Two grapevine cultivars, 'Kékfrankos'and 'Portugieser' rafted onto Teleki-Kober 5BB were investigated during regulated deficit irrigation under greenhouse conditions. Four-year old grapevine plants in 50 L white plastic containers were examined using perlite (20 %), loamy soil (30 %) and peat (50 %) (v/v) mixtureas a substrate. Two treatments were applied: 100 % (nonstressed)and 50 % (moderately stressed) field capacity.'Kékfrankos' has a stronger tolerance against water deficit compared to 'Portugieser' on tissue level. This characteristic is mainly due to the osmotic relations and the elastic tissue properties of this variety. Higher osmotic concentration resulted in delayed turgor loss point,and thus longer cell integrity

Bálo, Borbála

Villangó, Szabolcs

Zsófi, Zsolt

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Vitis 52 (4), 205–206 (2013)Research NotePressure-volume analysis of two grapevine cultivars ('Kékfrankos' and 'Portugieser', Vitis vinifera L.): water deficit, osmotic conditions and their possible relations with drought toleranceS. VILLANGÓ, Z. ZSÓFI and B. BÁLOKRC Research Institute for Viticulture and Enology, Eger, HungaryK e y w o r d s :  osmotic potential, pressure-volume curve, water stress.Introduction: One of mankind’s biggest challenges in the forthcoming decades will be to sustain the level of agricultural production with less water. Grapevine is a traditionally non-irrigated plant under cool climate condi-tions; however, climate change may have a great impact on vineyard water balance, and therefore vine water status (SCHULTZ 2000, 2003). Irrigation strategies such as partial root zone drying (DRY et al. 2000) and regulated deficit irrigation (DE SOUZA et al. 2005) have been improved re-cently in order to sustain the economic yield and produc-tion. Also, genetic variability plays an important role in the acclimation mechanisms to drier conditions. Grape scions and rootstocks may show different levels of physiological acclimation processes. Indeed, there are big differences in responses to drought among grapevine cultivars (BOTA et al. 2001, SCHULTZ 2003). Therefore, physiological charac-terization of grapevine cultivars helps to choose the proper variety-terroir combination and sustainable vine growing activity using less water. The aim of this study was to dem-onstrate the differences in osmotic relations between two grapevine cultivars ('Kékfrankos' and 'Portugieser', Vitis vinifera L.) during progressive drought stress.Material and Methods: Two grapevine cultivars, 'Kék-frankos' and 'Portugieser' grafted onto Teleki-Kober 5BB were investigated during regulated deficit irrigation under greenhouse conditions. Four-year old grapevine plants in 50 L white plastic containers were examined using perlite (20 %), loamy soil (30 %) and peat (50 %) (v/v) mixture as a substrate. Two treatments were applied: 100 % (non-stressed) and 50 % (moderately stressed) field capacity. Both treatments involved 8 plants, in separate pots. Physi-ological measurements were taken after 8 d when stressed plants reached the desired water deficit. Four leaves were collected from each treatment of the cultivars in order to develop pressure-volume curves ac-cording to TYREE and RICHTER (1981). Osmotic potential at full turgor (π100), osmotic potential at turgor loss point (π0), apoplastic and symplastic water fraction and leaf bulk modulus of elasticity (ε) were obtained from the PV curves (TURNER 1988).Leaf gas-exchange was measured with a CIRAS-1 in-frared gas analyser (PP Systems Ltd. UK) in the morning, at 11:00 am (local time). Each measurement was carried out under greenhouse conditions on 5 healthy leaves from different plants (one measurement/plant) and fully exposed to the sun at saturating light intensities. The greenhouse was opened at the front during the experiment; furthermore the air temperature of the green-house was half-controlled by an automatic system, which regulated the opening of the upper windows. Based on the measurements of the infrared gas analyser, air temperature of the greenhouse ranged between 28-34 °C at midday de-pending on the outside temperature. At the same time, leaf temperature of the plants was slightly lower (between 27-33 °C), however no differences were found between the leaf temperature of the severely stressed plants and the air in some cases. Relative humidity ranged between 70-85 % during the measurements.Statistical analysis was carried out by SigmaStat 8.0 software (Systat Software Inc., CA, USA) and Duncan's test was used for mean separations. Results: Stomatal conductance (gs) of the stressed vines ranged between 130-150 mmol∙m-2∙sec-1, generally with slightly lower values for the 'Kékfrankos' vines com-pared to 'Portugieser'. Similarly, in control plants the 'Por-tugieser' variety presented significantly higher gs compared to the 'Kékfrankos' leaves (data not shown). As a result of stomatal regulation, transpiration rate and net photosynthe-sis were reduced in both water stressed grapevine plants (data not shown). Based on the pressure-volume measure-ments, π100 and π0 values of 'Kékfrankos' were higher in both treatments compared to 'Portugieser'. No significant changes were observed in these parameters as a result of the water stress treatment in 'Kékfrankos'. In contrast, os-motic potentials at full turgor and at turgor loss were high-er in water stressed leaves of 'Portugieser'. No significant effect of the water stress was shown on water saturation deficit at TLP in 'Kékfrankos'. In parallel, increased val-ues were observed in this parameter in the water-stressed 'Portugieser' grapevine compared to well-watered plants. Furthermore, apoplastic water fraction of the 'Portugieser' grapevine was higher than in 'Kékfrankos', and apoplastic volume decreased as a result of water deficit in both varie-ties (Table). Discussion: Grapevine acclimation to water deficit in-volves several physiological processes. Similarly to other species stomatal closure is among the first responses of leaves to water deficit. It results in reduced water loss and thus improved water use efficiency under moderate water deficit (MEDRANO et al. 2002). In our study, stomatal con-ductance of the water stressed grapevines indicated mild to moderate water deficit according to MEDRANO et al. 2002. Besides, stomatal regulation mechanisms on tissue level (i.e. osmotic regulation, cell wall regulation) aiming to avoide water deficit are defined as relatively long term acclimation processes. Indeed, after 8 d of the acclimation period significant changes were found in pV parameters in both varieties. However, genotype had a great influence on Correspondence to: Dr. Z. ZSÓFI, KRC Research Institute for Viticulture and Enology, Kőlyuktető, PO Box: 83, 3301 Eger, Hungary. E-mail: zszs@szbki-eger.hu 206 S. VILLANGÓ et al.the extent and characteristics of the acclimation processes (DÜRING et al. 1984, BOTA et al. 2001). Moderate water deficit had no significant effect on osmotic relations of the 'Kékfrankos' variety. In contrast, water stressed 'Portugie-ser' showed lower osmotic potentials (π100 and π0) com-pared to the non-stressed leaves, indicating active osmotic adjustment in this cultivar. The lack of osmoregulation in the 'Kékfrankos' grapevine under moderate water stress is probably due to the originally low osmotic potential of this variety (Table). On the other hand, osmotic potentials of 'Portugieser' were higher under non-stressed conditions (close to -1 MPa) compared to 'Kékfrankos'. Therefore, moderate water deficit induced osmoregulation in 'Por-tugieser'. Although TLP was slightly delayed by decreased osmotic potential in stressed 'Portugieser' vines, osmotic concentration did not reach the concentration level of the non-stressed 'Kékfrankos' leaves. Similarly to other stud-ies (PATAKAS and NOITSAKIS 1999) apoplastic water fraction seemed to be highly dependent on water deficit. Indeed, in water stressed 'Portugieser' grapevines apoplastic volume was lower compared to well-watered plants. In contrast, in the case of 'Kékfrankos', no significant changes were observed in apoplastic water volume in stressed plants and this finding is in accordance with π100 and π0 values. Bulk modulus of elasticity of the 'Kékfrankos' grapevine was lower compared to 'Portugieser'. As a result of water defi-cit, ε increased slightly in 'Kékfrankos' leaves. In contrast, no significant changes were observed in ε in the case of 'Portugieser'.In conclusion, 'Kékfrankos' has a stronger tolerance against water deficit compared to 'Portugieser' on tissue level. This characteristic is mainly due to the osmotic rela-tions and the elastic tissue properties of this variety. Higher osmotic concentration resulted in delayed turgor loss point, and thus longer cell integrity.  This work was supported by the J. BOLYAI postdoctoral fel-lowship. BOTA, J.; FLEXAS, J.; MEDRANO, H.; 2001: Genetic variability of photo-synthesis and water use in Balearic grapevine cultivars. Ann. Appl. Biol. 138, 353-361.DRY, P. R.; LOVEYS, B. R.; DÜRING, H.; 2000: Partial drying of the root-zone of grape. I. Transient changes in shoot growth and gas ex-change. Vitis 39, 3-7. DÜRING, H.; 1984: Evidence for osmotic adjustment to drought in grape-vines (Vitis vinifera L.). Vitis 23, 1-10.MEDRANO, H.; ESCALONA, J. M.; BOTA, J.; GULÍAS, J.; FLEXAS, J.; 2002: Regulation of photosynthesis of C3 plants in response to progressive drought: stomatal conductance as a reference parameter. Ann. Bot. 89, 895-905.PATAKAS, A.; NOITSAKIS, B.; 1999: Osmotic adjustment and partitioning of turgor responses to drought in grapevines leaves. Am. J. Enol. Vitic. 50, 76-80.SCHULTZ, H. R.; 2000: Climate change and viticulture: A European per-spective on climatology, carbon dioxide and UV-B effects. Aust. J. Grape Wine Res. 6, 2-12. SCHULTZ, H. R.; 2003: Differences in hydraulic architecture account for near-isohydric and anisohydric behaviour of two field-grown Vitis vinifera L. cultivars during drought. Plant Cell Environ. 26, 1393-1405.SOUZA DE, C. R.; MAROCO, J. P.; DOS SANTOS, T. P.; RODRIGUES, M. L.; LOPES, C.; PEREIRA, J. S.; CHAVES, M. M.; 2005: Control of stomatal aperture and carbon uptake by deficit irrigation in two grapevine cultivars. Agr. Ecosyst. Environ. 106, 261-274. TURNER, N. C.; 1988: Measurement of plant water status by the pressure chamber technique. Irrig. Sci. 9, 289-308.TYREE, M. T.; RICHTER, H.; 1981: Alternative methods of analysing water potential isotherms: Some cautions and clarifications. I. The impact of non-ideality and of some experimental errors. J. Exp. Bot. 32, 643-653.Received December 14, 2012T a b l eResults of the pressure-volume analyses: osmotic potential by full turgor (π100), loss of turgor (π0), water saturation deficit, turgor loss point (WSDTLP), apoplastic water (A), elasticity modulus (ε). Different letters indicate the existence of statistically significant differences between the two cultivars. The * indicates the existence of statistically significant differences between the treatments (Duncan's test, n = 4, p≤0.05)Treatment Parameter Kékfrankos Portugieser100 % field capacityπ100 (-MPa) 1.56±0.09a 1.04±0.05b*π 0 (-MPa) 2.26±0.04a 1.50±0.04b*WSDTLP (%) 17.36±0.24a 9.25±0.09b*A (%) 43.37±4.04a* 71.45±2.00b*ε (-MPa) 7.44±0.61a* 10.48±1.71b50 % field capacityπ 100 (-MPa) 1.67±0.09a 1.35±0.08bπ 0 (-MPa) 2.27±0.18a 1.78±0.08bWSDTLP (%) 16.60±2.40a 11.32±0.92bA (%) 37.60±3.86a 55.12±10.56bε (-MPa) 8.57±1.13a 10.58±0.68b

Pressure-volume analysis of two

grapevine cultivars ('Kékfrankos' and

'Portugieser', Vitis vinifera L.): water deficit, osmotic conditions and their possible relations with drought tolerance

Pressure-volume analysis of two grapevine cultivars ('Kékfrankos' and 'Portugieser', Vitis vinifera L.): water deficit, osmotic conditions and their possible relations with drought tolerance

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