Effect of Soil Salinity on Growth, Proline, and Some Nutrient Accumulation in Two Genotypes Seedlings of Ziziphus Spina-christi (L.) Willd

Soil salinity in many parts of the world has become a very serious problem. Increasing soil salinity is one of the major abiotic factors limiting crop production in these regions. Therefore, growing salinity tolerant plants is a suitable way to optimize the use of saline soils. Ziziphus spina-christi (L) Willd is a fruit tree that grows wild in arid and semi-arid areas of south and southwest of Iran. The present study intends to illustrate the effect of salinity on the response of two genotypes of Ziziphus spina-christi to salt stress. The experiments were conducted in a completely randomized design as a factorial. Factor one was salinity (1.8, 5.8, 10.2, or 16.2 dS m(-1) NaCl) and the second factor was two genotypes and four replicates for each experimental unit. After 10 months, the results showed a significant decrease in all studied vegetative characteristics (stem height, total leaves area, shoot and root dry weight, chlorophyll index and number of leaves per plants) with increasing the salt concentrations. However, this decrease was not of the same extent for both genotypes. Low levels of salinity (5.8 dS m(-1)) did not cause a substantial inhibition of growth but increasing concentrations of salt induced a progressive decline in vegetative characteristics. Potassium (K), phosphorus (p), and the K/Na ratio of leaves in both genotypes significantly decreased with increasing the salt concentrations. Leaves of genotype 2 displayed higher the K/Na ratio and K content than genotype 1 in saline and non-saline conditions. In both genotypes, proline increased with salt concentration. The proline also was significantly higher in the leaves of genotype 2 than genotype 1.