Effect of calcium on the ion status and growth performance of a citrus rootstock grown under NaCl stress(Plant Nutrition)

概要

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Two-year-old own-rooted sour orange (Citrus aurantium L.) plants grown in a greenhouse were irrigated for 15 weeks with Hoagland nutrient solutions containing either NaCl (0, 20, 40, 60, 80 or 100mmolL^<-1>) or a combination of salts NaCl+CaCl_2・2H_2O (10+10mmolL^<-1>, 20+20mmolL^<-1>, 30+30mmolL^<-1>, 40+40mmolL^<-1> and 50+50mmolL^<-1>). The effect of the combined treatments on vegetative growth (fresh matter) was similar to the effect of NaCl. Salinity did not affect the leaf water potential, but did significantly increase the water content of the leaves and the shoot: root ratio (fresh matter). Furthermore, the N concentration of the leaves and the Mg concentration of the new stems were reduced, whereas the K concentrations of the leaves increased. Salinity led to a general increase in Na and Cl concentrations in all plant parts. Chloride concentrations were significantly greater than the corresponding Na values in all tissues. Little or no effect of salinity was recorded with regard to the P, Fe, Mn and Zn concentrations. The addition of Ca to the nutrient solution in the form of CaCl_2・2H_2O decreased the Na and Cl concentrations in the leaves. Thus, the application of CaCl_2・2H_2O might mitigate the accumulation of these toxic ions caused by NaCl.