Glycerol foliar application improves salt tolerance in three pistachio rootstocks

Salinity is one of the most important abiotic stress factors that affect pistachio growth and productivity. Researches has indicated that the detrimental effects associated with salt stress could be overcome by the external application of Glycerol. In the present study, the effects of foliar Glycerol (in three levels: 0, 30 and 60 mM) on three pistachio rootstocks (‘Ghazvini’, ‘Badami’ and ‘Italyayi’) under different salinity stress (0, 4, 8 and 12 dSm⁻¹) were investigated. Salinity significantly decreased the rootstocks’ biomass, number of grown leaves, leaf area, photosynthesis pigments, stomatal conductance, leaf water potential and K⁺ content in the leaves, shoots and roots. The foliar application of Glycerol at the concentration of 60 mM alleviated growth indices of pistachio rootstocks under saline condition. Foliar Glycerol spray (60 mM) at 12 dSm⁻¹ increased the dry weight of leaves and shoots, up to 176% and 57%, respectively, compared to the control. Leaf area and number of grown leaves increased up to 466% and 32%, respectively, under highest salinity level. Glycerol caused a slight increase in stomatal conductance at 40 and 75 days after imposing the salt stress while it did not have any effects on the leaf water potential. The highest increment percentage of chlorophyll a (51%), chlorophyll b (53%), and root K⁺ content (40%) was observed in 60 mM Glycerol treated rootstocks at 12 dSm⁻¹. Glycerol application reduce the Na⁺ concentration in the leaves, shoots and roots. Among three studied rootstocks, response to Glycerol under saline condition were different and was superior in ‘Badami’ In conclusion, Glycerol could be suggested as a cheap, safe and organic agrochemical for alleviating the negative impacts of salt stress in pistachio orchards cultivated in the saline soils.