Crop Load and Time of Thinning Interact to Affect Fruit Quality in Sweet Cherry

Abstract

Balanced crop load is key to the production of export-quality cherries. We investigated the level and timing of crop load regulation on fruit quality. Additionally we sought to investigate possible correlation between firmness estimated by compression test or flesh penetrability. Fruit diameter was similar between 1 and 2 bud/spur treatments but was significantly lower in the 4 bud/spur treatment at all thinning times in 'Van' in the 2010/11 season. In contrast 'Sweetheart' fruit diameter was only decreased at 6 and 8 WAFB in the 4 bud/spur treatment in 2010/11. This decrease in 'Sweetheart' was associated with significantly higher soluble solids and starch reserves in leaves, stem, trunk and roots 2-weeks post-harvest in trees thinned at dormancy, relative to trees thinned 8 WAFB. Fruit flesh firmness significantly increased with decreased crop load irrespective of time of thinning in 'Van' in 2010/11. In contrast flesh firmness was significantly higher in the 1 bud/spur treatment and similar between other treatments in 'Sweetheart' in 2010/11. In 2011/12 flesh firmness, soluble solids and colour significantly increased whilst fruit weight and TA significantly decreased 28 days post-harvest relative to at-harvest values. We found strong correlation between values obtained with the FirmTech II and the Guss fruit texture analyser. Sweet cherry fruit quality is optimised through attaining crop load of approximately 10 fruit per cm 2 of limb cross-sectional area through thinning at dormancy or full bloom.

Climate, Winter Chill, and Decision-making in Sweet Cherry Production

“…Harvest maturity was uniform in both varieties with the difference in fruit size an observed and supported varietal characteristic (De Franceschi et al, 2013;Measham et al, 2009). The crop should not have experienced any loss of size as a result of cropload or yield because the threshold for size reduction was not reached (Bound et al, 2013;Measham et al, 2009Measham et al, , 2012.…”

Effects of Summer Pruning and Cropload on Summer and Winter Bud Carbohydrates in Sweet Cherry

“…This difference in fruit size would not have been a result of different croploads because there was only a weak relationship between bud or flower numbers as a result of pruning treatments. Moreover, it was unlikely that loads were sufficient to induce a decrease in fruit size (Bound et al, 2013). Furthermore, Measham et al (2013) showed that pruning at Stage II of fruit development negatively impacted the current season's fruit quality indicating a competitive interaction.…”

“…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 an increase in glucose in apple fruit from trees with low croploads, whereas Roussos et al (2011) found a decrease in glucose in apricot (Prunus armeniaca) fruit from low-cropping trees but no impact on total soluble solids.…”

“…Klages et al (2001) found a decrease in starch and an increase in glucose in apple fruit from trees with low croploads, whereas Roussos et al (2011) found a decrease in glucose in apricot (Prunus armeniaca) fruit from low-cropping trees but no impact on total soluble solids. The impact of cropload on sweet cherry fruit quality appears to be a complex issue with inconsistent results, which may be explained partly by tree architecture (Bound et al, 2013). Manipulating cropload can additionally encourage bud development and flowering for the next season (Proebsting and Mills, 1981;Smith et al, 2007).…”

Effect of Prebloom Pruning on 13C and 15N Distribution during Early Spring in Sweet Cherry

“…Lack of crop load regulation either by winter or summer pruning (e.g., heading-back and tipping cuts), thinning (i.e., removal of buds, flowers, or fruits), or both cause an imbalance between reproductive and vegetative growth in dwarf and semidwarf sweet cherry combinations using 'Gisela' rootstocks (Gutzwiler and Lang, 2001;Wang et al, 2003;Whiting et al, 2005), resulting in premature tree aging and low-quality fruit. Lack of crop load regulation reduces size, SSC, and firmness in the fruits of sweet cherry (Ayala and Lang, 2008;Bound et al, 2013;Villasante et al, 2012;Whiting et al, 2005;Whiting and Lang, 2004).…”