Effect of Different NH4+: NO3 - Ratios on Reduction of Deleterious Effects of Salinity on Photosynthesis and Growth of Some Olive Cultivars

This experiment was carried to study the interactive effects of salinity and ammoniumnitrate ratios on olive seedlings. Experimental layout was factorial based on completely randomized design with three replications. In this research four levels of salinity (0, 50, 100 and 150 mM) and different ratios of ammonium/ nitrate including: N0: a solution without ammonium + 14 meq l-1 nitrate; N2: a solution containing 2 meq l-1 ammonium + 12 meq/l nitrate; N4: a solution containing 4 meq l-1 ammonium + 10 meq l-1 nitrate; N6: a solution containing 6 meq l-1 Ammonium + 8 meq l-1 nitrate, were applied on one-year old olive seedlings grown in perlite:sand media (1:1). Results indicated that different levels of salinity decreased the vegetative growth parameters, chlorophyll content and photosynthesis rate and increased the leaf abscission and Na absorption in different rates depending on cultivars. Also it was observed that increasing ammonium in the nutrient solution enhanced the leaf area, leaf number, leaf dry matter and photosynthesis rate in ‘Zard’ cultivar while reduced the mentioned parameters in ‘Arbiquina’ cultivar. Treatmeant 6:8 ratio nutrition in moderate salinity level was able to nullify some deleterious effects of salinity on leaf abscission, leaf area, leaf number, photosynthesis rate and chlorophyll index. This effect was more obvious in ‘Zard’ than ‘Arbiquina’ cultivar.