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9 páginas.- 7 figuras.- 3 tablas.- 36 referencias, The canopy temperature is a promising methodology for deficit irrigation scheduling. This measurement is used to calculate the crop water stress index (CWSI), which needs the estimation of non-water stress baseline (NWSB). In olive orchards, NWSB changed at different times of the day and throughout the season. The aim of this work was to evaluate a simplified methodology for estimating NWSB to allow reducing costs and facilitate the CWSI estimation. The experiment was performed during two consecutive seasons (2020 and 2021) in a young super-intensive density olive orchard (Olea europaea L. cv Manzanillo). Three irrigation treatments were evaluated in a completely randomized design with 6 repetitions: Control, Full Irrigated; Regulated Deficit Irrigation (RDI) with a period of water stress during pit hardening, and Rainfed. The midday stem water potential and leaf conductance were measured every week during the irrigation season. The canopy temperature was measured with a low-cost thermal camera attached to a tablet. The CWSI was estimated for the same trees used to measure the midday stem water potential and leaf conductance. The NWSB was calculated in different ways, considering several simplifications. Firstly, NWBS was obtained using previously published equations (one or several equations throughout the season). Secondly, climate data were measured in the orchard together with the canopy temperature or using daily values from a weather station nearby. CWSI estimations using different equations were closely related (R2 = 0.95; MSE = 0.008) and one fit was considered successful. Although the differences in the values from different sources was considerable and significant, the CWSI estimation did not present major variations and the use of data from the weather station could be assumed in commercial orchards. The CWSI successfully identified water stress in Rainfed conditions, mainly when the stomata closure was detected. However, the differentiation between Control and RDI was limited. © 2022 The Authors, This research was supported by the Junta de Andalucía government and the Fondo Europeo de Desarrollo (FEDER) project P20_00492.

9 páginas.- 6 figuras.- 5 tablas.- 38 referencias, Bruising is defined as the dark spots on the fruit surface that progress into the mesocarp as a consequence of mechanical damage during harvesting, handling or transport. Bruising is a relevant table olive quality trait since it may cause consumer rejection. In the last decades, olive orchards which were traditionally rainfed are being irrigated in order to increase productivity. However, currently Regulated Deficit Irrigation (RDI) strategies have been implanted in oil olive and recently in table olive orchards. Appropriate RDI strategies reduce total water consumption with little or no effect on production or fruit quality. In this work, the effect on bruise damage at harvest of three RDI treatments based on measurements of water potential during pit hardening compared to optimal plant water status (-1.2 MPa before pit hardening and -1.4 MPa after) has been studied in ‘Manzanilla de Sevilla’ olives. The strategies were as follows: RDI-1 aimed a moderate water stress at pit hardening (-2.0 MPa) and regular recovery at late August; RDI-2: severe water stress at pit hardening (-3.5 MPa) and early recovery (late July); RDI-3: severe water stress at pit hardening (-3.5 MPa) and regular recovery. This study was performed throughout the fruit growing season. The treatment with the highest Stress Integral (RDI-3) reduced pulp-to-pit ratio (on fresh weight basis) with no effect on fruit weight or oil content and more than 90% of the fruits reaching commercial categories according to the size. Furthermore, this treatment reduced the size of fruit bruises in comparison to early rehydration strategy. © 2019 Elsevier B.V., This research was supported by Spanish Research Agency (AEI) of the Ministry of Economy, Industry and Competitiveness (MINECO) and European Development Fund (FEDER) , projects AGL2013-45922-C2-1-R and AGL2016-75794-C4-4-R.

Quince tree (Cydonia oblonga Mill.) is known for bearing fruits that are rich in nutrients and health-promoting compounds while requiring low inputs of agrochemicals, and maintenance, but no information exists on the mechanisms developed at the level of leaf water relations to confront water stress and recovery. For this reason, the purpose of the present study was to identify the strategy (isohydric or anisohydric) by which quince plants cope with water stress and to further elucidate the resistance mechanisms developed in response to water stress and during recovery. In summer 2016, field-grown own rooted 17-years old quince trees (cv. BA-29) were subjected to two irrigation treatments. Control (T0) plants were drip irrigated (105% ETo) to ensure non-limiting soil water conditions, while T1 plants were irrigated at the same level as used in T0, except that irrigation was withheld for 42 days during the linear fruit growth phase, after which irrigation returned to the levels of T0 (recovery period). During the experimental period, T0 and T1 received a total of 374 and 143 mm water, respectively, including rain water. The quince trees exhibited extreme anisohydric behaviour under the experimental conditions. As water stress developed and during the recovery period, the plants exhibited high hydraulic conductivity, probably the result of resistance to cavitation. From the beginning of water stress to the time of maximum water stress, leaf turgor was maintained, possibly due to active osmotic adjustment (stress tolerance mechanism). This leaf turgor maintenance may have contributed to the high leaf conductance, and, therefore, good leaf productivity. The low quince leaf apoplastic water fraction under water stress could be considered as another drought tolerance characteristic because if the accumulation of water in the apoplasm is avoided a steeper gradient in water potential between the leaf and the soil can take place under water stress, thus favouring water absorption. peerReviewed

10 páginas.--6 figuras.-- 3 tablas.-- 49 referencias, Around the world, the tomato is considered the most important vegetable because of the extent of the cultivated area. In addition, it requires vast amounts of irrigation but little is known about the management of deficit irrigation. This study aims to evaluate the effect of regulated deficit irrigation (RDI) on development of crop and fruit quality for cherry tomatoes (ʽLazarinoʼ and ʽSummerbrixʼ). Two different cherry cultivars were used during two crop cycles (autumn and spring). RDI was scheduled with an initial period of no water stress and with a period of deficit from the beginning of the flowering, with a threshold of midday leaf water potential of around −1 MPa. It was found that the response to the irrigation treatment was affected by the season and even by the cluster considered. During the autumn cycle, there were no clear differences in yield despite water stress being mild but still significant. In the spring cycle, yield reduction peaked with different responses between cultivars. Water stress reduced fruit weight and fruit number per cluster in cv Summerbrix, producing a continuous decrease throughout the harvest period. In cv Lazarino, a yield reduction was detected only at the end of the harvest period and was related to the decrease in fruit weight and the number of inflorescence. The application of RDI reduced water by 85% and increased the content of soluble sugar, carotenoids and total phenols in both cultivars and cycles, the funding received from the Spanish Ministerio de Ciencia, Innovación y Universidades (Before Ministerio de Economía y Competitivida) , project ref. AGL2012-37610 , co-funded by FEDER). ECC, DH, AMBG, CMS and AJMM thank the Ibero-American Programme for Science, Technology and Development (CYTED, http://www.cyted.org ) for the funding of the IBERCAROT network. AJMM acknowledges the funding received from the Carotenoid Network: from microbial and plants to food and health (CaRed), funded by the Spanish Ministerio de Ciencia, Innovación y Universidades (Before Ministerio de Economía y Competitivida) (BIO2015-71703-REDT). The authors wish to thank the Fitó Company for the seeds provided.

22 páginas.- 6 figuras.- 6 tablas.- 41 referencias.- (This article belongs to the Special Issue Future of Irrigation in Agriculture), The tomato cultivated surface is one of the most important surfaces in the world. This crop needs a sufficient and continuous supply of water during vegetative growth. Therefore, production may be at risk in warm and water-scarce areas. Therefore, the implementation of irrigation alternatives such as regulated deficit irrigation (RDI) is of great importance to reduce the use of water and improve the production of the quality of tomatoes. The objective of this work was to evaluate the deficit irrigation scheduling using plant water status as a tool in deficit irrigation. Experimental design was a randomized design with four replications per treatment. Two irrigation treatments were applied: Control (125% of crop evapotranspiration (ETc)) and Regulated Deficit Irrigation (RDI). This latter treatment considered different threshold values of midday leaf water depending on crop phenological stage. No differences were observed in yield, with RDI treatment being more efficient in the use of irrigation water than the control. Besides, RDI tomatoes presented, in general, greater weight, size, Total soluble solids (TSS), sugars, antioxidant activity, lycopene, β-Carotene, and redder color with more intense tomatoes flavor. Finally, it might be said that RDI strategy helped to reduce 53% of irrigation water and to improve the nutritional, functional, and sensory quality of tomatoes.

Water, especially in arid and semiarid regions, is increasingly a disputed commodity among different productive sectors, the pressure for a more sustainable use of water in agriculture will grow. The main strategy to cope with water scarcity is the use of improved, innovative, and precise deficit irrigation management practices which are able to minimize the impact on fruit yield and quality. The aim of this paper was to develop a certification index or hydroSOS quality index for extra virgin olive oil and processed table olives. The hydrosSOS fruits and vegetables are those cultivated under regulated deficit irrigation (RDI). Different indicators in three quality areas ((i) fatty acids, (ii) phenolic compounds, and (iii) sensory attributes) were identified as showing characteristic or typical responses under RDI conditions. Marks or scores were assigned to each one of these indicators to calculate the proposed index. It can be concluded that an extra virgin olive oil (EVOO) or processed table olives are hydroSOStainable foods, if they meet 2 conditions: (i) fulfill the conditions established in the hydroSOS &ldquo, irrigation&rdquo, index, and (ii) fulfill the requirements of the hydroSOS &ldquo, quality&rdquo, index. HydroSOS quality index will be specific to each crop and variety and will depend on functional and sensory factors.

Selecting the rootstock in pistachio orchards is one of the most critical decisions, mainly in conditions of water scarcity. However, there are a few works that report the response of pistachio to water stress according to rootstock. Nowadays, UCB-I is one of the most important rootstock around the world. However, its commercial availability and high prices favour the selection of Pistacia terebinthus L. or Pistacia atlantica Desf. in some regions. The aim of this work is to study the water relations of these three rootstocks using cv Kerman as scion. Thirty pots, in the second year after budding, were subjected to a 28-days water stress period in outdoor conditions. Irrigation was stopped in the water stress treatments during all the 28 days period. The vegetative response was characterised at the end of the experiment. The diameter of the rootstock and scion, number of leaves and the percentage of leaves, trunk and root were measured. Along the experiment water relations parameters such as midday water potential and midday leaf conductance was measured. In order to compare the effect of rootstock and water stress pressure-volume curves were measured before and after the water stress period. Data of vegetative growth suggest that UCB-I was the rootstock less affected for water stress, because these data were not clearly affected. However, water relations parameters suggest that P. atlantica was the most resistant to water stress conditions, according to the results derivate from the pressure-volume curves. Possible mechanisms of response to water stress are discussed.

9 páginas.-- 9 figuras.-- 2 tablas.-- 35 referencias, The management of regulated deficit irrigation with a continuous measurement of the water status would allow obtaining an accurate estimation of the water needs. However, although different types of sensors are available, the threshold and daily management of these data are not clearly defined. Trunk diameter fluctuations are a good example of these type of data. The trunk growth rate (TGR) is considered an early indicator in olive trees. However, the daily TGR values are very changeable, and only cumulative values of TGR show a clear trend. The number of irrigation works using this indicator is scarce. The TGR thresholds considered in these papers are the average of values over a period, and this makes it difficult to use when preparing a daily schedule. The aim of this work is to present an approach that allows using daily TGR data. During the 2015 season, an irrigation experiment was carried out in the Doña Ana farm, a table olive orchard near Seville (Spain). The trees were 30 years old with a space of 7 × 4 m and they were irrigated using two drip lines with a flow rate of 2.5 l h−1. The experiment began in spring and involved three treatments. Control trees were irrigated to maintain the midday stem water potential values at around −1.2 MPa before pit hardening started and at −1.4 MPa after this point. The trees under a mild water stress treatment (MI) were irrigated in the same was as the Control trees, except from DOY (day of the year) 161, the beginning of pit hardening, to DOY 237, when threshold value decreased to −2.0 MPa. The Moderate water stress trees (MO) were irrigated in the same way as the Control trees, except in the same period that MI, but with a threshold value of −4.0 MPa. The midday water potential pattern and leaf conductance pattern suggested that the level of water stress in both treatments was low, slightly higher in MO than in MI at the end of the water stress period. The shoot elongation suggested a period of water stress before DOY 161 in MO trees that the midday stem water potential and leaf conductance did not detect. The maximum daily shrinkage (MDS) signal indicated water stress conditions during the drought period, but both treatments presented similar values. The trunk growth rate (TGR) indicator was useful when maximum perimeter curves, average TGR and daily TGR were used together. All the periods of water stress identified by other indicators were detected when the three TGR data were used. An approach to use these three sets of data is discussed herein., This research was supported by the Agencia Española de Investigación (AEI) and the Fondo Europeo de Desarrollo (FEDER) project AGL2013-45922-C2-1-R.

5 páginas.-- 1 figura.-- 3 tablas.-- 29 referencias, The olive tree (Olea europaea L.) is a Mediterranean tree adapted to drought conditions and traditionally rainfed. For irrigated olive groves, there is extensive knowledge about the effects of Regulated Deficit Irrigation (RDI) scheduling on the sensibility of different phenological stages and about the importance of rehydration in the last part of the fruit growth stage. Water stress in this period could reduce the fruit size, but the exact extent of this reduction is still unknown. Additionally, table olive varieties may be damaged during harvesting or processing. This results in bruising, superficial browning injuries that progress through the mesocarp. Bruising susceptibility is an important quality parameter in table olives, however it has been little studied in RDI research. Hand-harvested fruits of ‘Manzanilla de Sevilla’ for green processing, treated with two types of RDI and full irrigation, were bruise-induced with a standardized drop to evaluate bruising susceptibility. Bruising index (BI) and external (BAE) and internal (BAI) bruising damage were measured 3 and 24 h after the bruising treatment. A full irrigation treatment was set up in order to maintain the Ψh values higher than −1.2 MPa before pit hardening and −1.4 MPa until harvest. RDI-1 and RDI-2 were irrigated with a full irrigation treatment until 2 and 4 weeks before harvest, respectively. Then, water was withheld until −2.5 MPa. RDI-2 can save 50% of the water applied without affecting the fruit weight, volume or pulp-to-pit ratio (fresh and dry). Fruits under RDI treatments are less susceptible to bruising than fruits with a full irrigation treatment, as evidenced by the lower bruising index and the smaller external and internal damaged area. As for the bruising time line, 3 h after the bruise inducement, the bruising index and external damaged area had already developed, whereas internal bruising damage continued increasing up to 24 h after the bruising treatment., This work was supported by the Ministerio de Economía y Competitividad (grant number AGL2013-45922-C2-R).

18 páginas.- 9 figuras.- 3 tablas.- 46 referencias, Deficit irrigation scheduling is becoming increasingly important under commercial conditions. Water status measurement is a useful tool in these conditions. However, the information about water stress levels for olive trees is scarce. The aim of this experiment was to evaluate the effect on yield of a moderate controlled water stress level at the end of the irrigation season. The experiment was conducted in the experimental farm of La Hampa (Coria del Río, Seville, Spain) during three years. A completely randomized block design was performed using three different irrigation treatments. Deficit irrigation was applied several (4 or 2) weeks before harvest. Irrigation was controlled using the midday stem water potential, with a threshold value of −2 MPa and compared with a full irrigated treatment. This water stress did not reduced gas exchange during the deficit period. The effect on yield was not significant in any of the three seasons. In the high-fruit load season, fruit volume was slightly affected (around 10%), but this was not significant at harvest. Results suggest an early affection of fruit growth with water stress, but with a slow rate of decrease. Moderate water stress could be useful for the management of deficit irrigation in table olive trees., This research was supported by the Agencia Española de Investigación (AEI) and the Fondo Europeo de Desarrollo (FEDER) projects AGL2013-45922-C2-1-R and AGL2016-75794-C4-4-R.

9 páginas.- 11 tablas.- 43 referencias, Sustainability is a feature that most companies adopt in order to improve their profits, even when their activity is not sustainable or the definition in their sector is not clear. This concept actually relates to the management of natural resources. Agriculture, and particularly irrigation scheduling, is strongly linked to a sustainable management; however, it is not clear what defines a sustainable management. Several efforts have been made to improve the conservation of water resources, but most of them have not involved growers at the orchard level; and consequently, they have lost their opportunity to create a real improvement in terms of sustainability. The aim of this work was to design a “hydroSOStainable index” (or “hydroSOS index”) that evaluates different aspects at orchard level to improve the sustainability of the water resources. The hydroSOS index considers 16 indicators grouped in 4 areas: (i) hydraulic indicators, (ii) horticultural indicators not related to irrigation scheduling, (iii) horticultural indicators related to the moment when deficit irrigation is applied (when?), and (iv) horticultural indicators related to the way deficit irrigation is applied (how?). Each indicator provides different marks or scores, and their sum allows classifying orchard management into four labels. The weight of each indicator and each group is not in itself enough to obtain a maximum label. Groups allow to easily identify the main limitations for the orchard to achieve a sustainable irrigation management. This index was used to evaluate water management of two cases of study. © 2019 Elsevier B.V., This research was supported by the Agencia Española de Investigación (AEI) and the Fondo Europeo de Desarrollo (FEDER) projects AGL2013-45922-C2-1-R and AGL2016-75794-C4-4-R . It also received the financial support of the Galpagro company (Fundación para la investigación de la Universidad de Sevilla project PRJ201702989 ).

The resistance mechanisms (stress avoidance and stress tolerance) developed by persimmon plants (Diospyros kaki L. f. grafted on Diospyros lotus L.) in response to mild water stress and the sensitivity of continuously (on a whole-day basis) and discretely (at predawn and midday) measured indicators of the plant water status were investigated in 3-year old ‘Rojo Brillante’ persimmon plants. Control (T0) plants were drip irrigated in order to maintain soil water content at levels slightly above soil field capacity (102.3% of soil field capacity) and T1 plants were drip irrigated for 33 days in order to maintain the soil water content at around 80% of soil field capacity. The results indicated persimmon plants confront a mild water stress situation by gradually developing stomata control (stress avoidance mechanism) and exhibiting some xeromorphic characteristic such as high leaf relative apoplastic water content, which could contribute to the retention of water at low leaf water potentials. In addition, sap flow measurements made by the heat-pulse technique were seen to be the most suitable method for estimating persimmon water status, because it provided the highest signal intensity (actual value/reference value):noise (coefficient of variation) ratio in almost all intervals of time considered and provides continuous and automated registers of the persimmon water status in real time. © 2019 The Authors, We are grateful to the Arnau family from Explotaciones Ecológicas Harisa S.L. and Mr. J. Melgares from Oficina Comarcal Agraria Huerta de Murcia (Autonomous Comunity of the Region of Murcia) for all the help we have been given. AG and AJM acknowledge the postdoctoral financial support received from Ramón Areces Foundation and Juan de la Cierva program, respectively . IG is a predoctoral student at the Miguel Hernández University. Also, this work is a result of the PR internship (19925/IV/15) funded by the Seneca Foundation - Agency for Science and Technology in the Region of Murcia under the Jiménez de la Espada Program for Mobility, Cooperation and Internationalization.

7 páginas.- 3 figuras.- 6 tablas- 49 referencias, Water scarcity is considered one of the biggest global risks worldwide, not only because affects every continent but mostly because it can have dramatic impact in a long term. Deficit irrigation strategies can help in coping with this water scarcity and optimizing the water efficiency. Both regulated deficit irrigation (RDI) in moderate and severe levels and sustained deficit irrigation (SDI) were applied in almond nut crop within this study and quality parameters of obtained fruits were analyzed. Almost all morphological and physicochemical parameters were not affected by the water stress. However, statistically significant differences among treatments were observed for the fat content, the highest value being reached by moderate RDI treatment. Besides, differences were also found for total organic acids content, calcium, potassium, manganese and for six fatty acids (myristic, palmitic, margaric, cis-heptadecenoic, cis-vaccenic, and arachidic acids) content. According to experimental findings, it can be concluded that irrigation strategies do not affect almond fruit quality; being possible to increase the final quality of nuts, when moderate RDI is applied., The study has been funded (Spanish Ministry of Economy, Industryand Competitiveness) through a coordinated research project(hydroSOSmark) including the Universidad Miguel Hernández de Elche (AGL2016-75794-C4-1-R,hydroSOSfoods) and the Universidad deSevilla (AGL2016-75794-C4-4-R). Marina Cano-Lamadrid was fundedby a FPU grant from the Spanish Ministry of Education (FPU15/02158)

Continuous monitoring of the tree water status will enhance irrigation performance, particularly when applying deficit schedules. The olive tree is a highly drought-resistant species and management of the water stress could increase water savings. Trunk diameter fluctuations can be displayed as daily curves representing the shrinkage and swelling, and can provide information about tree water status. In olive trees, trunk growth rate (TGR) is the most useful indicator, but the daily variability reduced the commercial applications. Recently, weekly frequencies of TGR values were associated to the water status in one seasonal experiment. The aim of this work is to study the seasonal pattern and the interannual variations of these parameters in order to integrate them in an irrigation scheduling tool. The experiment was performed during two consecutive seasons (2018 and 2019) in a superhigh density mature olive orchard at Carmona (Seville, Spain). Three different irrigation scheduling treatments were considered in a randomized complete block design. The control treatment was fully irrigated with 150–175% crop evapotranspiration (ETc) in order to ensure an optimum water status. Regulated deficit irrigation-1 (RDI-1) was scheduled using only TGR data provided through the continuous measurements from a dendrometer. In this treatment, water stress conditions were controlled during the pit hardening period. RDI-2 was similar to RDI-1, but with a more severe water stress conditions during pit hardening and a maximum seasonal amount of water that limited rehydration. Water stress was greater during the 2019 season than the 2018 season, according to the midday stem water potential (SWP). Weekly frequencies of TGR values lower than − 0.3 mm day− 1 (Severe FR) and values between − 0.1 and 0.3 mm day− 1 (Good FR) described the water status pattern in the three treatments for both seasons. Only under severe water stress conditions (SWP more negative than − 4 MPa) the values of these frequencies did not identify accurately the water status. However, the use of weekly frequencies of values greater than 0.3 mm day− 1 (Alert FR) and the pattern of these Severe FR and Good FR themselves identified such conditions. The use of these three weekly frequencies (Severe, Good and Alert (SGA) approach) are suggested for continuous deficit irrigation scheduling in olive trees.

9 páginas.-- 12 figuras.- 1 tabla.- 44 referencias, Reduced water availability around the world drives the need for indicators that enable a better control of water stress at orchard level. Among the different parameters that could be used as indicators, trunk diameter fluctiations, are daily cycles suggested as tools for irrigation scheduling. These cycles can define different indicators and the trunk growth rate (TGR) was suggested as the most suitable for olive trees. Several works indicated that average TGR values are related to the tree water status even threshold values have been suggested. In addition, only daily TGR values below −0.1 mm day−1 were mentioned as water stress indicators. The aim of this work is to evaluate an irrigation scheduling approach based on those two results mentioned. To this end, an experiment was performed during the 2017 season, in a commercial, super-high-density orchard in Carmona (Seville, Spain). Four different irrigation treatments were applied based on midday stem water potential values and TGR. The Control treatment, with 100% ETc (crop evapotranspiration) and sustained deficit irrigation, was compared with two regulated deficit irrigation strategies based on TGR measurements. Severe water stress conditions were measured in the three deficit treatments. Irrigation scheduling using average TGR was not a suitable tool for the aim of the experiment because some data were lost and there were great variations in TGR values. However, it was found that average TGR values were related to midday stem water potential. The water potential and daily TGR data were grouped according to water stress levels (into values with water potential higher of −1.4 MPa and lower than −4 MPa). Daily TGR values greater than 0.3 mm day−1 were identified in response to severe water stress conditions. Weekly frequency of daily TGR values between −0.1 and 0.3 mm day−1 decreased from 60% to 25% when water stress level increased. Therefore, frequency and value of daily TGR are suggested as irrigation scheduling tools for olive trees. © 2019, This research was supported by the Agencia Española de Investigación (AEI) and the Fondo Europeo de Desarrollo (FEDER) project AGL2016-75794-C4-4-R

No previous information exits on the effect of preharvest chitosan, a plant biostimulant and antitranspirant, which has been considered as a food additive by the USFDA, spraying on pomegranate trees. Then, the effect of chitosan spraying in fully irrigated and water stressed trees on yield, fruit quality and the occurrence of fruit peel physiopathies was studied. Some of these effects were negative such as the reduction in fruit weight and the less reddish and duller appearance of the arils. However, these negative aspects could be regarded as being compensated by other very important positive effects, such as the increase in the antioxidant activity and the significant reduction in fruit peel cracking or splitting and fruit sunburn physiopathies occurrence, which would considerably improve the returns of pomegranate growers.

9 páginas.-- 10 figuras.-- 3 tablas.-- 32 referencias, Irrigation needs in mature almond orchards are very high. Although almond trees grow in rainfed conditions, the yield response is very sensitive to irrigation. Continuous monitoring of the water status could be an adequate tool to optimize deficit irrigation. In this sense, trunk diameter fluctuations appeared as a very promising indicator at the beginning of the century, but few data have been published. The aim of this work is to check threshold values of maximum daily shrikage (MDS) and identify possible limitations to their use in commercial orchards. The experiment was performed in a commercial farm in Dos Hermanas (Seville, Spain) during the 2017 season on a 7-years-old orchard (cv Vairo). The irrigation treatments were Control (100% ETc), sustained deficit irrigation (SDI) with a maximum seasonal irrigation of 100 mm and two regulated deficit treatments (RDI). Both RDI treatments (RDI-1 and RDI-2) were scheduled using the signal of maximum daily shrinkage (signal) and the midday stem water potential (SWP). In RDI-1, full irrigation conditions were provided before kernel filling and during postharvest, using the threshold values suggested in the bibliography. During kernel filling, the water stress level was designed to be -1.5 MPa (SWP) and 1.75 (signal). RDI-2 trees were irrigated using the same scheduling as RDI-1, but target water stress values were higher in kernel filling (-2 MPa and 2.75) and with a maximum seasonal amount of water of 100 mm. SWP in Control trees was near the McCutchan and Shackel baseline for most of the season. None of the deficit treatments reached the signal values suggested. Moreover, the signal values were almost equal between treatments, with no water stress effect. The trunk growth rate (TGR) presented clear differences depending on the water status., This research was supported by the Agencia Española de Investigación (AEI, Ministerio de Ciencia, Innovación y Universidades) and the Fondo Europeo de Desarrollo (FEDER) project AGL2016-75794-C4-4-R. Authors thank to Finca La Florida for their helpful assistance during the experiment, specially to Mr Carlos Angulo.

12 páginas.-- 10 figuras.-- 4 tablas.-- 43 referencias., Regulated deficit irrigation (RDI) results are affected by the actual water stress level reached during the treatments. The irrigation scheduling based on water status measurements, such as trunk diameter fluctuations, can control in an accurate way the water restrictions. However, the number of works that use these indicators as isolate parameter to control the schedule is scarce in general, and very scarce in olive trees. Building on previous works, the aim of this article is to schedule an RDI strategy in olive trees based on threshold values of maximum daily shrinkage (MDS) and trunk growth rate (TGR) without reference trees. The experiment was performed in a 40 years-old table olive orchard (cv Manzanillo) in Seville (Spain) for 3 years (seasons from 2011 to 2013). Three different irrigation treatments were considered in a completely randomized block design. Control trees were over-irrigated (125% crop evapotranspiration, ETc) in order to obtain fully irrigated conditions. Water stress conditions were applied during Phase II (pit hardening) in the RDI-2 treatment or during Phase II and Phase I (full bloom) in RDI-12. In both RDIs, a treatment recovery (Phase III) was performed before harvest. The trunk diameter fluctuation indicator was selected according to the phenological stage. TGR was used in conditions of full irrigation or moderate water stress level, such as Phase I and Phase III. TGR threshold values based on previous works were selected: 20 mday−1, RDI-2; 10 mday−1, RDI-12 (Phase I) and −5 mday−1, both treatments, Phase III. Only in one season RDI-2 was scheduled with TGR values (−10 mday−1) during Phase II. MDS threshold values were determined as the ratio between measured MDS and fully irrigated MDS (the so called MDS signal). The latter was estimated from a baseline. During Phase II, RDI-2 was irrigated with a threshold value of 0.9, while RDI-12 was irrigated with a threshold value of 0.75. MDS signal was not useful for most of the period considered and it did not agree well with fruit drop or fruit size. Conversely, the average of TGR during Phase II was significantly linked to fruit drop and fruit size, and so were the midday stem water potential and stress integral. Recommendations about the management of TGR are discussed. The water stress level in the experiments was moderate and no significant differences in yield were found. However, the trend of yield reduction in RDI-12 was likely related with a fruit drop and a reduction in crown volume. The yield quality did not decrease in the RDIs treatments, on the contrary, pulp:stone ratio improved significantly in some of the seasons., This research was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN), (AGL2010-19201-CO4-03 and AGL2013-45922-C2-1-R). Thanks are due to J. Rodriguez and A. Montero for help with field measurements.

Pistachio trees are capable to be profitable under rain-fed conditions. They also have a good response to low amounts of irrigation water, so are a great candidate to be considered for water-scarcity scenarios. The pistachio tree has a singular way of alternate bearing, losing a percentage of its floral buds in the year preceding the harvest year. This percentage of abscission of the fruit buds increases in situations of water stress, making irrigation strategy follow as a 1-year determinant for the next season fruit yield. Despite its high resistance to severe water stress conditions, the pistachio tree has high water requirements. To overcome this issue, regulated deficit irrigation (RDI) was tested as a technique to save water without affecting yield. Coupling the use of plant biosensors to this technique is a research approach that can improve its efficiency. The recourse to these techniques created a greater preference of the resultant product by the consumer.

14 páginas.-- 4 figuras.-- 3 tablas.-- 147 referencias.-- : Galindo,A., et al..., Water scarcity in Mediterranean climate areas will be progressively aggravated by climate change, population increase and urban, tourism and industrial activities. To protect water resources and their integrity for future use and to improve biodiversity, besides following advanced deficit irrigation strategies in fruit cultivation, attention could well be directed towards what are at present underused plant materials able to withstand deficit irrigation with minimum impact on yield and fruit quality. To this end, the state of the art as regards deficit irrigation strategies and the response of some very interesting emerging fruit crops [jujube (Zizyphus jujuba Mill.), loquat (Eriobotrya japonica Lindl.), pistachio (Pistacia vera L.) and pomegranate (Punica granatum L.)] are reviewed. The strengths and weaknesses of deficit irrigation strategies and the mechanisms developed by these emerging fruit crops in the face of water stress are discussed. The response of these crops to deficit irrigation, with special attention paid to the effect on yield but also on fruit quality and health-related chemical compounds, was analysed in order to assess their suitability for saving water in Mediterranean semiarid agrosystems and to analyze their potential role as alternatives to currently cultivated fruit crops with higher water requirements. Finally, the factors involved in establishing an identity brand (hydroSOS) to protect fruits obtained under specific DI conditions are discussed., We are also grateful to the Ministerio de Economía y Competitividad de España (MINECO) (CICYT/FEDER AGL2013-45922-C2-1-R, AGL2013-45922-C2-2-R, AGL2016-75794-C4-1-R and AGL2016-75794-C4-4-R) for grants to the authors. AG and JC-G acknowledge the postdoctoral financial support received from the Ramón Areces Fondation and the Juan de la Cierva program, respectively. Also, this work is a result of the PR internship (19925/IV/15) funded by the Fundación Séneca – Agencia de Ciencia y Tecnología de la Región de Murcia (Seneca Foundation – Agency for Science and Technology in the Region of Murcia) under the Jiménez de la Espada Program for Mobility, Cooperation and Internationalization.

9 páginas.-- 5 figuras.-- 8 tablas.-- 31 referencias.-- Corell, M. et al. (2016) Comparison of the water potential baseline in different locations. Usefulness for irrigation scheduling of olive orchards. Agricultural Water Management (177) 308-316, Deficit irrigation scheduling needs accurate indicators and in recent decades, continuous plant indicators have been developed. However, threshold values that could be useful in commercial orchards are not commonly reported. The water potential is a discontinuous measurement commonly used as a reference in the description of water stress level. In some fruit trees, such as olive trees, there are several works suggesting threshold values in fully irrigated conditions, but the influence of the evaporative demand is not taken into account. The aim of this work is to compare the values of the fully irrigated water potential in different locations in order to study the estimation of a common baseline. Three mature olive orchards were selected, two in Seville (South Spain) and one in Ciudad Real (Central Spain). There were clear differences between the three orchards during the 2015 season. Orchards in Seville (S-1 and S-2) were close (10 km apart) and had the same cultivar (table olive, cv Manzanilla) but they were different in terms of the fruit load (almost no fruit in S-1, medium fruit load in S-2) and distribution of water (single drip line in S-1, double drip line in S-2). The orchard in Ciudad Real (CR) was very different with regards to the olive cultivar (cv Cornicabra) and the location, as it was in a borderline zone for olives growing with very low temperatures that delay the phenological development. In all the orchards, the best baseline was obtained with different climatic measurements, even in S-1 and S-2. When all the data were considered, the best fit was obtained with the average vapour pressure deficit (VPDav). Influence of the location was significant in the interception term of the equations when Temperature was used but not with VPD. This source of variation was reltade with the level of fruit load. Slope of the equations was not affected for the location. The equation obtained was validated with water potential data from previous seasons of S-1 and CR orchards. Maximum temperature presented the best validation results. The usefulness of this baseline is discussed, This research was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN), (AGL2013-45922-C2-1-R).

Stem sap flow (Q) and leaf turgor pressure (P c) were measured simultaneously on 4-year-old, 2.4m tall 'Arbequina' olive trees in a hedgerow orchard. Measurements were performed on well-watered control trees as well as on 60RDI and 30RDI trees (RDI=regulated deficit irrigation). The 60RDI trees received 59.2% of the crop water needs (ET c), and the 30RDI trees received 29.4% of ET c. P c was determined non-invasively using the magnetic leaf patch clamp pressure probe (ZIM probe). The patch pressure P p measured by the probe is inversely correlated with turgor pressure at P c>ca. 50kPa. P c is coupled with xylem pressure; thus P p yields information about the development of tension in xylem. In the case of the control trees a positive correlation between Q and P p was generally found, i.e. Q increased usually with increasing P p and decreased with decreasing P p, as expected. However, Q peaking did not always coincided with P p peaking at noon. Occasionally, Q peaking preceded or followed P p peaking with a time difference of up to 3h in both cases. Under some circumstances, the onset of Q after sunrise was greatly delayed, even though a pronounced increase of P p was observed. A delayed onset of Q after sunrise resulted in hysteresis phenomena, i.e. the linear increase of Q and P p in the morning hours did not coincide with the corresponding decrease of Q and P p in the afternoon. The development of severe water stress (P c

Trunk diameter fluctuations (TDFs) have been suggested as an irrigation-scheduling tool for several fruit trees, but the works in olive trees has not obtained successful results with any of the indicators (maximum daily shrinkage (MDS) and trunk growth rate (TGR)) that are calculated from the daily TDF curves. No studies of olive trees have ever used reference trees to reduce the influence of the environment, as in work for other fruit trees. In this work, we compare different continuous and discrete water status measurements in a drought cycle. We suggest the calculation of a new and related indicator (DTGR), the difference between the TGR of stressed trees, and the TGR of reference trees. Negative DTGR values always indicate water stress conditions. The current work describes the variations of this new indicator (DTGR) in relation to water stress, and compares DTRG to the midday stem water potential, maximum leaf conductance and to the MDS. The midday stem water potential and the maximum leaf conductance describe the stress cycle clearer than the trunk diameter fluctuation indicators. No significant differences were found in the values of MDS between stressed and reference trees. On the other hand, the DTGR pattern values were near that of the stem water potential, though positive values were recorded in some dates during the water stress cycle. These variations indicate that DTGR is not a cumulative water stress indicators, as is water potential. Therefore, according to our data, water potential is a better indicator than the TDF parameters when no deficit irrigation scheduling is performed in olive trees. DTGR seems to be a good indicator of water stress from a threshold value around -1.4. MPa in olive trees. In addition, higher variability of DTGR than stem water potential may also be reduced with the increase in the number of sensors.

8 páginas.-- 7 figuras.-- 2 tablas.-- 32 referencias, Maximum daily trunk shrinkage (MDS) is the most popular indicator derived from trunk diameter fluctuations in most fruit trees and has been reported to be one of the earliest signs in the detection of water stress. However, in some species such as olive trees (. Olea europaea L.), MDS does not usually change in water stress conditions and trunk growth rate (TGR) has been suggested as better indicator. Most of this lack of sensitivity to drought conditions has been related to the relationship between the MDS and the water potential. This curvilinear relationship produces an uncertain zone were great variations of water potential do not imply any changes of MDS. The MDS signal, the ratio between measured MDS and estimated MDS with full irrigation, has been thought to be a better indicator than MDS, as it reduces the effect of the environment. On the other hand, though literature results suggest an effect of environment in TGR values, there are not clear relationship between this indicator and meteorological data. The aims of this work are, on one hand, to study the improvements of the baseline approach in the MDS signal and, on the other, study the influence of several meteorological variables in TGR. Three years' data from an irrigation experiment were used in to carry out the MDS analysis and six years' data for full irrigated trees during pit hardening period were used for TGR study. The comparison between MDS vs. water potential and MDS signal vs. water potential presented a great scattering in both relationships. Values of MDS signal between 1.1 and 1.4 were always identified with moderate water stress conditions (-1.4 to -2. MPa of water potential). However, since this MDS signal values are around the maximum in the curvilineal relationship with water potential, greater values of MDS signal (in the range of 1.1-1.4) were not necessary lower values of water potential. In addition, during low fruit load seasons MDS signal was not an accurate indicator. On the other hand, absolute values of several climatological measurements were not significantly related with TGR. Only daily increments explain part of the variations of TGR in full irrigated trees. In all the data analysed, the daily increment of average vapour pressure deficit was the best indicator related with TGR. The increase of this indicator decreased TGR values. In addition, the agreement between this indicator and TGR was affected for fruit load. Great yield seasons decrease the influence of VPD increment in TGR., This research was supported by the Spanish Ministerio de Ciencia e Innovación (MICINN), (AGL2010-19201-CO4-03). Thanks are due to J. Rodriguez and A. Montero for help with field measurements.

Aims: To evaluate the impact of the amount and distribution of soil water on xylem anatomy and xylem hydraulics of current-year shoots, plant water status and stomatal conductance of mature 'Manzanilla' olive trees. Methods: Measurements of water potential, stomatal conductance, hydraulic conductivity, vulnerability to embolism, vessel diameter distribution and vessel density were made in trees under full irrigation with non-limiting soil water conditions, localized irrigation, and rain-fed conditions. Results: All trees showed lower stomatal conductance values in the afternoon than in the morning. The irrigated trees showed water potential values around -1.4 and -1.6 MPa whereas the rain-fed trees reached lower values. All trees showed similar specific hydraulic conductivity (K s) and loss of conductivity values during the morning. In the afternoon, K s of rain-fed trees tended to be lower than of irrigated trees. No differences in vulnerability to embolism, vessel-diameter distribution and vessel density were observed between treatments. Conclusions: A tight control of stomatal conductance was observed in olive which allowed irrigated trees to avoid critical water potential values and keep them in a safe range to avoid embolism. The applied water treatments did not influence the xylem anatomy and vulnerability to embolism of current-year shoots of mature olive trees., This project was funding both by the Spanish Ministry of Science and Innovation (research project AGL2006-04666/AGR) and the Austrian Science Fund (FWF) (project No. P20852-B16). J. M. Torres Ruiz held a doctoral fellowship from the Spanish Ministry of Science and Innovation (BES-2007-17149, MCINN).

8th International Symposium on Sap Flow May 08-12, 2011 Volterra, ITALY Int Soc Hort Sci (ISHS); International audience; The aim of this work was to evaluate the potential of used sap flow (SF), trunk diameter variation (TDV) and leaf turgor (LT) sensors for assessing water stress in a 'Arbequina' hedgerow olive orchard with 1667 trees ha(-1). Measurements were made in control trees irrigated to replace 100% of the crop water needs, and in trees under two regulated deficit irrigation strategies, 60RDI and 30RDI, in which irrigation replaced ca. 60% and 30% of the control, respectively. From the SF and TDV measurements we calculated the daily difference, both for tree water consumption (D-Ep) and maximum trunk diameter (D-MXTD), between RDI trees and control trees. With the LT sensors we recorded the leaf patch output pressure (P-p), which is related to the leaf turgor pressure. Both D-Ep and D-MXTD responded quickly and markedly to changes in water stress. The seasonal dynamics of both indices agreed with that of the stem water potential. A decrease in the reliability of D-Ep was recorded on days of highly variable atmospheric demand. The LT sensors also showed to be highly sensitive to changes on water stress. Any of the three methods have a potential as indicators for precise irrigation in hedgerow olive orchards with high plant density and low soil water-holding capacity.

We used sap flow and trunk diameter measurements for assessing water stress in a high-density `Arbequina¿ olive orchard with control trees irrigated to replace 100% of the crop water needs, and 60RDI and 30RDI trees, in which irrigation replaced ca. 60% and 30% of the control, respectively. We calculated the daily difference both for tree water consumption (DEp) and maximum trunk diameter (DMXTD) between RDI trees and control trees. The seasonal dynamics of DEp agreed reasonably well with that of the stem water potential. We identified peculiarities on the response DEp to changes in water stressing conditions, which must be taken into account when using the index. An analysis of the water-stress variability in the orchard is required for choosing the instrumented trees. The reliability of the DMXTD index was poorer than that of DEp. The maximum daily shrinkage (MDS) was not a reliable water-stress indicator., This experiment was funded by the Spanish Ministry of Science and Innovation, research project AGL2009- 11310/AGR.

We applied two process-based models in a hedgerow olive orchard with the aim of understanding the limitations and mechanisms behind the control of transpiration in olive trees under drip irrigation. One model is based on the biophysics of water flow through the porous media of soil and xylem. The other is a hydromechanical model based on the observed dependence of stomatal aperture on whole-plant and epidermis water relations. The experiments were made in a hedgerow olive orchard (1667treesha -1) planted with 5-year-old 'Arbequina' trees. Measurements were made in control trees irrigated to replace 100% of the crop water needs, and in trees under regulated deficit irrigation (RDI) strategy, in which irrigation replaced ca. 30% of the control. Soil physical properties, root distribution, leaf area, sap flow, leaf osmotic pressure and key variables of leaf gas exchange and water status were measured and models were applied. Results show how in our orchard, with a shallow root distribution and very coarse soil, most of the limitation to transpiration was imposed by the hydraulics of the rhizosphere. The model shows how this limitation was related to the ratio of root to leaf area, and how this ratio can be managed by canopy pruning or by changing the number of drippers. Likewise, osmotic adjustment occurred similarly in both irrigation treatments, despite differences found on leaf water potential. Water stress largely affected plant hydraulic conductivity of RDI trees. A potential involvement of regulating signals, other than purely hydraulics, was evident in both treatments, although our data suggests that these signals were not regulated by the soil water status only.

9 pages, 7 figures., Sap flux (Q) and trunk diameter variation (TDV) are among the most useful plant-based measurements to detect water stress and to evaluate plant water consumption. The usefulness of both methods decreases, however, when applied to species that, like olive, have an outstanding tolerance to drought and a remarkable capacity to take up water from drying soils. Evidence shows that this problem is greater in old, big trees with heavy fruit load. Our hypothesis is that the analysis of simultaneous measurements of Q and TDV made in the same trees is more useful for assessing irrigation needs in old olive orchards than the use of any of these two methods alone. To test our hypothesis, we analysed relations between Q, TDV, midday stem water potential ( stem), relative extractable water and atmospheric demand in an olive orchard of 38-year-old ‘Manzanilla’ trees with heavy fruit load. Measurements were made during one irrigation season (May–October), in fully irrigated trees (FI, 107% of the crop evapotranspiration, ETc, supplied by irrigation), and in trees under two levels of deficit irrigation (DI60, 61% ETc; DI30, 29% ETc). Time courses of Q and TDV measured on days of contrasting weather and soil water conditions were analysed to evaluate the usefulness of both methods to assess the crop water status. We calculated the daily tree water consumption (Ep) from Q measurements. For both DI treatments we calculated a signal intensity by dividing daily Ep values of each DI tree by those of the FI tree (SI−Ep ).Wedid the same with the maximum daily shrinkage (MDS) values (SI−MDS). Neither SI−Ep nor SI−MDS rendered useful information for assessing the crop water needs. On the contrary, the daily difference for maximum trunk diameter (MXTD) between each of the DI trees and the FI tree (DMXTD) clearly indicated the onset and severity of water stress. A similar analysis with the Ep values, from which DEp values were derived, showed the effect of water stress on the water consumption of the trees. We concluded that the simultaneous use of DMXTD and DEp values provides more detailed information to assess water needs in mature olive orchards than the use of Q or TDV records alone., This work was funded by the IFAPA, Consejería de Innovación, Ciencia y Empresa de la Junta de Andalucía, research project ref. C03-056, and by the CICYT/FEDER, research projects AGL2004- 0794-CO3-02/AGR and AGL2007-66279-CO3-02.

Fernández Luque, José Enrique et al.-- 11 páginas, 7 figuras, 1 tabla, 37 referencias., The need for sophisticated irrigation strategies in fruit tree orchards has led to an increasing interest in reliable and robust sensor technology that allows automatic and continuous recording of the water stress of trees under field conditions. In this work we have evaluated the potential of the leaf patch clamp pressure (LPCP) probe for monitoring water stress in a 4-year-old ‘Arbequina’ hedgerow olive orchard with 1667 trees ha−1. The leaf patch output pressure (Pp) measured by the LPCP probe is inversely correlated with the leaf turgor pressure (>50 kPa). Measurements of Pp were made over the entire irrigation season of 2010 (April to November) on control trees, irrigated up to 100% of the crop water needs (ETc), and on trees under two regulated deficit irrigation (RDI) strategies. The 60RDI trees received 59.2% of ETc and the 30RDI trees received 29.4% of ETc. In the case of the RDI trees the irrigation amounts were particularly low during July and August, when the trees are less sensitive to water stress. At severe water stress levels (values of stem water potential dropped below ca. −1.70 MPa; turgor pressure < 50 kPa) half-inversed or completely inversed diurnal Pp curves were observed. Reason for these phenomena is the accumulation of air in the leaves. These phenomena were reversible. Normal diurnal Pp profiles were recorded within a few days after rewatering, the number depending on the level of water stress previously reached. This indicates re-establishment of turgescence of the leaf cells. Crucial information about severe water stress was derived from the inversed diurnal Pp curves. In addition Pp values measured on representative trees of all treatments were compared with balancing pressure (Pb) values recorded with a pressure chamber on leaves taken from the same trees or neighbored trees exposed to the same irrigation strategies. Concomitant diurnal Pb measurements were performed in June and September, i.e. before and after the period of great water stress subjected to RDI trees. Results showed close relationships between Pp and Pb, suggesting that the pressure chamber measures relative turgor pressure changes as the LPCP probe. Therefore the probe seems to be an advantageous alternative to the pressure chamber for monitoring tree water status in hedgerow olive tree orchards., This experiment was funded by the Spanish Ministry of Science and Innovation, research project AGL2009-11310/AGR. U.Z. and S.R. are very grateful for the financial support of the Bundesministerium für Wissenschaft und Technologie (EXIST-SEED grant) and of the Europäischer Fonds für regionale Entwicklung (EFRE 80145650; State Brandenburg).

[ES] En el presente trabajo se realiza una visión sobre aspectos relativos a la utilización de medidas continuas del estado hídrico del limonero en la programación del riego. Para ello, se analizó, la sensibilidad de distintos indicadores del estado hídrico medidos de forma continua o discontinua en las plantas, su significado fisiológico, la obtención de niveles de referencia de los indicadores y los primeros resultados sobre programación de riego., Este artículo se encuadra en las actividades de los proyectos CICYT/FEDER AGL2004-0794-C03-02, Consolider-Ingenio 2010 e IRRIQUAL (EC, FP6-FOOD-CT-2006-023120) (CSD2006-0067). W. Conejero y Y. Garcıa-Orellana son becarios del MEC (FPI) y Fundayacucho (Venezuela), respectivamente y E. Nicolas es contratado I3P (FSE-CSIC).