Salinity is one of the major environmental stresses that adversely affect fruit yield and quality. Thus, finding an effective way of ameliorating salinity damage is important for sustainable fruit production. Silicon (Si) treatment effectively counteracts the effects of many abiotic stress factors such as salinity, drought, cold, iron deficiency. To probe into the potential alleviating salinity malignant effects, we investigated the protective roles of Si. An apple plant (Malus domestica Borkh.) cv. ‘Fuji’ grafted on M9 clonal rootstock was chosen for the experiment and imposed to salinity stress for 4 months with 35 mM NaCl. Si with different three doses (0.5, 1 ve 2 mM) was applied to the roots of the salt-stressed apple plants except control. Si treatments inhibited apple plants growth depression through increasing stomatal conductivity, chlorophyll and decreasing electrolyte leakage. 0.5 mM Si improved root:shoot dry weight under salinity condition. The lowest values of membrane permeability were found in 0.5 and 2 mM Si treatments (21.45 and 21.55%, respectively) while salt had the highest value (48.43%). Salt exhibited a rapid decrease in stomatal conductivity by 49% compared to the control. We hypothesis that Si treatment contributed to cell walls, involving membrane stabilizing and fortification. Our findings showed that Si increased apple plant tolerance against salinity.

Salt stress is an environmental challenge that adversely influences plant responses. Silicon (Si) nutrition plays critical roles in plant tolerance to salt stress. Apple (Malus domestica Borkh.), a salt sensitive fruit species, was used in the present experiment to investigate the influences of Si on salt stress as well as on alterations of biochemical responses. Apple cv Fuji grafted on M9 clonal rootstock was exposed to salt stress for 4 months with 35 mmol·L-1 NaCl. CaSiO3 doses (0.5, 1 and 2 mmol·L-1) were applied to the roots of the salt-stressed apple plants except control. Si application resulted in mitigation of salt stress in apple plants. The highest chlorophyll a, b and a + b were obtained from the 1 mmol·L-1 Si treatment (5.37, 2.41 and 7.78 μg·g-1 fw, respectively). Moreover, Si treatment had higher chlorophyll content compared to the control as well as salt exposed plants. Silicon applications led to a reduction in malondialdehyde (MDA) content even lower than control. The 0.5 mmol·L-1 Si treatment had the highest values of ascorbate peroxidase (APX) and phenolic content. The results show that Si nutrition plays important roles in apple salt tolerance via biochemical mechanisms and that it can be used in areas subject to salt stress for apple growing.