Response of tomatoes,a crop of indeterminate growth,to soil salinity

Tomatoes were grown in tanks filled with loam and clay, and were irrigated with waters of three different levels of salinity. Osmotic adjustment was determined by analysing the pressure–volume curves at four growth stages. Owing to the osmotic adjustment, tomatoes are able to maintain the turgor potential and the stomatal conductance at the same value for the lower values of the leaf-water potential. Salinity affected the pre-dawn leaf-water potential, stomatal conductance, evapotranspiration, leaf area and fruit yield on both soils. Soil texture only affected the fruit yield. The evapotranspiration showed a moderate decrease, owing to the small decrease in leaf area and the effect of osmotic adjustment on the stomatal conductance, whereas the fruit yield decreased strongly. The tomato plant apparently favours under saline conditions, the growth of foliage at the expense of fruit formation.     

Effect of salinity on water stress, growth, and yield of maize and sunflower

Maize and sunflower were grown in tanks filled with loam and clay, and were irrigated with water of three different levels of salinity. Predawn leaf-water potential and stomatal conductance were used as parameters for water stress. The predawn leaf-water potential of maize was higher than that of sunflower, but the effect of salinity and soil texture on the predawn leaf-water potential was the same for both crops. The stomatal conductance of sunflower was much higher and more severely affected by salinity and soil texture than the stomatal conductance of maize.

Although salinity had a more serious effect on the development of leaf area and canopy dry matter of sunflower, its effect on evapotranspiration and grain yield was the same for both crops. Soil texture had a stronger effect on the development of leaf area and canopy dry matter of sunflower, which also appeared in the evapotranspiration and grain yield, indicating that sunflower is more sensitive to drought than maize.     

Salinity effect on crop development and yield,analysis of salt tolerance according to several classification methods

The publication is a synthesis of previous publications on the results of a long-term lysimeter experiment. From 1989 to 1998, the experimental variables were soil salinity and soil type, from 1999 onwards, soil salinity and crop variety. The plant was studied during the whole growing period by measuring the saline stress and analyzing its effect on leaf area and dry matter development and on crop yield. Salinity affected the pre-dawn leaf water potential, stomatal conductance, evapotranspiration, leaf area and yield.The following criteria were used for crop salt tolerance classification: soil salinity, evapotranspiration deficit, water stress day index. The classification according to soil salinity distinguished the salt tolerant group of sugar beet and wheat, the moderately salt sensitive group comprising broadbean, maize, potato, soybean, sunflower and tomato, and the salt sensitive group of chickpea and lentil. The results for the salt tolerant and the moderately salt sensitive groups correspond with the classification of Maas and Hoffman, excepted for soybean.The evapotranspiration deficit criterion was used, because for certain crops the relation between yield and evapotranspiration remains the same in case of drought and salinity. This criterion, however, did not appear useful for salt tolerance classification.The water stress day index, based on the pre-dawn leaf water potential, distinguished a tolerant group, comprising sugar beet, wheat, maize, sunflower and potato, and a sensitive group, comprising tomato, soybean, broadbean, chickpea and lentil. The classification corresponds with a difference in water use efficiency. The tolerant crops show a more or less constant water use efficiency. The sensitive crops show a decrease of the water use efficiency with increasing salinity, as their yield decreases stronger than the evapotranspiration. No correlation could be found between osmotic adjustment, leaf area and yield reduction. As the flowering period is a sensitive period for grain and fruit formation and the sensitive crops are all of indeterminate flowering, their longer flowering period could be a cause of their greater sensitivity.The tolerant group according to water stress day index can be divided according to soil salinity in a salt tolerant group of sugar beet and wheat and a moderately sensitive group, comprising maize, sunflower and potato. The difference in classification can be attributed to the difference in evaporative demand during the growing period.The sensitive group according to water stress day index can be divided according to soil salinity in a moderately sensitive group, comprising tomato, soybean and broadbean, and a salt sensitive group of chickpea and lentil. The difference in classification can be attributed to the greater salt sensitivity of the symbiosis between rhizobia and grain legume in the case of chickpea and lentil.     

Isohydrodynamic behavior in deficit-irrigated Cabernet Sauvignon and Malbec and its relationship between yield and berry composition

Cabernet Sauvignon and Malbec grapevines were irrigated at 70 or 23 % of estimated crop evapotranspiration throughout berry development over four growing seasons. Stomatal behavior was characterized by relating predawn leaf water potential and mid-morning stomatal conductance to mid-morning leaf water potential. Seasonal average weekly midday leaf water potential was lower in Cabernet Sauvignon than Malbec despite similar irrigation amounts. Both cultivars exhibited anisohydric behavior with midday leaf water potential decreasing linearly with declining predawn leaf water potential (r ² = 0.51) and stomatal conductance (r ² = 0.42). However, both cultivars utilized hydrodynamic mechanisms to maintain a soil-to-leaf water potential gradient of ?0.62 (±0.03) MPa under standard irrigation and ?0.75 (±0.04) MPa under reduced irrigation. Berry fresh weight and titratable acidity decreased, and the concentration of total anthocyanins increased in both cultivars in response to decreases in midday leaf water potential. The slope of regression equations for seasonal mean midday leaf water potential was used to estimate cultivar-specific levels of water stress associated with changes in berry weight and berry composition at fruit maturity.     

Effects of frequency of irrigation and gypsum treatment on leaf water potential and leaf stomatal conductance of lucerne (Medicago sativa L.) grown on a heavy clay soil

Summary Concurrent diurnal measurements of water potential, osmotic potential and conductance were made on leaves of lucerne grown under weekly (W) and fortnightly (F) irrigation on gypsum-treated (G) and untreated soil (C). Measurements were made throughout the period of vegetative growth.Leaf water potentials were lower both at dawn and in the afternoon under fortnightly as compared to weekly irrigation. Gypsum application led to a slower decline in water potential under fortnightly irrigation, although the effect was small compared with more frequent irrigation. Stomatal conductance was reduced under treatments F_G and F_C during the later stages of vegetative growth, coinciding with leaf water potentials of less than c. –1.6 MPa.The relationship between leaf water potential and turgor potential changed with time such that positive turgor was maintained as leaf water potential declined. Turgor maintenance was achieved through a decrease in leaf osmotic potential. These data suggest that lucerne is capable of osmotic adjustment.Stomatal conductance declined rapidly below a leaf turgor potential of c. 0.1 MPa. It is hypothesised that osmotic adjustment enabled stomatal adjustment, which contributed to continued assimilation despite increasing soil moisture deficits.     

Evapotranspiration of citrus as affected by soil water deficit and soil salinity

Summary The extent to which evapotranspiration (ET) of Valencia citrus trees is affected by differing soil water depletions (SWD) and soil salinity regimes was determined during five seasons during which soil salinity levels varied. Three weighing lysimeters, each with a 14 year old tree, were used to measure daily ET and to schedule irrigation to maintain SWD at maxima of 15, 75 and 150 mm respectively. Tensiometers and salinity sensors were used to indicate the in situ soil matric and soil solution osmotic potentials. Total soil water potential was calculated from tensiometer and salinity sensor readings weighted for root density with depth. The total of these for the summer months was found to be linearly related (Fig. 5) to the mean ET/Ep (Ep=A-pan evaporation). The slope and threshold of ET reductions with decreasing soil water potential for the low frequency irrigation treatment (150 mm SWD) show good agreement with the slope and threshold of yield decrease that is calculated from soil salinity in the lysimeter using previously reported salinity-yield relationships. The reduced water uptake due to increasing soil salinity has important implications for soil salinity control, since the lower uptake should in theory increase the leaching fraction. This implies a degree of self adjustment to the leaching fraction when irrigating with increasingly saline waters if water applications are scheduled as for non-saline conditions.     

Whole-tree water balance and indicators for short-term drought stress in non-bearing ‘Barnea’ olives

Drainage-weighing lysimeters allowed monitoring of water balance components of non-bearing olive (Olea europaea cv Barnea) trees over a 3-month period including short-term events of controlled but severe water stress. The objective of the study was to evaluate a variety of soil and plant-based water status and drought stress monitoring methods on the basis of tree-scale evapotranspiration (ET). As the trees entered into and recovered from water stress, meteorological data, actual ET (ET_a), soil water content and changes in leaf turgor pressure were continuously monitored. Additionally, midday measurements of stem water potential, stomatal conductance, canopy temperature, and quantum yield of PSII photochemistry were conducted. Diurnal (dawn to dusk) measurements of all the above were made hourly on days of maximum stress. Shoot elongation rate was measured for periods of stress and recovery. Quantum yield of PSII photochemistry, stomatal conductance, and stem water potential all successfully indicated reductions in whole-tree water consumption beginning at moderate stress levels. These measured parameters fully recovered to the levels of non-stressed trees soon after water application was renewed. Shoot elongation was reduced 25-30% for the 10-day period during and following drought and recovered thereafter to levels of non-stressed trees. Whole-tree ET_a was reduced by as much as 20% even following full recovery of the leaf level parameters, suggesting reduced canopy size and growth due to the stress period. Non-destructive, continuous (turgor pressure) and remotely sensed (canopy temperature) methods showed promising potential for monitoring effects of water stress, in spite of technological and data interpretation challenges requiring further attention.     

Response to soil salinity of two chickpea varieties differing in drought tolerance

Two chickpea varieties, differing in drought tolerance, were grown in lysimeters filled with clay, and were irrigated with waters of three different salinity levels. Under non-saline conditions, both varieties, slightly differing in pre-dawn leaf water potential during the growth period, gave almost the same yield.Salinity had a slight effect on the leaf water potential and the osmotic adjustment. Both were slightly higher for the drought tolerant variety, but much lower in comparison with sugar beet, tomato and lentil. The drought tolerant variety showed an earlier senescence in leaf and dry matter development and flowering which were accelerated by salinity. The drought sensitive variety, however, showed under slightly saline conditions (EC_e=2.5 dS/m) from 135 days after sowing onwards a different behaviour by the growth of new leaves and flowers, a delay in senescence, leading to the same yield as under non-saline conditions. Under saline conditions (EC_e=3.8 dS/m) the drought sensitive variety showed the same yield reduction of about 70% as the drought tolerant variety.     

Plant response to the soil water reserve: Consequences of the root system environment

Summary The ability of water balance models based on the concept of Transpirable Soil Water to predict the occurrence of water stress and the need for irrigation was tested for several environmental conditions of the root system, to determine in which conditions errors are likely to be appreciable. The response of evapotranspiration, stomatal conductance and leaf water potential to soil water reserve was studied under three conditions: (i) in pots with maize plants, (ii) in the field with deep soil and the root system placed in favourable conditions, with wheat during a dry year and with maize during four years with contrasting climate, (iii) in the field, with soil compaction which disturbed the maize root system, decreasing its efficiency for water uptake, during four year. (i) In the pot experiment, where the volume of the Transpirable Soil Water (TSW) is well defined, the responses followed the hypothesis of water balance models. (ii) The soil depletion was higher than the calculated TSW during two dry years in the field, because of an appreciable contribution of the non-rooted soil layers to the water balance. As a consequence, evapotranspiration, stomatal conductance and predawn water potential did not decrease over the whole range of soil water reserve. Grain yield was no lower in those years than in the wet years, in spite of the fact that the soil water reserve was depleted. Thus, a water balance based on the TSW would have underestimated in these conditions the ability of plants to withdraw soil water, overestimating the necessity of irrigation. Predawn water potential gave, on the contrary, indications consistent with the responses of the stomatal conductance and the net CO₂ assimilation. (iii) The water uptake by plants would have been overestimated in the case of compacted soil. Stomatal conductance was low even for high levels of the soil water reserve, except if the densely rooted top 0.1 m layer of soil was rewatered by irrigation. Water stress could not have been diagnosed in this case from indications of soil water potential or of pre-dawn water potential. These data confirm that some knowledge of the environmental conditions of the root system is necessary to determine if errors made using water balance models are likely to be appreciable, and to know if they lead to an underestimation or overestimation of the risk of water stress.     

Water use efficiency of narrow row cotton

Summary A field experiment was conducted on the west side of the San Joaquin Valley in California to determine water use, crop growth, yield and water use efficiency of Acala (SJ-2) cotton (Gossypium hirsutum L.) grown in 0.5 m spaced rows on a Panoche clay loam soil (Typic Torriorthents). Evapotranspiration was determined by water balance techniques utilizing neutron soil moisture measurements. All neutron measurements were made within a 3 m soil profile in 0.20 m increments. The measured evapotranspiration was compared to climatic estimates of potential evapotranspiration, and to calculations using a one-dimensional soil water balance model that separately computed soil water evaporation and plant transpiration. Crop growth was determined by weekly destructive plant sampling. Leaf area was determined along with dry matter components of leaves, stems, fruiting parts (flowers and squares) and bolls. Final yield was determined by machine harvesting (brush stripper) 720 m² from each plot. Lint yields and fiber quality were determined by sample ginning and fiber analysis at the U.S. Cotton Research Station at Shafter, California. Three irrigation regimes were established that resulted in an evapotranspiration range from a high deficit condition to full irrigation at the calculated atmospheric demand.The measured evapotranspiration of narrow row cotton under a full irrigation regime was 778 mm, 594 mm under a limited irrigation regime and 441 mm under a regime with no post-plant irrigation. The evapotranspiration from these irrigation treatments was accurately simulated by a water balance model. that used inputs of potential evapotranspiration, leaf area index, soil water holding capacity and root development.The average lint yield from narrow row cotton with a full irrigation regime was 1583 kg/ha, the average lint yield from a limited irrigation regime was 1423 kg/ha and the average lint yield from a treatment with no postplant irrigation (fully recharged soil profile at planting) was 601 kg/ha. The full irrigation regime resulted in a dry matter production of approximately 16 t/ha while the limited irrigated regime produce 11 t/ha and the no-postplant irrigation regime produced 7 t/ha of dry matter. The fiber quality results indicated significant (0.05 level) differences only in 50% span length and micronaire, with the 2.5% span length, uniformity index, elongation and strength indicating no difference.Cotton lint yield was found to be directly related to total evapotranspiration although the relationship was slightly non-linear while dry matter yield was found to be linearly related to evapotranspiration. Both lint and dry matter yield were found to have a linear relationship to estimated transpiration from the water balance model calculations.Contribution from the Unived States Department of Agriculture, Agricultural Research Service, Western Region and the University of California     

Response of sugarbeets to irrigation frequency and cutoff on a clay loam soil

Summary Sugarbeets (Beta vulgaris L.) on a Panoche clay loam soil were subjected to 3 different irrigation frequencies and 3 irrigation cutoff dates prior to harvest to determine the effects on evapotranspiration, growth, and sucrose yield. Lengthening the irrigation interval from 1 to 3 weeks reduced evapotranspiration without a significant decline in sucrose production. Increased irrigation cutoff from 3 to 7 weeks prior to harvest significantly increased sucrose percentage within the root and resulted in similar total sucrose yields. Lengthening the irrigation interval only slightly reduced both fresh vegetative biomass and leaf area index (significant differences occurred only at one plant sampling date). The combination of less frequent irrigation and an early cutoff date increased the amount of soil water extracted by sugarbeets. The water use of sugarbeets can be reduced without a significant decline in sucrose production through optimizing irrigation frequency to about 14 to 20 days on this soil and cutting off irrigations about 40 to 45 days before harvest, provided irrigations replenish soil water depletions.Contribution from USDA, Agricultural Research Service, Water Management Res. Laboratory, 2021 S. Peach Avenue, Fresno, CA 93747, USA     

水分和锌对番茄叶水势、光合特性及蒸腾效率的影响

通过盆栽试验,研究了3个土壤水分水平W1、W2、W3和2个锌溶液水平Z0、Z1对番茄叶水势、光合特性及水分利用效率的影响。结果表明,随着土壤水分的增加,番茄叶水势升高,晴朗天气中午12:00时W3处理叶水势可达-1.52 MPa;W3处理叶面积、光合速率、蒸腾速率和气孔导度分别比W1与W2高出25.7%与10.0%、19.6%与4.2%、20.7%与9.3%、26.6%与15.8%;叶面喷施锌不同程度的提高了叶片光合速率、蒸腾速率和气孔导度,在W2适宜水分下,三者分别提高9.1%、2.9%和7.3%;土壤水分的提高使植株的蒸腾效率增加,在W1、W2条件下叶面喷锌显著提高了叶片蒸腾效率。     

FAO-56 methodology for the stress coefficient evaluation under saline environment conditions: Validation on potato and broad bean crops

This study aims at validating the methodology proposed by Allen et al. (1998) to calculate the stress coefficient Ks (ratio between actual and maximal evapotranspiration) under saline environment conditions not affected by soil water shortage. Validation was performed in Mediterranean region (Bari, southern Italy) on two crops: a winter crop (broad bean) and a spring crop (potato) grown in lysimeters, on clay and loam soils, having different levels of salinity. Preliminary observations were carried out to verify that the conditions established by Allen et al. (1998) for applying this Ks calculation methodology were fulfilled.The measured Ks values showed an evolution during the growing cycle. Ks values were close to 1 after emergence, and decreased at the end of the growing cycle. Contrarily, the calculated Ks values showed steady values during the whole crop cycle, being lower than the measured Ks. Only at the end of the crop cycle the calculated Ks values approached those measured. The various causes of differences between measured and calculated values of Ks are analyzed in this study.The observed differences between calculated and measured values of Ks led to an underestimation of calculated actual evapotranspiration (AET), at different stages in the crop growing cycle, by an average of 12%. The analysis of seasonal evapotranspiration as a function of soil salinity allows for a modulation of this mean value. The underestimation was quite negligible (close to 4%), if the average value of ECe during the crop cycle was close or lower than 3 dS m⁻¹. On the contrary, the underestimation in evapotranspiration was close to 20% when the ECe raised up to 6 dS m⁻¹.An underestimation of calculated AET in saline environment conditions, by the methodology proposed by Allen et al. (1998), causes the appearance of an additional water stress, mainly when soil salinity, increases due to the combined effect of soil water shortage and water quality. Different solutions are proposed to improve the calculation of AET in this condition.     

Sugar beet production as influenced by limited irrigation

Summary Sugar beets (Beta vulgaris L.) were grown on a Millville silt loam soil at Logan, Utah to study the relationships between yield (total dry matter, fresh root, and sucrose) and various levels of irrigation simulating different types of limited irrigation under drought conditions. There were four harvest dates. A model, PLANTGRO, was tested for yield prediction under the imposed conditions. A line source sprinkler irrigation system which applied irrigation water from an excess to a zero amount, was used to impose the various levels of irrigation. Irrigation was continued throughout the season on half of the area and terminated at mid-season on the other half. For both irrigation treatments, yield responses to irrigation levels were large. Unlike continuous irrigation throughout the season, when irrigation was terminated in mid-season, there was no increase in yield (total dry matter, fresh root, or sucrose) from harvest 1 to harvest 4. The relation of yield to termination of irrigation depended on the amount of stored soil water at the time of termination. Yield and relative yield exhibited a strong linear relationship with ET. Percent sucrose was not significantly affected by irrigation regimes or harvest date, but tended to increase as amount of applied irrigation water increased. The model PLANTGRO gave good predictions for relative yields of fresh roots, sucrose, and total dry matter under full-season irrigation. The relative yield relations of fresh roots, sucrose and total dry matter were similar. Where irrigation was terminated in mid-season the model slightly under-predicted yield at high irrigation levels.Contribution from Utah Agricultural Experiment Station, Utah State University, UT 84322, USA     

A model for computing date palm water requirements as affected by salinity

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 ET_c 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 ET_c 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.     

Seasonal water production functions and yield response factors for maize and onion in Perkerra,Kenya

Water production functions (wpf) giving the relation between crop yield and water application under furrow irrigation on a clay loam soil in the semi-arid region in Kenya (Perkerra) were derived for maize and onion. Due to deep percolation the functions were found to be curvilinear. The seasonal yield response factors K_y, giving the relationship between evapotranspiration deficit and yield depression for maize and onion for the area was computed as 1.21 and 1.28, respectively. Analytical analysis using the derived wpf for maize and existing conditions in an irrigation system located in the area confirmed that if rainfall is significant, deficit irrigation will be more attractive, and at a certain point, it is profitable to cultivate all available area.     

Long term effects of saline irrigation on the yield and growth of mature Williams pear trees

Salt tolerance of mature Williams Bon Cretien pear trees was assessed in a field trial on a duplex, slowly permeable clay loam. The trees were irrigated with a range of salinities; electrical conductivity of irrigation water (EC_w) of 0.2 to 1.4 dS/m by flood for seven years or 0.2 to 2.1 dS/m by microjet sprinklers for nine years. Water-table levels were maintained below 3 m by a groundwater pump. Yield and leaf ion content were assessed during the treatment period. Aspects of growth and physiology were monitored in the 0.2 and 2.1 dS/m microjet treatments during the seventh irrigation season.Soil profile salinities varied between 3.0 and 4.3 dS/m for the most saline flood treatment and from 1.5 to 2.6 dS/m for the most saline microjet treatment. Soil sodicity (sodium absorption ratio) increased during the experiment, reaching a maximum of 9 in the most saline treatments. The salinity treatments caused reduced yields after seven years. In the most saline treatment (EC_w = 2.1 dS/m, microjet-irrigated), yield decreased to about 60 and 50% of the control in the eighth and ninth years, respectively, and 40% of trees were dead in the ninth year. Leaf ion concentrations (in January) of the most saline treatment were at excess levels (>0.1% Cl and >0.02% Na) from 1982 to 1990. There were significant (P<0.01) negative linear relationships between yield in 1990 and leaf Na and Cl, measured both in 1990 and in 1989. During the seventh season of saline irrigation, lateral shoot growth was reduced, leaves and fruit were smaller and leaf fall was earlier in the 2.1 dS/m treatment compared with the control. Dawn and midday water potential and osmotic potential were not significantly affected by saline irrigation. Midday CO₂-assimilation rates (A) and leaf conductance to water vapour diffusion (g) were similar for 2.1 dS/m irrigated and control trees, however there was a trend towards a reduction in A and g of these salt-treated trees late in the irrigation season when leaf Na and Cl had increased to 250 and 240 mM (tissue water basis) respectively.     

极端干旱区滴灌葡萄适时控制灌溉试验研究

以常规滴灌为对照,研究了适时滴灌条件下监测点土壤含水率、葡萄生长过程及产量的特征。结果表明,粘壤土条件下,与40cm和60cm监测点土壤含水率相比,20cm深度监测点土壤含水率具有代表性好、灵敏性高、达到设计土壤含水率下限的时间间隔比较合理的优点,可作为该地区葡萄适时控制灌溉的理想深度;适时滴灌条件下,葡萄的叶面积指数、地上净生物量、叶片生理指标和产量均略低于常规滴灌,但水分利用效率高于常规滴灌。     

不同矿化度咸水造墒对棉花出苗及幼苗生长的影响

采用坑栽土培试验和桶栽土培试验,研究了不同矿化度咸水造墒对3种土壤质地(粘壤土、壤土和沙壤土)条件下棉花出苗率和幼苗生长的影响。结果表明,矿化度低于3 g/L的微咸水造墒对棉花出苗率及幼苗的生长影响不明显,有时甚至表现为促进作用,但随着造墒水矿化度的进一步增加,棉花的出苗率、出苗时间以及株高、干物质累积等都受到不同程度...     

Influence of different water quantities and qualities on lemon trees and soil salt distribution at the Jordan Valley

The influences of water quantity and quality on young lemon trees (Eureka) were studied at the University of Jordan Research Station at the Jordan Valley for 5 years (1996–2000). Five water levels and three water qualities were imposed via trickle irrigation system on clay loam soil. The primary effect of excess salinity is that it renders less water available to plants although some is still present in the root zone. Lemon trees water requirements should be modified year by year since planting according to the percentage shaded area, and this will lead into substantial water saving. Both evaporation from class A pan and the percentage shaded area can be used to give a satisfactory estimate of the lemon trees water requirement at the different growth stages. The highest lemon fruit yield was at irrigation water depth equal to evaporation depth from class A pan when corrected for tree canopy percentage area. Increasing irrigation water salinity 3.7 times increased average crop root zone salinity by about 3.8–4.1 times.The high salt concentration at the soil surface is due to high evaporation rate from wetted areas and the nature of soil water distribution associated with drip irrigation system. Then, the salt concentration decreased until the second depth, thereafter, salt concentration followed the bulb shape of the wetted soil volume under trickle irrigation. Irrigation water salinity is very important factor that should be managed with limited (deficit) irrigation. But increasing amount of applied saline water could result in a negative effect on crop yield and environment such as increasing average crop root zone salinity, nutrient leaching, water logging, increasing the drainage water load of salinity which might pollute ground water and other water sources.