Measurement and Modeling of Carbon Balance of the Apple Tree

Lakso, Alan N.; Wünsche, J.; Palmer, John W.; Grappadelli, Luca Corelli

doi:10.21273/hortsci.34.6.1040

Cited by 96 publications

(80 citation statements)

References 37 publications

(70 reference statements)

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“…One of the current hypotheses explaining at least part of the abscission of young fruits is deWcit in the supply of assimilate to young developing fruits, resulting in abscission of weaker fruit (Bangerth 2000). This is supported by the high correlation of model estimates of carbohydrate balance and the sensitivity to chemical thinners (Lakso et al 2006) during a time in which carbon deWcits in the tree are the greatest (Lakso et al 1999). Also, we have found in preliminary unpublished studies that shade eVects on fruit drop can be reversed with trunk injections of sorbitol, the primary translocated photosynthate in apple (Loescher et al 1982).…”

Section: Discussionmentioning

confidence: 52%

“…The diameters of all fruits were measured 3 days before and just prior to the application of the shade cloth, to ensure that all fruit were growing well, and then measured again at 24 and 72 h after the treatment began. The shade treatments were applied 18 days after bloom when the largest fruit diameters averaged 12 mm and the shade was maintained on the trees for 72 h. This stage of fruit development has been shown to be the most responsive to low levels of light intensity (Byers et al 1991) and is the period of most likely carbon supply deWcits (Lakso et al 1999). After measuring diameters of the fruits on the trees at 24 and 72 h with a digital micrometer, fruits of consistent diameters and growth increments for each treatment were identiWed to limit variability in the sampled fruits.…”

Section: Plant Materials and Weld Treatmentsmentioning

confidence: 99%

“…During the post-bloom thinning period, at about 10-20 days after bloom, demand for carbohydrates and other nutrients from various sinks exceeds what the sources can supply (Lakso et al 1999). The carbon balance may integrate the negative eVects of shading, application of photosynthetic inhibitors, elevated temperatures on fruit abscission or the combined eVects of simultaneous shade and chemical thinners (McArtney et al 2004).…”

Section: Introductionmentioning

confidence: 99%

“…Since many environmental and physiological factors aVect the carbohydrate supply and demand balance and fruit abscission in the apple tree (Lakso et al 1999), a carbohydrate balance model has been developed to integrate these factors (Lakso et al 2001b). The model demonstrated that particularly good carbon supply status correlated with less-than-average response to a chemical thinner and vice versa (Lakso et al 2006), further suggesting that carbon metabolism may be a key aspect, and possibly an integrator, of fruit abscission.…”

Section: Introductionmentioning

confidence: 99%

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Isolation and characterization of genes associated with shade-induced apple abscission

et al. 2008

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Apple trees generally produce excessive number of flowers and young fruitlets, which negatively affects commercial value. Thus, thinning is an important practice by which excessive flowers and fruitlets abort. Fruit abscission is difficult to predict or control, as many factors including shading can cause fruitlets to abort. In order to understand the molecular basis of shade-induced fruit abscission, two cDNA libraries were constructed using the suppression-subtractive hybridization (SSH) method and 347 expressed sequence tags (ESTs) were obtained. 168 ESTs represent transcripts that are preferentially expressed after 24 h of shading, and the other 179 are derived from RNAs of small apple fruits that were shaded for 72 h. Sequence analyses revealed that these clones represent 68 (24 h) and 44 (72 h) unique genes; these genes belong in eight functional categories. The largest set of genes is related to carbohydrate metabolism including the sorbitol 6-phosphate dehydrogenase (S6PDH) gene that was generally believed not to be expressed in young fruits, while the second largest group contains unclassified or unknown genes. RNA gel blot analysis confirmed that at least 26 genes are up-regulated after shade treatment. Some of these known genes may serve as molecular markers for apple monitoring the induction of fruitlet abscission. Improved genetic understanding is critical to the development of targeted abscission agents to better control apple crop loads and optimize apple production.

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Section: Discussionmentioning

confidence: 52%

Section: Plant Materials and Weld Treatmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Isolation and characterization of genes associated with shade-induced apple abscission

et al. 2008

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“…The contribution of the various shoot categories to tree productivity is now well documented and, as a general trend, whole-tree yield has been shown to strongly depend on light interception by the spur canopy (CorelliGrappadelli et al 1994;Lakso et al 1999;Wünsche et al 1996;Wünsche and Lakso 2000). This probably arises from both morphological features of short as compared to long shoots, the former having higher leaf to shoot ratios (Lauri and Kelner 2001), and faster carbon exportation capacity early in the season (Sansavini and CorelliGrappadelli 1992).…”

Section: Introductionmentioning

confidence: 99%

Light interception in apple trees influenced by canopy architecture manipulation

Willaume

Lauri²,

Sinoquet

2004

Trees

104

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Improvement of light penetration within tree canopies has been a constant objective of fruit tree architecture manipulation through the setting up of training systems. Recently, centrifugal training, i.e. the removal of fruiting shoots in the tree centre and on the underside of branches, has been proposed to improve fruit size and colour as well as return-bloom as compared to conventional solaxe-trained trees with equivalent crop loads. The present study was conducted to quantify the benefits of centrifugal training on light interception by the fruiting shoots via computer-assisted three-dimensional representations of foliage geometry. Data were collected on six 5-year-old apple trees cv.Galaxy, trained either with solaxe or centrifugal training systems, using an electromagnetic 3D digitiser. The 3D distribution of the foliage in the tree canopy was recreated by combining both the spatial locations of shoots (as measured from 3D digitising) and foliage reconstruction. Light interception efficiency properties of the trees were characterised by silhouette to total area ratio (STAR) values computed from images of the 3D mock-ups. Compared to the solaxe system, centrifugal training significantly improved the STAR of the whole tree by 20%. It also increased both leaf area and STAR of the fruiting shoots by approximately 15%, regardless of their position in the canopy. In this paper, we discuss the role of this enhanced light interception by the canopy in increasing the autonomy of the fruiting shoot, i.e. improved fruit size and colour, and return-bloom.

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Analyzing Fruit Tree Architecture: Implications for Tree Management and Fruit Production

Costes

Lauri

Regnard

2006

Horticultural Reviews

121

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Measurement and Modeling of Carbon Balance of the Apple Tree

Cited by 96 publications

References 37 publications

Isolation and characterization of genes associated with shade-induced apple abscission

Isolation and characterization of genes associated with shade-induced apple abscission

Light interception in apple trees influenced by canopy architecture manipulation

Analyzing Fruit Tree Architecture: Implications for Tree Management and Fruit Production

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