Effects of potassium and zinc on physiology and chlorophyll fluorescence of two cultivars of canola grown under salinity stress

Salinity stress is one of the major limiting factors for agricultural production in the arid and semiarid regions. To understand salinity tolerance of canola, an experiment was conducted to determine the effects of fertilizer (optimum nutrient, 500 mg kg(-1) K, 2.4 mg kg(-1) Zn, and 500+2.4 mg kg(-1) K+Zn) and cultivar (Licord and Sarigol) on physiological attributes, chlorophyll fluorescence parameters (F-vi, F-v/F-m ratio, and area), and the concentrations of Ca, Mg, and K/Na in the root and in the shoot. The statistical analysis revealed that 500 mg kg(-1) K gives significantly higher F-v/F-m ratio and area, but significantly lower Ca in the roots and shoots of both cultivars. Regardless of the fertilizer, Sarigol gave higher F-v/F-m ratio. However, 2.4 mg kg(-1) Zn gave the highest F-vi in Licord, but the lowest F-vi in Sarigol. In both cultivars, Ca in the root and in the shoot was significantly lower in 500 mg kg(-1) K fertilizer. Optimum nutrient fertilizer applied to Sarigol cultivar gave the highest Mg in the root and in the shoot. K/Na values in the 8 combinations of fertilizer and cultivar were similar in the roots, but more variable in the shoots suggesting nutrient uptake differentials among the cultivars and the fertilizers. All in all, Sarigol cultivar and 500 mg kg(-1) K fertilizer performed better. Furthermore, F-vi and F-v/F-m parameters were demonstrated to be low cost, simple, and efficient techniques for monitoring the effect of soil salinity stress on the physiology and chlorophyll fluorescence of canola cultivars.