Carbon autonomy of peach shoots determined by 13C-photoassimilate transport

Abstract

We used (13)CO(2) tracing and source-sink manipulation to determine if fruiting shoots of peach (Prunus persica (L.) Batsch) trees are autonomous or if they import carbon from neighboring shoots, and if the degree of shoot autonomy is influenced by the source-sink relationship of the shoot. In three experiments, leaf to fruit ratio (L:F) of selected fruiting shoots was moderately (2005 and 2006) or strongly (complete sink removal, 2006) altered to either enhance or inhibit movement of carbon from (13)C-labeled fruiting shoots (LFS) to adjacent non-labeled shoots (NLFS), both located within 10 cm on the same main scaffold of V-shaped peach trees. At Stages I and III of fruit growth, fruit and shoot tips were sampled from LFS and NLFS to determine (13)C percentage on the day of labeling and after one week. Factors that differed among the three experiments in the two years were cultivar, tree age, source:sink ratios and labeling time. In all cases but one, no (13)C was found in fruits or shoot tips of NLFS. Only at Stage III of 'Redhaven' peach fruit growth (2005) was (13)C detected in fruits of NLFS, but only in the treatment favoring movement, and on the day of labeling. When L:F was altered to the maximum extent possible and branches were girdled at their base (complete sink removal, 2006), a detectable concentration of (13)C was recovered in fruits of NLFS at both growth stages, indicating that (13)C movement across adjacent shoots is possible, and detectable by (13)C tracing. According to our results, peach branches are relatively autonomous even at the fruiting-shoot level. However, conditions of strong imbalance between source supply and sink demand, either experimentally imposed or during periods of strong sink competition, may cause some movement of carbon among neighboring shoots.

Nectarine Fruit Ripening and Quality Assessed Using the Index of Absorbance Difference (IAD)

“…"SF26" was used to evaluate the effect of fruit density on fruit maturity of Tatura Trellis grown trees. Six branches with similar length (around 40 to 50 cm), one branch per each canopy layer (bottom, middle, and top), and orientation (East, West) were selected and tagged on each of the six trees in trial (thirty-six branches in total), based on the assumption that peach tree branches behaved as functionally autonomous units, as demonstrated by Volpe et al [24]. All tagged branches from three trees were hand thinned to 4 fruits per branch (1 fruit every 10-12 cm of shoot length) 15 to 20 DAFB (as suggested [10]), while all the tagged branches from the remaining three trees were left unthinned with roughly 8 fruits per branch (1 fruit every 5-6 cm of shoot length).…”

Translocation and distribution of photosynthetically assimilated <SUP>13</SUP>C to ‘Tsugaru’ apple fruits

“…A linear relationship exists between biomass increment i.e., relative growth rate and growth respiration Marcelis, 1996 . In contrast, 13 C-photoassimilate translocation from labeled fruiting shoots to adjacent non-labeled shoots is hardly observed on peach trees Volpe et al, 2008 . Since the relative growth rates of leaf, branch, and fruit biomass were higher at the earlier fruit development stages in our study, the greater loss of photoassimilates at the EFD stage may be attributable to higher growth respiration rate in the exposed shoots.…”

“…Photoassimilate translocation to fruit has been relatively well investigated in fruit trees Hansen, 1967a;Hansen, 1971;Finazzo et al, 1994;Darnell and Birkhold, 1996;Zhang et al, 2005;Carini et al, 2006;Volpe et al, 2008 , including apple Malus domestica Borkh. trees.…”

“…Klages et al 2001 observed that the larger biomass of individual apple fruits in low-cropping trees was primarily due to the supply of photoassimilates from source leaves rather than fruit sink metabolic activity. In a study of source-sink manipulation of peach trees at the shoot level, fruiting shoots with a higher ratio of leaf area to fruit mass tended to translocate more assimilated C to fruit at the peak stage of fruit sink strength Volpe et al, 2008 , suggesting that the supply of photoassimilates from source leaves is important for their translocation into fruit.…”

Flower bud differentiation and development in fruiting and non-fruiting shoots in relation to fruit set in apricot (Prunus armeniaca L.)

“…This lack of knowledge is based on the fact that these differences are established a posteriori and there are no criteria to determine a priori what will make a flower to set a fruit or to drop. Differences in flower quality are empirically known in different fruit tree species among flowers located in different type of shoots and while there are fruiting branches, long shoots are largely unproductive and are commonly pruned (Alburquerque et al 2003;Syvertsen et al 2003;Volpe et al 2008;Nortes et al 2009). In this work, we profit of this empirical knowledge to explore to which extent flower bud differentiation and bud development will affect the subsequent fruit set.…”