Thesis (MSc)--Stellenbosch University, 2005. | ENGLISH ABSTRACT: Sunburn on apple and pear fruit results in large losses of export volumes in South African orchards. Producers estimate that losses due to sunburn are often about 10- 20%. Knowledge of temperature thresholds for sunburn as well as technologies available to manage sunburn is important to increase producer earnings. The effect of evaporative cooling on fruit surface temperature and sunburn was evaluated on 'Cripps' Pink', 'Royal Gala' and 'Fuji' apples as well as 'Forelle' pears. Evaporative cooling was effective in reducing fruit surface temperature by 0.6-3.7°C. Apple fruit under evaporative cooling treatments appeared to have acclimatised and had significantly higher surface temperatures when dry (0.9-4.7°C) than non-cooled fruit. This acclimitasing effect could be due to a modification of the cuticular wax layer. Futher trials are needed to investigate the cause of this acclimatising effect. The acclimatising effect was not found on 'Forelle' pears. Sunburn was reduced significantly only on 'Royal Gala' apples. Spraying 'Braeburn', 'Granny Smith', and 'Fuji' apples with reflective kaolin-based particle film (Surround WP) significantly reduced sunburn on 'Braeburn', 'Granny Smith' and 'Fuji' apple cultivars. Surround WP applications reduced leaf stomatal conductance and photosynthetic rate. Four applications of Surround WP with a commercial blower sprayer increased total soluble solids in 'Braeburn' . Four applications with a blower and five applications with a tower sprayer resulted in increased fruit size, higher flesh firmness, and lower percentage starch breakdown in 'Granny Smith'. Surround WP treatments slightly improved fruit colour in 'Granny Smith' apples. Futher trials are needed to establish whether Surround WP can,be reliably and economically removed from apple fruit and to evaluate the storage quality of fruit cleansed in this way. The effect of fruit surface temperatures (24°C, 30°C, 33-35°C, 40-43°C and 48-49°C) for increasing periods of time (two, four, six or eight hours) on maximum quantum yield of fluorescence (Fv/Fm) was measured on exposed and shaded sides of detached 'Cripps' Pink' and 'Royal Gala' apples. Measurements were taken directly after removal from the chamber as well as 12 hours later to assess recovery. Permanent damage to Photo system II (PSII) occurred between 48-49°C irrespective of duration, with permanent damage possible at 42-43°C when exposure exceeded six hours. There were no meaningful differences in Fv/Fm between shaded and exposed sides of apple fruit after exposure to high temperature. Duration of exposure was important in lowering PSU efficiency in 'Cripps' Pink' but less so in 'Royal Gala'. 'Cripps' Pink' apples harvested later in the season appeared to be able to recover from heat stress better than apples harvested earlier in the season. However, we only studied the effects of high temperature on apple tissues. More research is needed to establish the reaction of apple tissues to high temperatures in the presence of sunlight. | AFRIKAANSE OPSOMMING: Sonbrand op appel en peervrugte kom jaarliks voor in Suid-Afrikaanse boorde en lei tot groot afnames in vrugte wat geskik is vir die uitvoermark. Produsente beraam dat verliese a.g.v. sonbrand jaarliks 10-20% beloop. Kennis van drempelwaarde temperature vir die ontwikkeling van sonbrand sowel as die tegnologieë wat beskikbaar is om sonbrand te bekamp, is van groot belang om uitpakke te verbeter. Die effek van oorhoofse besproeïng op vrugtemperature en sonbrand van 'Cripps' Pink', 'Royal Gala' en 'Fuji' appels sowel as 'Forelle' pere is ondersoek. Oorhoofse besproeïng het vrugtemperature betekenisvol verlaag in al die proewe. Dit wil voorkom of appels onder oorhoofse besproeïng geakklimatiseer het en dié appels het hoër skil temperature geopenbaar wanneer hulle droog was as die kontrole vrugte. Moontlik is die effek te wyte aan 'n verandering in die kutikulêre waslaag. Verdere proewe om hierdie verskynsel te probeer verklaar is nodig. Die effek is nie waargeneem op die 'Forelle' pere nie. Sonbrand is betekenisvol verminder op 'Royal Gala' appels. Toediening van weerkaatsende kaolin-gebaseerde partikels (Surround'" WP) het sonbrand betenisvol verlaag op 'Braeburn' , 'Granny Smith', en 'Fuji' appels. Surround® WP toedienings het blaarhuidmondjie-geleiding en die tempo van fotosintese verlaag. Vier toedienings van Surround® WP met 'n kommersiële waaierblaser het totale oplosbare vastestowwe (TOVS) beduidend verhoog in 'Braeburn' appels. Vier toedienings met 'n waaierblaser en vyf toedienings met 'n toring spuitkar het gelei tot 'n verhoging in vrugmassa en vrugferrnheid, en 'n verlaging in persentasie styselafbraak in 'Granny Smith' appels. Surround® WP toedienings het gelei tot effens beter kleur op 'Granny Smith' appels. Verdere proewe is nodig om te bepaal of Surround® WP op 'n betroubare en ekonomiese wyse van vrugte verwyder kan word in die pakstoor, en wat die hou-vermoë is van appels wat só behandel is. Die effek van vrugoppervlaktemperature (24°C, 30°C, 33-35°C, 40-43°C en 48-49°C) vir toenemende tydsdure (twee, vier, ses en agt ure) op maksimum kwantum-opbrengs van fluoressensie is gemeet op sonkante en skadukante van geplukte 'Cripps' Pink' en 'Royal Gala' appels. Metings is geneem direk na verwydering uit die oonde sowel as 12 ure later om moontlike herstel waar te neem. Permanente skade aan Fotosisteem II (PSII) het plaasgevind tussen 48-49°C ongeag tydsduur, met permanente skade ook moontlik by 42-43°C wanneer blootstelling aan genoemde temperature ses ure oorskry het. Daar was geen betekenisvolle verskille in Fv/Fm tussen skadu- en sonkante van appels na blootstelling aan hoë temperature nie. Die tydsduur van blootstelling was belangrik om PSII effektiwiteit te verlaag in 'Cripps' Pink', maar minder so in 'Royal Gala'. Dit wil voorkom of 'Cripps' Pink' appels later in die seisoen beter daartoe in staat is om te herstel van hitte stres as vroeër in die seisoen. Ons het egter slegs die effek van hoë temperature op appel weefsels ondersoek. Verdere proewe is nodig om die reaksie van appelweefsels op hoë temperature in die teenwoordigheid van sonlig te ondersoek.

We investigated the effectiveness of equipment for auditory and visual stimulus, repellents, and wrapping fruits for protecting a citrus crop from avian spoilage. Equipment that broadcast distress calls showed no effect against the brown-eared bulbul, but eye-pattern equipment with sound of explosive concussions that were set up 15m from a feeding station decreased fruits damage by about 30 to 40%. Use of bird-models combined with 3 kinds of bird-call showed high effectiveness against the crow. In case of dipping artificial bait in a repellent solution, the birds didn't feed. However, there was almost no practical repellent effect with volatilized smell only. Owl model decreased bird-caused damage by about 25 to 30%, but magnets set near a feeding station had no detectable effect against the brown-eared bulbul. Wrapping the fruits in translucent red, white or light blue bags were ineffective in preventing damage, but green or blue green bags that are similar in color to the citrus leaves had less damage. However, wrapping in green paper bags before the coloring of fruits of citrus cultivar 'Kiyomi' had a tendency to adversely affect rind color. Wrapping the fruits in polyester netting clearly gave better control than paper bags. There is a possibility that the effectiveness of these measures will decrease because of habituation of the birds over the course of long-term use, necessitating that their application be limited to use only when necessary.

Aminoethoxyvinylglycine (AVG) applied as a spray to 'Arlet' apple trees inhibited fruit drop and increased the pull force necessary to detach the fruit. AVG delayed the loss of fruit firmness, starch degradation, fruit shriveling, and red color development. 1-Methylcyclopropene (1-MCP), applied as a gas or spray to trees in the field, did not affect fruit drop or pull force. The combination of AVG + 1-MCP (spray or gas) provided better control of fruit drop, slowed the loss of fruit firmness, starch degradation, and decrease in pull force than AVG alone. Thirty five days after the optimum harvest date, fruit firmness from trees sprayed with AVG + 1-MCP was maintained at 74.3 N. Fruit of the control was significantly lower at 61.4 N firmness. The delay in harvest caused untreated control fruit stems to turn brown and die, but stems on AVG treated trees remained green and fruit continued to grow. In the 35 days after the optimum harvest date, treated fruit increased 2.5 cm in fruit diameter.

Effects of 1 - methylcyclopropene (1-MCP) and an ethylene absorbent (active carbon containing palladium chloride) treatment on fruit softening and shelf life after removal of astringency by dry ice (CO2) in Japanese persimmon 'Saijo' (Diospyros kaki Thunb.) harvested at various stages, were investigated. At the end of the dry ice treatment, 78.1% of the control (non - treated) fruit harvested at the early stage (October 1) softened, whereas no control fruit harvested at the middle stage of the harvesting season (between October 22 and 29) softened, 50.0% of the control fruit harvested on November 11 softened. The ethylene concentration in the polyethylene bag 48 hours after start of dry ice treatment was highest in fruit harvested at the early stage. It decreased gradually in fruits harvested at a more mature stage. Both 1 - MCP and ethylene absorbent treatments significantly decreased the fruit softening rate after the removal of astringency in fruit harvested at the early stage. However, there was little inhibitory effect of 1 - MCP and ethylene absorbent on the softening of fruit harvested at the late stage. In fruit harvested at the middle stage, 1-MCP treatment prolonged the shelf life of fruit by about 6 days, compared to the non-treated control fruits, the ethylene absorbent treatment was ineffective in prolonging shelf life.

Objectives: To replicate the finding of a negative association between parental control and fruit and vegetable consumption in girls. To extend the investigation to boys and examine sex differences. To test the hypothesis that children's food neophobia explains this association. Design: Cross-sectional questionnaire survey. Measures: The questionnaire included items assessing parents' and children's fruit and vegetable intake, the Parental Control Index, and the Child Food Neophobia Scale. Subjects: Parents of 564 2- to 6-year-old children, recruited from 22 London nursery schools. Statistical analysis: Relationships between continuous variables were examined with Pearson product moment correlation coefficients. Sex differences were tested using independent sample t tests, and sex differences in correlations were assessed from their 95% confidence intervals. Parental control and children's food neophobia were entered into a hierarchical multiple regression to test the hypothesis that neophobia explains the association between parental control and children's fruit and vegetable intake. Results: We replicated the finding that parental control was correlated with children's fruit and vegetable consumption and found no significant sex differences. Parental fruit and vegetable consumption and children's food neophobia were also strong predictors of children's fruit and vegetable consumption, and both were associated with parental control, suggesting that they might explain the association between control and intake. Controlling for children's food neophobia and parental intake reduced the association of parental control with children's fruit and vegetable intake to nonsignificance. Conclusions: These findings emphasize the importance of systematic research about associations between parental feeding styles and children's dietary habits so that dietetics professionals can give parents sound advice.

Muskmelon [Cucumis melo L. (Reticulatus Group)] fruit sugar content is directly related to potassium (K)-mediated phloem transport of sucrose into the fruit. However, during fruit growth and maturation, soil fertilization alone is often inadequate (due to poor root uptake and competitive uptake inhibition from calcium and magnesium) to satisfy the numerous K-dependent processes, such as photosynthesis, phloem transport, and fruit growth. Experiments were conducted during Spring 2003 and 2004 to determine if supplemental foliar K applications during the fruit growth and maturation period would alleviate this apparent inadequate K availability in orange-flesh muskmelon 'Cruiser'. Plants were grown in a greenhouse and fertilized throughout the study with a soil-applied N-P-K fertilizer. Flowers were hand pollinated and only one fruit per plant was allowed to develop. Starting at 3 to 5 days after fruit set, and up to 3 to 5 days prior to fruit maturity (full slip), entire plants, including the fruit, were sprayed with a glycine amino acid-complexed potassium (potassium metalosate, 24% K) solution, diluted to 4.0 mL.L(-1). Three sets of plants were sprayed either weekly (once per week), biweekly (once every 2 weeks) or not sprayed (control). Fruit from plants receiving supplemental foliar K matured on average 2 days earlier than those from control plants. In general, there were no differences in fruit maturity or quality aspects between the weekly and biweekly treatments except for fruit sugar and beta-carotene concentrations, which were significantly higher in the weekly compared to the biweekly or control treatments. Supplemental foliar K applications also resulted in significantly firmer fruit with higher K, soluble solids, total sugars, ascorbic acid (vitamin C) and beta-carotene concentrations than fruit from control plants. These results demonstrate that carefully timed foliar K nutrition can alleviate the developmentally induced K deficiency effects on fruit quality and marketability.

The effect of processing cantaloupe melon under ultraviolet-C (UV-C) radiation on storage properties of the cut fruit at 10 degrees C was compared with post-cut UV-C fruit treatment and the untreated control. Cutting fruit under UV-C light induced a hypersensitive defense response that resulted in increased accumulation of ascorbate peroxidase relative to the other 2 treatments. Fruit processed under UV-C radiation had the lowest esterase activity throughout the storage period. Lipase activity was higher in post-cut treated fruit than fruit processed under UV-C light and the control fruit. Lipase activity, however, decreased rapidly in fruit processed under UV-C and was undetectable after 7 d of storage. Human sensory aroma evaluation indicates reduced rancidity, and instrumental texture measurements suggested improved firmness retention in fruit cut under UV-C radiation. The treatment also reduced respiration during cut fruit storage. UV-C was effective in reducing yeast, mold, and Pseudomonas spp populations in both treatments. Fresh-cut pieces from whole melon cut under UV light had lower populations of aerobic mesophilic and lactic acid bacteria relative to the control and post-cut treated pieces. Results indicate that while post-cut application of UV improved shelf life of cut cantaloupe melon, cutting fruit under UV-C radiation further improves product quality.

The effects of adding deep seawater to a nutrient solution in hydroponics using organic substrates on the plant growth and fruit yield and quality of tomatoes pinched above the 4th truss were investigated. Deep seawater was added to the nutrient solution at concentrations of 20%, 10%, 2%, and 0% (control). With the addition of deep seawater at 2%, plant growth was almost the same as that of the control, but was depressed at 10 and 20%. The marketable fruit yield with 2% deep seawater addition was 65% of the control, while those of 10 and 20% additions were 36 and 38%, respectively. The reduction of marketable fruit yields by the addition of deep seawater was attributed to a decrease in fruit weight and number as well as an increase in defective fruit. However, the soluble solid content and titratable acidity of the fruit increased with the addition of deep seawater. The results indicated that the tomato fruit quality might be improved with the addition of deep seawater to a nutrient solution.