Can elevated CO(2) improve salt tolerance in olive trees?

We compared growth, leaf gas exchange characteristics, water relations, chlorophyll fluorescence, and Na(+) and Cl(-) concentration of two cultivars ('Koroneiki' and 'Picual') of olive (Olea europaea L.) trees in response to high salinity (NaCl 100mM) and elevated CO(2) (eCO(2)) concentration (700microLL(-1)). The cultivar 'Koroneiki' is considered to be more salt sensitive than the relatively salt-tolerant 'Picual'. After 3 months of treatment, the 9-month-old cuttings of 'Koroneiki' had significantly greater shoot growth, and net CO(2) assimilation (A(CO(2))) at eCO(2) than at ambient CO(2), but this difference disappeared under salt stress. Growth and A(CO(2)) of 'Picual' did not respond to eCO(2) regardless of salinity treatment. Stomatal conductance (g(s)) and leaf transpiration were decreased at eCO(2) such that leaf water use efficiency (WUE) increased in both cultivars regardless of saline treatment. Salt stress increased leaf Na(+) and Cl(-) concentration, reduced growth and leaf osmotic potential, but increased leaf turgor compared with non-salinized control plants of both cultivars. Salinity decreased A(CO(2)), g(s), and WUE, but internal CO(2) concentrations in the mesophyll were not affected. eCO(2) increased the sensitivity of PSII and chlorophyll concentration to salinity. eCO(2) did not affect leaf or root Na(+) or Cl(-) concentrations in salt-tolerant 'Picual', but eCO(2) decreased leaf and root Na(+) concentration and root Cl(-) concentration in the more salt-sensitive 'Koroneiki'. Na(+) and Cl(-) accumulation was associated with the lower water use in 'Koroneiki' but not in 'Picual'. Although eCO(2) increased WUE in salinized leaves and decreased salt ion uptake in the relatively salt-tolerant 'Koroneiki', growth of these young olive trees was not affected by eCO(2).

[1]  F. Loreto,et al.  The use of low [CO2] to estimate diffusional and non‐diffusional limitations of photosynthetic capacity of salt‐stressed olive saplings , 2003 .

[2]  P. Verslues,et al.  Mechanisms of salt tolerance in plants , 2006 .

[3]  C. Osmond,et al.  Two components of onset and recovery during photoinhibition of Ulva rotundata , 1992, Planta.

[4]  E. Maas,et al.  CROP SALT TOLERANCE–CURRENT ASSESSMENT , 1977 .

[5]  Pierluigi Villa.  El cultivo del olivo , 2004 .

[6]  R. Munns,et al.  Mechanisms of salt tolerance in nonhalophytes. , 1980 .

[7]  P. F. Scholander,et al.  Sap Pressure in Vascular Plants , 1965, Science.

[8]  R. Munns,et al.  Plant Responses to Salinity Under Elevated Atmospheric Concentrations of CO2 , 1992 .

[9]  J. Flexas,et al.  Drought-inhibition of photosynthesis in C3 plants: stomatal and non-stomatal limitations revisited. , 2002, Annals of botany.

[10]  W. W. Adams,et al.  Carotenoid composition in sun and shade leaves of plants with different life forms , 1992 .

[11]  R. Gucci,et al.  Growth, gas exchange and ion content in Olea europaea plants during salinity stress and subsequent relief , 1995 .

[12]  T. Sharkey,et al.  Stomatal conductance and photosynthesis , 1982 .

[13]  R. Gucci,et al.  Salinity Tolerance in Olive , 2010 .

[14]  F. Loreto,et al.  Photosynthetic limitations in olive cultivars with different sensitivity to salt stress , 2003 .

[15]  W. Inskeep,et al.  Extinction coefficients of chlorophyll a and B in n,n-dimethylformamide and 80% acetone. , 1985, Plant physiology.

[16]  Paul S. Johnson,et al.  Growth and yield. , 2009 .

[17]  F. Loreto,et al.  Gas-Exchange Properties of Salt-Stressed Olive (Olea europea L.) Leaves. , 1989, Plant physiology.

[18]  J. Syvertsen,et al.  Salinity Tolerance of Cleopatra Mandarin and Carrizo Citrange Citrus Rootstock Seedlings Is Affected by CO2 Enrichment during Growth , 2006 .

[19]  R. Tognetti,et al.  Genotypic differences in the response to elevated CO2 concentration of one-year-old olive cuttings (Olea europaea L. cv. Frantoio and Moraiolo) , 2002 .

[20]  H. W. Hunt,et al.  Simulating growth and root-shoot partitioning in prairie grasses under elevated atmospheric CO2 and water stress , 1998 .

[21]  M. Talón,et al.  Morphological factors determining salt tolerance in citrus seedlings: the shoot to root ratio modulates passive root uptake of chloride ions and their accumulation in leaves , 1999 .

[22]  F. Day,et al.  Effects of elevated atmospheric CO2 on fine root length and distribution in an oak‐palmetto scrub ecosystem in central Florida , 1996 .

[23]  N. Keutgen,et al.  Effects of NaCl salinity and CO2 enrichment on pepino (Solanum muricatum Ait.): II. Leaf photosynthetic properties and gas exchange , 1999 .

[24]  Anthony Yeo.  Predicting the interaction between the effects of salinity and climate change on crop plants , 1998 .

[25]  J. Syvertsen,et al.  Moderate shade can increase net gas exchange and reduce photoinhibition in citrus leaves. , 2003, Tree physiology.

[26]  D. Porath,et al.  Chlorophyll determination in intact tissues using n,n-dimethylformamide. , 1980, Plant physiology.

[27]  K. Chartzoulakis,et al.  EFFECTS OF NACL SALINITY ON GROWTH, ION CONTENT AND CO2 ASSIMILATION RATE OF SIX OLIVE CULTIVARS , 2002 .

[28]  M. Benlloch,et al.  Screening of olive cultivars for salt tolerance , 1995 .

[29]  G. Piccinni,et al.  The effects of elevated carbon dioxide on static and dynamic indices for tomato salt tolerance , 2002 .

[30]  N. Keutgen,et al.  Effects of NaCl salinity and CO2 enrichment on pepino (Solanum muricatum Ait.) I. Growth and yield , 1999 .

[31]  K Maxwell,et al.  Chlorophyll fluorescence--a practical guide. , 2000, Journal of experimental botany.

[32]  L. Bernstein,et al.  Effects of Salinity and Sodicity on Plant Growth , 1975 .

[33]  V. Reddy,et al.  Elongation and Branching of Roots on Soybean Plants in a Carbon Dioxide‐Enriched Aerial Environment , 1989 .

[34]  V. Martínez,et al.  Effect of NaCl on citrus cultivars , 2004 .

[35]  R. Gucci,et al.  Analysis of leaf water relations in leaves of two olive (Olea europaea) cultivars differing in tolerance to salinity. , 1997, Tree physiology.

[36]  J. Syvertsen,et al.  Growth depression of mycorrhizal Citrus seedlings grown at high phosphorus supply is mitigated by elevated CO2 , 2002 .

[37]  R. Gucci,et al.  The effect of NaCl stress and relief on gas exchange properties of two olive cultivars differing in tolerance to salinity , 1997, Plant and Soil.

[38]  M. Tattini,et al.  Genotipic responses of olive plants to sodium chloride , 1992 .

[39]  J. F. B. Anguís.  Métodos de multiplicación de plantas ornamentales , 1998 .

[40]  J. Grosser,et al.  Limitations on growth and net gas exchange of diploid and tetraploid Citrus rootstock cultivars grown at elevated CO2. , 2000 .

[41]  J. Roden,et al.  Growth and photosynthesis of two eucalypt species during high temperature stress under ambient and elevated [CO2] , 1996 .

[42]  G. Mavrogianopoulos,et al.  Effect of carbon dioxide enrichment and salinity on photosynthesis and yield in melon , 1999 .