Effect of Partial substitution of nitrate by ammonium on some physiological parameters and the uptake of macro element in olive cultivars under saline conditions

A factorial experiment based on Completely Randomized Design (CRD) was performed with three replications to investigate the interaction between salinity and NH+4 / NO-3 ratio on olive saplings. Four levels of salinity (0, 50, 100,150 mM) and different ratios of NH+4/ NO-3 (0:14, 2:12, 4:10, 6:8) were applied on one-year old olive saplings grown in perlite: sand media (1:1). Results indicated that different levels of salinity, decreased N, P, K absorption, K/Na ratio, chlorophyll content index and photosynthesis rate and increased proline content and Na absorption in different rates. Zard cultivar was more affected by the deleterious effects of salinity. Also it was observed that increasing NH+4 in the nutrient solution enhanced K/Na ratio and photosynthesis rate in Zard cultivar while reduces mentioned parameters in cultivar Arbequina.Nutrient solution containing NH+4 and NO-3 ions (8 to 6 ratio) in comparison with others with the increase of photosynthesis rate and K/Na ratio was more efficient in adjustment of deleterious effects of salinity. This effect was more obvious in ‘Zard’ than ‘Arbequina’.