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C.H. Crisosto and M.A. Nagao

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Hakan Aktas, Derya Bayındır, Tuba Dilmaçünal and M. Ali Koyuncu

storage period (5, 10, 15, 20, or 25 d) with electronic balance, which is sensitive to 0.01 g (Scaltec SBA51). The results obtained are expressed as percent weight loss and were calculated by the following formula: Fruit removal force. The force required

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Antònia Ninot, Agustí Romero, Joan Tous and Ignasi Batlle

with ethephon, reduces the fruit removal force of olives ( Barranco et al., 2004 ; Burns et al., 2008 ). Taken as a whole, these studies suggest that each ethephon–P compound combination needs be tested at each site as a result of the great influence

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Carl E. Motsenbocker

Field and greenhouse studies examined the fruit detachment force (FDF) and fruit and pedicel characteristics of two lines of tabasco pepper (Capsicum frutescens L.) at several stages of maturity. The detachment force of red-mature `McIlhenny Select' fruit at the calyx-fruit detachment area was lower than that of less mature fruit stages. The force required to detach red-mature Hard Pick (HP) tabasco fruit was higher than that of redmature `McIlhenny Select' fruit in the field and greenhouse. The fruit detachment force of red field-grown HP fruit was higher, and in the greenhouse was lower, than that of green or breaker fruit. HP fruit of all maturity stages, except red-mature, separated similarly to `McIlhenny Select' fruit with little or no fruit tissue attached to the calyx. Fruit detachment force was not correlated with any fruit or pedicel characteristics studied.

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J. Touss, J. Lloveras and A. Romero

Ethephon was applied at 0, 625, 1250, 1875, and 2500 m·gliter-1 in 2 consecutive years to `Arbequina' olive trees to determine its effect on fruit removal with mechanical harvesting and on fruit oil composition. Ethephon increased the mechanical harvesting efficiency by 20%. Ethephon at 1250 and 1875 mg·liter-1 were the optimum treatments, resulting in 63% and 66% of the olives being mechanically harvested, respectively, with a preharvest olive drop of 10% and 11%. Leaf drop (4.6 and 4.8 kg/tree fresh weight, respectively) at these concentrations did not reduce flowering the following year. Oil acidity, peroxide value, and fatty acid composition were affected little by ethephon and the values observed were within the range of normal annual variation. These results suggest that ethephon did not modify oil quality and that its use on traditionally pruned `Arbequina' trees is not economically justifiable. Chemical name used: (2-chloroethyl)phosphonic acid (ethephon).

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Tjasa B. Tiefengraber, Kitren G. Weis, George C. Martin and Barbara D. Webster

Ethephon reduces olive fruit removal force but also results in leaf loss when used as a harvest fruit loosening agent and in reduction of flower production in the subsequent year. Phosphorus (P) has been implicated in the fruit loosening process. Nuclear magnetic resonance analyses indicate that P accumulates rapidly in olive leaf explant abscission zones. P also causes ethylene evolution prior to abscission; this effect appears to be direct. In combination with AOA an ethylene synthesis inhibitor, P accelerates `Manzanillo' leaf explants abscission, inducing significant abscission 3 days after treatment. These results will assist in development of a P use strategy that leads to fruit but not leaf abscission.

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Marco Beyer, Stefanie Peschel, Moritz Knoche and Manfred Knörgen

Water uptake in different regions of the sweet cherry fruit (Prunus avium L. cv. Sam) was investigated following selective application of silicone sealant to the pedicel end, pedicel cavity, pedicel/fruit juncture, or stylar scar of detached fruit. The time course of water uptake was monitored gravimetrically during a 3-hour incubation period in deionized water (20 °C). Sealing the pedicel end and/or pedicel/fruit juncture significantly reduced rates and total amount (3 hours) of water uptake, but sealing the stylar scar had no effect. The amount of water penetrating via the pedicel/fruit juncture increased between 50 and 85 days after full bloom. During the same period the maximum force required to detach pedicels from fruit (fruit removal force) fell from 5.2 ± 0.5 to 2.1 ± 0.2 N. The amount of water penetrating via the pedicel/fruit juncture and the fruit removal force were negatively related. Nuclear magnetic resonance (NMR) imaging of mature fruit incubated in D2O indicated that D2O accumulated in the pedicel cavity region and the pedicel. Our data suggest that the pedicel end and pedicel/fruit juncture, but not the stylar scar, are regions of preferential water uptake in detached fruit. Chemical name used: deuterium oxide (D2O).

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K.C. Taylor

For peach fruit to withstand the rather vigorous postharvest handling during the packing and shipping process, growers pick them fairly early when they are very firm. Yet they soften very quickly, giving them a shelf life of generally 5–15 days. It may be desirable to allow fruit to remain on the tree longer, allowing them to increase in size, while improving in flavor and color. The fact that aminoethoxyvinyl glycine (AVG), ReTain™, interferes with ethylene synthesis was borne out by findings that AVG applications prior to harvest delayed ripening, increased fruit removal force in apple, and reduced preharvest drop. Seven-day preharvest application of 50 g AVG/100 gal to two peach varieties increased firmness from 12% to 54% and moved 7% of the harvest to a date 3–7 days after AVG treatment. The additional time to peak harvest may indicate that the fruit can hang on the tree for a longer period, allowing additional time for fruit expansion. Preliminary indications are that only a 2% to 4% size increase can be achieved. However, this appears to be enough to move 5% to 7% of the fruit into the next ring size.

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James O. Denney and George C. Martin

Fruit removal force (FRF) and percent leaf drop (LD) of fruit-bearing olive (Olea europaea L.) shoots were examined 120 hours after being sprayed with ethephon at 600 mg·liter-1 and held under controlled-environmental conditions analogous to those found in the field in California at harvest time in mid-October. FRF was not significantly affected by solution pH, but FRF of all treated shoots was significantly lower than that of the untreated controls. Only at pH 5 was percent LD significantly greater than that of the controls, but, of the shoots treated with ethephon, the lowest percent LD occurred at pH 3. Percent LD after treatment with ethephon at pH 3 was not affected by application time, but FRF was significantly less than the controls' when shoots were treated at 7 am or 12 pm but not at 5 pm or 10 pm. Adding NAA to the ethephon solution raised FRF and adding BA lowered FRF compared to ethephon alone. Adding NAA or BA did not mitigate percent LD significantly. Adding BA advanced anthocyanin production in fruit. Ethephon penetration of rachides was ≈70% that of petioles. Correlation between ethephon penetration of petioles and percent LD was greater than that between penetration of rachides and FRF. Correlation was significant for both tissues only in the 12 pm pH 3 treatment; correlation was also significant for petiole penetration and percent LD at pH 5. Autoradiographic studies of the 14C-ethephon penetration showed no pH effect, greater penetration into petioles than rachides, and that radioactivity was limited largely to intercellular spaces, with accumulation in vascular bundles, especially xylem. Regardless of treatment, FRF and percent LD are negatively correlated (r 2 = 0.615). Mean results to be expected using ethephon as an olive harvest aid under these conditions are an FRF of ≈3 N and a percent LD of ≈15%. The desired low FRF and percent LD were obtained by applying ethephon alone at pH 3 at 7 am. Raising ethephon solution pH does not increase harvest effectiveness. Chemical names used: (2-chloroethyl)phosphonic acid (ethephon), naphthalene acetic acid (NAA), 6-benzylaminopurine (BA).

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Luis Rallo, Diego Barranco, Raúl de la Rosa and Lorenzo León

. ‘Chiquitita’ also showed a shorter length of the ripening period (53 versus 71 d), which can facilitate the determination of an optimum harvesting date. Fruit traits. ‘Chiquitita’ showed higher fruit weight and fruit removal force than ‘Arbequina