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Introduction. The aim of this work was to study the effects of regulated deficit irrigation (RDI) on fruit yield, fruit weight and fruit quality parameters, as well as soil-plant water relations, in apple orchards under high-frequency subsurface drip irrigation in a region with a continental climate. Materials and methods. Four irrigation treatments were applied in 2010 and 2011 to apple trees cv. ‘Gala’: T1, no irrigation; T2, optimal irrigation except during summer; T3, optimal irrigation except during summer when RDI with a threshold for irrigation at –1.2 MPa midday stem water potential (Ψ stem) was utilised; T4, optimal irrigation. The soil water status and plant water status were followed over two growing seasons. Results and discussion. The irrigation treatments had no significant impact on fruit yield. However, compared with optimal irrigation (T4) and RDI (T3), the absence of irrigation in summer (T1, T2) induced low Ψ stem ( The RDI treatment saved 47% water compared with optimal irrigation without negative impacts on yield and fruit quality. In the temperate conditions of Switzerland, Ψ stem, as well as Ψ soil, are well adapted for scheduling RDI in apple orchards.

Four different regulated deficit irrigation treatments were applied in 8-year-old apple trees in field conditions, in Switzerland. Soil water and plant water status were followed in the different treatments, during about 100 days, from 40 to 140 days after full bloom and are reported. Our results show that in spite of clear differences in water status, there were no important differences in yields.

Inner and surface temperatures of several 'Golden Delicious' apples in orchard and air temperature were measured during more than 2 months. In addition to temperature measurements, the 3D canopy structure was measured to compute the light interception of each measured 'Golden Delicious' apple. From this we extracted quantitative information about fruit temperature dynamics and fruit temperature variability within a tree crown in relation to air temperature fluctuations and fruit sunniness. Especially, fruit temperature dynamics were analyzed at daily and monthly time scales and compared to the air temperature dynamics. Results showed that when an averaged fruit per tree and a daily time scale were considered, as it is commonly done in fruit or pest development models, fruit temperature was equal to air temperature. However, during daytime, large departure from air temperature and large inner temperature gradients which could have significant effect on fruit physiological processes were measured. Moreover, such departures were highly variable among fruits within a tree canopy. To explain such within tree variability, the light interception by fruits must be taken into account. From this experiment, useful relationships between fruit temperature, air temperature and fruit light interception for fruit physiological model were derived and explained from physical principles. (C) 2008 Elsevier B.V. All rights reserved.

UMR DAP équipe AFEF;UMR DAP équipe AFEF;; Orchard planting systems are often associated with tree shape management which has direct and practical implications on training and pruning strategies. The objective of horticultural practices is to reach the required height and shape as fast as possible and maintain the tree framework in time and space. Scientific studies consider the individual crown shape and the spatial organization of trees within the orchard, which encompass tree height, planting distances, alley width and/or the leaf area index (LAI). Therefore, eco-physiological studies are mostly dedicated to the optimisation of orchard performances, highlighting the importance of light interception and distribution. At orchard level, the individual tree is often considered as a black box, and the turbid medium analogy hypothesized, i.e., tree crowns are filled with a uniform leaf area density and isolines of canopy light distribution are computed. An incremental improvement in the understanding of tree growth and fruiting strategies has been developed in the last three decades. Minimal pruning concepts have been proposed to fruit growers, limiting undesired vegetative reactions and taking advantage of the genetic variability of architecture. Applications of these concepts lead to early and more regular yield, and favour the homogeneity of fruit quality. Recent studies also showed that interactions exist between components of tree architecture, namely branching density and shoot growth dynamics, and development of orchard pests and diseases. Paralleling the better understanding of tree architecture, dramatic improvements of ecophysiological studies have been performed now including an explicit description of plant geometry. Using computer-generated three dimensional representations of digitised trees light interception and distribution can now be accurately modelled at tree and orchard scales. These approaches are therefore, capable of taking branch organisation into account and this can in turn open new hypotheses related to pest and disease occurrence. Emerging concepts in fruit tree manipulation, and their impacts on architecture and eco-physiology, undoubtedly open new avenues in orchard management with the objectives to meet horticultural sustainability, i.e., optimising labour efficiency and fertilizer and water use, and demanding less pesticide

In this study, the apple production in the three most important apple- growing regions in Switzerland (Wallis, Vaud and Thurgau) are analysed. The amount of water which is used to irrigate a standard orchard will be identified via water balance model (Grattan et al. 1998). On the basis of the evaluated required amount of water used from 1981 to 2007 in the three chosen regions it will be possible to estimate if the required amount of water has increased within the last 27 years. With the managerial calculation model Arbokost 2006/07, the required amount of water used in the past will be combined with a full cost accounting based on latest techniques, prices and yields. Hence, the managerial key data (earned income, internal earned income and production costs of the best class) will be evaluated. With Arbokost 2006/07, the quality- and yield-losses and therefore the lower income caused by water deficiency will be calculated. This data will be compared with the production with irrigation for the three analysed regions. The maximum water price that apple growers can pay until they have to give up the orchard will be identified.

* Simple models of light interception are useful to identify the key structural parameters involved in light capture. We developed such models for isolated trees and tested them with virtual experiments. Light interception was decomposed into the projection of the crown envelope and the crown porosity. The latter was related to tree structure parameters. * Virtual experiments were conducted with three-dimensional (3-D) digitized apple trees grown in Lebanon and Switzerland, with different cultivars and training. The digitized trees allowed actual values of canopy structure (total leaf area, crown volume, foliage inclination angle, variance of leaf area density) and light interception properties (projected leaf area, silhouette to total area ratio, porosity, dispersion parameters) to be computed, and relationships between structure and interception variables to be derived. * The projected envelope area was related to crown volume with a power function of exponent 2/3. Crown porosity was a negative exponential function of mean optical density, that is, the ratio between total leaf area and the projected envelope area. The leaf dispersion parameter was a negative linear function of the relative variance of leaf area density in the crown volume. * The resulting models were expressed as two single equations. After calibration, model outputs were very close to values computed from the 3-D digitized databases.