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.     

The effect of gibberellins and cytokinins on fruit development of Bramley’s Seedling apple

Two applications of a 1 : 1 mixture of gibberellins A₄ and A₇ to either frost damaged or artificially decapitated Bramley's Seedling apple flowers resulted in increased fruit set and yield. It also increased the crop in an orchard without pollinators. Gibberellic acid was not effective. The addition of cytokinins had no beneficial effects and caused malformation.     

The effect of rootstock on yield and quality of ‘Mutsu’ apples

Summary

Yield and fruit quality parameters were studied during three years in a rootstock trial with ‘Mutsu’ apple. M.9 provided the highest total yield per tree as well as the highest quantity of intermediate and yellow fruit as compared with J.9, M.26 and B.9. Within similar colour categories, significant differences among rootstocks were also recorded for fruit starch degradation pattern (SDP), firmness, titratable acidity (TA), and soluble solids concentrations (SSC). Generally, the lowest SDP and highest fruit firmness was found in fruits from trees on rootstocks M.26 and B.9. The highest TA was found in fruits from trees on rootstocks M.26 and J.9 and the highest SSC in fruits from trees on rootstocks J.9 and B.9. However, considerable variations among years were also recorded. Correlation coefficients between rootstock and several yield and quality parameters revealed high correlation to SSC for green fruit and TA for medium and yellow fruit and some correlation to yield and number of fruits per tree.     

Improvement of fruit quality and storage potential of ‘Braeburn’ apple through deficit irrigation

Summary

We explored the potential of deficit irrigation (DI) applied at different times during the growing season for improving fruit quality and storage potential of ‘Braeburn’ apple growing in a commercial orchard. Because DI often reduces fruit size, effects of fruit size on fruit quality were also examined. The irrigation treatments were: commercially irrigated control (C), early deficit irrigation (EDI) applied from 63 to 118 d after full bloom (DAFB), and late decifit irrigation (LDI) applied from 118 DAFB to final harvest on 201 DAFB. Both EDI and LDI improved fruit quality in terms of increases in: dry-matter concentration (DMC) at harvest, flesh firmness, total soluble solids, and total soluble sugars both at harvest and after storage. The DI fruit had less weight loss during storage than did C fruit. Deficit irrigation affected the concentrations of a few individual aroma volatiles but not total volatile concentration. Incidence of physiological disorders was not affected by irrigation treatments. Mean fruit weight was lower in DI than in C but the difference was not significant. Among the quality attributes studied, only firmness and DMC were affected by fruit size with their values being higher in smaller fruit.     

The effect of selective picking on the harvest fruit size distribution of ‘Royal Gala‘ apples

Summary

The size distribution of fruit on an apple tree on any potential harvest date can be estimated by measuring a sample of fruit early in the season and projecting forward in time using standard growth curves. However, ‘Royal Gala‘ apples grown in New Zealand are picked in multiple harvests spread over about three weeks, so the overall size distribution of harvested fruit can differ significantly from that on any single harvest date. On each havest date, fruit are selected for picking according to background colour, not size. By measuring the sizes at harvest of all fruit on selected limbs of eight ‘Royal Gala‘ trees in Hawkes Bay, New Zealand, we show that the relationship between the size distributions of picked and unpicked fruit can be described by a single-parameter model. Although size is not used directly in fruit selection, we find that larger fruit still tend to be picked first, with the odds of a fruit being selected approximately doubling for each 20.g increase in size. The mean harvest fruit size is largest for the first harvest, and decreases in later harvests, despite ongoing fruit growth. Because the smaller fruit left on the trees continue to grow, the standard deviation of the overall fruit size distribution from multiple harvests can be expected to be significantly smaller than it would have been had all fruit been harvested on the same date. The model is tested using size and background colour measurements collected on tagged fruit at three sites in two years, including a range of shading and crop load treatments. For most combinations of site, year and treatment, the model predicted the size distribution of picked fruit well, but in a few cases a different parameter value was need to obtain a good fit.     

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 influence of endothal and 6-benzyladenine on crop load and fruit quality of red ‘Delicious’ apple

Summary

Trial work over a two year period examined the aquatic herbicide endothal as a blossom thinner in conjunction with 6-benzyladenine (CyLex?) as a post-bloom thinner. The aim was to develop an effective thinning programme using endothal and CyLex?, to examine any interactions between the two chemicals, and to assess the impact of endothal on fruit quality. Time of application of endothal was shown to be critical in achieving a satisfactory level of thinning. Multiple applications of lower chemical rates were also successful, and may have potential to provide an effective programme for cultivars with long flowering periods, which are traditionally most difficult to thin. Addition of a surfactant to the spray mix significantly increased the thinning effect of endothal, resulting in severe over-thinning. This work has demonstrated that endothal is an effective thinner of red ‘Delicious’ apples. It is most effective when applied twice during the blossom period, the first application at 20% bloom and the second at 80% bloom. There is no advantage in increasing the concentration above 1.0 cm³ dm^-3 (v/v). Endothal can also be effectively combined in a programme with the post-bloom thinner CyLex? applied at 150 mg l”¹ at a spray volume of 12001 ha^-1. Addition of CyLex? to the spray programme has the added benefits of increasing fruit weight and size. Fruit sugar content and firmness were both increased by application of endothal. The greater the number of applications the higher the firmness and sugar content of the fruit. Both these findings are additional benefits to the thinning effect. Both pip number and fruit length/diameter ratio were slightly reduced by endothal. Cylex and some endothal treatments increased the incidence of fruit russet.     

The effect of defoliation on bulb production of tulip cultivar ‘Apeldoorn’

The distribution of dry matter between the different bulblets of tulip is not markedly influenced by either changes in leaf area or the position of the leaf. On the contrary, total bulb yield is strongly affected.A reduction factor, S_c, for incomplete soil coverage, when the leaf area index (LAI) is less than 4, normally used for evaluation of planting density effects, can also be used for the effects of defoliation on dry matter increase. This LAI-dependent factor shows a distinctly asymptotic pathway closely resembling

$\text{S}{}_{\mathrm{c}}\text{=}\text{P}{}_{\mathrm{act}}\text{P}{}_{\mathrm{pot}}\text{=1?e}{}^{\mathrm{?k1LAI}}$

where k ～ 0.6 and in which P_act is the actual measured dry weight increase and $\text{P}\text{?}{}_{\mathrm{<mtext>pot</mtext>}}$ the potential net dry weight increase for a closed canopy.     

The thinning effect of benzyladenine on red ‘Fuji’ apple trees

A trial, at the Grove Research Station in southern Tasmania, studied the thinning effect of benzyladenine (BA) on five year old red ‘Fuji’ apple trees. Untreated control trees were compared with trees treated at four timings, from full bloom (FB) to 30 d after full bloom (AFB), with four concentrations of BA (50, 100, 200 or 400 mg I-1). The most effective time of thinning was 20 d AFB, when increasing concentration also increased thinning. Further advantages of this successful thinning were reflected in better fruit size and weight. At 30 d AFB high concentrations of BA depressed fruit weight. Return bloom was improved significantly by both 20 and 30 d. AFB sprays with a concentration effect at 20 d AFB. Timing of sprays had no effect on the incidence of russet which was increased only by applications of 400 mg l-1. Both the higher concentrations and later timings resulted in an increase in shoot numbers and total growth. Reduction in mean shoot length was related more to the concentration of BA used than to differences in the timing of sprays. BA has shown potential as a thinner for red ‘Fuji’ apple at 20 d AFB.     

Influence of rootstock on orchard productivity and fruit quality in peach cv. ‘Redhaven’

Summary

We have evaluated the influence of four different peach rootstocks (Prunus pumila,‘GF 655/2’ ,‘Missour’ and ‘GF 677’ as a standard) planted in medium-heavy to heavy soil on phenological events (flowering and harvest date), growth, yield, fruit quality and mortality of peach (P. persica L.) scions of cv. ‘Redhaven’. At the end of flowering, there were no significant differences between the different rootstocks in the years 1999, 2000, 2003 and 2004. In 2001, trees grafted on P. pumila reached the end of flowering 2 d before trees grafted on the other rootstocks. ‘Redhaven’ fruits ripened on the same day on trees grafted on the different rootstocks. The differences were only between years. The results showed that significantly less vigorous trees, according to their trunk cross-sectional area (TCSA) and canopy volume, with the lowest yield, were observed on P. pumila rootstock. The rootstock P. pumila had a significant negative influence on fruit dimensions and mortality was 50%. Trees grafted on ‘GF 655/2’ rootstock produced significantly lower yields than those grafted on ‘GF 677’ or ‘Missour’ rootstocks. Only the ‘GF 655/2’ rootstock had root suckers. Trees grafted on ‘GF 677’ rootstock were significantly more vigorous than on the other rootstocks, and produced the highest yield with good fruit quality. The final canopy volumes of peach trees grafted on the different rootstocks were very different. The most vigorous trees were those grafted on ‘GF 677’ rootstock, where the final tree volume was 12.8 m³. Trees grafted on P. pumila and ‘GF 655/2’ had significantly lower TCSA values than on the other rootstocks.     

The effect of summer pruning and nitrogen on growth,cropping and storage quality of Cox’s Orange Pippin apple

Pruning in late summer was compared with winter pruning on mature 23-year-old spur pruned trees of Cox’s Orange Pippin on M.2 rootstock. Two nitrogen treatments were superimposed, namely a standard dressing of 126 units N (sulphate of ammonia) applied in March as compared with 288 units N (nitrate of soda) applied in mid-August at the time of summer pruning. Summer pruning reduced trunk girth increment, advanced blossom development, increased the amount of red colour on the fruits and drastically reduced the incidence of bitter pit in stored fruit. The treatments did not affect cropping. Nitrogen treatments had no overall effect upon the incidence of bitter pit, but in the first season, when bitter pit was most prevalent, high levels of N applied in August reduced the amount, a similar trend being recorded the following year.     

Effect of storage regimes on pectolytic enzymes,pectic substances,internal conductivity and gel breakdown in cold stored ‘Songold’ plums

Summary

Plums (Prunus salicina cv. Songold) were cold stored according to a single-temperature regime comprising 28 d at ?0.5°C, and a dual-temperature regime comprising 10 d at ?0.5°C followed by 18 d at 7.2°C. After cold storage, the plums were ripened for 8 d at 10°C. Pectolytic enzyme activity, pectic composition, internal conductivity and gel breakdown were determined at seven stages during storage and ripening. Although not exposed to chilling temperatures prior to harvest, approximately 10% of the plums exhibited gel breakdown at harvest, indicating that the disorder cannot be classified solely as a cold-storage chilling disorder. The higher temperatures of the dual-temperature regime resulted in higher polygalacturonase activity than with the single-temperature fruit. Consequently, protopectin degradation and the concomitant production of water- soluble pectins were greater in the dual-temperature fruit. Single-temperature storage resulted in higher pectinmethylesterase activity during the latter stages of storage and during ripening. Increases in temperature after 10 d and 28 d in dual- and single- temperature fruit, respectively, were associated with significant increases in the viscosity of water-soluble pectins, internal conductivity and gel breakdown. The significant positive correlation between internal conductivity and gel breakdown suggested that membrane integrity is closely associated with development of gel breakdown.     

Differential propylene induced ethylene production in ‘Anjou’ pears during storage at chilling and non-chilling temperatures

Summary

‘Anjou’ pears were harvested from the Mid-Columbia Experiment Station, Hood River, Oregon, at 67 N firmness, stored at –1° or 20°C for 85 d and periodically tested for sensitivity to 0 or 500 µl l^?1 propylene for at least 14 d at 20°C. Climacteric ethylene of pears stored at 20°C remained at low levels and started rising on the 90th day. Pears chilled at –1°C required 70 d to ripen and produced climacteric ethylene immediately upon transfer to 20°C. The sensitivity of the fruit to exogenous propylene increased progressively with storage time at –1°C. However, the non-chilled fruit responded to propylene similarly to freshly harvested fruit during the first 55 d of storage, then similarly to –1°C-stored fruit up to 85 d. Anjou pear ripening events and the sensitivity of the fruit to exogenous propylene developed differently in storage at non-chilling temperature compared with chilling temperature.     

Preharvest applications of ethephon reduce superficial scald of ‘Fuji’ and ‘Granny Smith’ apples in storage

In 1989 and 1990, preharvest applications of 2-chloroethyl phosphonic acid (ethephon) at dosages from 50–400 mg 1’1 were applied to ‘Fuji’ and ‘Granny Smith’ apples. In 1989, the greatest reduction in scald after storage on both ‘Fuji’ and ‘Granny Smith’, relative to the untreated control resulted from applying 400 mg 1^?1 ethephon five weeks before harvest and was 45% and 55% of controls, respectively. On ‘Granny Smith’ 400 mg 1^? was also effective when applied three weeks before harvest. In 1990, preharvest applications of ethephon at either 200 or 400 mg 1^?1 reduced scald in both cultivars relative to the controls. Ethephon applied six weeks before harvest had no dosage effect on scald reduction after storage. There was no consistent effect on fruit maturity at harvest from any treatment in either year, and no effect on quality of fruit out of storage.     

The effects of low temperatures on the vegetative growth and flowering of the primocane fruiting raspberry ‘Autumn Bliss’

Summary

The effects of low temperatures on subsequent vegetative growth and flowering in the raspberry ‘AutumnBliss’ were investigated. In the first experiment, a number of lifting dates were used to determine the seasonal pattern of dormancy and the effect of natural chilling on plant development. In the second, different durations of artificial chilling(0, 2, 4, 6, 8 and 10 weeks at 0?C) were combined with two lifting dates to investigate the effect of natural and artificial chilling. In these experiments, plants which received little chilling grew slowly and failed to develop beyond short rosettes of leaves but as chilling increased, the rate of vegetative growth increased. This coincided with a decline in the time toflowering. These two responses, however, were distinct. In a third experiment, the effect of vernalization of actively growing canes was tested in an attempt to separate the effects of cold on time to flowering, and on the removalof dormancy. The plants responded significantly to cold treatment and flowering was advanced, indicating a distinct vernalizing effect     

Effect of calcium supply on the physiology of fruit tissue in ‘Andesu’ netted melon

Summary

Fruit development and physiological traits were evaluated in ‘Andesu’ netted melon plants grown with and without calcium. Calcium exclusion accelerated softening, alcoholic fermentation and ethylene evolution of fruit compared with those supplied with calcium, but the opposite trend occurred with sucrose accumulation. A significant difference of calcium concentrations in the fruit between treatments was observed at the developing stage of the fruit (P<0.05), but the difference became smaller as fruit matured. In the mesocarp tissue from the basal hemisphere, calcium concentrations in the NaCl soluble fraction at ripe fruit stage differed significantly (P<0.05) between calcium treatments but no significant difference was detected in the inner mesocarp of the distal hemisphere. Calcium exclusion did not lead to the development of water-soaked symptoms in the mesocarp tissue of ripe fruit. Uronic acid concentrations in ionically bound pectin fraction did not differ between calcium treatments throughout fruit development. In covalently-bound pectin fraction, however, uronic acid concentration of ripe fruit was significantly lower in calcium-excluded plants than in calcium-supplied plants (P<0.05). Our results suggest that: first, accelerated fruit softening under calcium deficient conditions might result from promoted ethylene evolution rather than from the shortage of ionically-bound calcium in cell walls, second, calcium deficient condition does not necessarily lead to water-soaked symptoms in tissue of ‘Andesu’ melon fruit.     

Effects of rate of establishment of storage conditions and ethylene removal on the storage performance of ‘Cox's Orange Pippin’ apples

The use of rapid establishment of temperature and CA storage conditions, as well as ethylene removal to reduce loss of firmness and ground colour, during storage of apples (Malus domestica Borkh, ‘Cox's Orange Pippin’) in <1% CO₂ + 1.25% O₂ at 3.5°C was investigated. Samples subjected to rapid establishment (RE) of storage conditions had a higher peel chlorophyll content after 5 months storage, but not after 8 months, than samples from containers where the conditions had been established at a rate typical of normal, well-maintained commercial stores (CR). RE samples were considered firmer than CR by a sensory panel in February but not in May, while penetrometer readings were the same on both occasions. RE samples which had additionally been subjected to a pre-harvest daminozide spray and ethylene removal during storage (LE) were firmer, had a higher peel chlorophyll content and, on the green parts of the surface, a lower Hunter “b” value in February than both CR and RE samples. The effects of LE on chlorophyll and ground colour were maintained until May, but in both February and May only the ground colour effect was maintained during a simulated marketing period of 14 days at 10°C in air following storage.     

The effect of ε-aminocaproic acid on self-incompatibility and incongruity in Phaseolus

Summary

The effects of ε-aminocaproic acid (EACA) on self-incompatibility was tested in a Phaseolus coccineus line which failed to form pods in controlled pollinations. Scanning electron microscope (SEM) and fluorescence miscroscopy confirmed problems in pollen-germination and pollen-tube growth but EACA-treated self- pollinations resulted in fairly normal pollen germination and pollen tube growth. In a few cases, pollen tubes were seen entering the embryo sac and occasionally pods were formed. Incongruity barriers also exist in crosses of P. coccineus × P. vulgaris, P. acutifolius × P. coccineus and their reciprocals. Effects of EACA on flower abscission, pod development and pod abscission were studied. Increased pod formation was observed in EACA treated materials, except in P. acutifolius × P. coccineus and P. coccineus × P. vulgaris cv. Jacobs Cattle. EACA seems to act at the stigmatic and stylar levels, thereby enhancing pollen germination and pollen tube growth and delaying flower abscission. The net result is fertilization and delayed senescence which permit the pod to grow for a longer period of time.     

Effects of crop load and time of thinning on the incidence of split pits,fruit yield,fruit quality,and leaf mineral contents in ‘Andross’ peach

Summary

The effects of light, moderate, or heavy thinning (5, 10, or 20 cm between fruit, respectively), conducted before (7 d or 15 d), during, or after (7 d or 15 d) pit hardening (PH), on the incidence of split pits, fruit yield, fruit quality characteristics, and leaf mineral contents, were studied in the canning peach (Prunus persica L. Batsch.) cultivar ‘Andross’ over two growing seasons. The percentage of fruit with split pits increased by 58.2% in heavily-thinned trees compared with moderately- or lightly-thinned trees, and by 22.9% for the earliest time of thinning (15 d before PH) compared with thinning during, or after PH. Fruit fresh weight (FW) was greater in moderately- and heavily-thinned trees compared with lightly-thinned trees, but yields were similar among the different crop-load treatments. The latest time of thinning (15 d after PH) also had a negative impact on yield at first harvest and on total yield, fruit FW, and delayed fruit ripening compared to thinning during, and 15 d before PH. Total anti-oxidant capacities and phenolic contents were usually greater in fruit from heavily-thinned compared with lightly- or moderately-thinned trees only when thinning was conducted during, or 15 d after PH. Moreover, anti-oxidant levels were highest in fruit from the earliest-thinned trees. There was no significant effect of crop load, or of time of thinning application treatment on fruit colour, or on the K, P, Fe, Mn, and Cu contents of leaf tissues. In conclusion, light or moderate thinning during PH resulted in minimal split pits during processing, and in optimal yields and fruit quality characteristics in the canning peach cultivar ‘Andross’.