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Peach tree horizontal root distribution described by the interception of a plan registered on a plastic film. Comparison of root map of four horizontal soil layers (study with micro-sprinkler irrigation = " study MS " ).
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Introduction. Plant water stress indicators have become valuable for moving towards deficit irrigation strategies and saving water. In this case evapotranspiration (ET) is below its maximum value for the crop and stage (ETc), and a stress coefficient (Ks) is applied to obtain actual ET (Era). Predawn leaf water potential (Psi(p)) can be related to...
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... in our study, given the narrower wet bulb resulting from drip irrigation, roots were more concentrated, while, in "study MS", water accessed deeper layers and roots explored a larger soil volume (fig- ure 6). The differences in root development observed between the two experiments were induced by the irrigation method that, due to differences in irrigation frequency, and consequently irrigation depths, in their turn, influenced root bulk volume. ...
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We conducted a two-year study of deficit irrigation impact on peach yield and quality in semi-arid northwest China. Over two years, four-year-old peach trees were irrigated at 100, 75, 50 and 25% of peach evapotranspiration (ETc), here, ETc= Coefficient (Kc)×Local reference evapotranspiration (ETo). During the April–July fruit production season we...
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Citations
... As a consequence, several methodologies have been proposed aiming to increase the accuracy of Ks estimation. In particular, do Paço et al. (2013), estimated stress coefficient Ks in peach orchards by correlating transpiration data measured with sap flow sensors and ΨPD D R A F T measurements. Similar approaches were proposed for olive orchards and vineyards respectively (Conceição et al., 2017;Ferreira et al., 2012). ...
... Recent research has shown that it may be possible to adjust in-season IMZ boundaries using crop water status data (Cohen et al., 2017;O'Shaughnessy et al., 2015). Leaf water potential (LWP) has been identified as a reliable indicator of plant water status (Argyrokastritis et al., 2015;Bellvert et al., 2016;Paço et al., 2013) and Cohen et al. (2017) used measured LWP in cotton to develop temporally-variable IMZ boundaries. LWP has also been reported to directly affect other cotton physiological parameters that affect yield such as photosynthetic assimilation rate (Turner et al., 1986), stomatal conductance (Lacerda et al., 2022), and plant growth (Chastain et al., 2016a(Chastain et al., , 2016b, and these parameters can in turn be used to indicate field variability in water stress. ...
Current irrigation management zones (IMZs) for variable rate irrigation (VRI) systems are static. They are delineated in the beginning of the season and used thereafter. However, recent research has shown that IMZ boundaries are transient and change with time during the growing season. The primary goal of this study was to explore the potential of using vegetation indices (VIs) developed from unmanned aerial vehicle (UAV) and satellite images to predict cotton physiological parameters that can be used to delineate in-season boundaries of IMZs. A 2 year study was conducted in a 38 ha commercial cotton field in southwestern Georgia, USA. Throughout the two growing seasons, VIs were calculated from UAV, PlanetScope, and Sentinel-2 images. Predawn leaf water potential (LWP PD ) and plant height were measured at 37 locations in the field on the same day as the flights and correlated with UAV and satellite based-VIs. GNDVI (Green normalized difference vegetation index) was the best predictor of plant height with correlation values of 0.72 (p < .0001) and 0.84 (p < .0001) for 2019 and 2020, respectively. A secondary goal was to compare the performance of dynamic VRI (DVRI) to conventional irrigation. The field was divided into alternating parallel conventional, and DVRI strips to compare the two scheduling methods. The conventional strips were irrigated using the farmer’s standard method and individual IMZs within the DVRI strips were irrigated based on soil water tension (SWT) measured with a wireless soil moisture sensor network. LWP and SWT measurements correlated well. IMZs were initially delineated using soil texture, apparent soil electrical conductivity (ECa), and yield maps and satellite images from previous years and were modified in-season to reflect patterns observed in the plant height maps. In 2020, the DVRI system prescribed an average irrigation amount of 50.8 mm while conventional irrigation applied an average of 58.4 mm. Average yields for DVRI and conventional were 1248 and 1191 kg ha ⁻¹ , respectively. The DVRI system resulted in average yield 4.6% higher than conventional irrigation, while applying 14.0% less water. Despite the lower water application by the DRVI system, the performance comparison between the DRVI and the conventional irrigation was not conclusive.
... In numerous studies, Ks is not only estimated with FAO's original formula but it is also coupled with hydrodynamic parameters such as predawn or midday water potential in order to confirm the water status of plants. Specifically, in peach orchards, Afonso do PaÇo et al. [21] estimated stress coefficients from transpiration data measured with sap flow sensors and correlated it with Ψ PD measurements, similarly to Conceição et al. [22] in olive orchards and Ferreira et al. [23] in rainfed and drip irrigated vineyards. In citrus orchards Rallo et al. [24] calculated Ks values based on soil water content and water status (midday stem water potential) measurements, while Rallo et al. [25] calculated Ks using measured soil water content data combined with midday stem water potential, in correlation with actual transpiration fluxes in a 17 year-old table olive grove orchard. ...
The Mediterranean basin is characterized by hot and dry summers, which are aggravated by climate change, leading to water shortages for irrigation purposes. Olive trees (Olea europea L.) which are the most common cultivation in the area, while tolerant to drought conditions, are often irrigated due to the fact that they suffer from water deficits with negative impacts on yield. The knowledge of the onset and water stress intensity, essentially determines the accuracy of an irrigation schedule that avoids yield reduction and waste of water. Water stress can be quantified by stress coefficient Ks, as suggested by Food and Agriculture Organization (FAO). Combinations and adjustments of the FAO method with field measured data have been used to calculate Ks more precisely and apply it on single experimental fields. The FAO method and a validation method were compared and evaluated with in situ measurements in two different olive orchards in terms of tree age and irrigation system. The results indicate that the FAO method fails to distinguish the differences between cultivars, attributed mainly to the tree age and irrigation system, rendering almost a similar slope of Ks and calculating a nearly simultaneous onset of stress, which was not confirmed by pre-dawn water potential (ΨPD) measurements.
... Dans le contexte actuel, ces exemples sont utilisés pour accentuer la nécessité de vérifier et de modifier les paramètres de la fonction de stress, TAW et p, si l'on suppose que cette forme (équation ) décrit relativement bien la réalité observée, ce qui n'est pas toujours le cas (Paço et al., 2012). La méthode d'analyse de cette courte présentation consiste à montrer les paramètres appliqués aux conditions sous analyse et à les comparer avec ceux qui émaneraient des recommandations des manuels. ...
Après avoir présenté le contexte de l'irrigation au Portugal, les auteurs de cet article examinent la robustesse de deux approches et leur combinaison afin de mieux programmer les campagnes d'irrigation à l'échelle de la parcelle. Deux cas d'application sont présentés et discutés : l'un sur des cultures horticoles à enracinement superficiel (piment, Capsicum annuum L. ) et l'autre sur des cultures avec racines ligneuses profondes (olivier, Olea europea 'Arbequina').
... Promisingly, developments in Information and Communication Technologies (ICT) including sensors and robotics provide the potential for precise measurement of crop water status for irrigation management and precise estimation of optimal harvest timing, among others. Plant water stress indicators are recognized to having promising potential for irrigation management under water stress conditions (Paço et al., 2013). ...
Precision management has become vital in agriculture with possibilities growing alongside developments in information and communication, robotics and sensor technologies. On the other side of expected benefits of precision management in terms of environmental friendliness, yield margin, input efficiency, etc., is the upfront expensiveness of such technologies. There is hence a need to quantitatively assess expected net benefits and provide useful information for farmers and stakeholders to enable informed choice on the potential adoption of precision technologies and management practices. This study presents economic assessment of precision irrigation and harvest management system with integrated use of sensor technologies and Farm Management Information System (FMIS) as compared to conventional practice applying partial budgeting as a tool. Relevant scenarios are defined based on data from an experimental apple orchard field situated in Prangins, Switzerland. The precision management system is found to be economically justifiable in situations of high demand for irrigation characterized by limited rainfall and considerable variabilities in weather conditions. Its economic feasibility is found to be sensitive to changes in fruit price and capital cost.
... Using the relationship between (RT) and Ψ pd, it was observed [73] that the Ψ pd threshold corresponding to RT equal to 0.7 is −0.33 MPa. Using CWSI, based on the temperature differences between canopy and air, a threshold of 0.5 was found to trigger irrigation [74]. ...
In regions with Mediterranean climate, water is the major environmental resource that limits growth and production of plants, experiencing a long period of water scarcity during summer. Despite the fact that most plants developed morphological, anatomical , physiological, and biochemical mechanisms that allow to cope with such environments , these harsh summer conditions reduce growth, yield, and fruit quality. Irrigation is implemented to overcome such effects. Conditions of mild water deficit imposed by deficit irrigation strategies, with minimal effects on yield, are particularly suitable for such regions. Efficient irrigation strategies and scheduling techniques require the quan-tification of crop water requirements but also the identification of pertinent water stress indicators and their threshold. This chapter reviews the scientific information about deficit irrigation recommendations and thresholds concerning water stress indicators on peach trees, olive trees, and grapevines, as case studies.
... However a water restriction also modified the relationship between aphid and vegetative growth, which indicated additional physiological consequences of water restriction on tree suitability for aphid. However, we did not find clear difference among treatments in midday leaf water potential which is correlated to predawn leaf water potential considered as the most accurate indicator of plant water stress (Paço et al., 2013). We therefore hypothesize that water restriction modified several variables related to plant water status, which possibly impact aphid performance. ...
Regulated deficit irrigation, which is a common practice to cope with water scarcity, can impact plant-aphid interactions, and possibly lead to a reduction in the use of pesticides. To test the possible effect of water restriction on the apple tree-rosy apple aphid (Malus domestica-Dysaphis plantaginea) system, we performed a factorial experiment with two levels of water supply and two genotypes on artificially infested trees. Plant growth and aphid abundance were characterised during the entire infestation period at two scales of analysis: the apical shoot scale and the tree scale, and additional measures were performed to evaluate plant water status. Aphid abundance increased with plant vegetative growth at both scales of analysis, which is consistent with the Plant Vigor Hypothesis (i.e. with the fact that most of the phloem feeders prefer fast growing plants). At the tree scale, aphid abundance was lower on trees that underwent water restriction, but at the shoot scale, aphid abundance responded differently to water restriction depending on the tree genotype. Water restriction modified the relationship between aphid abundance and growth, thus indicating that host suitability for aphids was affected by different plant variables susceptible to water stress, among which growth. The different response patterns at the two scales of analysis highlight the importance of scale choice in the study of plant-insect interactions.
... It is well known that this relationship, even when expressed in percentage of TAW, RAW or the water remaining in soil as in Equation (2), varies not only with several soil characteristics and the rate of ET, as already considered in the FAO 56 approach [29], but also with the root patterns [79,80], which are dependent on the irrigation method and frequency, as discussed later and illustrated in Figure 3. Moreover, plants change their ability to extract water from drying soil, during critical developmental periods. ...
... GC was 29% (shadowed areas near solar noon), and LAI was 1.2 (1998) and 1.4 (1999). Other details about this experiment and its results can be found in Paço et al. [80,114,115]. ...
... ΣETa + 1.30, valid for the range 0 to 20 mm (Figure 3). Using Ψ p , Ks obtained experimentally = 1.60 exp (2.54 Ψ p ), in the range −0.2 to −0.9 with r 2 = 0.92 [80]. The differences between the two lines for similar peach orchards are discussed in Section 9. ...
There are several causes for the failure of empirical models to estimate soil water depletion and to calculate irrigation depths, and the problem is particularly critical in tall, uneven, deficit irrigated (DI) crops in Mediterranean climates. Locally measured indicators that quantify water status are useful for addressing those causes and providing feed-back information for improving the adequacy of simple models. Because of their high aerodynamic resistance, the canopy conductance of woody crops is an important factor in determining evapotranspiration (ET), and accurate stress coefficient (Ks) values are needed to quantify the impact of stomatal closure on ET. A brief overview of basic general principles for irrigation scheduling is presented with emphasis on DI applications that require Ks modelling. The limitations of existing technology related to scheduling of woody crops are discussed, including the shortcomings of plant-based approaches. In relation to soil water deficit and/or predawn leaf water potential, several woody crop Ks functions are presented in a secondary analysis. Whenever the total and readily available water data were available, a simple Ks model was tested. The ultimate aim of this discussion is to illustrate the central concept: that a combination of simple ET models and water stress indicators is required for scheduling irrigation of deep-rooted woody crops.
... Thus we evidenced effects of water restriction on both aphid performance and plant growth, but we did not find clear difference in midday leaf water potential. Therefore even if midday leaf water potential is known to be well correlated to predawn leaf water potential, which is considered as the most accurate indicator of plant water stress (Paço et al. 2013), in our experimental design it might not be the most relevant water status indicator. Water restriction induced modifications in other variables related to plant water status, which may have impacted aphid performance. ...
Les pucerons sont des ravageurs importants des principales espèces fruitières en France, pêcher et pommier notamment. Dans le but de réduire l’usage des produits phytosanitaires, différentes alternatives sont envisagées pour contrôler les pucerons en verger. Nous avons commencé ce travail de thèse par une synthèse des différentes méthodes alternatives de contrôle envisageables et leur positionnement au cours des différentes étapes du cycle biologique du puceron. Puis nous avons étudié les effets de la modulation des caractéristiques de la plante hôte, via les pratiques culturales, sur l’abondance des pucerons. Notre étude se base sur l’hypothèse « Plant Vigor » qui énonce que les insectes phytophages sont plus performants sur les plantes ou les organes de forte vigueur. Par conséquent, sur nos deux dispositifs expérimentaux factoriels nous avons combiné des suivis dynamiques de croissance végétative et d’abondance de pucerons : Prunus persica - Myzus persicae (2 niveaux d’irrigation × 2 niveaux d’apport azoté) et Malus domestica - Dysaphis plantaginea (2 niveaux d’irrigation × 2 génotypes d’arbre). Les facteurs ont été choisis pour leur impact potentiel sur la croissance végétative et la qualité nutritionnelle de la plante hôte. Les expérimentations ont été menées sur de jeunes arbres en pot, ne portant pas de fruit. Au niveau du rameau, l’abondance des pucerons est positivement corrélée à la croissance végétative sur les deux systèmes étudiés. Sur pêcher, la relation disponibilité en azote et abondance de pucerons semble être médiée par le fort impact de l’azote sur la croissance végétative. L’effet négatif de la restriction hydrique sur l’abondance de pucerons ne semble pas lié à un impact sur la croissance végétative. Aussi sur le second système étudié : pommier-puceron cendré, nous avons choisi de faire varier les apports en eau et de travailler sur deux génotypes, pour tester la généricité de la réponse observée. A l’échelle du rameau, l’effet de la restriction hydrique sur l’abondance de pucerons est négatif pour un génotype et positif pour l’autre. Par contre à l’échelle de l’arbre, sur les deux génotypes l’abondance de pucerons est corrélée positivement à la croissance végétative et la restriction hydrique impacte négativement l’abondance de pucerons, ce qui suggère que la performance des pucerons est limitée sur les arbres en restriction hydrique par une autre composante que la vigueur de l’arbre. Ce travail de thèse montre que la restriction hydrique et le contrôle de la vigueur via les apports azotés peuvent s’avérer être des leviers pour le contrôle des pucerons en verger fruitier. Cependant les relations mises en évidence sont dépendantes du génotype, ainsi que de l’échelle d’analyse. Il reste à évaluer l’applicabilité de telles mesures sur des arbres en conditions de production, en prenant en compte notamment l’effet des restrictions hydrique et azotée sur la production fruitière.
... Presently, an increasing commitment for optimizing water productivity is being developed, especially in dry areas (Paço et al. 2013). For example, in the Mediterranean basin, agriculture is limited by water scarcity and often by the poor quality of this resource. ...
Water scarcity makes necessary the use of tools for increasing water productivity such as regulated deficit irrigation strategies (RDI). The effect of RDI on fresh-cut white flesh extra-early nectarine was studied. Initially, the soluble solids content of nectarines from RDI was higher than in control and over-irrigated fruits (9.72 ± 0.20 vs. 8.57 ± 0.05 °Brix, respectively) but after shelf-life storage no differences were found. During storage, RDI fruits had a more stable antioxidant capacity and soluble phenolic content. This treatment showed 10% more vitamin C than the other irrigation treatments, due to an increase in dehydroascorbic acid content. No pathogenic bacteria growth was found and all microbial counts were below the European legal limits. For all the irrigation treatments, the final sensorial scores were above the limit of marketability. Overall, RDI enabled savings of about 1,260 m3 of water/ha per year, without negatively affecting the quality of the fruit, allowing for their use as a fresh-cut product with a shelf-life of 8 days at 5°C.
