The effect of fruit maturity on quality and colour shift of dried ‘Patterson’ apricot during eight months of cold storage

Summary

Fresh ‘Patterson’ apricot was harvested at three fruit maturity levels and characterized with measurements of flesh colour, Brix, acidity and levels of specific sugars. Fruit from the three maturity classes were sun-dried under uniform conditions. Dry fruit was again analysed for the content of specific sugars before cold storage. Stored fruit were sampled periodically for colour coordinates L*, C* and H° during an eight-month period. The study was repeated for two harvest seasons. In each season, significant differences (P≤0.05) were observed between the three fruit maturity classes for Brix, acidity, C* and H8. Levels of specific sugars varied significantly (P≤0.01) with regard to fruit maturity class, tissue type and fruit status. Regression analysis of colour coordinate changes during the storage period indicated significant (P≤0.05) differences in rate of colour shift of L*, C* and H8 relative to fruit maturity class. While dried fruit of the immature class was of substandard quality after the storage period, both medium and most mature dry fruit were of sufficient quality to warrant marketing even after eight months of cold storage.     

Response of the phenylpropanoid pathway to Venturia inaequalis infection in maturing fruit of ‘Braeburn’ apple

Summary

This study investigated the activities of key enzymes in the phenylpropanoid pathway and the accumulation of phenolic products in apple peel in response to infection with Venturia inaequalis [(Cooke) G. Wint.]. We compared healthy apple peel with apple peel showing symptomatic scab lesions, and with peel tissue from 1 – 2 mm around the scab lesions in fruit 1 month before maturity [140 d after full bloom (DAFB)] and at physiological maturity (175 DAFB). Infection with V. inaequalis enhanced the synthesis of some phenolic compounds. Compared to healthy peel, scab lesion tissue had ≤ 3.1-times higher hydroxycinnamic acid content, ≤ 1.3-times higher dihydrochalcone content, and ≤ 3.9-times higher flavan-3-ol content. Scab lesions showed slightly higher phenylalanine ammonia-lyase, chalcone synthase, chalcone isomerase, flavonol synthase, and dihydroflavonol 4-reductase activities. The total amount of phenolics remained relatively stable between the two sampling dates, except for epicatechin and caffeic acid which decreased in amount toward fruit maturity, and levels of catechin which increased in more mature fruit. During fruit maturation, only chalcone synthase and chalcone isomerase activities decreased in all tissues examined. This study showed that the phenylpropanoid pathway in apple fruit peel changed significantly following infection with the apple scab pathogen.     

Harvest parameters to improve the storability of high quality ‘Reinette du Canada’ apple

Summary

‘Reinette du Canada’ apple (Malus domestica Borkh.), which has been declared a Protected Designation of Origin (PDO) product throughout the European Community, is severely affected by bitter pit during storage, but increasing demand for organic produce requires chemical post-harvest treatments to be replaced with organic practices. The objective of this work was to determine the optimum stage of fruit maturity to improve the storability of high quality ‘Reinette du Canada’ apple during storage without applying post-harvest treatments. Seasonal conditions influenced fruit quality and the occurrence of storage disorders in ‘Reinette du Canada’. Harvest maturity also influenced the quality of ‘Reinette du Canada’ apple during storage, with later harvests reducing the development of bitter pit and increasing the soluble solids content:titratable acidity (SSC:TA) ratio. This study suggests that the SSC:TA ratio was a useful parameter for determining the optimum harvest maturity for high acidity, ‘Reinette du Canada’ apple. High quality fruit were obtained after long-term storage when the SSC:TA ratio exceeded 11.0, and fruit firmness at harvest exceeded 90 N. If these thresholds were not achieved, the quality of harvested ‘Reinette du Canada’ apples may not be sufficient to market fruit with the PDO designation. The results of our study also suggested that skin hue angle (hº) measurements may provide a quick and useful index that could replace fruit firmness measurements in the future.     

The effect of temperature on certain chemical changes and the storage behaviour of jujube fruits (Zizyphus spinachristi (L.), Willd.)

Summary

Jujube fruits (Zizyphus spinachristi (L.) Willd.) cv. Bambawi were harvested at the mature green stage and stored at 10°C and 27–30°C. Titratable acidity and total chlorophyll decreased as the fruit matured, the rate of decline being more rapid at the higher temperature. Total soluble solids, carotenoids and ascorbic acid contents of the fruit increased towards maturity, the increase being faster at the higher temperature. Jujube fruits could be stored for six days at room temperature and twenty-five days under refrigeration at 10°C.     

Bioherbicide Research: Defining Success (A Tribute to RaghavanCharudattan)

Summary

Corky tissue (CT) is a major disorder affecting the fruit of sapota (Manilkara achras) ‘Cricket Ball’ in India. Affected fruit have a hard lump in the pulp and dry acidic flesh, but have no external symptoms. The main objective of the present study was to investigate the role of seed in the disorder. Treating fruit with 1.0 g l^–1 gibberellic acid (GA₃) at 50% maturity increased fruit fresh weight and presumably seed growth, and reduced the incidence of CT compared with that in untreated control fruit. In contrast, fruit treated with 3.0 g l^–1 paclobutrazol (PBZ) showed the opposite response. Fruit treated at 70% or 90% maturity gave no response, suggesting that poor seed viability during the early stage of fruit development was associated with CT. Seed stored for 30 d under ambient conditions lost water and had lower viability. There were decreases in the moisture content and calcium concentration in seed and pulp as the severity of CT increased in fruit harvested in the field, indicating a “reverse flow” of water and nutrients from the fruit. It is proposed that the incidence of CT is related to reduced seed viability and the consequent losses of water and calcium from fruit due to competition for resources with the rest of the tree. Further studies are required to assess the potential of the application of GA₃ to reduce the incidence of CT in commercial orchards.     

Site and fruit maturity influence on the quality of European plum in organic production

Information available on the role of site and fruit maturity in the quality of European plums in organic production has not been studied to date. European plum cv. ‘Green Gage’ grown in organic production was harvested in order to study the effect of site and fruit maturity on fruit quality. At harvest, significant differences were found in fruit weight, colour, firmness and TSS between harvest dates, whereas significant differences were found in fruit weight, colour, firmness and fruit Ca content between sites. Differences remained during storage. Fruit weight loss during storage was affected by site. Fruit with high Ca content showed higher firmness both at harvest and during storage. Harvest moment should not be chosen according to date, since differences between sites at the same date have been found. Firmness and colour parameters a* and h° would be useful to distinguish maturity at harvest between different sites and harvest dates. Linear regression between h° and firmness at harvest would allow the use of the h° colour parameter as a non-destructive measurement to distinguish maturity. Organic orchards should keep a minimum level of Ca in order to assure a slower fruit softening during storage.     

Effects of post-harvest salicylic acid treatment on fruit quality and anti-oxidant metabolism in pineapple during cold storage

Summary

Pineapple (Ananas comosus L. ‘Comte de Paris’) fruit at commercial maturity (180 fruit per treatment, three replicates) were immersed in 0, 1.0, 3.0, or 5.0 mM salicylic acid (SA) for 15 min, then stored at 10ºC and 90% relative humidity (RH) for 20 d. After 20 d in cold storage, they were moved to 20ºC for 2 d to simulate shelf-life. Physiological and biochemical responses were studied. The results showed that the 3.0 or 5.0 mM SA treatments lowered the internal browning (IB) index, while the 5.0 mM SA treatment decreased the soluble solids content (SSC), titratable acidity (TA), and soluble sugar content, but increased ascorbic acid (AsA) levels at the end of shelf-life. Furthermore, during cold storage, all SA treatments significantly decreased the rate of tissue respiration in pineapple fruit. SA at 5.0 mM significantly decreased the activities of peroxidase (POD), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL), but increased the activities of superoxide dismutase (SOD) and ascorbate peroxidase (APX) compared with the non-SA treated (untreated) controls. Overall, these results indicate that post-harvest treatment with 5.0 mM SA delayed the occurrence of IB in pineapple, extended its shelf-life, and maintained fruit quality during cold storage.     

An Evaluation of Blueberry Cultivars Grown in Plastic Tunnels in Douglas County,Oregon

Abstract

Growing fruits and vegetables in plastic tunnels is known to accelerate maturity and protect quality. There are several studies on highbush blueberry (Vaccinium corymbosum) that demonstrate the ability of row covers to advance or delay crop maturity depending on how they are manipulated. Accelerating or delaying harvest time can prove to be very lucrative for producers. However, before producers start putting plastic tunnels over their crops it is important to know how blueberry cultivars will behave when grown under plastic. Six cultivars of southern highbush blueberry and eight cultivars of northern highbush blueberry were grown in a high hoop plastic tunnel for two seasons. Blueberry plants were grown under plastic from February 1 until their harvest was completed each year. After harvest, the plastic covering over the hoops was removed to help the blueberry plants develop fruit buds and meet winter chill requirements. On February 1 the plastic covering was returned to the high hoop tunnel after chilling requirements were met. As expected, fruit maturity dates were 1-3 weeks earlier for all the highbush blueberries grown inside the tunnel versus the same cultivars grown outside. The difference in maturity dates between cultivars grown under plastic and outside did change from one year to the next because of variation in the weather. Despite potential for poor pollination of blueberries in plastic tunnels, yields were significantly enhanced for four cultivars when grown under plastic tunnels. ‘Toro’, ‘Nui’, ‘Legacy’, and ‘Misty’ showed yield gains ranging from 1 to 4 times when grown under a plastic tunnel. Seed numbers per fruit were not significantly impacted by growing plants inside our tunnel.     

Comparative studies on the postharvest physiology of fruit from different species of Annona (custard apple)

Summary

Fruit of three Annona species, viz. cherimoya (A. cherimola Mill), sugar apple (A. squamosa L.) and custard apple (atemoya, Annona X) were ripened in ethylene-free air and under propylene. Differences were found in patterns of respiration, ethylene production and fruit firmness changes during ripening. Cherimoya and custard apple fruits showed two successive rises in respiration rate whereas sugar apple fruits showed only one. Ethylene production showed one main peak but the onset of rapid ethylene production occurred after the beginning of the respiration climacteric in all three species. Custard apple fruit had acceptable eating quality (as judged by sensory assessments and chemical analyses of pulp) for up to four days after first detectable softening, when ripened at 20°C in ethylene-free air or under propylene. Fruit ripened in ethylene-free air had better ripe fruit quality than fruit ripened under propylene.     

Leaf-to-fruit ratio affects water and dry-matter content of mango fruit

Summary

Changes in water and dry-matter content of developing mango fruit (Mangifera indica L. ‘Lirfa’) were investigated over a single season in Réunion Island, along with the effects of leaf:fruit ratio (10, 25, 50, 100 and 150 leaves per fruit on girdled branches). As the fruit developed, about 8–13% of fruit water weight was in the peel compared with 78–86% in the pulp and 6–9% in the stone. When the data were expressed on a dry-weight basis, 12–20% was in the peel, 60–70% was in the pulp and 18–20% in the stone. At harvest, larger fruit, on treatment 100, had a higher proportion of weight in the pulp. Good relationships between water and dry weight of each fruit component were found, regardless of the treatment. They showed that the rate of water accumulation decreased when the dry weight increased and that the dry-matter content increased as the fruit developed as well. Increasing leaf:fruit ratio to 100 leaves per fruit improved fruit yield by 300 g and pulp dry-matter content by 6%, for a total of 550 g and 20% at harvest. Fruit quality as estimated by pulp dry-matter content could be calculated easily during the changes in fruit weight over the season. Moreover, this indicator could be useful to assess the maturity of mango fruit.     

The effects of hydrogen cyanamide on budburst and fruit maturity of ‘Thompson Seedless’ grapevine

Summary

The effect of hydrogen cyanamide (H₂CN₂) on budburst and fruit maturity of `Thompson Seedless' grapes was examined. Nine year old vines of cv. Thompson Seedless grafted on R.110 rootstock and supported on overhead tendone trellis (parral), were treated with either 2% or 4% of H₂CN₂, 53 and 67 d before expected budbreak and compared with unsprayed vines. The earliest treatment with 4% H₂CN₂ enhanced budbreak and advanced fruit maturity by 17 d. However, the same concentration applied 53 d before natural budbreak advanced the date of maturity by only 4 d. All the treatments increased significantly the percentage of budburst compared with the control. H

² CN₂ had no significant effect on yield, but a positive effect on fruit quality. A higher index of maturity was obtained by the treatment: 4% H₂CN₂, 67 d before budbreak. All the treatments of H₂CN₂ induced more uniform budburst compared with the control. The best uniformity was obtained by the earliest spray using the higher concentration (4%).     

The chemical composition and sensory flavour quality of ‘Mineola’ tangerines. II. Relationship between composition and sensory properties

Summary

A method is suggested for quantitative determination of ‘Mineola’ tangerine “maturity” based on four parameters sugar:acid ratio, acid content, ethanol content, and fruit weight. A high correlation (r=0.9) was found between maturity and “taste acceptability”—a combination of four parameters of taste: sweetness, sourness, aroma and edibility.     

Effect of overhead shading on yield and fruit quality of kiwifruit (Actinidia deliciosa)

Summary

Kiwifruit vines (cv. Hayward) were shaded from early spring until fruit harvest at levels of 100% (control), 70% or 45% full sun. Although shoot growth during the early part of the season was not significantly affected by the shading, the percentage bud burst was reduced and the time of full bloom appeared to be slightly delayed. The mean fresh weight of individual fruits was significantly reduced by shading, and fruit on shaded vines reached commercial harvest maturity of 6.2% soluble solids two to three days later than those on unshaded vines. During cool storage, fruit from vines grown under 45% full sun were slightly but consistently less firm and had lower soluble solids concentrations than unshaded fruit. No differences in the starch or total sugar contents were found between shaded or unshaded fruit, either at harvest or after cool storage. Shading vines did not affect either the colour (HunterLab values) or the chlorophyll concentration of fruit. Possible implications of these results for commercial orchards are discussed.     

Ascorbic acid level of Belgian apple genetic resources

With the help of the public, a wide collection of old apple cultivars (cvs) was established progressively at our Department from 1975 onwards. Currently, more than 1400 apple accessions are being maintained and three quarters of them are subjected to field evaluation for disease resistance and agronomic characters. This paper presents results of the ascorbic acid (Vitamin C) contents of old cvs combining interesting disease resistance and agronomic features in order to promote them as cvs adapted to production systems which are more environmentally friendly or to be used as parents in breeding programmes. First, a methodological study shows the importance of the variability of ascorbic acid content depending on fruit position in the trees, fruit size, fruit skin colour and maturity stage. Statistical analyses show that the sample size of six fruits per cv is sufficient to detect a difference of 20% between cvs. Old apple cvs such as Grenadier^RGF, Transparente de Croncels, Bramley’s Seedling, Reinette des Capucins, Reinette Libotte and Reinette de Waleffe contain three and seven times more ascorbic acid than the commercial cvs Gala and Elstar, respectively. The paper highlights the need to evaluate the rich potential in our genetic resources.     

Biochemical and physiological changes during chlorophyll degradation in lime (Citrus aurantifolia Swingle cv. ‘Paan’)

Summary

Lime (Citrus aurantifolia Swingle cv. ‘Paan’) native to South East Asia, has a distinct flavour and quality characteristics. Maintenance of the green colour in the peel of lime is a desirable quality attribute during storage. Post-harvest chlorophyll degradation in lime was studied in fruit stored at room temperature (30°C) at a relative humidity (RH) of 70 – 85%. Within 7 d of storage, the total chlorophyll content decreased to 53.9% of its initial level. The highest chlorophyllase activity (1.68 units mg^–1 protein) was observed after 4 d of storage and declined thereafter. Peroxidase activity differed from chlorophyllase activity and increased significantly to 6.25 units mg^–1 protein after 9 d of storage, (i.e., at the late maturity stage). Respiration rate and 1-aminocyclopropene-1-carboxylic acid (ACC) oxidase activity did not significantly affect the chlorophyll degradation process in lime.The total nitrogen content of lime peel was inversely correlated with its chlorophyll content. A higher soluble protein content was observed in yellow peel than in mature green peel. A colour index chart was developed for maturity stages 1–4 in lime based on peel colour changes from mature green to full-yellow, and its correlation with chlorophyll content and fruit quality attributes.     

Determination of optimal harvest boundaries for ‘Ambrosia’ apple fruit using a delta-absorbance meter

In this study, a new chlorophyll measurement tool, the delta absorbance (DA) meter, was used to develop an optimal harvest maturity model for ‘Ambrosia’ apple (Malus × domestica Borkh.) fruit. Fruit from four commercial orchards in the Annapolis Valley, Nova Scotia, Canada, were sampled (25 fruit from three or four trees per location) over nine consecutive weekly harvests during the 2011 and 2012 growing seasons, and 8 weeks in the 2013 season. At each harvest, five fruit from each orchard site had their index of absorbance difference (I_AD) values, firmness, mass, titratable acidity (TA), soluble solids content (SSC), red skin colouration and internal core ethylene concentrations measured. Following approx. 3 months of storage at 3.5°C, 20 fruit from each site were removed and assessed for the incidence of disorders such as senescent breakdown, cortical browning and coreflush. Chlorophyll concentrations in the epidermis were strongly and positively related to I_AD values in the same tissue (P ≤ 0.001), confirming the assumption that chlorophyll was the basis for the DA meter I_AD signal. In addition, I_AD values declined significantly during fruit maturity and were negatively related to harvest week (P ≤ 0.001). The optimum harvest period was identified by aligning all ‘at harvest’ I_AD values, fruit quality measurements, and ‘post-storage’ disorder data with the corresponding harvest week. I_AD values associated with harvests having the highest commercial fruit quality then delineated the optimal harvest boundaries. The upper boundary I_AD value of 0.47 was defined as ‘when to begin harvest’, while the lower boundary I_AD value of 0.28 was considered to be ‘when to end harvest’ for long-term storage. The use of a DA meter and its I_AD value to define the optimal harvest boundaries may be applicable to all commercial apple cultivars, but should be developed for each cultivar and growing region.     

Rootstock influence on the incidence of rind breakdown in ‘Navelate’ sweet orange

Summary

The influence of three rootstocks, Carrizo citrange (Citrus sinensis (L.) Osb. × Poncirus trifoliata (L.) Raf.), Cleopatra mandarin (Citrus reshni Hort. ex Tanaka) and sour orange (Citrus aurantium L.) on the incidence and severity of rind breakdown in ‘Navelate’ sweet oranges was studied over seven years in four orchards. The proportion of affected fruit was greater in trees on Carrizo citrange (60% on an average) followed by Cleopatra mandarin (38%) and then on sour orange (9%). There were also significant differences in the severity of the disorder among rootstocks; more than 35% and 20% of fruit from trees on Carrizo citrange and Cleopatra mandarin, respectively, were rejected for commercialization, whereas only 4% of fruit on sour orange was rejected. Cryo-scanning electron microscopy (SEM) of fruit peduncles showed that average diameter of xylem vessel elements of peduncles of fruits on Carrizo citrange rootstock were 6% and 17% larger than those on Cleopatra mandarin and sour orange, respectively. Defoliation of fruit-bearing branches reduced water loss from fruit, maintained fruit peel water potential at a higher value than that of fruit on undefoliated branches and reduced the proportion and severity of affected fruit. It is concluded that fruit-tree water relationships are related to rind breakdown in ‘Navelate’ oranges and low fruit water content might be responsible for the disorder.     

Rootstock influences the fruit mineral,sugar and organic acid content of a very early ripening peach cultivar

Summary

The influence of rootstocks differing in genetic origin and agronomic performance on the commercial characteristics and chemical composition of the fruit was investigated on the low-chill, very early ripening (fruit development period = 100 d) cv. Maravilha (Prunus persica (L.) Batsch) trained to a Y in a high density planting (2,500 trees per ha). Of the rootstocks tested, five belonged to P. persica (Harrow Blood, Ps B2, Ps C14, Rubira and Rutgers Red Leaf), three were hybrids of P. persica x P. dulcis (GF677, Hansen 2168 and Hansen 536) and two were complex hybrids of P. cerasifera (Mr S 2/5, M x P). The more vigorous graft combinations gave significantly higher yields. Rootstocks significantly influenced mineral content (N, K, Fe and Zn), sugars (sucrose and fructose) and organic acids (succinic) of the fruit, although these differences are not so important as to affect the commercial value of the fruit and to direct the choice towards one rootstock rather than another. Neither fruit weight, skin overcolour, shape nor refractometer value (°Brix) were affected by rootstocks. The short fruit development period together with the heavy pruning required for high density plantings presumably minimized differences in fruit quality between the graft combinations.     

The roles of cytokinins and abscisic acid in the pericarp of litchi (Litchi chinensis Sonn.) in determining fruit size

Summary

Variations in the concentrations of cytokinins (CTKs) and abscisic acid (ABA) were studied in the pericarp of litchi (Litchi chinensis Sonn.) fruit using the large-fruited cv. ‘Erdanli’ (55.3 g per fruit) and the small-fruited cv. ‘Huaizhi’ (20.9 g per fruit), as well as large fruit (32.4 g) from early blooms and small (20.8 g) fruit from late blooms on the same inflorescences of cv. ‘Feizixiao’ from the same commercial orchard in Guangdong, China in 2000. ‘Erdanli’ had higher concentrations of CTKs than cv. ‘Huaizhi’ on three out of six sampling dates during fruit development, and lower concentrations of abscisic acid (ABA) from 40 d after anthesis. In cv. ‘Feizixiao’, fruit from early blooms had higher concentration of CTKs than fruit from late blooms at all sampling dates, and lower concentrations of ABA on three out of five sampling dates. Therefore, the former had a higher CTK:ABA ratio. These data suggest that a high CTK:ABA ratio favours fruit growth in litchi.     

Effects of fruit thinning,pollination and paclobutrazol on fruit set and size of persimmon (Diospyros kaki L.) in subtropical Australia

Summary

A factorial combination of three cultural factors (± hand-pollination, ± growth retardant, ± fruit thinning) were evaluated for their effects on fruit set and fruit size of ‘Fuyu’ persimmon (Diospyros kaki L.) in subtropical Australia (Lat. 27° S). Treatments were applied to individual shoots on mature seven year old trees. Fruit set of pollinated flowers was high compared with non-pollinated flowers (91% vs. 47%). Pollinated fruit also grew faster at all stages of fruit development and, at harvest, fresh weights were 25% heavier. Palcobutrazol significantly (P<0.05) increased fruit weight by 7% compared with controls but did not increase fruit set. Irrespective of treatment, fruit weight was not correlated (r<0.3, n.s.) with shoot length, number of nodes per shoot, fruit nodal position, shoot dry weight, leaf area per shoot, and number of leaves per shoot. Fruit fresh weight was only poorly correlated with shoot base diameter (r = 0.41*). Pollinated fruit had significantly (P<0.05) higher concentrations of nutrients (N, K, Ca, and Zn).