Manipulation of Whole-vine Carbon Allocation Using Girdling, Pruning, and Fruit Thinning Affects Fruit Numbers and Quality in Kiwifruit

Abstract

<jats:p>We compared the long-term effects of whole-vine source-sink manipulation on yield, composition, and quality of fruit from mature field-grown kiwifruit (<jats:italic>Actinidia chinensis</jats:italic> Planch. var. <jats:italic>chinensis</jats:italic>) ‘Hort16A’ vines. Four contrasting source/sink-modifying treatments were applied to vines each year from Spring 2003 to 2007: 1) control—standard canopy management techniques, no trunk girdle; 2) extended trunk girdle (ETG)—girdle was opened in late summer, kept open over winter, and allowed to heal the next spring; 3) “feast”—cropload was kept low and leaf numbers kept high, no trunk girdle; and 4) “famine”—fruit numbers were kept high and vines were heavily pruned to stimulate regrowth, no trunk girdle. Fruit from the famine vines were smaller with lower dry matter concentration (DMC; dry weight as a percentage of fresh weight) and had delayed maturity relative to fruit from the control vines. Return bloom was reduced in the famine vines, resulting in ≈42% less fruit in the famine vines compared with the feast vines, and this difference remained consistent across all three seasons. Fruit from the feast treatment were larger with advanced maturity relative to fruit from control vines; there were no differences in fruit numbers in subsequent seasons. Fruit DMC was higher and maturity was advanced in the ETG vines relative to the control vines. Fruit numbers in the ETG vines consistently increased relative to the control vines each season. There were no consistent treatment effects on fruit mineral concentrations, except that fruit from the feast vines had higher nitrogen concentrations than fruit from the famine vines. Seasonal variation in the incidence of storage disorders was large; in years when disorders were present, physiological pitting incidence was higher in fruit from the treatments that advanced maturity and the incidence of low temperature breakdown was highest in treatments that delayed maturity. Although the treatments affected vine productivity, fruit DMC, and storage performance, there was no evidence of a gradual decline in quality and productivity after 4 years of treatment application.</jats:p>

Effects of environmental factors and management practices on microclimate, winter physiology, and frost resistance in trees

“…Girdling, which is the partial or total removal of a ring of phloem around the bole, stops the basipetal movement of assimilates through the phloem, resulting in carbohydrate accumulation above the girdle ( Mataa et al, 1998 ; Urban et al, 2004 ; Frame C, Figure 2 ). This practice is used to manipulate (i) tree growth and development and (ii) fruit growth, load, quality, and maturation in fruit species ( Krezdorn, 1960 ; Barry and Veldman, 1997 ; Goren et al, 2004 ; McQueen et al, 2004 ; Pretorius et al, 2004 ; Urban et al, 2004 ; Boyd and Barnett, 2011 ). Girdled branches exhibit lower water contents, higher soluble carbohydrates, and more vigorous growth ( Manoury-Danger et al, 2010 ; Poirier et al, 2010 ).…”

Crop management impacts the efficiency of quantitative trait loci (QTL) detection and use: case study of fruit load×QTL interactions

“…One of the most clearly observable effects of high numbers of competing fruits per plant is the reduction in average fruit size. The limited availability of assimilates and other nutrients for growth generally leads to a decrease in the accumulation of dry as well as fresh weight in fruits of tomato (Bertin, 2005;Guichard et al, 2005;Massot et al, 2010;Fanwoua et al, 2012), apple (Dal Cin et al, 2007;Naor et al, 2008;Dash et al, 2013), citrus (Guardiola & García-Luis, 2000;Poiroux-Gonord et al, 2013), kiwifruit (Boyd & Barnett, 2011), mango (Léchaudel et al, 2005), peach (Quilot et al, 2002), and grape (Dai et al, 2009(Dai et al, , 2011. Fruit development can be affected by the prevailing concentration of hexose and sucrose, showing a more pronounced and earlier transition to ripening when sugar is plentiful (e.g.…”

“…basis decline with high fruit load in some species (Iglesias et al, 2002;Dai et al, 2009;Boyd & Barnett, 2011), although water and sugar accumulation usually decrease proportionally in fruits like tomato (e.g. Massot et al, 2010).…”

QTL mapping and identification of SNP-haplotypes affecting yield components of Theobroma cacao L.

“…Growing vegetative tissues and harvestable organs compete for the available assimilated carbon in the translocation stream. Competition for assimilated carbon has been shown in which changes in number of fruits (fruit load) affect fruit growth, fresh weight and carbohydrate concentration in Malus domestica 18 , Citrus clementina 19 , and Actinidia Chinensis 20 . In our study, we found a significant negative correlation between DBW with all the other variables, which indicates a competition for the assimilated carbon among those harvestable organs.…”