Postharvest cold storage-induced oxidative stress in Japanese plums (Prunus salicina Lindl. cv. Amber Jewel) in relation to harvest maturity

Cold storage-induced oxidative stress in relation to harvest maturity and storage duration together with its implications on fruit quality and storage potential of Japanese plums (Prunus salicina Lindl.) were investigated. ‘Amber Jewel’ plums harvested at commercial maturity and one week after commercial maturity (delayed harvest) were stored at 0 °C for 7 weeks. Oxidative stress related parameters were determined at weekly intervals. Similar to lipid peroxidation, the incidence and severity of chilling injury (CI) was higher in fruit from the delayed harvest compared to commercial harvest. The activities of primary antioxidant enzymes and ascorbate-glutathione cycle enzymes were determined in context to the levels of antioxidant pools of ascorbate and glutathione and the development of CI symptoms. The predominance of the oxidized state of the tissue as reflected by lower ratios of ascorbate (AA) to dehydroascorbate (DHA) and reduced glutathione (GSH) to oxidized glutathione (GSSG) was linked to the severity of CI symptoms during the last 3-4 weeks of storage. The status of enzymatic and non-enzymatic antioxidative system during cold storage of Japanese plums appeared to be more important in providing protection against oxidative injury expressed as CI than at-harvest antioxidant status. Delayed harvested fruit experienced more oxidative stress during cold storage compared to the fruit harvested at commercial maturity. In conclusion harvesting ‘Amber Jewel’ plums at commercial maturity is of paramount importance to ensure long-term cold storage with minimal adverse effects on fruit quality for better consumer experiences

Deficit irrigation in nectarine: Fruit quality, return bloom and incidence of double fruits

Deficit irrigation (DI) at phenological stages less sensitive to water stress (pit hardening and post-harvest stage) influenced fruit quality, plant growth, return bloom and incidence of double fruits in nectarines. Four irrigation levels: control irrigation (CI), DI 75 (75 % of CI), DI 58 (58 % of CI) and DI 33 (33 % of DI) were applied in ‘Spring Bright’ and ‘Summer Bright’ nectarines during pit hardening and post-harvest stages. DI 58 and DI 33 treatments resulted in development of intense red fruit colour and early maturity in ‘Spring Bright’. DI 33 improved fruit colour in ‘Summer Bright’, soluble solids concentrations (SSC) and SSC/acid ratio in both cultivars. DI 33 treatment decreased glucose and fructose at harvest in ‘Spring Bright’ and increased glucose in ‘Summer Bright’. DI 58 and DI 33 treatments improved the levels of total phenolics, antioxidant capacity, ascorbic acid and carotenoids in the fruit of both cultivars with acceptable fruit weight in comparison to CI. DI 33 treatment significantly increased the total anthocyanin content in fruit peel and reduced water sprout length in both cultivars. In subsequent season, the DI 58 and DI 33 treatments increased flower density in ‘Spring Bright’ and incidence of double fruit in either cultivar. Conclusively, DI improved fruit colour, SSC/acid ratio and nutraceutical levels; and reduced water sprout length. Further, it increased flower density and double fruits in the subsequent season

1-MCP application suppresses ethylene biosynthesis and retards fruit softeningduring cold storage of 'Tegan Blue' Japanese plum

Plum is a highly perishable fruit and postharvest fruit softening limits its cold storage life. To investigate the role of 1-methylcyclopropene (1-MCP) in ethylene biosynthesis and fruit softening during cold storage, Japanese plum (Prunus salicina Lindl. cv. Tegan Blue) as harvested at commercial fruit maturity and exposed to 1-MCP (0.0, 0.5, 1.0 and 2.0 μL L-1) at 20 ± 1 °C for 24 h. Following 1-MCP treatments, fruit were stored at 0 ± 1 °C and 90 ± 5% RH for 0,3 and 6 weeks. 1-MCP treatments significantly reduced endogenous ethylene production in plum fruit after 3 and 6 weeks of cold storage when compared to untreated fruit. Fruit treated with 1-MCP (1.0 and 2.0 μL L-1) were more firm (31% and 33.5% respectively) when compared untreated fruit. Activities of 1-aminocyclopropane-1-carboxylic acid synthase (ACS) and 1-aminocyclopropane-1-carboxylic acid oxidase (ACO) enzymes during cold storage also decreased in 1-MCP-treated fruit skin and pulp tissues and 1-aminocyclopropane-1-carboxylic acid (ACC) content was not detected in the skin and pulp tissues of fruit treated with 1.0 and 2.0 μL L-1 1-MCP. Activities of exo-polygalacturonase (exo-PG) and endo-polygalacturonase (endo-PG) enzymes in the fruit skin tissues were not affected by 1-MCP whereas activities of exo-PG and endo-PG enzymes in fruit pulp tissues, and activities of pectin esterase (PE) and endo-1,4-β-D-glucanase (EGase) enzymes in both fruit skin and pulp tissues were significantly reduced during cold storage. Activities of ethylene biosynthesis and fruit softening enzymes were concentration dependent, and both were reduced with increased concentrations of 1-MCP. In conclusion, 1-MCP application extends cold storage life of 'Tegan Blue' plum by suppressing ethylene biosynthesis and reducing fruit softening

Nitric oxide fumigation delays mango fruit ripening

Hard mature green Kensington Pride mango fruit were fumigated with 0, 5, 10, 20 and 40 µL.L−1 NO gas for 2 h and allowed to ripen at ambient temperature (21±1°C) to evaluate its effects on fruit ripening. NO-fumigation treatments significantly (P ≤ 0.05) suppressed ethylene production and respiration rates during fruit ripening. NO treatments (20 and 40 µL.L−1) retarded fruit softening (hand firmness) and delayed fruit ripening by 2-days as compared to all other treatments. NO-fumigated (40 µL.L−1) ripe fruit exhibited significantly higher pulp cohesiveness, springiness and chewiness as compared to all other treatments. NO fumigation retarded fruit color development (visual colour, L*, a*, b*, C*) and delayed the reduction of h° during fruit ripening. The concentrations of SSC, total sugars, glucose and fructose in the ripe fruit were significantly reduced in response to NO treatments. In conclusion, the postharvest fumigation of NO (20 µL.L−1) suppressed climacteric ethylene production, respiration rate, retarded colour development, softening consequently delayed mango fruit ripening

Impact of Regulated Deficit Irrigation on Fruit Quality and Postharvest Storage Performance of ‘Cripps Pink’ Apple

This study aimed to develop an irrigation strategy for apples to improve fruit skin colour without adversely affecting postharvest life and quality. Regulated deficit irrigation (RDI) at different levels [(i) 100%, commercial irrigation (CI) (70 L•h-1); (ii) 25% RDI (50 L•h-1); (iii) 50% RDI (35 L•h-1); and (iv) 75% RDI (20 L•h-1)] was applied from 135 days after full bloom (DAFB) continuously for 72 days till harvest. RDI (75%) significantly reduced leaf water potential as compared to CI. RDI (75%) improved fruit skin colour via enhanced accumulation of anthocyanins, increased soluble solids concentration (SSC), fruit firmness and slightly decreased fruit diameter. The RDI fruit (75%) stored for 135 days at 0±0.1°C, 90±2% RH remained firmer and had higher SSC compared to CI fruit. Similarly, RDI fruit (75%) stored for 155 days in controlled atmosphere (CA) comprising of 2.7% O2 + 1.9% CO2 at 0°C had higher SSC and fruit firmness than in CI fruit. In conclusion, RDI (75%) imposed at the late fruit development stage improved the fruit quality of ‘Cripps Pink’ apple at harvest without adversely affecting postharvest quality in cold and CA storage, and also saved irrigation water

In vitro plant regeneration in seedless grapes (Vitis vinifera L.)

Young leaves, shoot apices, nodal and internodal segments from mature field-grown grapevines (Vitis vinifera L.) cvs Thompson Seedless and Perlette were cultured on MS medium containing different concentrations and combinations of NAA, 2,4-D, Kin and BAP. The genotype, nature of explant and chemical composition of medium affected the callusing frequency and type of callus. The media containing auxins produced friable, soft and creamish white to green calli. Such calli turned brown and died within 4-6 weeks. The medium containing BAP or Kin produced green compact and nodular calli. The subculturing of green nodular calli on MS basal medium induced 20.0 and 12.5 % rooting in cvs Perlette and Thompson Seedless respectively. Subculturing of calli on MS medium containing BAP (2 mg/l) resulted in 12.1 % complete plant regeneration in Thompson Seedless, cv. Perlette failed to regenerate. Adventitious shoots developed in 65.4 and 50.0 % of the cases from the in vitro derived leaves of Thompson Seedless and Perlette when cultured on MS medium containing BAP (2 mg/l). More than 85 % of the adventitious shoots of both the cultivars rooted successfully on MS medium containing IBA (1 mg/l)

Dynamics of anthocyanin and flavonol profiles in the 'Crimson Seedless' grape berry skin during development and ripening

'Crimson Seedless' grapes (Vitis vinifera L.) do not develop adequate berry colour in different parts of theworld including Australia and USA leading to serious economic losses to the growers. In the present study, various anthocyanins and flavonols were identified in the skin of the 'Crimson Seedless' grapeberries using LC/PDA/ESI-MS and their changes in the berry skin during development and ripening of 'Crimson Seedless' grape berries were investigated during 2005-2006 and 2006-2007. Eleven anthocyanins and two flavonols were identified in the berry skin using LC/PDA/ESI-MS. Of the anthocyanins identified, four anthocyanins including cyanidin 3-O-(600-O-acetyl)-glucoside, peonidin 3-O-(600-O-acetyl)-glucoside, malvidin 3-O-(600-O-acetyl)-glucoside and malvidin 3-O-(600-O-coumaroyl)-glucoside were not reported earlier. During both the years, the concentration of the 3-O-glucosides of delphinidin, petunidin, peonidin, and malvidin as well as the acetyl and coumaroyl esters of the 3-Oglucosides of cyanidin, peonidin, and malvidin in the berry skin increased during berry development and ripening.During 2006-2007, the concentration of cyanidin 3-O-glucoside in the berry skin increased during the early stages of berry ripening and subsequently declined till harvest while in 2005-2006, the concentration increased during the initial phase of berry ripening and remained relatively stable thereafter till harvest. The concentration of total anthocyanins in the berry skin was higher during 2006-2007 as compared to 2005-2006. During both years, the concentration of quercetin 3-O-glucoside in the berry skin increased during berry development and ripening while the concentration of quercetin 3-Oglucuronide in the berry skin decreased during the same period. To the best of our knowledge, this is the first report on the evolution of different anthocyanins and flavonols in the 'Crimson Seedless' berry skin during berry development and ripening

In vivo development of ovule in seedless and seeded cultivars of grapes (Vitis vinifera L.)- a particular reference to in ovulo embryo culture

Ovule development was examined in the three seedless cvs Perlette, Thompson Seedless, Beauty Seedless and the seeded cv. Anab-e-Shahi, to identify the proper developmental stage of the embryo for in ovulo embryo culture. The number of shrivelled ovules started increasing 20 d post anthesis. At the same time, the number of viable ovules started declining in all the seedless cultivars. Amongst seedless cultivars, the growth of ovules was least in cvs Thompson Seedless and Beauty Seedless. The ovule development was faster in Anab-e-Shahi as compared to all the seedless cultivars. Total number of ovules per berry declined 20 and 30 d post anthesis in cvs Beauty Seedless and Perlette, respectively. Keeping in view the above mentioned parameters, the embryos in seedless cultivars of grapes may be rescued in vitro prior to 20 d post anthesis to obtain plantlets from these abortive ovules.Die Entwicklung der Samenanlagen bei kernlosen und kernhaltigen Rebsorten (Vitis vinifera L.) in vivo im Hinblick auf die Embryokultur in vitroUm das geeignetste Entwicklungsstadium der Embryonen für ihre in-vitro-Kultur zu ermitteln, wurde bei den drei kernlosen Rebsorten Perlette, Thompson Seedless und Beauty Seedless sowie der kernhaltigen Sorte Anab-e-Shahi die Entwicklung der Samenanlagen verfolgt. Die Anzahl geschrumpfter Samenanlagen begann 20 d nach der Anthese anzusteigen. Gleichzeitig setzte bei allen kernlosen Sorten die Abnahme der vitalen Samenanlagen ein. Von den kernlosen Sorten zeigten Thompson Seedless und Beauty Seedless das schwächste Wachstum der Samenanlagen. Bei Anab-e-Shahi entwickelten sich die Samenanlagen schneller als bei den drei kernlosen Sorten. Bei Beauty Seedless und Perlette ging die Gesamtzahl der Samenanlagen 20 bzw. 30 d nach der Anthese zurück. Unter Berücksichtigung der oben genannten Entwicklungszeiten sollten die Embryonen binnen 20 d nach der Anthese in Kultur genommen werden, um aus den später absterbenden Samenanlagen in-vitro-Pflanzen zu gewinnen