Fruit Quality Indices Research Articles

Influence of First-Generation White Apple Leafhopper (Homoptera: Cicadellidae) and Leaf-to-Fruit Ratio on Apple Fruit Size and Quality

Girdled limbs of ‘Campbell Redchief Delicious’ apple ( Malus domestica Bork-hallser) trees were treated with a factorial combination of four first-generation white apple leafhopper, Typhlocyba pamaria McAtee, populations and three leaf-to-fruit ratios. Fruit size, fruit soluble solids concentration, and fruit surface red color were related positively to leaf- to-fruit ratio, whereas none of the indices of fruit size or quality was consistently influenced by leafhoppers. These data indicate that action threshold levels for first-generation leafhoppers should be increased to three or more leafhoppers per leaf.

Effects of Cultivars and Culture Systems on Yield and Postharvest Quality of Greenhouse Tomato

Our purpose was to determine cultivar and culture system effects on yield and postharvest quality of greenhouse tomato Lycopersicon esculentum. Nine tomato cultivars were sown into rockwool cubes on 2 Feb. 1994. The plants were transplanted into peat bags or nutrient film (NFT) systems on 9 Mar. Harvesting began on 2 May until 26 Sept. for a total of 21 harvest weeks. Fruit yield, rejected or nonmarketable fruit and four fruit quality indicators (fruit texture, color, titrable acidity, and soluble sugars) were measured during the harvest period. In addition, these indicators were further evaluated every 7 days during 28 days of storage at 20C and 90% RH for `Trust' and `Cencara', a long shelf-life cultivar. `Bounty', `Panther', and `Cencara' gave higher yields on rockwool but `Irazu', `Correct', `73-53', and `Medallion' gave better results on NFT. `Trust' produced the best yield for either rockwool or NFT. Culture systems (peat bags or NFT) did not affect fruit quality. `Cencara', which is a long shelf-life cultivar, kept high texture quality until 28 days of storage. However, titrable acidity of `Cencara' was higher and soluble sugars content was lower than that of `Trust'

Hawaiian tephritid fruit flies (Diptera): integrity of the infestation-free quarantine procedure for 'Sharwil' avocado.

In 1990, the infestation-free quarantine procedure for 'Sharwil' avocados grown in Kona, HI, was approved based on the assumption that fruits on trees are not hosts of tephritid fruit flies. In February 1992, the infestation-free quarantine procedure was suspended because of discovery of oriental fruit fly, Bactrocera dorsalis (Hendel), larval infestation in fruits on trees in certified orchards. Subsequently, an intensive field study was conducted to determine the level of tephritid fruit fly infestations in 'Sharwil' fruits. Results gathered negated two assumptions of the infestation-free quarantine procedure. First, the procedure assumed that only immature and mature green fruits are attached on trees; our data showed that, although most fruits on trees were either immature or mature green, a few ripe fruits occurred during the fruiting season. Second, the procedure assumed that mature green fruits have absolute resistance to tephritid fruit flies occurring in Hawaii; our field data showed that mature green 'Sharwil' avocados are suitable hosts of oriental fruit fly, albeit poor hosts. We present several hypotheses that may explain the failure of the infestation-free quarantine procedure for 'Sharwil' avocados. Morphological, physical, and chemical attributes of maturing 'Sharwil' fruits that may be useful in developing indices of fruit maturity and quality are also presented.

Fusion Classification Techniques for Fruit Quality

This study presents an approach to automated fruit sorting using information that is acquired from selected sensors which measure and quantify parameters (color, firmness, size, shape, weight) that are indicators of fruit quality. The information is used as input to a recurrent autoassociative memory that classifies the fruits into four maturity stages. This approach achieved excellent results in the classification of cantaloupes (85.1% correct classification and 10.1% neighbor class classification), and has the advantages of rapid training using small numbers of samples and classification capability for different cultivars (of cantaloupes) without additional training. This approach has been developed to simulate manual fruit classification by human sorters.

Individual Variation in Fruit Choice by American Robins (Turdus migratorius)

A13STRACT.--I tested American Robins (Turdus migratorius) for individual differences in fruit consumption and preference when offered six trials of a three-way choice of white mulberry (red variety; Morus alba L.), Bella honeysuckle (Lonicera x bella), and red-osier dogwood (Cornus stolonifera Michx.) fruits. Fruit choice was examined secondarily in relation to indices of fruit quality (fruit mass, percent water, refractive index, trial date, source plant) and in relation to age, sex, and individual morphometric variation of the birds. Pooling all trials and all birds, mulberry was eaten significantly more than either honeysuckle or dogwood. Although adults differed from juveniles in body mass at capture and in relative bill dimensions, fruit choice did not vary in relation to age or sex. Also, juveniles were not more variable than adults in fruit choice. However, individual birds differed significantly in fruit choice (15 preferred mulberry, 2 preferred dogwood, 0 preferred honeysuckle), and 15 individuals were consistent in fruit choice from trial-to-trial. Indices of fruit quality changed over the course of the study. For each of the three fruit species, some variables were significantly different among individual plants, over time, or both. Some fruit-quality variables explained small but significant amounts of variation in fruit consumption (numbers of fruits eaten) and preference (number of fruit A eaten/[(number of fruit B eaten) + (number of fruit C eaten)]. Robins preferred fruits from mulberry trees that had fruits of relatively lower mass and higher refractive index. After I controlled for effects of fruit quality, trial date, and source plant in multiple regression analyses, residual consumption and preference scores still differed significantly among individuals. Residuals for mulberry and dogwood were negatively correlated, which implies a trade-off in consumption of these two fruits. Individual differences in body mass, but not in bill or wing dimensions, explained significant amounts of the variation in residual mulberry consumption and in mulberry and dogwood preference. Heavier robins tended to prefer and eat more mulberries, the largest fruit, whereas lighter robins preferred dogwood fruits, which were the smallest. Dietary diversity correlated positively with wing length. Received 26 December 1990, accepted 8 June 1991.

Influences of gibberellins A4, A4+7and A4+iso-A7on apple fruit quality and tree productivity. II. Other effects on fruit quality and importance of fruit position within the tree canopy

Post-bloom gibberellin sprays increased fruit length:diameter (L/D) ratio and juice soluble solids but did not influence flesh firmness of ‘Golden Delicious’ apples grown in a maritime (Quebec) or desert (Okanagan Valley, B.C.) climate. Irrespective of GA treatment, ‘exterior’ fruit at both Canadian locations was larger, yellower, exhibited less russet, and contained more soluble solids at harvest than ‘interior’ fruit. Fruit shape (L/D ratio) was not influenced by position of the fruit within the canopy. Correlation analyses showed that surface russet development is poorly related to seed set, fruit size and other measures of fruit quality. However, a correlation matrix examining the degree of interrelatedness of all fruit size, fruit development and fruit quality indices revealed other relationships that may provide clues to understanding the relationship between fruit growth and quality development of ‘Golden Delicious’ apple.

Leaf Attributes as Indices of Fruit Quality in Prune Tree Canopies

Leaf dry weight per leaf area (LDW/LA); weight of leaf N per unit leaf area (LN/LA); leaf dry weight (LDW); and fruit quality, particularly sugar per fruit (SF); fruit fresh weight (FFW); and fruit dry weight (FDW) were measured over a range of daily average incident photosynthetic photon flux values (PPF) (50 to 1000 μmol·s-1·m-2) in 7-year-old prune (Prunus domestics L. syn. `Petite d'Agen') tree canopies. Linear or curvilinear relationships between these leaf attributes and fruit characteristics were significant over the PPF range. Analysis of LDW/LA or LN/LA may be used to indicate tree canopy locations in which fruit size and quality is limited by suboptimal PPF.

Whole fruit mineral element composition and quality of harvested ‘Delicious’ apples1

Abstract ‘Wellspur Delicious’ apple trees received preharvest foliar sprays of CaCl2 at rates of 0, 5.9 or 19.6 kg Ca/ha. season. Fruits of uniform size (7.65 to 8.05 cm diameter) were harvested on a single date and were allowed to ripen at 19°C or were placed in controlled atmosphere storage for five months and then allowed to ripen at 19°C. Fruit quality indices were measured at various times during ripening. The CaCl2 sprays failed to influence fruit mineral element composition, skin color, soluble solids, titratable acidity, firmness, bitter pit or watercore. At all times during ripening, fruit skin color, soluble solids, titratable acidity and firmness were independent of whole fruit Ca, Mg, K, N and P concentrations, and whole fruit Mg/Ca, K/Ca, (K+Mg)/Ca, K/(Ca+Mg), N/Ca and P/Ca concentration ratios. Fruits with and without bitter pit had identical whole fruit Ca concentrations and K/Ca concentration ratios. Whole fruit mineral element composition was an insensitive predictor of quality indices of harvested ‘Delicious’ apples.

Effects of forms and rates of organic and inorganic nitrogen fertilisers on the yield and some quality indices of tomatoes (Lycopersicon esculentumMiller)

Abstract The effects of two organic (blood and bone, compost) and two inorganic (potassium nitrate, KNO3; ammonium sulphate, (NH4)2 SO4) forms of nitrogen (N) fertilisers on the yield and some quality indices of tomatoes were studied in a pot experiment using Waimairi peaty loam soil obtained from an area currently used for vegetable production. Four rates (0,150, 300, 600 kg N/ha, based on soil bulk density) of each fertiliser form were used. Fruit yield was significantly correlated with foliage N concentration, but not with fruit N concentration. Increasing rates of all N fertilisers, except compost, produced significant increases in fruit yield. Compared with the control, at 600 kg N/ha applied, compost increased fruit yield by 40% only whereas the other N fertilisers studied increased fruit yield by 120%. Fruit quality indices measured showed variable response to treatments. Fruit colour increased significantly on application of blood and bone, (NH4)2 SO4, and KNO3, whereas compost showed no effect. Fruit vitamin C concentrations decreased when all N fertilisers were applied. Increasing N rate produced significant negative linear trends with vitamin C concentration decreasing by 18–28% depending on the form applied. Fruit size was unaffected by treatments but visual quality of fruit decreased when N in any form was applied.

Effect of waxing and cellophane lining on chemical quality indices of citrus fruit

Effects of waxing of the fruit and of the use of cellophane for lining storage boxes on chemical quality indices (including ethanol and acetaldehyde) and flavour scores of Feutrell's Early mandarin during storage at room conditions were determined. Maximum changes during storage of waxed mandarins in film-lined boxes occurred in ethanol contents which were followed by acetaldehyde, total soluble solids (TSS)/acid ratio, TSS and acid contents. There were negative and highly significant linear relationships between flavour scores, and ethanol content and acetaldehyde content. The r2 values indicated that over 90% of the variation in flavour scores could be explained by changes in ethanol and acetaldehyde contents whereas only 50% of the variation in flavour scores could be predicted by changes in total acid and TSS/acid ratios. There were comparatively greater increases in ethanol and acetaldehyde content, lesser increases in TSS and greater decreases in total solids of waxed mandarins during storage than those of unwaxed fruits stored in film lined boxes; the ratio of ethanol and acetaldehyde (E/A) of waxed mandarins was also higher. Decreases in citric acid content during storage correlated linearly to increases in the E/A ratio at the 1% level of significance indicating that citric acid metabolism was affected during storage of waxed mandarins at ordinary room conditions.

Sampling Procedures for Minimizing Variation in Peach Fruit Quality

Abstract Peach [Prunus persica (L.) Batsch cv. Harken] fruit were harvested at the firm-mature stage on 5 different dates. Fruit of uniform size were sampled randomly on each date from each of 4 quadrants per tree and evaluated for color, firmness, and soluble solids using the red and green sides of each fruit. A statistical model was used to identify and separate the sources of within- and among-tree variation in fruit quality indices. All quality indices were affected by harvest date. Fruit- and tree-related interactions accounted for a major part of the total random variation. Variance estimates were used to determine numbers of trees per treatment and fruit per tree needed to detect fruit quality differences of a desired magnitude. In general, 6 trees per treatment and 12 to 16 fruit per tree could be expected to detect meaningful differences in fruit quality in experiments involving 2 treatments.

Studies in citrus nutrition. 2. Phosphorus deficiency and fruit quality

The effects of four cultural treatments and four nitrogen levels on fruit quality, percentage leaf phosphorus, and percentage leaf nitrogen in an experimental citrus orchard are presented. In general, the trees in the tilled treatments, which receive some superphosphate to secure a good growth of the winter cover crop, produce fruit of better quality than those in the notillage treatments. Increasing levels of nitrogen supply in the latter cause a marked decrease in fruit quality. This effect is associated with a decrease in leaf phosphorus in these treatments. Analyses of soils in the different cultural treatments point also to an unfavourable phosphorus status for the no-tillage treatments. A comparison with earlier results in this experiment indicates that fruit quality, particularly in the no-tillage treatments, is deteriorating. This progressive decline is shown to be related to a deterioration in the phosphorus status of the trees in these treatments. Highly significant correlations are reported between fruit quality indices and leaf phosphorus content. Less significant correlations were established with readily available soil phosphorus. These correlations were established in a survey of selected orchards in the Murrumbidgee Irrigation Areas, and similar correlations were obtained for the experimental orchard.