm-2) maintained low ethylene production and low respiration rates after 28days storage with no differences between the different UV-C intensities. In terms of fruit acceptability, limes were exposed to 10.5kJm-2UV-C had a 60% acceptability index after 28days storage, while untreated control fruit retained acceptability of 39%. In general, the pre-storage UV-C treatments did not affect fruit weight loss, TSS or TA contents during storage.

Preharvest treatment of ‘Gala’ apples with 1-MCP and AVG – I: effects on fruit maturation on the tree

The study evaluated the efficacy of a sprayable formulation of 1-methylcyclopropene (1-MCP) to delay fruit maturation on the tree in comparison to aminoethoxyvinylglycine (AVG). 1-MCP (150 mg L-1) and AVG (124 mg L-1) were sprayed to 'Imperial Gala' and 'Royal Gala' apple trees from two commercial orchards, 7 and 28 days before commercial fruit harvest maturity, respectively, during four consecutive years. Untreated trees were used as control. Fruit were harvested weekly, during four weeks from the 7th day after 1-MCP spray and assessed one day after harvest. The extent of fruit maturation delay on the tree by 1-MCP and AVG was quantified by linear regression analysis of fruit firmness as a function of harvest date. The estimated date when apple fruit reached firmness of 71.1 N on the tree was delayed for 5.3 to 5.6 days by 1-MCP and for 9.0 to 9.4 days by AVG in comparison to the control, depending on cultivar-orchard. Indices of fruit maturity and quality at harvest were also estimated by linear regression analysis for the estimated date when fruit reach flesh firmness of 71.1 N on the tree. 1-MCP and/or AVG treated fruit had similar or lower ethylene production rates, starch index, titratable acidity and red color and similar or greener background color than control, at estimated harvest dates when fruit of all three treatments reached the same firmness of 71.1 N. 1-MCP and AVG treatments did not affect rates of fruit growth. However, at estimated dates when fruit of all treatments reached the firmness of 71.1, 1-MCP and AVG treated fruit were 2.1 to 7.1% larger than control fruit.

Effects of aminoethoxyvinylglycine treatment by vacuum infiltration method on postharvest storage and shelf life of tomato fruit

The aim of this study was to determine effects of postharvest aminoethoxyvinylglycine (AVG) treatment using vacuum infiltration method on retardation of ripening, storage and shelf life of tomato fruit. In the Experiment-1, beefsteak ‘Grando F1’ tomato fruit was harvested at breaker stage and treated with AVG at six different doses (0, 62.5, 125, 250, 500 and 1000mgL−1) and three different vacuum pressures (0kPa, −20kPa and −30kPa) using vacuum infiltration method and kept at 20°C for 8d. The AVG treatment of 1000mgL−1 at −30kPa reduced ethylene production rate by 45.53%, delayed color changes and extended the number of days reaching to red ripe stage from 6 to 8 d at 20°C and was confirmed as the optimal treatment for the maximum retardation of tomato fruit ripening by response surface methodology. In Experiment-2, untreated and treated breaker ‘Grando F1’ tomato fruit with 1000mgL−1 at −30kPa were kept at 12°C for 0, 5, 10, 15 or 20d and for 2d at 20°C after cold storage. AVG treated fruit had lower ethylene production rate, lycopene content, a* and C* values and higher fruit firmness, chlorophyll content, L* and h° values, compared to control during storage and shelf life period. For shipping to distant markets, storage and shelf life of untreated fruit were 10d at 12°C plus 2 d at 20°C while AVG treatment extended storage and shelf life to 20d at 12°C plus 2d at 20°C.

Postharvest quality and storage life of ‘Makapuno’ coconut (Cocos nucifera L.)

Makapuno is a high-value commercial coconut with distinct sensory attributes, however the postharvest conditions required to maintain quality are unknown. To address this, partially de-husked mature Makapuno coconut fruit were stored at 2, 5 or 30°C and were then evaluated after transferring to 30°C for 3 days to simulate conditions in retail markets. During storage at 30°C, the fruit showed a moderate respiration rate of 40–60mgCO2kg−1h−1, a low ethylene production rate of 0.6–0.8μLC2H4kg−1h−1 and storage life was 3 days. In contrast, storage at 2°C or 5°C markedly reduced respiration rates to 4 and 20mgCO2kg−1h−1, respectively, and storage-life increased dramatically from 3 days to 6 weeks. Generally, cold storage delayed fruit deterioration by limiting weight loss, kernel browning and malondialdehyde content, however, after the fruits were transferred to 30°C, those previously held at 2°C showed signs of chilling injury, while those held at 5°C did not. Modified atmosphere packaging (MAP) using high oxygen transmission rate (OTR) bags in combination with 5°C storage extended fruit storage-life 20-fold, from 3 days at ambient conditions to 10 weeks. The combination of MAP and 5°C storage reduced weight loss (4-fold), the incidence of surface mold and the quality parameters measured were comparable to values in freshly harvested fruit.

Ethylene synthesis, ripening capacity, and superficial scald inhibition in 1-MCP treated ‘d’Anjou’ pears are affected by storage temperature

A continuing challenge for commercializing 1-methylcyclopropene (1-MCP) to extend the storage life and control superficial scald of ‘d’Anjou’ pear (Pyrus communis L.) is how to initiate ripening in 1-MCP treated fruit. ‘D’Anjou’ pears harvested at commercial and late maturity were treated with 1-MCP at 0.15μLL−1 and stored either at the commercial storage temperature −1.1°C (1-MCP@−1.1°C), or at 1.1°C (1-MCP@1.1°C) or 2.2°C (1-MCP@2.2°C) for 8 months. Control fruit stored at −1.1°C ripened and developed significant scald within 7 d at 20°C following 3–5 months of storage. While 1-MCP@−1.1°C fruit did not develop ripening capacity due to extremely low internal ethylene concentration (IEC) and ethylene production rate for 8 months, 1-MCP@1.1°C fruit produced significant amounts of IEC during storage and developed ripening capacity with relatively low levels of scald within 7 d at 20°C following 6–8 months of storage. 1-MCP@2.2°C fruit lost quality quickly during storage. Compared to the control, the expression of ethylene synthesis (PcACS1, PcACO1) and signal (PcETR1, PcETR2) genes was stable at extremely low levels in 1-MCP@−1.1°C fruit. In contrast, they increased expression after 4 or 5 months of storage in 1-MCP@1.1°C fruit. Other genes (PcCTR1, PcACS2, PcACS4 and PcACS5) remained at very low expression regardless of fruit capacity to ripen. A storage temperature of 1.1°C can facilitate initiation of ripening capacity in 1-MCP treated ‘d’Anjou’ pears with relatively low scald incidence following 6–8 months storage through recovering the expression of certain ethylene synthesis and signal genes.

Effects of 1-MCP on chlorophyll degradation pathway-associated genes expression and chloroplast ultrastructure during the peel yellowing of Chinese pear fruits in storage

The peel yellowing is an important pigment physiological process of green fruit ripening, which mainly results from chlorophyll degradation in the fruit peel. In this work, two typical cultivars with different ripening speed, a slow ripening pear ‘Emerald’ (Pyrus bretschneideri Rehd. cv. Emerald) and a fast ripening ‘Jingbai’ (Pyrus ussuriensis Maxim. cv. Jingbai) were used to investigate the molecular mechanism of chlorophyll degradation in pear yellowing/ripening during postharvest storage. The fruits after harvest were treated with 1-methylcyclopropene (1-MCP), an ethylene action inhibitor at 1.0μLl−1 to determine its effect on chloroplast ultrastructure and the expression of chlorophyll degradation associated genes in peel tissues. Our results show that the pears treated with 1-MCP had a lower ethylene production rate and higher chlorophyll content compared to those of untreated fruit. The more intact chloroplasts with well-organised grana thylakoids and small plastoglobuli were maintained in the peel of 1-MCP treated fruit for up to 30 and 15d in ‘Emerald’ and ‘Jingbai’, respectively. The expression of chlorophyll degradation associated genes: pheophorbide a oxygenase (PAO), non-yellow colouring (NYC), NYC1-like (NOL), stay-green 1(SGR1), was suppressed, while no significant change was found in chlorophyllase 1 (CHL1) and red chlorophyll catabolite reductase (RCCR) in both cultivar fruits treated with 1-MCP. These results suggest that 1-MCP can delay chlorophyll degradation by inhibiting ethylene production and suppressing the gene expression of PAO, NYC, NOL and SGR1, which are closely associated with chlorophyll catabolic pathway.

Qualidade de ameixas 'Laetitia' em função da temperatura e da atmosfera de armazenamento

O objetivo deste trabalho foi avaliar o efeito da temperatura e de atmosferas de armazenamento sobre a manutenção da qualidade de ameixas 'Laetitia'. Os tratamentos avaliados constituíram-se na combinação de duas temperaturas (-0,5ºC e 0,5ºC), com três atmosferas de armazenamento: armazenamento refrigerado (AR), com 21,0 kPa de O2 + 0,03 kPa de CO2; atmosfera controlada (AC), com 1,0 kPa de O2 + 3,0 kPa de CO2; e AC, com 2,0 kPa de O2 + 5,0 kPa de CO2. Após 60 dias de armazenamento, foram avaliadas: taxas respiratória e de produção de etileno, acidez titulável (AT), firmeza de polpa, atributos de textura, índice de cor vermelha e ângulo 'hue' (hº) da casca, e incidência de rachaduras, podridões e degenerescência da polpa. O armazenamento refrigerado a -0,5ºC resultou em menores valores para o índice de cor vermelha, taxa respiratória e de produção de etileno e incidência de frutos rachados. Em ambas as condições de AC, a temperatura de 0,5ºC resultou em menor índice de cor vermelha, cor da epiderme mais verde, maior firmeza de polpa e menor taxa de produção de etileno, tanto na abertura da câmara como após quatro dias em condição ambiente. As condições de AC retardaram o amadurecimento dos frutos e reduziram a incidência de degenerescência de polpa. O armazenamento em AC, com 2,0 kPa de O2 + 5,0 kPa de CO2, a 0,5ºC, proporcionou menor taxa respiratória e menor incidência de podridões na saída da câmara, mas maior AT e força para penetração da polpa, após quatro dias em condição ambiente. No entanto, o armazenamento da ameixa 'Laetitia', nas condições de AC avaliadas, por um período de 60 dias, não reduziu a incidência de degenerescência da polpa.

DETERMINATION OF RIPENING STAGE IN DATE CULTIVAR 'BARHI' BY THE LEVEL OF ETHYLENE EMISSION

'Barhi' dates change their color from green to yellow during ripening and they are marketed as slightly astringent yellow fruits. 'Barhi' dates which contain above 25-27% total soluble solids (TSS) are regarded as matured and will have the desirable color, taste and texture. In order to improve the quality of 'Barhi' dates postharvest life, we study various indices, for determination of the best stage for fruit harvesting. During breaking stage from green to yellow there is an increase in ethylene emission which decreased when the fruit color was changed to complete yellow. There is high correlation between increased yellowing expressed as hue angle and reduction in ethylene emission. The decrease in ethylene production rate was also highly correlated with levels of TSS which was determined by near infrared (NIR) spectrometry. The highest ethylene production rate was found in yellow fruits with low TSS of 17%, while, high TSS level of 37% was correlated with low ethylene production rate. It is noteworthy that in fruits with high TSS levels (37%) although ethylene levels are low in the first week after harvest, later during storage at 20°C, ethylene levels increased probably because of fungal contamination. Our results show that the ethylene production rate at harvest time can be a good index for determination of 'Barhi' maturity.

Effects of two pre-harvest calcium treatments on physiological and quality parameters in ‘Vogue’ cherries during storage

SummaryThe effects of two pre-harvest spray treatments with calcium chloride (CaCl2) concentrations up to 58.5 mM on physiological and quality parameters were investigated in ‘Vogue’ cherries during storage from 1 – 23 d in air at 1° – 3.5°C, at 85 – 95% RH, in two experimental years. No foliar or fruit toxicity was observed. Ca-treated fruit showed greater firmness, lower soluble pectin content, more resistance to stem removal, and less stem browning than watersprayed control fruit during storage. Ca spraying had no effect on fruit weight, fruit size, pH, titratable acidity, total soluble solids, Mg content, or peel colour; whereas there was an increase in Ca content and inconsistent changes in malic acid concentrations in fruits measured after 1 d in storage. Ca did not affect carbon dioxide (CO2) production rates, and showed only slight effects on the already low ethylene production rates, and on the low 1-aminocyclopropane-1-carboxylic acid (ACC) content during storage. In conclusion, treatment with 45 mM CaCl2 had positive effects on most of the quality parameters measured, with no negative effect under our particular experimental conditions.

Cultivar Effects on Quality of Fresh Cut Apple Slices from 1-Methylcyclopropene (1-MCP)-Treated Apple Fruit

ABSTRACT: The effects of 1 -methylcyclopropene (1 -MCP) treatment of whole fruit on the subsequent quality and shelf-life of fresh-cut apple slices have been investigated. ‘Delicious,’ Empire, ‘Idared’, Law Rome, and ‘Mutsu’ apples were treated at 0.5°C with 1 μL/L of 1 -MCP for 24 h and stored in air 1 and 4 mo before being used for preparation of slices. 1-MCP reduced internal ethylene concentrations and maintained firmness of the whole fruit in‘Delicious,’ Empire, and ‘Idared’, but not consistently for ‘Law Rome’ and ‘Mutsu.’ Slices prepared from fruit of cultivars that responded to 1 -MCP had lower ethylene production rates and were firmer than those from untreated fruits. However, 1-MCP treatment did not consistently affect the extent of browning or aroma volatile concentrations. In cultivars in which treatment of apples with 1-MCP at harvest maintained the original fresh quality of intact fruit by suppressing ethylene production, fruit were firmer, and thus a superior fresh- cut product with an extended shelf-life potential was obtained. However, in general, slices prepared from untreated and 1-MCP-treated fruit deteriorated at similar rates.

Effect of nitric oxide on ethylene production in strawberry fruit during storage

Strawberry is a non-climacteric fruit, with low ethylene production rate after harvest. Its response to nitric oxide (NO), which can be released from sodium nitroprusside (SNP), was studied. We have examined the effect of 1.0, 5.0 and 10.0 μmol l −1 SNP aqueous solution on ethylene production, respiration rate, 1-aminocyclopropane-1-carboxylic acid (ACC) content and the activities of ACC synthase and ACC oxidase in post-harvest strawberry (“Fengxiang”). The most remarkable effect was obtained with 5 μmol l −1 SNP aqueous solution, which significantly inhibited ethylene production, respiration rate, the activity of ACC synthase and reduced the content of ACC, but did not significantly affect the activity of ACC oxidase. SNP at 10 μmol l −1 harmed the fruits; 1 μmol l −1 SNP was too low to significantly extend strawberry storage life. It was suggested that NO could decrease ethylene output, through inhibiting ACC synthase activity reducing ACC content.

EFFECTS OF DIFFERENT FRUIT CALCIUM LEVELS ON THE POSTHARVEST PHYSIOLOGY OF PLUMS (PRUNUS DOMESTICA L.)

Plum fruits (Prunus domestica L. cv. 'Rainha Claudia Verde' ) were grown in a calcareous soil (more fertile) and in a schistose soil (less fertile) with two types of rootstocks characterized by different vigour. The influence of the rootstock in fruit calcium concentration was investigated. More vigorous rootstock produced fruits with lower calcium content than those produced by less vigorous rootstock. This effect was more evident in fertile soils. The postharvest behaviour of fruits with higher and lower calcium content was also monitored. Changes in texture and chemical composition of pulp fruits (acidity, soluble solids content, and ethylene evolution) during cold storage (0-2°C) were determined. Ethylene production rate was studied in fruits after cold storage (10, 17, 24, 31, 38 days). Fruits with higher calcium content showed higher firmness values and lower ethylene production rates as compared with fruits with lower calcium content.

Effect of chilling on ethylene production in eggplant fruit

Eggplant is a non-climacteric fruit, with low ethylene production rates after harvest, whose response to storage at low temperature was studied. To this end, fruit were stored for 13 days at 0 and 10 °C. Fruits stored at 10 °C were unaffected, but those maintained at 0 °C suffered severe chilling injury (CI) from day 6. Electrolyte leakage, considered an indirect measure of membrane damage, showed no variation at 10 °C, whereas at 0 °C, leakage increased in parallel to CI. At 0 °C ethylene, 1-aminocyclopropane-1-carboxylic acid (ACC) and 1-(malonylamino)cyclopropane-1-carboxylic acid (MACC) contents increased during the first 6 days, though, from days 9–13, their contents decreased to about the initial levels. ACC oxidase activity decreased considerably during storage at 0 °C, reaching non-detectable values by day 13. At 10 °C, not important changes were observed in ethylene biosynthetic pathway. These results suggest that chilling stress stimulated ethylene, ACC and MACC accumulation in eggplant, and their levels remained high until CI symptoms became severe.

Survey of wound‐induced ethylene production by excised root segments

Ethylene production was measured from excised 10‐mm apical and subapical root segments from 50 cultivars in 19 species of 7 families. Monocotyledonous species tended to have much lower rates of ethylene production than dicotyledonous species. Ethylene production was generally higher in apical root segments than in subapical segments within 1 h of wounding. However, cultivars of Cucumis melo, C. sativus, Helianthus annuus, Hibiscus esculentus, and Zea mays had higher rates of ethylene production from subapical segments. In apical root segments, Phaseolus aureus cv. Berken had the highest ethylene production rate (76.7 ηl g−1 h−1), while Zea mays cv. Silver Queen had the lowest rate (0.6 ηl g−1 h−1). In subapical root segments, Cucumis sativus cv. Armenian had the highest rate (55.7 ηl g−1 h−1), while Zea mays cv. Silver Queen again had the lowest rate (0.6 ηl g−1 h−1). The many different responses in magnitude and kinetics of wound‐induced ethylene production among the species, cultivars and tissues should provide interesting and useful systems with which to study wound responses and induced ethylene production.