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Jacqueline K. Burns, Louise Ferguson, Kitren Glozer, William H. Krueger, and Richard C. Rosecrance

characteristic white milky juice from fruit when squeezed ( Ferguson et al., 2005 ). Fruit detachment force (FDF) was measured at various times up to 17 d after application using an Imada DPA-11 digital force gauge (Imada, Northbrook, IL). At various times

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Lisa Tang, Shweta Chhajed, and Tripti Vashisth

, there was no obvious difference in peel color for tight fruit and loose fruit (irrespective of HLB severity). Fig. 2. The percentages of tight and loose fruit (fruit detachment force >6 and ≤6 kgf, respectively) collected 3 weeks before harvest from

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Nikolaos Ntoulas, Panayiotis A. Nektarios, and Glykeria Gogoula

OMC soil amendment effects on bermudagrass establishment and growth was performed through turf visual quality ratings, clipping yields, root growth, and vertical detachment force measurements. In addition, substrate properties were also evaluated and

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Blair Buckley III and Katharine C. Pee

A force gauge was used to measure the force required to detach pods from plants of 16 southernpea [Vigna unguiculata (L.) Walp.] cultigens. Pod detachment force (PDF) measurements ranged from 21.4 N for MN-13 to 11.8 N for `Royal Cream'. Pod length, diameter, and weight; basal pod vacancy (inverse of fill); and peduncle synapse length were recorded for each pod sampled for detachment force. There was no strong association between PDF and any of the five traits.

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Kelly T. Morgan, Smita Barkataky, Davie Kadyampakeni, Robert Ebel, and Fritz Roka

that reduces long-term productivity. The objective of the current field study was to determine the effect of short-term drought stress before and/or after harvesting on: 1) fruit detachment force required to remove fruit at harvest; 2) tissue loss and

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Karthik-Joseph John-Karuppiah and Jacqueline K. Burns

, fruit detachment force, and gene expression. Leaf abscission and FDF were measured immediately after treatment and after 6 h and 1, 2, 4, and 7 d of application. Ten branches (each with about 100 leaves; ≈1 year old) per treatment were tagged to follow

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Robert C. Ebel, Jacqueline K. Burns, and Kelly T. Morgan

detachment force of fruit inside the canopy is naturally higher than fruit on the periphery ( Kender and Hartmond, 1999 ). Optimum sprayer design will also need to include thorough coverage of fruit near the top of the canopy, because this fruit tends to have

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Luis Pozo and Jacqueline K. Burns

America Corp., Aurora, IL). In the 2007–2008 cropping year, fruit detachment force (FDF, kg-force) was measured 6 d after spray treatments in both mature and developing fruit with a digital force gauge (Force Five; Wagner Instruments, Greenwich, CT). For

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Ramón A. Arancibia and Carl E. Motsenbocker

Pectin metabolism was analyzed in tabasco pepper (Capsicum frutescens L.) to determine the metabolic process associated with the ease of fruit detachment from the calyx. The ease of fruit detachment (deciduous fruit) is a desirable trait in peppers that facilitates mechanical harvest. Two genotypes that differ in the fruit detachment force were used: `Easy Pick' (EZ), which requires a low force, and `Hard Pick' (HP), which requires higher force. Pectin dissolution in water from fresh-ripe EZ tissue was 20 times higher than from HP tissue. EDTA-soluble uronide from inactivated EZ cell wall, however, was only 1.8 times higher. Pectin dissolution was inversely correlated to the fruit detachment force and followed a sigmoidal curve during fruit ripening. Size-exclusion chromatography of EDTA-soluble polyuronides indicated that pectin was degraded in ripe fruit tissue from both genotypes. The degree of depolymerization, however, was more extensive in EZ fruit. Consequently, the ease of fruit detachment was attributed to pectin ultra-degradation. Total pectin content in dry tissue and ethanol/acetone-extracted cell wall was similar in both genotypes. Pectin content in dry tissue was maintained throughout ripening, while extracted cell wall pectin increased slightly. In contrast, the degree of pectin esterification of extracted cell wall decreased only in ripe EZ fruit. These results suggest that pectin de-esterification may have a role in the enhanced pectin depolymerization and consequently in the ease of fruit detachment of the EZ genotype.

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J.K. Burns, U. Hartmond, R. Yuan, and W.J. Kender

Methyl jasmonate (Me-Ja) is a naturally occurring ubiquitous compound in plants. Me-Ja is considered to be a putative plant hormone because of its effect on plant processes such as senescence, germination, tuber formation, signal transduction, ethylene production, and abscission at low exogenous concentrations. We applied Me-Ja to fruit or whole trees of `Hamlin' or `Valencia' orange to determine the potential of this compound as a mature fruit abscission agent. Me-Ja (0, 1, 5, 10, or 20 mM in 0.1% Kinetic adjuvant) was applied to whole trees with a handgun or boom sprayer rates of 4850 and 1790 L·ha–1, respectively. Alternatively, tree fruit were dipped in Me-Ja solutions. Fruit drop, leaf drop and ethylene production in both fruit and leaves and fruit detachment force in fruit were monitored at various times up to 2 weeks after application. Me-Ja treatment resulted in increased ethylene production in fruit and leaves 1 to 2 days after application. Fruit detachment force significantly declined 6 to 10 days after application followed by significant fruit drop. Applications of Me-Ja >10 mM resulted in an unacceptable amount of canopy defoliation. The results suggest that Me-Ja has potential as an abscission agent for citrus. Future work will focus on improving uniformity of application and response.