Date palms are a cash crop and commonly irrigated using saline water. A better understanding of the processes involved in water use by date palms and their carbon budget is key to sustainable cultivation and saline irrigation scheduling. In this study, the process-oriented CoupModel was used to investigate the linked water and carbon fluxes in date palms under saline irrigation conditions. We compared experimental data for actual evapotranspiration (ETc act) and yield from trees grown in weighing lysimeters and irrigated at two salinity levels in 2006–2007 with an uncertainty-based calibration approach. The daily ETc act and annual yield of trees with the low-salinity irrigation in 2006 were used to calibrate the selected parameters, investigate model performance, and analyze parameter correlations. Further tests were undertaken, including the application of low-salinity irrigation in 2007 and high-salinity irrigation over two years. Dynamic modeling of the tree canopy and a radiation use efficiency approach, along with incorporating the salinity effects on plant respiration and consideration of internal water storage, accurately simulated the measured data. The model determined the direct responses of the date palms to varying irrigation water amounts and salinity, and atmospheric conditions. It robustly determined the characteristics of daily ETc act and annual yield for both irrigation salinities in each year. Based on the selected parameterization, the daily ETc act was accurately simulated for both irrigation salinities in each year. However, the yield was only accurately simulated for both irrigation salinities in 2006. In addition, the simulated amounts and calculated electrical conductivity of daily drainage water suggested that the model performed well in simulating the soil water and salinity conditions, particularly during the fruit growing season. In general, the lysimeter-based parameterization of the CoupModel applied to inter-yearly growth of palms under saline irrigation conditions helps long-term continuous simulations and agronomic applications.

Dryland agriculture has extensive impacts on surrounding ecosystems through its unintentional provision of food and water resources to local wildlife. We analyzed the response of a predator community of jackals, wolves and foxes to land-management choices, and how that response in turn affects native gazelles and Acacia vegetation in the Arava Valley of Israel. This hyperarid region is characterized by contrasting regimes comprising privatized (Moshavim) and communal (Kibbutzim) agricultural settlements, which provides ideal conditions for evaluating how land-management differences translate into crop choices, affecting resource availability and ecosystem changes. Integrating multi-year field observations of predators and gazelles with agricultural datasets, we show that shifts in land-use strategies have cascading ecological impacts. This is evident in the association of date orchards, an expanding land use especially in Kibbutzim, with shifts in the geographical and seasonal distributions of predators. Increased predator presence due to resource availability has displaced gazelles farther from settlements, subsequently impacting Acacia seed dispersal and recruitment. Considering the global expansion of dryland agriculture, the evidence of such socio-ecological cascading effects suggests the necessity to approach agricultural management at the landscape scale in desert regions.

The date palm (Phoenix dactylifera), an important agricultural crop in arid and semi-arid areas around the Mediterranean Sea, has high nutritional, cultural, and economic values. Date palm cultivation in Israel is practiced in the arid and hyper-arid Jordan and Arava Valleys and is associated with high water and nitrogen (N) fertilization inputs, with rates of up to similar to 170 m(3) water and similar to 6 kg N per full-grown tree annually, on average. While the palm's water needs and budget have been intensively studied, the fate of applied N has received little attention to date. Understanding this fate is especially important since high fertilization rates of similar to 740 kg N ha(-1) may have deleterious effects on the environment. Specifically, soil emissions of nitrous oxide (N2O) and leaching of nitrate (NO3-) are of major concern, due to their impact on climate change and groundwater contamination. We have measured the effect of four levels of N fertigation (fertilization + irrigation), between 0 and 2.55 kg N tree(-1 )yr(-1), on N2O and NO3- fluxes during an annual growth season in a three-year-old date palm orchard located in Israel's hyper-arid Arava Valley. We used static chambers for soil N2O flux estimations and measured drainage water NO3- concentrations at a 60-cm depth, together with a CF mass-balance-based water budget to estimate the NO3- leaching. We observed trivial soil N2O emissions of up to similar to 0.02% of applied N, while NO3- leaching was estimated to be as high as 36%. Dry areas between the trees, which did not receive any fertilization or irrigation, exhibited even lower N2O emissions than the irrigated areas. Inorganic N, however, accumulated during the dry months in the upper layer of the soil and was later lost at the onset of the winter rains. Our results provide the first-ever estimations of the potential environmental impact of date palm plantations in Israel and the Mediterranean Sea Basin.

An integrated research coupling a field study with an agronomic-economic model (ANSWER-APP) was conducted to investigate the combined effects of irrigation levels and crop loads on fruit quality, water productivity and profitability of mature date palms. The study took place in Israel's hyper-arid Arava Valley, where date palm trees are widely cultivated and rely exclusively on brackish water irrigation. Three fruit load intensities (low, FL1; commercial, FL2; high, FL3) and two irrigation levels (W1 and W2, equal to and higher than the local irrigation regime, respectively) were applied in a 22-year-old date palm orchard in 2018-2019. Irrigation amount, fruit quality and yield were measured. Profitability for each treatment was analyzed with the ANSWER-APP. Higher fruit load resulted in higher yield and water productivity, but on the other hand led to reduced fruit physical properties (size and mass), regardless of the irrigation treatment. The improved fruit physical properties and net profits in W2 compared to W1 treatment in each fruit load group resulted from excess salt leaching in the root zone. Notably, trees under W2FL2 treatment were found to have highest net profits. It is concluded that adequate irrigation amounts contribute to net profits in date palm trees treated with high fruit load intensity under saline irrigation conditions.

The transfer of 226Ra from irrigation water to basil crops was studied in field conditions. A dedicated basil plot was established and divided into test and control subplots irrigated with water having high (2.1 Bq L-1) and low (0.05 Bq L-1) activity concentrations of 226Ra, respectively. The experiment was performed over a period of 18 months during the autumn, winter and spring seasons, altogether eight cycles of growth and harvest. The activity concentration of 226Ra in basil grown in the test subplots was found to increase from a value of 0.6 Bq kg-1 up to 5.1 Bq kg-1 with successive cycles, compared to a mean value of 0.2 Bq kg-1 for basil grown in the control subplots. The increase in activity concentration of 226Ra in basil grown in the test subplots is mainly attributed to its build-up in the soil in which the level of 226Ra was found to increase by ~ 40%. The effective uptake of 226Ra from the irrigation water (via soil) by the basil plants was found to be approximately 0.4%. The maximal radiation dose following consumption of basil crops grown in the test subplots is negligible (~3 μSv/y).

Anticipating benefits of leaching salts when irrigating with low quality water is problematic due to the complexities of water and salt balances in soil–crop systems and diverse and changing economic realities. We hypothesized that coupling of current physical–biological modeling of soil–crop–salinity interactions with robust economic data would provide novel and important tools for decision makers. We present a biological–physical model of water and salt balance, plant water use and plant response to stress coupled with economic calculations of grower net profit to consider options for irrigating with water of varying salinity. The coupled model is implemented in a user-friendly menu- and web-based platform (http://app.agri.gov.il/answerapp/). Model inputs characterize the physical (soil hydraulic properties, weather), biological (crop response to water and salt), management (applied water salinity and quantity), and economic (yield value, yield determined and static expenses, capital return, water pricing, farm unit size, etc.) parameters. The application returns yield and net profit data for scenarios of interest and allows consideration of the environmental repercussions of economic decisions through calculation of leachate carrying excess water and salts out of the root zone. To demonstrate the potential of the application, a case study is presented for evaluation of maximizing profits in production of bell peppers grown in greenhouses in Israel's Arava Valley. In this study, we consider sensitivity to irrigation water salinity and application rate, market pricing, potential yield and water price scheduling. We additionally consider date palm as an alternative crop choice. We suggest that the application, while limited by some of the assumptions it is based on, represents a powerful first order tool for agricultural water management decision making when parameterized wisely for any particular question of interest.

The cultivation of date palms in Israel’s Arava Valley, which is characterized by a high evaporative demand, is widespread and exclusively depends on high-frequency irrigation. Fruit sets are usually thinned early in their development to produce large, high-quality dates. However, no effort has yet been made to comprehensively examine fruit load effects on date palm water use, CO2 fluxes and growth. The objective of this study was to investigate the effects of fruit load on these factors. Twelve date palms, six with fruit removed (“without fruit”) and six untreated (“with fruit”), were irrigated with equal amounts of water at sufficient levels for maintaining optimal soil water conditions. Sap flow and frond elongation were continuously measured. Gas exchange parameters (i.e., stomatal conductance and CO2 assimilation rate) and fruit growth (i.e., fruit size, mass, and sugar content) were monitored periodically. No significant differences were found in gas exchange, water consumption and frond elongation between the two treatments several weeks after the onset of the fruit load differentiation. However, a pronounced increase in stomatal conductance and CO2 assimilation rates in palms with fruit compared to those without fruit was identified during the sugar accumulation and post-harvest periods. Continuously increasing water consumption in palms with fruit was also observed during these periods, probably as a result of the progressive recovery of depleted carbohydrate and water storage in the tree. In addition, the frond elongation rate of palms with fruit was remarkably lower than those without fruit until the end of the harvest. It is concluded that crop load has a pronounced effect on physiological behaviors and water use of the cultivated date palm. Therefore, irrigation management must consider fruit load to achieve optimal yield.

There are gaps in our knowledge of the effects of irrigation water quality and amount on yield and postharvest quality of pepper fruit (Capsicum annuum L.). We studied the effects of water quality and quantity treatments on pepper fruits during subsequent simulated storage and shelf-life. Total yield decreased with increasing water salinity, but export-quality yield was not significantly different in fruits irrigated with water of either 1.6 or 2.8 dS/m, but there was a 30–35% reduction in export-quality yield following use of water at 4.5 dS/m. Water quantity hardly affected either total or export-quality yield. Water quality but not quantity significantly affected fruit weight loss after 14 days at 7 °C plus three days at 20 °C; irrigation with water at 2.8 dS/m gave the least weight loss. Fruits were significantly firmer after irrigation with good-quality water than with salty water. The saltier the water, the higher was the sugar content. Vitamin C content was not affected by water quality or quantity, but water quality significantly affected antioxidant (AOX) content. The highest AOX activity was found with commercial quality water, the lowest with salty water. Pepper yield benefited by irrigation with fresh water (1.6 dS/m) and was not affected by water quantity, but post-storage fruit quality was maintained better after use of moderately-saline water (2.8 dS/m). Thus, irrigation water with salinity not exceeding 2.8 dS/m will not impair postharvest quality, although the yield will be reduced at this salinity level.

Growth rate is one of the indicators for a plant’s physiological condition. Date palms are characterized by high frond elongation rates, which are mainly subjected to drought and salinity stresses. Thus, continuous measurement of these rates can provide real-time growth information, for assessing water status within the soil-plant-atmosphere continuum of cultivated date palms. This study introduces a novel device, the Palmeter, which continuously measures real-time date palm frond elongation. The Palmeter was calibrated in the laboratory and tested in a date palm orchard with a measurement resolution of 0.52mm. A field test indicated that the Palmeter could wirelessly transmit acquired data to a signal receiver over a distance of 100m with a success rate of more than 98%, facilitating the establishment of wireless sensor networks in date palm orchards. Neither temperature nor wind affected the Palmeter measurement within the orchard. The temporal patterns of the frond elongation measured by the Palmeter were found to be sensitive to various cultivation treatments, such as fruit load regimes, applied within a field study. Additionally, a six-volt power supply is recommended in order to reduce the Palmeter’s power consumption. The feasibility and robustness of the Palmeter system guaranteed the accurate measurement of the frond elongation under harsh field conditions. Therefore, the Palmeter can be potentially applied to measure the frond elongation of date palms and perhaps other palms, such as oil palms and coconut palms, for irrigation scheduling and cultivation management in large orchards.

Interest in desalination to provide irrigation water is on the rise, but there are few tools enabling consideration of feasibility based on both crop responses and economic parameters. We present a biological-physical model for crop response to salinity coupled with economic calculations of farm based costs and benefits to determine profitability of irrigation of various crops in Israel as a function of water salinity. We then evaluate the economic feasibility of investment in farm- or community-scale desalination plants to supply high quality water as an alternative to irrigation with brackish water.The predicted profit from production of high-value, salinity-sensitive crops irrigated with either pure desalinated or desalinated blended with locally available brackish water was high enough to justify desalination for agriculture at prices expected in the market today, at least for mid- to large-capacity scale plants ( > 1 MCM/yr). The coupled model, accessible as an online application (http://app.agri.gov.il/AnswerApp/) was demonstrated as an effective tool to evaluate the sensitivity of any or all variables affecting crop profitability, combining both sound agronomic, biological and physical understanding of crop growth and response processes with sound economic data and considerations.

Agriculture is a major source of livelihood for rural communities in the Middle East. Lacking freshwater resources, brackish aquifers are often exploited as sources of irrigation water, but the practice is unsustainable. The "Solar-powered desalination of brackish water with nanofiltration membranes for intensive agricultural use in Jordan, the Palestinian Authority and Israel" (AGRISOL) project aims at developing and testing a solar-powered, nanofiltration desalination system for the production of irrigation water and high-value crops in arid environments. Such solution has the potential to reduce groundwater abstraction rates, increase agricultural yields, and enhance farmers' wellbeing by enlarging their portfolio of crops. Two pilot plants are designed and installed in Israel (Hatzeva) and Jordan (Karama). Agronomic experiments are conducted to determine the technical and economic viability of the new technology. The potential market penetration of desalinated water irrigation is explored through surveys, aimed at eliciting farmers' perceptions and their potential concerns in switching to desalinated water irrigation. This paper presents selected results from the project and highlights additional expected major outcomes. We find that a market potential for the proposed innovation exists both in Israel and Jordan. This is largely determined by the perceived importance by farmers in both countries for sustainable solutions to their irrigation needs, particularly as a result of the observed rising salinity levels in the irrigation water. Moreover, experiments conducted in Hatzeva on strawberry demonstrate the technology's potential to enable the cultivation of salt-sensitive cash crops in the region. We conclude that desalination may be a valuable strategy towards more sustainable water management in the regional arid land agriculture.

Irrigation water salinity effects on colour and health ingredients in the pomegranate peel were studied in two accessions, 'Wonderful' and 'SP-2', grown under a wide range of salinities, 1.2 to 9 dS m–1. Ripe fruit peels were analysed for phenolics and anthocyanins composition, and antioxidative capacity. Total phenolics concentration and antioxidative capacity were determined by the Folin-Ciocalteau and FRAP assays, respectively. Phenolics and anthocyanins composition was analysed by RP-HPLC. Increased salinity enhanced considerably the overall accumulation of phenolics and anthocyanins, and the antioxidative capacity in both cultivars; the magnitude of the effects was accession dependent. Mono- and di-glucosides of cyanidins, pelargonidins, and delphinidines were detected at proportions that varied with accession and salinity. Increased concentrations of gallotannins, flavonols and ellagic acid derivatives in 'Wonderful', and punicalagins, flavonols and ellagic acid derivatives in 'SP-2' accompanied elevated salinity levels. The results may benefit the pomegranate juice and byproduct valourisation industries, especially in the face of global water quality deterioration.

Irrigation of crops in arid regions with marginal water is expanding. Due to economic and environmental issues arising from use of low-quality water, irrigation should follow the actual crop water demands. However, direct measurements of transpiration are scant, and indirect methods are commonly applied; e.g., the Penman–Monteith (PM) equation that integrates physiological and meteorological parameters. In this study, the effects of environmental conditions on canopy resistance and water loss were experimentally characterized, and a model to calculate palm tree evapotranspiration ETc was developed. A novel addition was to integrate water salinity into the model, thus accounting for irrigation water quality as an additional factor. Palm tree ETc was affected by irrigation water salinity, and maximum values were reduced by 25 % in plants irrigated with 4 dS m−1 and by 50 % in the trees irrigated with 8 dS m−1. Results relating the responses of stomata to the environment exhibited an exponential relation between increased light intensities and stomatal conductance, a surprising positive response of stomata to high vapor pressure deficits and a decrease in conductance as water salinity increased. These findings were integrated into a modified ‘Jarvis–PM’ canopy conductance model using only meteorological and water quality inputs. The new approach produced weekly irrigation recommendations based on field water salinity (2.8 dS m−1) and climatic forecasts that led to a 20 % decrease in irrigation water use when compared with current irrigation recommendations.

Relatively elevated concentrations of naturally occurring radium isotopes ((226)Ra, (228)Ra and (224)Ra) are found in two main aquifers in the arid southern part of Israel, in activity concentrations frequently exceeding the limits set in the drinking water quality regulations. We aimed to explore the environmental implications of using water containing Ra for irrigation. Several crops (cucumbers, melons, radish, lettuce, alfalfa and wheat), grown in weighing lysimeters were irrigated at 3 levels of (226)Ra activity concentration: Low Radium Water (LRW)<0.04 Bq L(-1); High Radium Water (HRW) at 1.8 Bq L(-1) and (3) Radium Enriched Water (REW) at 50 times the concentration in HRW. The HYDRUS 1-D software package was used to simulate the long-term (226)Ra distribution in a soil irrigated with HRW for 15 years. Radium uptake by plants was found to be controlled by its activity in the irrigation water and in the soil solution, the physical properties of the soil and the potential evapotranspiration. The (226)Ra apeared to accumulate mainly in the leaves of crops following the evapotranspiration current, while its accumulation in the edible parts (fruits and roots) was minimal. The simulation of 15 years of crop irrigation by HYDERUS 1-D, showed a low Ra activity concentration in the soil solution of the root zone and a limited downward mobility. It was therefore concluded that the crops investigated in this study can be irrigated with the natural occurring activity concentration of (226)Ra of 0.6-1.6 Bq L(-1). This should be accompanied by a continuous monitoring of radium in the edible parts of the crops.

In a world of diminishing water reservoirs and a rising demand for food, the practice and development of water stress indicators and sensors are in rapid progress. The heat dissipation method, originally established by Granier, is herein applied and modified to enable sap flow measurements in date palm trees in the southern Arava desert of Israel. A long and tough sensor was constructed to withstand insertion into the date palm's hard exterior stem. This stem is wide and fibrous, surrounded by an even tougher external non-conducting layer of dead leaf bases. Furthermore, being a monocot species, water flow does not necessarily occur through the outer part of the palm's stem, as in most trees. Therefore, it is highly important to investigate the variations of the sap flux densities and determine the preferable location for sap flow sensing within the stem. Once installed into fully grown date palm trees stationed on weighing lysimeters, sap flow as measured by the modified sensors was compared with the actual transpiration. Sap flow was found to be well correlated with transpiration, especially when using a recent calibration equation rather than the original Granier equation. Furthermore, inducing the axial variability of the sap flux densities was found to be highly important for accurate assessments of transpiration by sap flow measurements. The sensors indicated no transpiration at night, a high increase of transpiration from 06:00 to 09:00, maximum transpiration at 12:00, followed by a moderate reduction until 08:00; when transpiration ceased. These results were reinforced by the lysimeters' output. Reduced sap flux densities were detected at the stem's mantle when compared with its center. These results were reinforced by mechanistic measurements of the stem's specific hydraulic conductivity. Variance on the vertical axis was also observed, indicating an accelerated flow towards the upper parts of the tree and raising a hypothesis concerning dehydrating mechanisms of the date palm tree. Finally, the sensors indicated reduction in flow almost immediately after irrigation of field-grown trees was withheld, at a time when no climatic or phenological conditions could have led to reduction in transpiration.

This study presents a novel investigation of long-term apparent steady state conditions under a prescribed leaching fraction criterion. The research was carried out during a 7-year investigation of date palm (Phoenix dactylifera L., cv. Medjool) trees exposed to elevated levels of irrigation water salinity. High resolution weighing lysimeters were designed and constructed to generate an accuracy of +/- 0.0075 mm. The lysimeters were equipped with precision flux data acquisition that measured the oscillations of their daily water storage difference (Delta W) and evapotranspiration. The leaching fraction was kept constant throughout the study.The results generally confirmed that the assumption of apparent steady state conditions under the preprogrammed irrigation procedure was correct, even though inter- and intra-seasonal climate variations were observed. Measured Delta W oscillated slightly around zero even under high evapotranspiration demands. Drainage water electrical conductivity and leaching fraction were also found to stay fairly constant. The evapotranspiration of the date trees was found to be a function of the potential evapotranspiration, and rather insensitive to changes in the soil water storage (Delta W). Our analysis also indicates that for most practical purposes of monitoring and sustaining apparent steady state conditions, simple low-cost lysimeters, without weighing capability, can serve to monitor and sustain apparent steady state conditions, as long as there is water outflow from the lysimeters.However, the high resolution (high cost) weighing lysimeters proved to be an efficient system for accurate data acquisition, which is necessary for accurate modeling. An annual numerical crop yield model, modified for a date palm field study, was successfully calibrated using data from a 2 month period, and subsequently validated against measured data from the following 8 months. The modified model closely predicted the daily oscillations of drainage water salinity and actual leaching fraction throughout the eight-month period. (C) 2012 Elsevier B.V. All rights reserved.

Actual measurements of water uptake and use, and the effect of water quality considerations on evapotranspiration (ET), are indispensable for understanding root zone processes and for the development of predictive plant growth models. The driving hypothesis of this research was that root zone stress response mechanisms in perennial fruit tree crops is dynamic and dependent on tree maturity and reproductive capability. This was tested by investigating long-term ET, biomass production and fruit yield in date palms (Phoenix dactylifera L, cv. Medjool) under conditions of salinity. Elevated salinity levels in the soil solution were maintained for 6 years in large weighing-drainage lysimeters by irrigation with water having electrical conductivity (EC) of 1.8, 4, 8 and 12 dS m(-1). Salinity acted dynamically with a long-term consequence of increasing relative negative response to water consumption and plant growth that may be explained either as an accumulated effect or increasing sensitivity. Sensitivity to salinity stabilized at the highest measured levels after the trees matured and began producing fruit. Date palms were found to be much less tolerant to salinity than expected based on previous literature. Trees irrigated with low salinity (EC = 1.8 dS m(-1)) water were almost twice the size (based on ET and growth rates) than trees irrigated with EC = 4 dS m(-1) water after 5 years. Fruit production of the larger trees was 35-50% greater than for the smaller, salt affected, trees. Long term irrigation with very high EC of irrigation water (8 and 12 dS m(-1)) was found to be commercially impractical as growth and yield were severely reduced. The results raise questions regarding the nature of mechanisms for salinity tolerance in date palms, indicate incentives to irrigate dates with higher rather than lower quality water, and present a particular challenge for modelers to correctly choose salinity response functions for dates as well as other perennial crops. (C) 2011 Elsevier B.V. All rights reserved.

The well-established health beneficial value of pomegranate juice is leading to increased demand for pomegranate products and to the expansion of pomegranate orchards worldwide. The current study describes differences in the chemical composition of major ingredients of the arils and peels of 11 accessions grown in Mediterranean and desert climates in Israel. In most of the accessions, the levels of antioxidant activity and content of total phenolics, total anthocyanins, total soluble solids, glucose, fructose, and acidity were higher in the aril juice of fruit grown in the Mediterranean climate compared to those grown in the desert climate. However, the peels of fruit grown in the desert climate exhibited higher antioxidant activity, and the levels of total phenolics, including the two hydrolyzable tannins, punicalagin and punicalin, were higher compared to those in the peels of fruit grown in the Mediterranean climate. The results indicate that environmental conditions significantly affect pomegranate fruit quality and health beneficial compounds.

Fruits of diverse pomegranate (Punica granatum L.) cultivars were analyzed for soluble phenolics content, antioxidant activity, soluble solid concentration, acidity and internal red color intensity. Analysis was carried out at various dates throughout the harvest season, corresponding to different climatic conditions during fruit ripening. Values obtained varied with cultivar and ripening date. In three cultivars of different sensory properties and harvest season, comparison between late- and early-ripening fruit revealed that arils of fruit ripening later in the season contained more soluble phenolics (1.21–1.71 compared to 0.22–0.88 pyrogallol equivalents, g L−1) and exhibited a higher antioxidant activity, as measured by the ferric reducing ability (FRAP) assay (1.22–2.37 compared to 0.86–1.95 vitamin C equivalents, g L−1). The red color intensity of the arils inversely related (R2 = 0.89–0.94) to the sum of heat units accumulated during fruit ripening. Multiple linear regression analysis on fruit characteristics in 11 diverse cultivars indicated that juice antioxidative capacity linearly correlated with soluble phenolics content (R2 = 0.98), but not with the red color intensity of the arils (R2 = 0.38). Also, no significant correlation was established between aril color and either juice pH or total soluble phenolics content. The results imply that pomegranate fruit antioxidant and sensory quality traits can be enhanced by the choice of cultivar and controlled-climate cultivation management.

An accessible solution capable of reliably predicting plant‐environmental interrelationships for variable species, climates, soils, and management options is a necessary tool for creating sustainable agriculture and environmental preservation. A mechanism‐based analytical solution, the first of its kind that considers multiple environmental variables and their combined effects on plant response, was developed and tested. Water uptake by plants, water and salt leakage below the roots, and yield are calculated by solving for transpiration in a single mathematical expression according to limitations imposed by root zone salinity and water status. Input variables include the quantity and salinity of applied water, terms for plant sensitivity to salinity and to water stress, potential evapotranspiration, and soil hydraulic parameters. Where water was not limiting, regression of predicted versus measured data resulted in r2 = 0.96 with slope of 0.937 and intercept of 0.033 (not different from 1 and 0 at 99% confidence), where irrigation varied and salinity was not limiting the r2 = 0.94 with slope of 0.906 and intercept of 0.044 (not different from 1 and 0 at 99% confidence), where both salinity and water levels varied r2 = 0.94 with slope of 0.966 and intercept of 0.033 (not different from 1 and 0 at 99% confidence). Application of the model for agricultural and environmental management and economic analysis is discussed. For example, a farmer in the Arava in Israel where irrigation water salinity is high (electrical conductivity of 3 dS m−1) cannot expect to reach greater than 70% of the potential yield for a pepper crop with any amount of irrigation. By choosing melon, the farmer can achieve 90% of potential yield with the same quality and quantity of water.