کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
4555362 1329254 2009 10 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
On the mechanism of salt tolerance in olive (Olea europaea L.) under low- or high-Ca2+ supply
موضوعات مرتبط
علوم زیستی و بیوفناوری علوم کشاورزی و بیولوژیک بوم شناسی، تکامل، رفتار و سامانه شناسی
پیش نمایش صفحه اول مقاله
On the mechanism of salt tolerance in olive (Olea europaea L.) under low- or high-Ca2+ supply
چکیده انگلیسی

The effect of changes in Ca2+/Na+ ratios at the root zone has been reported in Olea europaea, a species mostly cultivated in calcareous soils. Plants were exposed to low (2.0 mM, low-Ca) or high-Ca2+ supply (9.0 mM, high-Ca) and supplied with 0 or 200 mM NaCl. Measurements were performed on water relations, gas exchange and photosynthetic performances, ion fluxes at whole-plant and leaf level, Na+ allocation at organismal level, the elemental and soluble carbohydrate concentration in the leaf. Most parameters were also measured during a period of relief from salinity stress, as Olea europaea suffers from fluctuating root zone NaCl concentrations over the whole growing season. High-Ca2+ supply decreased stomatal conductance, especially during the first two weeks of treatment. In response to salinity stress (i) leaf turgor potential was more severely depressed in high-Ca than in low-Ca plants, whereas net CO2 assimilation rate and relative growth rate were unaffected by root zone Ca2+ concentrations (ii) high-Ca plants had a markedly superior ability to both exclude Na+ from the shoot and to selectively transport K+ over Na+ than low-Ca plants; (iii) both CO2 carboxylation efficiency and maximal efficiency of PSII photochemistry (Fv/Fm) were significantly smaller in low-Ca than in high-Ca plants, likely as a result of a greater accumulation of toxic ions. Consistently, when osmotic stress was relieved by supplying plants with good quality water (relief period), both photosynthetic (+44%) and growth rates (+65%) recovered to a markedly superior degree in high-Ca than in low-Ca plants which had been previously treated with 200 mM NaCl. We conclude that (1) high-Ca2+ supply expose olive leaves to a more severe dehydration, but allowed to restrict both the entry and the allocation of potentially toxic ions to sensitive shoot organs; (2) a transient restriction of water-mass flow to the shoot during salinization may be of relatively minor significance in Olea europaea, which is very tolerant to drought; (3) overall salt tolerance in Olea europaea, as in most evergreen sclerophylls inhabiting Mediterranean areas, tightly depends upon the ability to reduce water uptake and transpiration during the dry/warm period and to recover photosynthetic and growth rates when low-salinity flood water is available. Therefore, data from the present experiment allow conclude that an increase in root zone Ca2+ concentration enhances tolerance to salinity stress in olive plants.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Environmental and Experimental Botany - Volume 65, Issue 1, January 2009, Pages 72–81
نویسندگان
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