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One of the ambitions of ‘crop systems biology’ is to combine information from molecular biology with a broader view of plant development and growth. In the context of modeling, this calls for a multiscale perspective that focuses on the interplay between cellular and macroscopic studies. With this in mind, in this review we aim to draw attention to a panel of approaches that were developed in the context of systems biology and are used for analyzing and describing the behavior of cellular networks. Ultimately, insights obtained from these methods can be exploited to refine the description of plant processes, leading to integrated plant-cellular models. [Copyright &y& Elsevier]

Abstract: To check if bunch trimming improves quality traits of banana, its effect on the dry matter content of the pulp and peel of two banana cultivars (Grande Naine, and a hybrid named Flhorban 924) were investigated during fruit growth. For both cultivars, bunches with six hands (controls) were compared with trimmed bunches with only two hands at two fruit development stages, one early fruit pruning treatment at 160 degree days (dd) and one late fruit pruning treatment at 540 dd. Early bunch trimming increased fruit weight by more than 25%. An allometric relationship of type Y = aX b was found between fruit and pulp dry weight, in which the coefficients mainly depended on the cultivar concerned. In the allometric relationship between the weight of water in the fruit and the pulp, coefficient b was the same in the two cultivars. During fruit growth, the dry matter content of the pulp and peel increased rapidly between 160 and 600 dd, then continued to increase, but more slowly, to reach maximum at between 600 and 800 dd depending on the cultivar, and finally declined slowly until the end of growth. The early bunch trimming treatment led to an increase of 1g100g−1 in the dry matter content of the peel. However, the dry matter content of the pulp was not affected by bunch trimming irrespective of when the treatment was carried out. In conclusion, this common cultivation practice did improve fruit weight but had no significant impact on the dry matter content of the banana pulp at harvest. [Copyright &y& Elsevier]

• Fruit water conductance strongly decreased under high temperature. • Rising temperature reduced starch accumulation in contrast to hexoses. • Rising temperature reduced the fresh and dry matter accumulation in tomato fruit. • The ascorbate and carotenoid concentrations increased under high temperature. • A broader change in ED temperature is necessary to assess its role on fruit quality. In the present study, tomatoes were grown under control conditions (CT), a moderate (MT, up to 2 °C) or a higher rise in temperature (HT, up to 5 °C), and a moderate rise followed by a lower air temperature at the end of the day (ED), in order to analyze the effects of increased temperature as well as management system impact on fruit quality. Rising temperatures up to 5 °C reduced the fruit growth duration by five days and greatly reduced the fresh (29.7 %) and dry matter (30 %) accumulation rate. Increasing the temperature during the day and lowering it at the end of the day increased citric and malic acid concentrations in the fruit, therefore reducing the sugar/acid ratio. The ascorbate concentration and carotenoids increased in the fruits grown under high temperature, while phenolics concentrations did not change. Fruit water conductance was strongly reduced under HT (−37 %), and so was starch accumulation, in contrast to hexoses. Dropping the air temperature at the end of the day could help mitigate HT impacts as it slightly increased the pericarp dry matter content. It could also improve seeds quality as it increased their dry matter content. It would be interesting to consider broader changes in ED temperature to confirm its potential role in improving fruits dry matter content. [ABSTRACT FROM AUTHOR]

• An integrated high-efficient irrigation strategy is proposed, WSQI. • Details of WSQI are described including theory, modelling and practice. • WSQI would motivate the transition of irrigation strategy from water-yield relationship to water-yield-quality relationship The cash crop industry has been developed extensively around the world, but in some cases high yields are obtained at the expense of large water and fertilizer input. Although the yield is higher under these practices, it may not be a high-efficient approach from the perspective of crop quality, economical revenue and sustainability in a long term. To solve this problem, an integrated high-efficient irrigation strategy for water-saving and quality-improving of cash crops (WSQI) has to be proposed. Here, we review the research frontiers in this field and the findings of our research group, aiming to expound WSQI with the following perspectives (1) Deficit irrigation under certain conditions and reasonable fertilization can significantly improve the quality of cash crops. Based on the screening of water/nutrient-sensitive quality traits, comprehensive evaluation methods combining the determination of weight for single quality attributes can be used to evaluate and compare comprehensive fruit quality index. (2) Statistical models of water-yield-quality for cash crops were developed that consider the compromise between crop yield and quality. The exploration of biophysical models revealed the mechanisms underlying crop quality formation. (3) Linear, non-linear, dynamic and multi-objective programming models can be powerful tools for supporting irrigation decision-making while considering crop water-yield-quality relationships, market supply and demand, consumer preferences, crop price and resource availability. The integrated high-efficient irrigation strategy proposed in this review would motivate the transition of irrigation strategies from the conventional field irrigation theory, to a new chapter of irrigation management for water conservation and quality improvement in cash crops. The first one is based on water balance and water-yield models, while the second one is based on the information of crop water demand and comprehensive consideration of the water-yield-quality relationship. In addition, this review will provide a theoretical basis and decision-making guidance for research innovation and agricultural production. [ABSTRACT FROM AUTHOR]

• Supplemental LED light only compared to HPS + LED lighting increased average fruit fresh weight. • Adding far-red LED to red/blue LED light increased the production of soluble sugar in the fruit. • Far-red LED light increased the effect of the dilution by soluble and storage compounds, but reduced the dilution by water. • Far-red LED light strongly increase glucose, fructose and sucrose concentration in the fruit. Understanding how greenhouse crops respond to supplemental lighting with light-emitting diodes (LEDs) compared with traditional lighting systems is essential to utilize the full potential of LEDs and their further adoption in energy efficient greenhouses. This study quantified the effects of supplemental lighting with high-pressure sodium (HPS) lamps and LED light on the dynamics of fruit growth and composition in tomato (Solanum lycopersicum L.). Two tomato genotypes ('Foundation' and 'Progression') were grown under daylight supplemented either with HPS (125 μmol m−2 s−1) combined with red/blue LED lighting (106 μmol m−2 s−1, HPS + LED light treatment) or red/blue LED light only (106 + 110 μmol m−2 s−1, LED + LED light treatment); and two genotypes ('Foundation' and 'NUN09204') under daylight supplemented either with red/blue LED light (200 μmol m−2 s−1, red/blue LED light treatment) or red/blue LED + far-red LED light (200 μmol m−2 s−1 + 40 μmol m−2 s−1, red/blue + far-red LED light treatment). Fresh weight and composition in glucose, fructose, sucrose, starch, citric acid and malic acid of tomato fruits at different stages of development were measured and analyzed in terms of three main underlying components: water dilution, dilution by soluble and storage compounds and metabolism. Growing fruits under the LED + LED compared to the HPS + LED light treatments increased average fruit fresh weight in all genotypes. The red/blue + far-red LED light treatment increased the production of soluble sugar, increased the dilution by soluble and storage compounds, and reduced water dilution leading to a strong increase in glucose, fructose and sucrose concentration in the pericarp. The LED + LED light treatment did not affect the metabolism of fruit biochemical compounds compared to the HPS + LED light treatments, but caused small changes in water dilution, which were reflected in the concentration of biochemical compounds. Dilution and metabolism were involved in genotypic differences in fruit composition. Our results show that altering the spectral composition of the supplemental light in energy efficient greenhouses can be done without an effect on fruit quality or even with an improvement of tomato fruit quality. Possible physiological processes underlying these light-induced changes in fruit biochemical compounds during fruit development in different genotypes were discussed. [ABSTRACT FROM AUTHOR]

In the spring of 1987, point-count surveys of breeding birds (passerines and picidae) were conducted, resulting in a dataset of 197 counts. The purpose was to analyze the effects of forest fragmentation on bird community composition in a mountain pine forest located in the Néouvielle National Nature Reserve in the central French Pyrenees between 1800 and 2400 metres. The study aimed to differentiate between the impacts of landscape factors (patch area, isolation) and habitat characteristics (altitude, vegetation structure). Additional information was gathered regarding the presence of Common Crossbill (Loxia curvirostra), Great Spotted Woodpecker (Dendrocopos major), Red Squirrel (Sciurus vulgaris), and Capercaillie (Tetrao urogallus) in the forest. The sampling design ensured that the selected patches represented a wide range of sizes and distances to the nearest large pine patch or low-altitude forest stand. Bird sampling utilized the point-count technique [3], focusing on singing passerines and Picidae within a 50-metre radius. The altitude, the percentage of open areas, of stones, boulders and of herbaceous and ligneous plant cover at various heights, the canopy height and number of dead trees, along with landscape variables describing patch size and isolation from large pine stands or low-altitude forests, were assessed for each point count. This dataset offers insight into the breeding bird community and squirrel occurrence in a typical high-altitude mountain pine forest in the Pyrenees in 1987, serving as a baseline for future comparisons to study changes in bird and squirrel populations, the impact of climate change, habitat fragmentation, and conservation priorities. These data aim to inspire further research and enhance our understanding of bird and squirrel ecology in mountain regions ., (© 2024 The Author(s).)

The Pyrenees is a mountain range in south-western Europe that supports a rich diversity of bird species. In 1981, point count surveys of breeding birds (passerines and picidae) were carried out in the Vanera valley, a valley in the eastern Pyrenees, resulting in a data set of 228 counts. These data provide valuable information on the distribution and abundance of bird populations on 5350 ha of heterogeneous land (including cropland, grasslands, heaths and river banks, and pine forest) at altitudes ranging from 1100 to 2600 meters. Additional point count surveys were carried out in the pine forest from 1982 to 1985, resulting in a data set of 144 counts. Habitat descriptors (percentage of herbaceous and ligneous plant cover at different heights - 0-1m, 1-4m and more than 8m; vegetation type) and altitude were assessed around each point count. This dataset provides a complete picture of the breeding bird community in a typical valley of eastern Pyrenees in the early 1980s, which could be compared with future censuses to contribute to a variety of research questions, such as quantifying changes in birds between the early 1980s and now in mountain areas, understanding the effects of climate change on bird populations, examining the effects of habitat fragmentation and land-use change, and identifying priority areas for conservation and management. These data could inspire new research and contribute to our collective understanding of bird ecology in the Pyrenees., (© 2023 The Authors.)

The size of fruit cells, seeds and fruits depends on their number. Could this density-dependence effect result from sugar resource sharing and, if so, does it involve phloem sugar flow or the intensity of sugar unloading to the sink? A density-dependence model (DDM) describing these processes was designed and parameterised for six species at five levels of organisation: cells and seeds within fruits, fruits within clusters, fruits within plants and plants within plots. Sugar flow was driven by phloem conductance, determined by parameters α , governing the shape of its relationship to population size, and κ , its value for a population size of one. Sugar unloading followed Michaelis-Menten kinetics with parameters V m (maximal unloading rate) and K m (Michaelis constant). The DDM effectively reproduced the observed individual mass dynamics, the undercompensating density dependence observed in most species at all sub-plant levels and the undercompensating, exact and overcompensating density dependence observed at the plant level. Conductance ( κ ) was a scaling factor varying with the level of organisation. V m was positively correlated with density dependence, and α was negatively correlated with density dependence only if the plant-within-plot level was not considered. Analysis of the model's behaviour indicates that density dependence of fruit growth could be a result of sugar sharing, and that both phloem sugar flow and sugar unloading contribute to these effects., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2022 Génard, Lescourret, Bertin and Vercambre.)

Brown rot in stored stone fruits, caused by Monilinia spp., may be due to preharvest and storage factors, but the combined effect of these factors has yet to be investigated. We set up two experiments to monitor the progression of brown rot during the storage of nectarines subjected to various preharvest and storage conditions. We assessed the effects of different agricultural practices (irrigation regimen × fruit load) and harvest dates on brown rot progress during storage in 2018 and the effect of different storage temperatures in 2019. We found that the cumulative incidence of brown rot during storage increased with individual fruit mass, which was influenced by agricultural practices, and for later harvest dates. It also increased with storage temperature. We observed that during storage no secondary infections developed in nectarines not in direct contact with fruits infected with Monilinia laxa . These findings led to the identification of candidate variables describing the brown rot risk on nectarines during storage, such as individual fruit mass, meteorological conditions before fruit harvest, prevalence of brown rot at harvest, and storage temperature. We used these variables to build a mathematical model for estimating the time-to-appearance of brown rot symptoms in stored nectarines. This model fitted the experimental data well, highlighting the need to pay greater attention to the interaction between preharvest and storage conditions. This model could be used to evaluate management strategies for reducing the impact of brown rot in nectarines during storage.

Productivity of fruit tree crops depends on the interaction between plant physiology, environmental conditions and agricultural practices. We develop a mechanistic model of fruit tree crops that reliable simulates the dynamics of variables of interest for growers and consequences of agricultural practices while relying on a minimal number of inputs and parameters. The temporal dynamics of carbon content in the different organs (i.e., shoots-S, roots-R and fruits-F) are the result of photosynthesis by S, nutrient supply by R, respiration by S, R and F, competition among different organs, photoperiod and initial system conditions partially controlled by cultural practices. We calibrate model parameters and evaluate model predictions using unpublished data from a peach (Prunus persica) experimental orchard with trees subjected to different levels of branch pruning and fruit thinning. Fiinally, we evaluate the consequences of different combinations of pruning and thinning intensities within a multi-criteria analysis. The predictions are in good agreement with the experimental measurements and for the different conditions (pruning and thinning). Our simulations indicate that thinning and pruning practices actually used by growers provide the best compromise between total shoot production, which impacts next year's abundance of shoots and fruits, and current year's fruit production in terms of quantity (yield) and quality (average fruit size). This suggests that growers are not only interested in maximizing current year's yield but also in its quality and its durability. The present work provides for modelers a system of equations based on acknowledged principles of plant science easily modifiable for different purposes. For horticulturists, it gives insights on the potentialities of pruning and thinning. For ecologists, it provides a transparent quantitative framework that can be coupled with biotic and abiotic stressors., (© The Author(s) 2021. Published by Oxford University Press. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.)

The cuticle is composed of cutin and cuticular waxes, and it is the first protective barrier to abiotic and biotic stresses in fruit. In this study, we analysed the composition of and changes in cuticular waxes during fruit development in nectarine (Prunus persica L. Batsch) cultivars, in parallel with their conductance and their susceptibility to Monilinia laxa. The nectarine waxes were composed of triterpenoids, mostly ursolic and oleanolic acids, phytosterols, and very-long-chain aliphatics. In addition, we detected phenolic compounds that were esterified with sugars or with triterpenoids, which are newly described in cuticular waxes. We quantified 42 compounds and found that they changed markedly during fruit development, with an intense accumulation of triterpenoids during initial fruit growth followed by their decrease at the end of endocarp lignification and a final increase in very-long-chain alkanes and hydroxylated triterpenoids until maturity. The surface conductance and susceptibility to Monilinia decreased sharply at the beginning of endocarp lignification, suggesting that triterpenoid deposition could play a major role in regulating fruit permeability and susceptibility to brown rot. Our results provide new insights into the composition of cuticular waxes of nectarines and their changes during fruit development, opening new avenues of research to explore brown rot resistance factors in stone fruit., (© The Author(s) 2020. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

The growth of plant organs is a complex process powered by osmosis that attracts water inside the cells; this influx induces simultaneously an elastic extension of the walls and pressure in the cells, called turgor pressure; above a threshold, the walls yield and the cells grow. Based on Lockhart's seminal work, various models of plant morphogenesis have been proposed, either for single cells, or focusing on the wall mechanical properties. However, the synergistic coupling of fluxes and wall mechanics has not yet been fully addressed in a multicellular model. This work lays the foundations of such a model, by simplifying as much as possible each process and putting emphasis on the coupling itself. Its emergent properties are rich and can help to understand plant morphogenesis. In particular, we show that the model can display a new type of lateral inhibitory mechanism that amplifies growth heterogeneities due e.g to cell wall loosening., Competing Interests: The authors have declared that no competing interests exist.

The growth of fleshy fruits is still poorly understood as a result of the complex integration of water and solute fluxes, cell structural properties, and the regulation of whole plant source-sink relationships. To unravel the contribution of these processes to berry growth, a biophysical grape (Vitis vinifera L.) berry growth module was developed and integrated with a whole-plant functional-structural model, and was calibrated on two varieties, Cabernet Sauvignon and Sangiovese. The model captured well the variations in growth and sugar accumulation caused by environmental conditions, changes in leaf-to-fruit ratio, plant water status, and varietal differences, with obvious future application in predicting yield and maturity under a variety of production contexts and regional climates. Our analyses illustrated that grapevines strive to maintain proper ripening by partially compensating for a reduced source-sink ratio, and that under drought an enhanced berry sucrose uptake capacity can reverse berry shrinkage. Sensitivity analysis highlighted the importance of phloem hydraulic conductance, sugar uptake, and surface transpiration on growth, while suggesting that cell wall extensibility and the turgor threshold for cell expansion had minor effects. This study demonstrates that this integrated model is a useful tool in understanding the integration and relative importance of different processes in driving fleshy fruit growth., (© The Author(s) 2018. Published by Oxford University Press on behalf of the Society for Experimental Biology.)

The concentrations of sugars in fruit vary with fruit development, environment and genotype. In general, there were weak correlations between the variations in sugar concentrations and the activities of enzymes directly related with the synthesis or degradation of sugars. This finding suggests that the relationships between enzyme activities and metabolites are often non-linear and are difficult to assess. To simulate the concentrations of sucrose, glucose, fructose and sorbitol during the development of peach fruit, a kinetic model of sugar metabolism was developed by taking advantage of recent profiling data. Cell compartmentation (cytosol and vacuole) was described explicitly, and data-driven enzyme activities were used to parameterize equations. The model correctly accounts for both annual and genotypic variations, which were observed in 10 genotypes derived from an interspecific cross. They provided important information on the mechanisms underlying the specification of phenotypic differences. In particular, the model supports the hypothesis that a difference in fructokinase affinity could be responsible for a low fructose-to-glucose ratio phenotype, which was observed in the studied population., (© 2018 The Authors The Plant Journal © 2018 John Wiley & Sons Ltd.)

Climate change projections predict warmer and drier conditions. In general, moderate to severe water stress reduce plant vegetative growth and leaf photosynthesis. However, vegetative and reproductive growths show different sensitivities to water deficit. In fruit trees, water restrictions may have serious implications not only on tree growth and yield, but also on fruit quality, which might be improved. Therefore, it is of paramount importance to understand the complex interrelations among the physiological processes involved in within-tree carbon acquisition and allocation, water uptake and transpiration, organ growth, and fruit composition when affected by water stress. This can be studied using process-based models of plant functioning, which allow assessing the sensitivity of various physiological processes to water deficit and their relative impact on vegetative growth and fruit quality. In the current study, an existing fruit-tree model (QualiTree) was adapted for describing the water stress effects on peach ( Prunus persica L. Batsch) vegetative growth, fruit size and composition. First, an energy balance calculation at the fruit-bearing shoot level and a water transfer formalization within the plant were integrated into the model. Next, a reduction function of vegetative growth according to tree water status was added to QualiTree. Then, the model was parameterized and calibrated for a late-maturing peach cultivar ("Elberta") under semi-arid conditions, and for three different irrigation practices. Simulated vegetative and fruit growth variability over time was consistent with observed data. Sugar concentrations in fruit flesh were well simulated. Finally, QualiTree allowed for determining the relative importance of photosynthesis and vegetative growth reduction on carbon acquisition, plant growth and fruit quality under water constrains. According to simulations, water deficit impacted vegetative growth first through a direct effect on its sink strength, and; secondly, through an indirect reducing effect on photosynthesis. Fruit composition was moderately affected by water stress. The enhancements performed in the model broadened its predictive capabilities and proved that QualiTree allows for a better understanding of the water stress effects on fruit-tree functioning and might be useful for designing innovative horticultural practices in a changing climate scenario.

Process-based models are effective tools to predict the phenotype of an individual in different growing conditions. Combined with a quantitative trait locus (QTL) mapping approach, it is then possible to predict the behavior of individuals with any combinations of alleles. However the number of simulations to explore the realm of possibilities may become infinite. Therefore, the use of an efficient optimization algorithm to intelligently explore the search space becomes imperative. The optimization algorithm has to solve a multi-objective problem, since the phenotypes of interest are usually a complex of traits, to identify the individuals with best tradeoffs between those traits. In this study we proposed to unroll such a combined approach in the case of peach fruit quality described through three targeted traits, using a process-based model with seven parameters controlled by QTL. We compared a current approach based on the optimization of the values of the parameters with a more evolved way to proceed which consists in the direct optimization of the alleles controlling the parameters. The optimization algorithm has been adapted to deal with both continuous and combinatorial problems. We compared the spaces of parameters obtained with different tactics and the phenotype of the individuals resulting from random simulations and optimization in these spaces. The use of a genetic model enabled the restriction of the dimension of the parameter space toward more feasible combinations of parameter values, reproducing relationships between parameters as observed in a real progeny. The results of this study demonstrated the potential of such an approach to refine the solutions toward more realistic ideotypes. Perspectives of improvement are discussed.

Carbon fluxes in plants have been subject to many modeling studies. The conceptual framework of models of carbon acquisition, allocation, and metabolism in plants are first introduced, together with methods to calibrate and evaluate the validity of the resulting models. The possibility to combine different models within an integrated plant-organ system is illustrated. In the last part of the chapter, methods used to measure the carbon flows at the plant scale are discussed.

Background and Aims: The mechanisms involving light control of vitamin C content in fruits are not yet fully understood. The present study aimed to evaluate the impact of fruit and leaf shading on ascorbate (AsA) accumulation in tomato fruit and to determine how fruit sugar content (as an AsA precursor) affected AsA content., Methods: Cherry tomato plants were grown in a glasshouse. The control treatment (normally irradiated fruits and irradiated leaves) was compared with the whole-plant shading treatment and with leaf or fruit shading treatments in fruits harvested at breaker stage. In a second experiment, the correlation between sugars and AsA was studied during ripening., Key Results: Fruit shading was the most effective treatment in reducing fruit AsA content. Under normal conditions, AsA and sugar content were correlated and increased with the ripening stage. Reducing fruit irradiance strongly decreased the reduced AsA content (-74 %), without affecting sugars, so that sugar and reduced AsA were no longer correlated. Leaf shading delayed fruit ripening: it increased the accumulation of oxidized AsA in green fruits (+98 %), whereas it decreased the reduced AsA content in orange fruits (-19 %), suggesting that fruit AsA metabolism also depends on leaf irradiance., Conclusions: Under fruit shading only, the absence of a correlation between sugars and reduced AsA content indicated that fruit AsA content was not limited by leaf photosynthesis or sugar substrate, but strongly depended on fruit irradiance. Leaf shading most probably affected fruit AsA content by delaying fruit ripening, and suggested a complex regulation of AsA metabolism which depends on both fruit and leaf irradiance and fruit ripening stage.

Source-sink relationships of field-grown plants of Coffea arabica L. cultivar 'Caturra' were manipulated to analyze the contribution of soluble sugars to sink feedback down-regulation of maximal leaf net CO2 assimilation rate (Amax). Total soluble sugar concentration (SSCm) and Amax were measured in the morning and afternoon on mature leaves of girdled branches bearing either high or low fruit loads. Leaf Amax was negatively correlated to SSCm, increased with fruit load and decreased during the day, indicating that limiting sink demand for carbohydrates caused SSCm to accumulate in the leaf tissue which results in down-regulation of Amax. To further analyze source-sink feedback on Amax, we compared Amax of mature, non-sink-limited coffee leaves fed with water or sucrose for 5, 10 or 30 min with that of non-fed control leaves. Sucrose-feeding reduced Amax compared with the control and water-feeding treatments, indicating that down-regulation of Amax is related to phloem sucrose concentration in coffee source leaves, independent of SSCm concentration in other leaf tissues. Although sucrose appeared to be more closely related to the mechanism underlying sink feedback down-regulation of Amax in coffee leaves than SSCm, Amax was closely related to SSCm by a nonlinear equation that may be useful for integrating sink limitations in coffee leaf photosynthetic models.

A virtual fruit model simulating seasonal changes in several peach (Prunus persica (L.) Batsch) fruit quality traits during the final growth stage is presented. The quality traits considered are fruit size, the proportion of total fruit mass consisting of fruit flesh, dry matter content of the flesh and the concentrations of sucrose, glucose, fructose and sorbitol in the flesh, which are used to calculate a sweetness index. The virtual peach fruit model was developed by adapting and integrating three existing process-based models describing fruit dry mass growth, fruit fresh mass growth and sugar accumulation in the flesh into one complex system. Data sets of peach fruit growth and quality obtained from one field site over several years were used to estimate parameters and evaluate the virtual peach fruit model. Output from the model showed good agreement with the field data. Insight into the complex nature of the virtual peach fruit model, i.e., its ability to show emergent properties, was accomplished by conducting a series of theoretical experiments. The virtual peach fruit model was shown to be sensitive to management and environmental factors (leaf:fruit ratio, stem water potential and, to a lesser extent, weather). Its ability to generate simple laws relating to physiological variables and quality parameters was also demonstrated. Finally, the virtual peach fruit model was able to reveal complex behaviors resulting from changes in water potentials or leaf:fruit ratios over time.

Background and Aims: A model of fruit surface conductance to water vapour diffusion driven by fruit growth is proposed. It computes the total fruit conductance by integrating each of its components: stomata, cuticle and cracks., Methods: The stomatal conductance is computed from the stomatal density per fruit and the specific stomatal conductance. The cuticular component is equal to the proportion of cuticle per fruit multiplied by its specific conductance. Cracks are assumed to be generated when pulp expansion rate exceeds cuticle expansion rate. A constant percentage of cracks is assumed to heal each day. The proportion of cracks to total fruit surface area multiplied by the specific crack conductance accounts for the crack component. The model was applied to peach fruit (Prunus persica) and its parameters were estimated from field experiments with various crop load and irrigation regimes., Key Results: The predictions were in good agreement with the experimental measurements and for the different conditions (irrigation and crop load). Total fruit surface conductance decreased during early growth as stomatal density, and hence the contribution of the stomatal conductance, decreased from 80 to 20 % with fruit expansion. Cracks were generated for fruits exhibiting high growth rates during late growth and the crack component could account for up to 60 % of the total conductance during the rapid fruit growth. The cuticular contribution was slightly variable (around 20 %). Sensitivity analysis revealed that simulated conductance was highly affected by stomatal parameters during the early period of growth and by both crack and stomatal parameters during the late period. Large fruit growth rate leads to earlier and greater increase of conductance due to higher crack occurrence. Conversely, low fruit growth rate accounts for a delayed and lower increase of conductance., Conclusions: By predicting crack occurrence during fruit growth, this model could be helpful in managing cropping practices for integrated plant protection.