Quantification and modelling of the stomatal, cuticular and crack components of peach fruit surface conductance

Abstract

This study describes the components of fruit surface conductance. It aims to revise a modelling framework examining water loss across the fruit epidermis in relation to time and fruit growing conditions. For this purpose, cuticular crack surface area, healing artificial wounds in vivo, stomatal number and total fruit surface conductance were quantified during nectarine (Prunus persica L. nucipersica) fruit growth under contrasted irrigation regimes or thinning intensities. The contribution of stomatal component to total conductance decreased very early. A sub-model of the specific cuticular conductance according to fruit age was proposed that accounted for the complex temporal variation of the cuticular component. The occurrence of cracks was modelled by considering the relative expansion rate of the cuticle as a function of fruit fresh mass and relative expansion rate of the fruit. Healing decreased with fruit age. The observed temporal variations of fruit surface conductance and cuticular crack surface area were well simulated by the modified model whatever the fruit growing conditions. Tests on independent data revealed that the model was highly sensitive to parameters related to cuticular crack development and to cuticular properties.

QualiTree, a virtual fruit tree to study the management of fruit quality. II. Parameterisation for peach, analysis of growth-related processes and agronomic scenarios

“…Data from Lescourret et al (1998) and Gibert et al (2005Gibert et al ( , 2010 S 59.22 Lescourret and Génard (2005) Reserve mobilisation Rm ls Leafy shoot and fine roots mobile fraction of reserves -Dimensionless 0.026 Lescourret and Génard (2005) Rm ow Old wood, coarse root and 1-year-old stem wood mobile fraction of reserves -Dimensionless 0.02 Moing and Gaudillère (1992), Ashworth et al (1993), Spann et al Mediene et al 2002;Rieger and Marra 1994). For unpruned and unthinned peach trees under no water stress, the shoot:root ratios observed ranged from 3.5 to 6.3, with an average of 4.6, which was taken as a parameter value (Table 1).…”

“…A, AC Degreedays -1 0.0107 Data from Lescourret et al (1998) and Gibert et al (2005Gibert et al ( , 2010 S 4.04 9 10 -3 Lescourret and Génard (2005) DM max f Potential dry mass of fruits at maturity (Eq. 2) A, AC g 36.86…”

“…The shoot:root ratio at equilibrium (SReq), defined as the ratio between current-year aboveground and belowground parts of the tree at the end of the reproductive period, was estimated from peach trees under different growing conditions (Grossman and DeJong 1994a;Hipps Trees (2011) Lescourret et al (1998) and Gibert et al (2005Gibert et al ( , 2010 S 1,800 Lescourret and Génard (2005) RGR ini f Fruit initial relative growth rate (Eq. 2)…”

Integrating Physiology and Architecture in Models of Fruit Expansion

“…The cause of this disorder may be a consequence of reduced xylem density or hydraulic conductance that prevents adequate supply of water to the stylar end (Clearwater et al, 2012). At the fruit's surface, the pattern and the density of cuticular cracks (Gibert et al, 2007, 2010) together with the microclimate surrounding the fruit (Li et al, 2001; Saudreau et al, 2007) may impact water loss due to transpiration. As a consequence, the soluble solids content (sugar level) inside the fruit may change and thus ground a direct connection between the distribution of sugars inside the fruit and the biophysical properties of its skin.…”

QualiTree, a virtual fruit tree to study the management of fruit quality. I. Model development

“…For example, fruit micro-cracking, which is strongly related to fruit growth (Gibert et al 2007), changes fruit skin conductance to water vapour and, as a result, organoleptic quality, while at the same time rendering fruit more susceptible to fungal attack. By including the corresponding cracking and contamination models in QualiTree (Gibert et al , 2010 we could establish direct and original interactive links between fruit quality and pest development. In addition, pruning has a strong effect on both shoot growth and aphid infestation (Grechi et al 2008).…”