`Bing' Sweet Cherry on the Dwarfing Rootstock `Gisela 5': Thinning Affects Fruit Quality and Vegetative Growth but not Net CO2 Exchange

Abstract

ADDITIONAL INDEX WORDS. carbohydrate assimilation, fruit to leaf area ratio, photosynthesis, Prunus avium, sink strength, yield ABSTRACT. Canopy fruit to leaf area ratios (fruit no./m 2 leaf area, F:LA) of 7-and 8-year-old 'Bingʼ sweet cherry (Prunus avium L.) on the dwarfi ng rootstock 'Gisela 5ʼ (P. cerasus L. x P. canescens L.) were manipulated by thinning dormant fruit buds. F:LA infl uenced yield, fruit quality, and vegetative growth, but there were no consistent effects on whole canopy net CO 2 exchange rate (NCER canopy ). Trees thinned to 20 fruit/m 2 LA had yield reduced by 68% but had increased fruit weight (+25%), fi rmness (+25%), soluble solids (+20%), and fruit diameter (+14%), compared to unthinned trees (84 fruit/m 2 ). Fruit quality declined when canopy LA was ≈200 cm 2 /fruit, suggesting that photoassimilate capacity becomes limiting to fruit growth below this ratio. NCER canopy and net assimilation varied seasonally, being highest during stage III of fruit development (64 days after full bloom, DAFB), and falling more than 50% by 90 DAFB. Final shoot length, LA/spur, and trunk expansion were related negatively to F:LA. F:LA did not affect subsequent fl oral bud induction per se, but the number of fl owers initiated per bud was negatively and linearly related to F:LA. Although all trees were thinned to equal fl oral bud levels per spur for the year following initial treatment (2001), fruit yields were highest on the trees that previously had no fruit, refl ecting the increased number of fl owers initiated per fl oral bud. Nonfruiting trees exhibited a sigmoidal pattern of shoot growth and trunk expansion, whereas fruiting trees exhibited a double sigmoidal pattern due to a growth lag during Stage III of fruit development. Vegetative growth in the second year was not related to current or previous season F:LA. We estimate that the LA on a typical spur is only suffi cient to support the full growth potential of a single fruit; more heavily-set spurs require supplemental LA from nonfruiting shoots. From these studies there appears to be a hierarchy of developmental sensitivity to high F:LA for above-ground organs in 'Bingʼ/ʼGisela 5ʼ sweet cherry trees: trunk expansion > fruit soluble solids (Stage III) > fruit growth (Stage III) > LA/spur > shoot elongation > fruit growth (Stages I and II) > LA/shoot. Current season F:LA had a greater infl uence on fruit quality than prior cropping history, underscoring the importance of imposing annual strategies to balance fruit number with LA.

Modeling Seasonal Dynamics of Canopy and Fruit Growth in Grapevine for Application in Trellis Tension Monitoring

“…Shoots that emerged subsequently from secondary and tertiary buds grew vigorously (most evident in number of leaves per shoot; Fig. 3B), a compensatory growth mechanism that has long been demonstrated in grapevines and other perennial fruit crops (e.g., Candolfi-Vasconcelos and Koblet, 1990;Edson et al, 1995;Petrie et al, 2000;Whiting and Lang, 2004). In grapes, secondary and tertiary buds are known to produce fewer and smaller clusters than do primary buds (Pratt, 1974).…”

Foliar Applications of Urea Affect Nitrogen Reserves and Cold Acclimation of Sweet Cherries (Prunus avium L.) on Dwarfing Rootstocks

“…Nitrogen is the most important element for maintaining growth and high productivity in tree fruits (Titus and Kang, 1982). Sweet cherries (Prunus avium L.) on precocious, interspecific (P. cerasus · P. canescens) Gisela Ò (Gi) rootstocks (e.g., Gi3, Gi5, Gi6, Gi12) are likely to produce large crops but small-sized fruit when total leaf area is not adequate to support such crop loads (Andersen et al, 1999;Lang, 2000;Whiting and Lang, 2004). When root uptake of N is limited in early spring by cold soils and low canopy transpiration rates (Zavalloni, 2004), the restricted availability of N for growth may contribute to unfavorable leaf area-to-fruit ratios.…”

Comparing Novel Sweet Cherry Crop Load Management Strategies

“…Indeed, Whiting et al (2005) reported 2-to 6-fold higher yields and reduced fruit quality of 'Bing' sweet cherry grown on 'Gisela 5' and 'Gisela 6' rootstocks, compared to the industry standard, Mazzard (P. avium). However, Whiting and Lang (2004a) showed that high quality 'Bing' sweet cherries can be grown on 'Gisela 5' when fruit number per tree is balanced with the vegetative capacity to supply photoassimilates. Indeed, a negative relationship exists between sweet cherry canopy fruit-to-leaf area ratio (F:LA) and fruit quality Whiting and Lang, 2004a), irrespective of rootstock.…”

“…However, Whiting and Lang (2004a) showed that high quality 'Bing' sweet cherries can be grown on 'Gisela 5' when fruit number per tree is balanced with the vegetative capacity to supply photoassimilates. Indeed, a negative relationship exists between sweet cherry canopy fruit-to-leaf area ratio (F:LA) and fruit quality Whiting and Lang, 2004a), irrespective of rootstock. Earlier reports also have documented poor quality fruit harvested from heavily cropped sweet cherry trees (Proebsting, 1990;Proebst-ing and Mills, 1981) and similar relationships have been reported for apple (Malus ×domestica Borkh.)…”

“…(Naor et al, 1997;Palmer et al, 1997;Stopar et al, 2002), though few studies have empirically quantifi ed F:LA. Whiting and Lang (2004a) suggested that conditional fruit growth capacity is limited by the supply of growth resources (i.e., source-limited condition) at less than 200 cm 2 leaf area per fruit, within mature 'Bing'/'Gisela 5' canopies. Based on this, and measured canopy leaf area at tree maturity, they suggested an optimum crop load of about 1800 fruit per tree.…”