Seasonal trends in hydraulic conductance of field-grown ‘Valencia’ organge trees

Leaf water potential (ψ₁), whole tree transpiration (F) and leaf surface conductance (g), together with a number of environmental parameters, were measured from early summer until late winter in a well-watered mature ‘Valencia’ orange (Citrus sinensis (L.) Osb.) orchard during the growing season of 1977/78. F and g showed a seasonal trend, with maximum values reached during the late summer. Tree conductance (C_tree), calculated as the ratio between transpiration and the water potential difference between the wet soil and the sunlit leaves, was found to vary seasonally and showed maximum values during late summer. The soil temperature (T_s) showed a seasonal trend similar to C_tree. Analysis of this and other data from the literature confirmed that the sensitivity of tree conductance to soil temperature is related to the climatic origin of the plant species.The linear regression fitted to the relationship between C_tree and T_s was used to calculate soil temperature at apparent zero C_tree. This datum can be used as an index of plant sensitivity to root medium temperature.     

Gewurztraminer Grapevines Respond to Length of Water Stress Duration

Abstract

Gewurztraminer grapevines planted in 1989 were subjected to one of three durations of water stress (deficits imposed at postbloom, lag phase, veraison) in combination with three vineyard floor management strategies (clean cultivated, total herbicide, permanent sod). Data were gathered on vine performance, fruit composition, and water relations from 1991-96. Yield per vine, cluster weight, and berry weight were reduced linearly with duration of water deficit. Transpiration, stomatal conductance, and leaf water potential were likewise reduced with increased duration of water stress. Titratable acidity decreased and pH increased with duration of water stress, but °Brix was unaffected. Decreasing duration of water stress increased free volatile terpenes (FVT) at harvest, as well as increased potentially volatile terpenes (PVT) at both veraison and harvest. Maintaining a permanent sod tended to reduce all yield components, especially berry weight, but basic fruit composition was unaffected. FVT were highest at both veraison and harvest in berries from clean cultivated plots; however, PVT concentration was highest in berries from permanently sodded plots. Permanent sod treatments displayed lowest transpiration rate and stomatal conductance. Monitoring physiological response (particularly stomatal conductance) of the plant to reduced soil moisture provides a reliable indication of when to relieve irrigation deficits, as opposed to relying on soil moisture monitoring and/or visual assessment of water stress.     

水分胁迫下三种李属红叶树种光合作用的日变化

以2 a生桃砧紫叶李、紫叶桃、美人梅为试材,利用LI-6400便携式光合作用分析仪测定在水分胁迫下这3个红叶树种净光合速率(Pn)、气孔导度(Gs)、蒸腾速率(Tr)的日变化特征。结果表明:在干旱胁迫之前这3个红叶树种的净光合速率、气孔导度以及蒸腾速率日变化动态都呈双峰曲线,但随着胁迫时间的延长,3个树种叶片的3个光合参数均由双峰曲线变成了单峰曲线,峰值陡度变缓。     

Microsprinkler Irrigation Influences Clementine Fruit Quality,Leaf Temperature and Physiology

Abstract

The effect on leaf physiology and fruit quality, of two irrigation schedules, daily and twice a week irrigation (control), were tested on ‘SRA 63’ Clementine (Citrus reticulata Blanco) during 2002 and 2003. Micrometeorological data revealed a higher impact of everyday irrigation on air and leaf temperature compared with the control. While in 2002 daily irrigation treatment reduced air temperature up to 3.4°C with respect to the control, in 2003 the cooling effect was greater, with reductions of air temperature up to 9°C as compared with the control. In 2002, gas-exchange related parameters were influenced little by daily undertree microsprinkler irrigation, on the contrary, in 2003 net photosynthetic rates were significantly increased by daily irrigation with respect to the control.     

Effect of combined water and salinity stress factors on evapotranspiration of Sedum kamtschaticum Fischer in relation to green roof irrigation

In dryland areas, secondarily treated municipal wastewater could be used in extensive green roof systems. In this study, the effects of water and salt stress on a crassulacean acid metabolism (CAM) plant, Sedum kamtschaticum Fischer, was evaluated under intermittent saline irrigation. The salinity of irrigation water varied from 6.0 to 18.0 dS m^?1. A reduction in soil water content and an increase in soil water electrical conductivity (EC) were observed during the irrigation interval (5–17 d) as a result of evapotranspiration (ET). The effect of soil water potential (SWP) on reduction of the ET ratio (ET_r) was successfully described with an equation that could be applicable to a wide range of soil salinities and water contents, to estimate ET. In this study, the stress factor was defined as the integration of solute potential, and matric potential less soil water content for optimum growth (less than ?0.1 MPa) with elapsed time. The stress factor rapidly reduced total ET in CAM plants but effectively increased water-use efficiency (WUE). Thus, by using CAM plants for green roofs under intermittent saline irrigation, the need for irrigation water is reduced without a considerable loss of plant biomass.     

Improved water-use efficiency by deficit-irrigation programmes: Implications for saving water in citrus orchards

Water efficiency is a key concept to solve water-shortage problems in semiarid areas. Deficit irrigation (DI) in many crops has frequently proved to be an efficient tool to optimise water-use efficiency. Three different DI strategies were studied for commercial orchards of mature sweet orange (Citrus sinensis L. Osbeck, cv. Salustiana and cv. Navelina) from 2006 to 2008: sustained deficit irrigation (SDI), regulated deficit irrigation (RDI), and low-frequency deficit irrigation (LFDI) all defined physiologically with stem-water potential thresholds. The experimental research plots were located in the Guadalquivir river basin, SW Spain. The effects of DI treatments on the fruit yield and on the crop-water status, by the integrated stem-water potential (Ψ_int) were analysed. Also, the benefits of DI in terms of agricultural water-use efficiency (WUE_agr) and financial water-use efficiency (WUE_f) were estimated for each irrigation strategy. Different relationships were estimated between these parameters and irrigation and total water applied, in order to establish the best irrigation strategy for different irrigation regimes. Yield and Ψ_int showed significant differences consistent with the water amounts applied, although the crop response was influenced by other parameters such as crop variety and irrigation strategy. In this sense, treatments with similar irrigation rates and Ψ_int resulted in different yield values, evidencing the importance of these factors. Regarding the crop variety, the results showed that cv. Salustiana responded better than cv. Navelina to DI, from the physiological and agricultural perspectives. In terms of water savings, the RDI and LFDI reduced water use by between 1000 and 1250 m³ ha⁻¹, respectively, with similar yields in comparison to the fully irrigated treatment, significantly improving the WUE. Consequently, the WUE_f, and WUE_agr were more strongly affected by deficit-irrigation strategy rather than the total water supplied. Thus, the amount of irrigation water would have a relative importance but other variables such as the irrigation strategy, would decidedly influence prudent water management in semiarid areas.     

Citrus rootstock responses to water stress

Tolerance to drought-stress (DS) of the citrus rootstock Forner–Alcaide no. 5 (FA-5) was tested and compared with that of its parents, Cleopatra mandarin (CM) and Poncirus trifoliata (PT). Nine-month-old seedlings of CM, PT and FA-5 and 15-month-old grafted trees of ‘Valencia’ orange scions on these three rootstocks were cultivated in sand under glasshouse conditions and irrigated with a nutrient solution. Plants were drought-stressed by withholding irrigation until leaves were fully wilted. Survival time of both seedlings and grafted trees under DS was linked to the water extraction rate from the soil, which depended mainly on leaf biomass and on transpiration rate. Seedling responses to DS affecting leaf water relationships and gas exchange parameters varied among genotypes. FA-5 seedlings survived longer than the other seedlings, maintaining the highest levels of water potential, stomatal conductance, transpiration rate and net CO₂ assimilation towards the end of the experiment, when water stress was most severe. Thus, FA-5 was more resistant to DS than its parents (CM and PT). Moreover, rootstock affected the performance of grafted trees under water stress conditions. The higher drought tolerance induced by FA-5 rootstock could be related to the greater osmotic adjustment (OA), which was reflected by smaller reductions in leaf relative water content (RWC) and in higher turgor potentials and leaf gas exchange than the other rootstocks.     

Response of container-grown photinia to moisture stress

Two experiments were conducted to determine the effect of Vapor Gard (VG), an antitranspirant, and moisture stress on shoot water potential of container-grown photinia. In Experiment 1, plants sprayed with VG has less moisture stress than plants with no VG when 24.0 and 27.5 mm of net evaporation occurred prior to watering. Recovery periods for shoot water potential were within 4, 8 and 24 h for photinia stressed to 21.5, 24.0 and 27.5 mm of net evaporation, respectively. Photinia with and without VG were compared in Experiment 2. Shoot water potential and stomatal opening were measured pre-dawn daily (for 9 days) on photinia stressed to ?25 and ?35 bars pre-dawn shoot water potential before watering. Plants watered daily had a maximum pre-dawn shoot water potential of ?3 bars, and watered plants had a higher shoot water potential than stressed plants. Within 8 h after watering, plants with a pre-dawn stress of ?25 bars recovered to shoot water potentials of plants watered daily, and stomates closed regardless of VG treatment. Pre-dawn stress to ?35 bars resulted in a longer recovery period of shoot water potential (about 36 h). Stomates were closed on plants treated with VG and open on plants not treated with VG. Defoliation (25–75%) occurred on plants stressed to ?35 bars and not treated with VG.     

Transpiration efficiency of Amaranth (Amaranthus sp.) in response to drought stress

Drought is a major abiotic stress responsible for severe crop losses worldwide. Development of new crop varieties with increased drought tolerance is one way to increase crop productivity. The aim of this study was to characterise the diversity of nine accessions belonging to Amaranthus tricolor and A. cruentus, in response to drought stress using a dry-down protocol to characterise the transpiration efficiency (TE). Plants were subjected to either a gradual dry down or well-watered conditions. Results showed that TE was significantly higher (P < 0.01) in water-deficient (WD) plants compared to water-sufficient (WS) plants, 2.40 g kg^?1–7.13 g kg^?1 and 2.19 g kg^?1–4.84 g kg^?1, respectively. There was no significant difference in the fraction of transpirable soil water (FTSW) threshold decline between the amaranth genotypes. TE was highly correlated with yield under both WS (r = 0.89, P < 0.001) and WD conditions (r = 0.662, P < 0.001), and negatively correlated with root-to-shoot ratio under both WS (r = ?0.488, P < 0.05) and WD conditions (r = ?0.460, P < 0.05). Significant genotypic differences were seen for growth rate and stress susceptibility index (SSI). The result obtained in this investigation underline the need to identify genotypic variation in water use efficiency in amaranth.

Abbreviations: FTSW: Fraction of transpirable soil water; NTR: normalised transpiration rate; SSI: Stress susceptibility index; TE: transpiration efficiency; WHC: water holding capacity; WD: water-deficient; WS: water-sufficient.     

Transpiration characteristics of banana leaves (cultivar ‘Williams’) in response to progressive depletion of available soil moisture

Young parent-crop banana plants (cultivar ‘Williams’) were subjected to two soil moisture potential (SMP) regimes, namely, continuous field capacity and progressive depletion of total available soil moisture (TAM). Experiments were conducted in a fibreglass tunnel under mild or enhanced conditions of vapour pressure deficit (VPD), and also in the field during summer. Transpiration rates, stomatal resistance, photosynthetically-active radiation and leaf temperature were measured simultaneously with a steady-state porometer, according to a developed technique which minimised natural sources of error.

Under mild conditions of VPD (± 5 hPa) plants responded slowly to soil drying, and at a SMP of −82 kPa, transpiration was reduced by 27% compared to fully-irrigated plants. Under enhanced VPD (15–20 hPa), plants responded rapidly to soil drying, and at a SMP of −75 kPa transpiration was reduced by 73%.

In the field, reduction of transpiration in response to SMP at high VPD followed a similar pattern to the covered experiment. At a SMP of −46 kPa the reduction in transpiration rate was 41% in the late afternoon at high VPD, but the following morning transpiration rates of the two treatments were similar due to lower VPD and overnight re-establishment of turgor. At −525 kPa SMP, reduction of transpiration was 70% and plants could not regain turgor overnight. Stomatal conductance seemed more sensitive to water stress than transpiration, but leaf temperature only differentiated advanced levels of stress (± 2°C difference between stressed and non-stressed leaves).

These results hold important implications for irrigation scheduling of bananas. Initiation of stress occurred at a SMP of around −20 to −25 kPa which occurred at a 20% depletion of TAM, thus necessitating a summer irrigation frequency of daily or every 2 days.     

Zinc influence and salt stress on photosynthesis,water relations,and carbonic anhydrase activity in pistachio

A greenhouse study was conducted to evaluate the ameliorative effects of zinc (0, 5, 10 and 20 mg Zn kg⁻¹ soil) under saline (800, 1600, 2400 and 3200 mg NaCl kg⁻¹ soil) conditions on pistachio (Pistacia vera L. cv. Badami) seedlings’ photosynthetic parameters, carbonic anhydrase activity, protein and chlorophyll contents, and water relations. Zn deficiency resulted in a reduction of net photosynthetic rate and stomatal conductance. The quantum yield of photosystem II was reduced at zinc deficiency and salt stress. Zinc improved plant growth under salt-affected soil conditions. Increasing salinity in soil under Zn-deficient conditions, generally decreased carbonic anhydrase activity, protein, chlorophyll a and b contents. However, these adverse effects of salinity alleviated by increasing Zn levels up to 10 mg kg⁻¹ soil. Under increasing salinity, chlorophyll a/b ratio significantly increased. Zinc treatment influenced the relationship between relative water content and stomatal conductance, and between leaf water potential and stomatal conductance. It concluded that Zn may act as a scavenger of ROS for mitigating the injury on biomembranes under salt stress. Adequate Zn also prevents uptake and accumulation of Na in shoot, by increasing membrane integrity of root cells.     

桃枝条梢端生长及其与温度,叶水势和比叶重关系的研究

以金冠、汉瑞、红港、卡尔红为试材，探讨了桃枝条梢端生长与环境温度、叶水势和比叶重之间的关系及其昼夜变化规律。表明：在试验条件下枝条梢端生长速率与环境温度呈显著正相关，与一天中早、晚碳水化合物积累也呈显著相关，而与叶片水势变化无关。梢端生长速率昼夜总的变化趋势与气温变化相吻合，最大值出现在平均气温最高的傍晚（１６：００～２０：００），最小值出现在平均温度最低的凌晨（０：００～８：００）。在２５±０．５℃恒温条件下，梢端生长速率最大值出现后，并不随即下降，而是保持这个生长速率直至午夜，尔后逐渐降至最低值。太阳升起后，生长速率又逐渐回升。     

几种果树水分生理指标的比较研究

以盆栽２年生苹果、杏、桃和葡萄为试材，研究了水分逆境对果树水分关系的形响及差异。从正常灌水（田间持水量８０％）所测定的萎蔫点相对合水量（ＲＷＣｐ）、萎蔫点水势（ψｗｐ）和总体原初渗透压（ψｚ０）判断， ４种果树抗旱性的顺序是：杏、桃＞苹果＞葡萄。干旱下测定的 ３种参量所反映的结果与上述一致。４种果树正常灌水处理弹性大小的顺序是：苹果＞杏＞葡萄＞桃，最大体积弹性模量（Ｅｖ０）分别是：３８．７、４４．９、５１．７、５５．６ＭＰａ。干旱条件下使苹果、杏弹性变差，葡萄、桃弹性增大。Ｅｖ０分别是：７１．７６、９０．６７、５４．０８和４０．４８ＭＰａ，说明ＣＫ弹性好坏不能反映对长期干旱的适应性。弹性系数与膨压（ψｐ）成显著直线正相关，说明弹性越好（Ｅｖ０越小），维持ψｐ能力越强，有利于气孔开张、维持光合。Ｅｖ０小者（苹果、杏）， Ｅｖ０随ＲＷＣ降低而缓慢降低，细胞伸缩范围大。 水分协迫下，苹果、各具有明显的渗透调节作用，苹果ψｗｐ和ψｚ０分别比ＣＫ下降０．５和０．４ＭＰａ，杏分别下降 ０． ６１和 ０． ５９ＭＰａ，葡萄只具有微弱的渗透调节能力，ψｗｐ和ψｚ０分别下降 ０． １６和 ０． １３ＭＰａ，桃无渗透调节能力。多一位处理使     

Regulated deficit irrigation in potted Dianthus plants: Effects of severe and moderate water stress on growth and physiological responses

The purpose of this study was to analyze the physiological and morphological response of carnation plants to different levels of irrigation and to evaluate regulated deficit irrigation as a possible technique for saving water through the application of controlled drought stress. Carnations, Dianthus caryophyllus L. cultivar, were pot-grown in an unheated greenhouse and submitted to two experiments. In the first experiment, the plants were exposed to three irrigation treatments: (control); 70% of the control (moderate deficit irrigation, MDI) and 35% of the control (severe deficit irrigation, SDI). In the second experiment, the plants were submitted to a control treatment, deficit irrigation (DI, 50% of the control) and regulated deficit irrigation (RDI). After 15 weeks, MDI plants showed a slightly reduced total dry weight, plant height and leaf area, while SDI had clearly reduced all the plant size parameters. RDI plants had similar leaf area and total dry weight to the control treatment during the blooming phase. MDI did not affect the number of flowers and no great differences in the colour parameters were observed. RDI plants had higher flower dry weight, while plant quality was affected by the SDI (lower number of shoots and flowers, lower relative chlorophyll content). Leaf osmotic potential decreased with deficit irrigation, but more markedly in SDI, which induced higher values of leaf pressure. Stomatal conductance (g_s) decreased in drought conditions more than the photosynthetic rate (P_n). Osmotic adjustment of 0.3 MPa accompanied by decreases in elasticity in response to drought resulted in turgor less at lower leaf water potentials and prevented turgor loss during drought periods.     

Impacts of water stress on gas exchange,water relations,chlorophyll content and leaf structure in the two main Tunisian olive (Olea europaea L.) cultivars

Leaf structural adaptations for the reduction of water loss were examined in two olive (Olea europaea L.) cultivars (Chemlali and Chétoui) growing under water stress conditions. Leaf measurements included leaf tissue thickness, stomatal density, trichome density, specific leaf area, leaf density, water relations, and gas exchange. We found considerable genotypic differences between the two cultivars. Chemlali exhibited more tolerance to water stress, with a thicker palisade parenchyma, and a higher stomatal and trichome density. Chemlali leaves also revealed lower specific leaf area and had higher density of foliar tissue and lower reduction in net CO₂ assimilation rate. The mechanisms employed by these two cultivars to cope with water deficit are discussed at the morpho-structural level. The morphological and structural characteristics of the leaves are in accordance with physiological observations and contribute to the interpretation of why the olive cv. Chemlali is more drought-tolerant than cv. Chetoui. Furthermore, from the behaviour of Chemlali plants we consider this cultivar very promising for cultivation in semi-arid areas.     

干旱胁迫下桃树各部位贮存水调节能力的研究

干旱胁迫使桃品种瑞光5号(Prunuspersicavar.nectarinacv.RuiguangNo.5)的叶片水势和茎流下降,并且干旱越严重下降越多。干旱胁迫对贮存水调节量的影响不显著,但是绝对调节能力随干旱胁迫程度的增加而增加。各部位间的相对调节能力主要是由其水容、贮存水阻力和体积决定的,干旱胁迫对各部位间的相对调节能力的影响不显著。在充分灌水条件下各部位贮存水夜间的相对调节能力为:主根18.8%、主干38.5%、枝条17.8%、叶片3.4%、细根2.9%、果实6.7%、粗根12.0%,处理之间绝对调节能力的差异不显著。贮存水的调节主要来自主干、主根、粗根和枝条,这4部分占全部调节量的80%以上。     

The response of different almond genotypes to moderate and severe water stress in order to screen for drought tolerance

In order to screen almond genotypes for drought tolerance, three different irrigation levels including moderate and severe stress (Ψs = −1.2 and −1.8 MPa respectively) and a control treatment (Ψs = −0.33 MPa) were applied for five weeks to six different cultivated almond seedlings. A factorial experiment was conducted with a RCBD which included 3 irrigations factors, 6 genotype factors and 3 replications. Seeds were prepared from controlled pollination of the bagged trees (after emasculation and flower isolation using isolator packets in the previous year). Genotypes included: homozygote sweet (Butte), heterozygote sweet (SH12, SH18, SH21 and White) and homozygote Bitter (Bitter Genotype). Leaf and root morphological and physiological traits including; midday relative water content, midday leaf (xylem) water potential, shoot dry weight and growth, total leaf area, leaf size, total leaf dry weight, specific leaf area, leaf greenness (SPAD), stomatal size and density, root and leaf nitrogen content and chlorophyll fluorescence were measured throughout the study. Results showed the six genotypes had different reactions to water stress but all genotypes showed an ability to tolerate the moderate and severe stresses and they showed different degrees of response time to drought stress. Almond seedling leaves could tolerate Ψ_w between −3 and −4 MPa in short periods. Water availability did not significantly affect stomatal density and size of young almond plants. The analysis of leaf anatomical traits and water relations showed the different strategies for almond genotypes under water stress conditions. Although almond seedlings even in severe stress kept their leaves, they showed a reduction in size to compensate for the stress effects. All genotypes managed to recover from moderate stress so Ψ_w = −1.2 could be tolerated well by almond seedlings but Ψ_w = −1.8 limited young plant growth. Leaf greenness, leaf size, shoot growth, shoot DW, TLDW and stomatal density were not good markers for drought resistance in almond seedlings. Root DW/LA, lower stomatal size and lower SLA might be related to drought resistance in cultivated almonds. Butte had the least resistance and White showed better performance during water stress while other genotypes were intermediate. Bitter seedlings showed no superiority in comparison with other genotypes under water stress conditions except for better germination and greater root DW which might make them suitable as rootstocks under irrigation conditions.     

桃果实蒸腾强度对源叶净光合效率及相关生理反应的影响

在果核硬化期和果实最后迅速生长期,对艳丰一号桃果实浸涂10倍和100倍的液体石蜡溶液,与果实未浸涂液体石蜡的对照相比,果实蒸腾强度分别降低了57.9%和41.4%,且源叶净光合效率(Pn)和气孔导度(Gs)降低而叶表面温度(Tl)升高,并在果实迅速生长期间,果实浸涂液体石蜡处理和对照之间存在显著性差异。进一步研究表明,无论是在果核硬化期还是在果实最后迅速生长期,当Gs小于0.2mol/m2·s时,Pn和Gs呈极显著直线正相关关系,且果实浸涂液体石蜡处理的源叶的Tl随Gs减小急剧升高。源叶Pn对Tl的响应均呈极显著抛物线相关关系,但同一Tl条件下,果实浸涂液体石蜡处理的Pn低于对照。因此认为,果实蒸腾强度可能通过作用叶片的Gs调节Tl进而对源叶的Pn进行调控,气孔开张度减小、Tl升高,可能是果实蒸腾强度减弱时调控Pn重要机制之一。     

Plant growth,water relations and transpiration of two species of African nightshade (Solanum villosum Mill. ssp. miniatum (Bernh. ex Willd.) Edmonds and S. sarrachoides Sendtn.) under water-limited conditions

The adaptation to drought stress of two African nightshade species, Solanum villosum and S. sarrachoides was investigated in pot and field experiments between 2000 and 2002. Two genotypes of S. villosum (landrace and commercial) and one accession of S. sarrachoides were grown under droughted, moderate stress and well-watered conditions. Leaf expansion, stem elongation and transpiration began to decline early in the drying cycle with fraction of transpirable soil water (FTSW) thresholds of 0.46–0.64. Osmotic adjustment (OA) of both species was in the range of 0.16–0.19 MPa and could not maintain positive turgor below water potentials of −1.80 to −2.04 MPa. The responses evaluated were similar in the three genotypes suggesting similar strategies of adaptation to drought stress. Under field conditions, the S. sarrachoides accession showed a higher leaf area than the S. villosum commercial genotype. It is concluded that the three African nightshade genotypes have limited OA capacity and adapt to drought mainly by regulating transpiration. This was achieved by reduction of leaf area. In general, it is necessary to maintain FTSW above 0.5–0.6 to prevent decline in leaf expansion, stem elongation, and transpiration.     

Rootstock influences the response of pistachio (Pistacia vera L. cv. Kerman) to water stress and rehydration

Pistachio cultivation requires the use of rootstock because grafting is the only form of vegetative propagation. The main commercial rootstocks are Pistacia integerrima L., Pistacia atlantica Desf., Pistacia terebinthus L. and Pistacia vera L. Pistachio is considered to be a drought and saline-resistant crop; however, there is little information describing varietal responses of rootstocks to water stress. Some studies have suggested that P. terebinthus L. is the most drought and cold resistant rootstock. The effect of the rootstock on the water relations of the grafted plant is crucial for improving crop performance under water stress conditions and for developing the best irrigation strategy. This work studied the physiological response to water stress of pistachio plants (P. vera L. cv. Kerman) grafted onto three different rootstocks P. terebinthus L., P. atlantica Desf. and a hybrid from crossbreeding P. atlantica Desf. × P. vera L. Plant physiological responses were evaluated during a cycle of drought and subsequent recovery in potted plants. Parameters measured were soil moisture, trunk diameter, leaf area, leaf number, leaf and stem dry weight, stem water potential, leaf stomatal conductance. The results showed different responses of cv. Kerman depending on the rootstock onto which it had been grafted. The hybrid rootstock was associated with a higher degree of stomatal control and reduced leaf senescence compared to P. atlantica and P. terebinthus, despite being associated with the most vigorous shoot growth. P. terebinthus enabled very effective stomatal control but was also associated with the most rapid leaf senescence. P. atlantica was associated with less vigorous shoot growth and similar levels of water stress as occurred with the others rootstocks under conditions of high evaporative demand, which was associated with lower stomatal control. The selection of the most effective rootstock choice for different environmental conditions is discussed.