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Penelope F. Measham, Audrey G. Quentin, and Nicholas MacNair

; Flore and Layne, 1999 ). Cropload (or simply the number of fruit per tree) can also influence fruit sugars in the current season ( Bound et al., 2013 ; Measham et al., 2012 ; Roper et al., 1988 ). Klages et al. (2001) found a decrease in starch and

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Terence L. Robinson* and Christopher B. Watkins

In 2001 and 2002, we imposed a wide range of croploads (0-15 fruits/cm2 of TCA) on 4- and 5-year-old Honeycrisp/M.9 trees by manual hand thinning soon after bloom to define appropriate croploads that give adequate repeat bloom and also the best fruit quality. At harvest each year we evaluated fruit ripening and quality. Samples were stored for 5 months in air at 38 °F and 33 °F and evaluated for fruit firmness and storage disorders. Cropload was negatively correlated with tree growth, return bloom, fruit size, fruit red color, fruit sugar content, fruit starch content, fruit firmness, fruit acidity, fruit bitter pit, fruit senescent breakdown, fruit rot and fruit superficial scald, but was positively correlated with leaf blotch symptoms, fruit internal ethylene concentration at harvest, and fruit soggy breakdown. There was a strong effect of cropload on fruit size up to a cropload 7, beyond which there was only a small additional effect. Although there was considerable variation in return bloom, a relatively low cropload was required to obtain adequate return bloom. Fruit red color was reduced only slightly up to a cropload of 8 beyond which it was reduced dramatically. The reduced fruit color and sugar content at high croploads could indicate a delay in maturity of but, fruits from high croploads were also softer, had less starch and greater internal ethylene. It that excessive croploads advance maturity. Overall, croploads greater than 10 resulted in no bloom the next year, and poor fruit size, color and flavor, but these fruits tended to have the least storage disorders. Moderate croploads (7-8) resulted in disappointing return bloom and mediocre fruit quality. For optimum quality and annual cropping, relatively low croploads of 4-5 were necessary.

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Ed Stover, Mike Fargione, Richard Risio, Xiaoe Yang, and Terence Robinson

at the Univ. of Florida, for assistance with statistical methods for assessing effects of treatments on fruit weight adjusted for cropload. The cost of publishing this paper was defrayed in part by the payment of page charges. Under postal regulations

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Joseph Masabni, S. Kaan Kurtural, Dwight Wolfe, and Chris Smigell

The effect of cropload (kg yield/kg pruning weight) on yield components and fruit composition of 17 eastern European grapevine cultivars was evaluated from 2000 to 2004 in a vineyard, at the research station in western Kentucky, characterized by a long and warm season. There was a cubic relationship between number of clusters retained per vine and the cropload (R 2 = 0.6374, P < 0.0001). Similar relationship was evident between yield per vine and cropload (R 2 = 0.5908, P < 0.0001). Of the observed variation in cluster weight, 28% was attributed to variation among predictions, based on the value of cropload in a quadratic relationship (P < 0.0001). As cropload increased, pruning weight per meter of row decreased (R 2 = 0.4513, P < 0.0001). However, there was very little effect of cropload on the percentage of total soluble solids and juice pH measured at harvest. Optimum cropload values fell in between 13–18 (kg yield/kg pruning weight) depending upon cultivar evaluated, based on optimum ranges for pruning weight per meter of row for optimum vine balance in the lower Midwest.

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Shijian Zhuang, Letizia Tozzini, Alan Green, Dana Acimovic, G. Stanley Howell, Simone D. Castellarin, and Paolo Sabbatini

to improve the fruit zone microclimate ( Howell, 2001 ). The ratio between vegetative growth and reproductive growth is manipulated to achieve targeted fruit characteristics and often indexed as cropload, the ratio between fruit yield and 1-year

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Imed Dami, Said Ennahli, and David Scurlock

Cropload (CL), defined as a ratio of crop weight and pruning weight, is an indicator of vine balance between vegetative growth and fruit production ( Bravdo et al., 1984 , 1985 ; Dami et al., 2005 , 2006 ; Howell, 2001 ; Naor et al., 2002

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Thomas M. Todaro and Imed E. Dami

grapevine recovery. Therefore, the purpose of this study was to evaluate different training and pruning methods for trunk renewal and recovery of ‘Cabernet franc’ and their impacts on growth, yield, cropload, and fruit composition following severe winter

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Robert C. Ebel, Edward L. Proebsting, and Robert G. Evans

A standard fruit growth curve, used commercially as an aid to hand thinning, was compared to periodic volume measurements of apple fruit (Malus domestica Borkh. `Delicious') subjected to early season regulated deficit irrigation (RDI) to determine when to end RDI, which is used to control vegetative growth and save water. RDI suppressed stem water potential, stomatal conductance, and fruit growth rate compared to the trickle- and furrow-irrigated controls, which wetted about one-half and the entire soil volume, respectively. Full irrigation was restored to RDI trees by trickle and microsprinklers, which wetted about one-half and the entire soil volume, respectively, after terminal buds set. Stem water potential, stomatal conductance, and fruit growth rate of RDI trees increased to that of the controls, except for RDI/trickle trees, which had 80% the stomatal conductance of the other treatments. Fruit weight at harvest was affected by an interaction of irrigation treatment and cropload. RDI trees had similar or less vegetative growth and similar or higher yield efficiency than the controls. We recommend ending RDI before fruit growth declines below the standard curve.

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Ed Stover, Ferdinand Wirth, and Terence Robinson

Analysis of apple (Malus×domestica Borkh.) and citrus thinning experiments indicates that the relationships between cropload, fruit size, and total yield can be used to assess optimal cropload for highest crop value. Mean fruit size increased and total yield declined as the cropload (number of fruit/cm2 trunk cross-sectional area) was reduced through the use of chemical thinners. Because crop value is influenced by fruit size and total yield, intermediate croploads gave the highest economic returns in all experiments evaluated. For `Empire' apple, croploads greater than those expected to provide good return bloom often produced the highest crop value for a single year. In citrus, optimal crop values resulted from a broad range of intermediate croploads. A method is described to analyze optimum cropload from thinning experiments.

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James R. Schupp and T. Auxt Baugher

Crop thinning is required in tree fruit production to ensure optimum fruit size and quality. The conventional method of cropload management in peach orchards is to remove excess fruit by hand after danger of frost is over, which is generally 35 to