Pedicel Transpiration in Sweet Cherry Fruit: Mechanisms, Pathways, and Factors

Abstract

<jats:p>Pedicel appearance is a good indicator of freshness in sweet cherries (<jats:italic>Prunus avium</jats:italic> L.). Fruit with shriveled, discolored pedicels have reduced market value. Shriveled pedicels are thought to result from postharvest water loss due to transpiration. The objectives of our study were to 1) quantify the transpiration permeances of fruit and pedicel surfaces; 2) determine the role of the fruit in pedicel transpiration; and 3) identify the effects of selected factors on pedicel transpiration. Fruit with and without pedicels were incubated under controlled conditions [usually 22 °C, 75% relative humidity (RH)] and their mass losses determined gravimetrically. Pedicel transpiration was calculated by subtracting measured transpiration of fruit without pedicels from that of fruit with pedicels. Cumulative pedicel transpiration increased with time. Rates of pedicel transpiration were essentially constant over the first 0 to 1.5 hours but declined thereafter, approaching an asymptote over the subsequent period of 1.5 to 96 hours over which measurements were made. Cumulative pedicel transpiration exceeded the amount of water in the pedicel, indicating that at least some of the transpired water originated from the fruit. There was no significant effect of steam girdling on pedicel transpiration suggesting that water moved from the fruit to the pedicel through the xylem (steaming prevents phloem conduction). Abrading the cuticular membrane (CM) from a pedicel surface or extracting the cuticular wax by dipping pedicels once or five times in chloroform/methanol (1:1 v/v) increased rates of transpiration 12-, 3-, and 5-fold, respectively. The water vapor permeance of the pedicel surface determined under steady-state conditions (8.7 ± 0.4 × 10<jats:sup>−4</jats:sup> m·s<jats:sup>−1</jats:sup>) exceeded that of the fruit (2.1 ± 0.1 × 10<jats:sup>−4</jats:sup> m·s<jats:sup>−1</jats:sup>), possibly because of a more permeable CM and/or a higher stomatal density (38.5 ± 1.3 stomata/mm<jats:sup>2</jats:sup> for pedicels vs. 1.1 ± 0.0 stomata/mm<jats:sup>2</jats:sup> for fruit). Treatments known to affect stomatal opening (incubation in buffered abscisic acid at 0.1 m<jats:sc>m</jats:sc> or in CO<jats:sub>2</jats:sub>- or N<jats:sub>2</jats:sub>-atmospheres) had no effects on pedicel transpiration. Rates of transpiration were negatively correlated with RH but positively with temperature. There was no effect of RH and/or temperature on the permeances of pedicel or fruit surfaces. From our results it is inferred that 1) pedicel transpiration is a physical process governed by Fick’s law of diffusion, where cuticle and wax in particular represent the major rate-limiting barriers; 2) the permeances of pedicel surfaces exceed those of fruit surfaces; and 3) pedicel transpiration can be minimized by minimizing the driving force (difference in water vapor concentration) during postharvest handling and storage.</jats:p>

Insights Into Olive Fruit Surface Functions: A Comparison of Cuticular Composition, Water Permeability, and Surface Topography in Nine Cultivars During Maturation

“…However, the percentage of n -alkanes over total waxes was very low in comparison with other fruit species: for example, n -alkanes accounted for 29.4% of total waxes in “Jesca” peaches at harvest (Belge et al, 2014b), whereas in the present study the highest amount detected was 4.8% in “Marfil” mature olives ( Table 4 ). Accordingly, the ACL of acyclic wax compounds was lower than that found in other fruit species: ACL values were 28.8 to 29.9 in apple (Leide et al, 2018), sweet cherry (Athoo et al, 2015), and tomato ( S. lycopersicum L.) (Leide et al, 2011).…”

“…Similar results were found in the current study for “Arbequina,” but not for all the rest of varieties: changes in water permeance throughout fruit maturation were determined for five out of the nine cultivars studied, data indicating significant increases for “Morrut” and “Picual” samples, which incidentally displayed the highest loss in water content from the green to the ripe stages (27.1 and 13.3% for “Morrut” and “Picual,” respectively) ( Table 1 ). Water permeances observed in this study ranged from 6.6 to 11.9 × 10 −5 m s −1 , and were higher in comparison with those found for other fruit crops such as tomato ( S. lycopersicum L.) and apple ( Malus domestica Borkh), ranging respectively from 0.9 to 4.9 × 10 −5 m s −1 (Leide et al, 2007; Leide et al, 2011) and from 4.6 to 5.3 × 10 −5 m s −1 (Leide et al, 2018), but one order of magnitude lower than those observed for sweet cherry ( Prunus avium L.) (1.4 to 3.7 × 10 −4 m s −1 ) (Athoo et al, 2015).…”

Characterizing Neck Shrivel in European Plum

“…To identify the role of the pedicel in transpiration, transpiration of whole fruit of 'Doppelte Hauszwetsche' with and without the pedicel attached was quantified as described previously (Athoo et al, 2015). To summarize, fruit without pedicels were prepared by cutting the pedicel and sealing the cut end of the pedicel stub (including the pedicel/fruit junction) using epoxy glue (UHU plus schnellfest; UHU, B€ uhl/Baden, Germany).…”

Evolution of cherries texture in brine: Impact of harvest conditions during long-time storage

“…The pedicel of a sweet cherry fruit is a useful indicator of its postharvest freshness (Drake & Elfving, 2002;Sekse & Lyngstad, 1993;Wani, Singh, Gul, Wani, & Langowski, 2014). Although studies have been carried out on molecular composition of peduncle (Khalid, Gellert, Szendrei, & Duddeck, 1989) and transpiration mechanism (Athoo, Winkler, & Knoche, 2015) in sweet cherries or abscission and physical zone separation in rabbiteye blueberry (Vashisth & Malladi, 2013), little is known about impact of peduncle removal. Here we show for the first time that peduncle removal had a marked effect on texture of cherry during brine storage leading to improved fruit texture, mostly by increasing the firmness gain between crop days and 2 months.…”