An Analysis of Photosynthetic Response to Salt Treatment in Vitis vinifera

Abstract

Rooted cuttings of grapevines (Vitis vinifera L. cv. Sultana; syn. Thompson Seedless) were grown under glasshouse conditions and supplied with dilute nutrient solution containing either 0 or 90 mM of added NaCl. Growth and photosynthetic response to salt treatment and subsequent recovery were followed over 80 days. Shoot growth and photosynthesis were reduced by salt treatment. At relatively low concentrations of leaf chloride (< c. 150 mM, on a tissue water basis), photosynthetic reduction was largely due to increased stomatal resistance. Internal disturbances were involved at higher leaf Cl- concentrations (> c. 150 mM) and included an apparent reduction in photochemical efficiency and a faster rate of photorespiration. Levels of fraction I protein, and specific activity of ribulose-1,5-bisphosphate carboxylase measured in vitro, were not reduced by salt treatment. Vines showed remarkable adaptation to salinity insofar as leaves maintained positive turgor despite leaf Cl- concentrations exceeding 300 mM, implying osmotic adjustment. Cessation of salt treatment led to an immediate decrease in leaf Cl-, a promotion of shoot growth and a progressive recovery in photosynthesis accompanied by a marked but not necessarily concurrent reduction in both stomatal and internal resistances. Leaves tolerated Cl- levels up to 200 mM (under glasshouse conditions) without sustaining permanent reduction in photosynthetic activity. New shoots formed subsequent to stress relief are not a prerequisite for Cl- retranslocation from mature leaves as decapitation at the time of stress relief did not prevent attenuation of leaf Cl- or recovery in photosynthesis.

Salinity effects on the stomatal behaviour of grapevine

“…Although we did not utilize chlorophyll fluorescence quenching methodology in this study, it seems likely that at least part of the apparent non-stomatal inhibition of photosynthesis evident at the higher levels of tissue chloride arises from the non-uniform stomatal conductance to CO2 evident in the autoradiograms. This is supported by observations that cessation of salt treatment to Sultana vines results in a complete recovery of photosynthesis in leaves with high mesophyll resistances and containing about 200 mM chloride (Walker et aL, 1981). Furthermore, although high salt treatment of Plantago maritima leads to a reduced A-C^ relationship at atmospheric levels of CO2, there is no difference from low-salt plants in oxygen evolution when measured at high partial pressures of CO2 in a leaf disc electrode (Flanagan & Jefferies, 1989).…”

“…This increased labelling of the photorespiratory pathway with salt stress, which resembles the effect of decreased partial pressure of CO2 on photosynthesis originally described by Wilson & Calvin (1955), can now be interpreted simply in terms of stomatal inhibition of photosynthesis and CO2 depletion in regions of low stomatal conductance, rather than to unknown direct effects on salinity or carbon metabolism itself. These changes in stomatal behaviour accompanying salt stress also account for the larger than expected low oxygen enhancement of photosynthesis in leaves with seemingly high mesophyll resistances (Walker et aL, 1981).…”

“…These effects have been associated with increased photorespiration as evidenced by greatly enhanced photosynthesis when oxygen is lowered from 21 to 2% O^ (Walker et al, 1981;Walker & Downton, 1982) and stimulated labelling of photorespiratory pathway intermediates in leaves exposed to ^^COg (Downton, 1977).…”

Identifying the future water and salinity risks to irrigated viticulture in the Murray-Darling Basin, South Australia

“…The average median seasonal EC sw increased almost three times (6.05 dS/m) compared to the corresponding baseline value (1.97 dS/m) and remained higher than the viticulture salinity threshold (4.2 dS/m) in 97% of climate change realizations. Eventually, enhanced levels of salt concentrations in the root zone exert an increased osmotic impact and reduce vine water uptake by roots, which in turn influences many physiological processes of the plant such as transpiration, photosynthesis (Russo et al, 2009), stem and leaf water potential (Walker et al, 1981), stomatal conductance (Walker et al, 1981;Prior et al, 1992a), and net assimilation rate (Downton et al, 1990). Ultimately, negative impacts of increased salinity and water stresses on physiological traits are transmitted into the fruit yield reduction (Prior et al, 1992b;Stevens et al, 1999;Walker et al, 2002;DeGaris et al, 2015) and the V. Phogat et al Agricultural Water Management 201 (2018) 107-117 deterioration of the berry juice composition (Prior et al, 1992a;DeGaris et al, 2015) and wine quality.…”

Physiological Response of Vi tis vinif era L. ( cv. Chenin blanc) Grafted onto Different Rootstocks on a Relatively Saline Soil

“…Salinity, therefore, affects plant growth by diminishing the availability of soil water for the plant and increasing the presence of toxic ions (Bernstein, 1975;Gale, 1975;Greenway & Munns, 1980). Photosynthesis in the grapevine is affected by a number of climatic factors (Smart, 1974;Kriedemann, 1977;Sepulveda & Kliewer, 1986) and cultivation practices (Hofacker, 1978;Hunter & Visser, 1988;Archer & Strauss, 1990) and is reduced by salinity (Downton, 1977;Walker et al, 1981;Downton & Millhouse, 1985). In the grapevine, however, variation in salt tolerance is well known with respect to both the rootstock (Sauer, 1968;Downton, 1985;Arbabzadeh & Dutt, 1987) and scion cultivar (Alexander & Woodham, 1968;Groot Obbink & Alexander, 1973;Barlass & Skene, 1981;West & Taylor, 1984).…”