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Abstract

Preharvest application of naphthaleneacetic acid (NAA) at 10, 20, 40, and 60 ppm concentrations to immature ‘Zahdi’ date palm (Phoenix dactylifera L.) fruit 15 to 16 weeks after pollination (late chimri stage) influenced fruit size, quality, and ripening. Compared with the controls, 40 and 60 ppm NAA treatments increased fruit size, weight, volume, pulp to seed ratio, and moisture content At 60 ppm fruit weight was increased by 39%. Total soluble solids were not altered significantly. Fruit ripening was delayed at least one month by 40 and 60 ppm.

Open Access

Poor fruit set and sub-optimum berry size are potential yield- and profit-limiting factors for southern highbush (Vaccinium corymbosum) blueberry production in Florida. The cytokinin N-(2-chloro-4-pyridyl)-N'-phenylurea (CPPU) has increased fruit size and fruit set of a number of fruit crops including rabbiteye blueberry. The purpose of this study was to determine the effects of CPPU applied at different rates and phenological stages of bloom and/or fruit development on fruit size, set, and yield of southern highbush blueberry. `Millennia' and `Star' southern highbush blueberry plants located on a commercial blueberry farm in Alachua County, Fla., were treated with 5 or 10 ppm CPPU at various stages of development ranging from full bloom to 20 days after full bloom. In contrast to findings with rabbiteye blueberry, fruit set in this study of southern highbush blueberry was not affected by any of the CPPU treatments when compared to the controls. Nor was total fruit yield affected by CPPU treatments. The most noticeable potential benefit found in this study was an increase in mean fruit fresh weight from CPPU treatments. However, cultivars responded differently to CPPU with respect to mean fruit fresh weight. For `Millennia', only one CPPU treatment increased mean fruit weight compared to controls. However, for `Star', all but one CPPU treatment increased mean fruit fresh weight. Several CPPU treatments resulted in delayed fruit ripening for `Star' but not for `Millennia'. For `Star', the treatments that most consistently delayed fruit ripening tended to have greater fruit fresh weights.

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Whole fruit clusters were collected from three shoot types: terminal and lateral shoots without secondary growth, and shoots with secondary growth. Fruit per cluster was counted and nuts were individually weighed, shelled and graded. Return bloom of the same shoots was measured. Results indicated that cluster size of lateral bearing shoots was negatively related to next year's average kernel weight, nut weight, and kernel percentage. However, only kernel percentage was related to cluster size on terminal bearing shoots, and none of these parameters were related to cluster size on shoots with secondary growth. Cluster size and total kernel weight per shoot were positively related for the three shoot types. Return bloom of terminal shoots was negatively related to cluster size, but cluster size did not affect return bloom of the other shoot types.

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Abstract

Fruit of equal size but varying Ca concentrations were harvested 4 times at weekly intervals for measurements of firmness, titratable acidity, soluble solids and starch, and of Ca, N, P, K, Mg, B, Fe, Mn, Zn, and A1 concentrations. In another experiment, fruit of 3 different sizes were measured generally as above. These measurements were compared with incidences of senescent breakdown, scald and rot after air storage at 0°C, and stepwise multiple linear regression was used to develop equations for predicting apple storage life. Among minerals and maturity indices, Ca, and starch concentrations, respectively, accounted for the most variations in senescent breakdown. Fruit diameter and fruit firmness also accounted for significant amounts of variation in breakdown after storage when fruit size varied. These results show that predictions of storage life based solely on mineral concentrations can be improved by incorporating maturity and size measurements at harvest when these factors are variable.

Open Access

Panicles of `Kohala' longan (Dimocarpus longan Lour.) trees often retain more than 250 fruit, which results in small fruit (<10 g) of reduced market value. During 1997 and 1998, we conducted experiments to increase fruit size in commercial groves. Trees flowered and fruited normally in 1997, but very scarcely and late in 1998. In 1997, treatments consisted of panicle pruning (clipping off half of the panicle) and/or removal of entire panicles (50% per tree) when young fruits were 5 or 10 mm in diameter. Control trees were left intact. The number of fruit per panicle varied greatly within trees. Panicles (pruned or intact) with <125 fruit generally developed fruit >15 g (32–33 mm equatorial diameter). Total soluble solid content of mature fruit generally decreased with increasing fruit size. Removing whole panicles did not increase average fruit size in remaining intact panicles, suggesting that panicles were fed primarily by leaves within the same branch. In 1998, treatments consisted of applications of GA3 and/or CPPU (a synthetic cytokinin) when fruits were 6 to 9 mm in diameter. Panicles were not pruned since they generally had <150 fruit. Control panicles were not sprayed. There was no consistent effect of treatments on average fruit weight, and no treatment significantly increased fruit size in relation to controls. These preliminary results indicate that other factors besides current fruit set, such as previous fruit load of a branch, branch position (exposure to sunlight and/or wind, and proximity to major limbs), and the amount/age of leaves, may influence the fruiting potential of individual branches.

Free access

Benzyladenine (BA), reported to increase fruit growth in apples, was evaluated with NAA to overcome NAA-induced inhibition of fruit growth. High volume sprays of NAA (15 mg·liter-1), BA (25 to 100 mg·liter-1) and combinations were applied to Redchief `Delicious' (king fruit = 10 mm). Yield was not significantly reduced. The combinations (NAA + BA 25, 50 or 100 mg·liter-1) resulted in the highest percentage of small fruit (39% < 70 mm) and the lowest percentage of large fruit (35% > 77 mm) compared to NAA, BA and hand thinned control. There was no significant effect of NAA or BA on size of king fruit in absence of lateral fruit competition on a given spur, while the combinations decreased (P = 0.01) king fruit size. NAA, but not BA, reduced growth of lateral fruit, with or without competition. However, the combinations caused marked suppression of lateral fruit growth and reduced seed content. With `Empire', both NAA (10 mg·liter-1) and BA (25 to 150 mg·liter-1) effectively thinned. Fruit size was greater with BA than NAA. The combinations (NAA, 10 mg·liter-1 + BA, 25 or 50 mg·liter-1) over-thinned and did not increase the amount of small fruit as in `Delicious'.

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Percentage of fruiting uprights, fruit set, number of fruit per upright, and flower bud formation of `McFarlin' and `Stevens' cranberries (Vaccinium macrocarpon Ait.) were reduced by removal of old leaves, new leaves, or both on the upright. Results varied slightly, based on which leaves were removed, time of removal, cultivar, year, and bog site. Percentage of fruiting uprights, flowers and fruit per upright, and fruit set were higher on uprights with a terminal bud size >1 mm in diameter in September than for those <1 mm in diameter. Effects were cultivar and site dependent. Terminal bud size of `McFarlin' was negatively related to the subtending number of fruit and positively related to leaf fresh weight of the upright.

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ReTain™, a commercial plant growth regulator containing aminoethoxyvinylglycine, an inhibitor of ethylene production, was applied 4 weeks before normal harvest to `Jonagold' trees and the effects on fruit maturity and quality at harvest, and quality after air and controlled atmosphere storage was investigated. When fruit were harvested from 3 to 6 weeks after treatment, fruit ripening was inhibited as indicated by lower internal ethylene concentrations, delayed starch hydrolysis, and lower levels of skin greasiness. A number of factors indicated that other aspects of fruit metabolism were affected by the compound. Treated fruit were softer than nontreated fruit at the first harvest, and the benefits of ReTain on firmness appeared only at the later harvests. Also, at each harvest date, average fruit weight of ReTain-treated fruit was lower than nontreated fruit. We have investigated the possibility the ReTain and/or the accompanying surfactant, Silwet, inhibited leaf photosynthesis, thereby leading to altered carbon metabolism. Trees were unsprayed, or sprayed with surfactant, and ReTain plus surfactant. No treatment effects on photosynthesis were detected. However, leaf photosynthesis rates were generally low and quite variable. Measurements of fruit diameter confirmed that the increase in fruit volume following treatment was ≈2% less on the ReTain plus surfactant-treated fruit than nontreated fruit. The increase in fruit volume for the Silwet treatment was ≈1.5% less than in untreated fruit. The data indicates a rapid change in fruit volume as fruit changed in color. Inhibition of ethylene by ReTain may be an important factor influencing fruit size.

Free access

The nature and magnitude of genotype × environment interactions will determine the extent of testing required (locations, years) to accurately evaluate a genotype's performance. Data from yearly T-AES muskmelon variety trials were analyzed to determine the level of variety (V) × year (Y), V × location (L), and V × Y × L interactions for yield and fruit size. Data analyzed were of nine hybrids grown at three commercial farms over two years. Fruits were harvested similar to grower practices, and were sorted into size classes (9 - 30) or culls. V × Y and V × L interactions for marketable yield and total yield were not significant. V × Y × L interaction was significant for marketable yield, but not for total yield. V × Y × L interactions were highly significant for percentage culls and percentage of fruit in each size class. V × L interactions were also significant for percentage of fruit in most size classes. Data indicate that specific location-year combinations differentially affect a genotype's fruit size, most likely due to weather, planting time, and stress factors. Multiple year and location testing of genotypes is therefore critical, particularly for evaluation of fruit size.

Free access

Field thinning studies were conducted in two orchards at Geneva and Milton, N.Y., over 3 years (2003–05) using mature Gala/M.9 trees. A range of final croploads was achieved with various chemical thinning treatments, including, benzyladenine combined with carbaryl, or napthaleneacetic acid combined with carbaryl. The most-aggressive thinning treatments in the year with high rainfall achieved an average fruit size of 190–200 g; however, the yield was reduced considerably, resulting in a reduced farm gate crop value compared to less-aggressive thinning. In a dry year, the fruit sizes were smaller even with aggressive thinning. The optimum yield for maximum crop value varied for each orchard block for each year. The optimum croploads varied less than the optimum yield, since cropload normalizes the tree size between blocks. Optimum fruit size to maximize crop value varied narrowly between 155–170 g (113–100 count size) across blocks and years. This was true despite a substantial price difference between large, 80-count fruits and the moderate-size 113-count fruits. If lower prices received for processed apples were used in the analysis, then the optimum yield was significantly higher than with fresh fruit prices. In New York State, it appears that achieving 80-count fruit requires too large of a reduction in yield, which causes a reduction in crop value.

Free access