title: Studies on water transport through the sweet cherry fruit surface: II. Conductance of the cuticle in relation to fruit development.
abstract: Water conductance of the cuticular membrane (CM) of sweet cherry (Prunus avium L. cv. Sam) fruit during stages II and III (31-78 days after full bloom, DAFB) was investigated by gravimetrically monitoring water loss through segments of the exocarp. Segments were mounted in stainless-steel diffusion cells, filled with 0.5 ml of deionized water and incubated for 8 h at 25 +/- 2 degrees C over dry silica. Conductance was calculated by dividing the amount of water transpired per unit surface area and time by the difference in water vapor concentration across the segment (23.07 g m(-3) at 25 degrees C). Fruit mass and fruit surface area increased 4.9- and 2.8-fold between 31 and 78 DAFB, respectively. However, CM mass per unit area decreased from 3.9 to 1.5 g m(-2) and percentage of total wax content remained constant at about 31%. Stomatal density decreased from 0.8 to 0.2 mm(-2) (31-78 DAFB). Total conductance of the CM on the fruit cheek (gtot.) remained constant during stage II of development (approx. 1.38 x 10(-4) m s(-1) from 31 to 37 DAFB), increased to 1.73 x 10(-4) m s(-1) during early stage III of fruit growth (43-64 DAFB) then decreased to 0.95 x 10(-4) m s(-1) at maturity (78 DAFB). Partitioning gtot. into cuticular (gcut.) and stomatal conductance (gsto.) revealed that the relative contribution of gcut. to gtot. increased linearly from 30% to 87% of gtot. between 31 and 78 DAFB. respectively. On a whole-fruit basis, g,tot. and gcut. consistently increased up to 64 DAFB, and decreased thereafter. A significant negative linear relationship was obtained between gcut. and CM thickness, but not between the permeability coefficient (p) and CM thickness. Further, p was positively related to strain rate, suggesting that strain associated with expansion of the fruit surface increased p.
authors.affiliation: Institut für Acker- und Pflanzenbau, Martin-Luther-Universität Halle-Wittenberg, Halle, Saale, Germany. knoche@landw.uni-halle.de
authors.forename: M
authors.initials: M
authors.lastname: Knoche
authors.forename: S
authors.initials: S
authors.lastname: Peschel
authors.forename: M
authors.initials: M
authors.lastname: Hinz
authors.forename: M J
authors.initials: MJ
authors.lastname: Bukovac
mesh_terms: D000465:Algorithms; D001692:Biological Transport; D005638:Fruit / Q000254:growth & development / Q000378:metabolism*; D008954:Models, Biological; D010539:Permeability; D019441:Plant Epidermis / Q000737:chemistry / Q000254:growth & development / Q000378:metabolism; D018526:Plant Transpiration; D027861:Prunus / Q000254:growth & development / Q000378:metabolism*; D014867:Water / Q000378:metabolism*; D014885:Waxes / Q000032:analysis / Q000302:isolation & purification
chemical_list: D014885:Waxes; D014867:Water