The rate of salicylic acid (SA) degradation in the experimented peat soil was conducted to determine the degradation by five concentrations of 14C radioactive salicylic acid (i.e. 0.001, 0.01, 0.1, 1.0 and 10 µM) at different time periods. Results showed that the rate of salicylic acid degradation increased as the concentration raised from 0.0001 to 10 mM. Thereafter, the rate of SA degradation increased slightly to reach about 28.7% after one week (168 h). In addition, a pot experiment was carried out at Bilqas city, Dakhalia Governorate during summer season of 2017 to study the effect of salicylic acid spraying on its translocation in lettuce (Lactuca sativa L.) tissues, as well as its effect on fresh yield and chemical analysis. Salicylic acid was sprayed at concentrations of 0, 0.0001, 0.001, 0.01, 0.1, 1.0 and 10 mM at pH values of 4 and 7 after one week from cultivation once a week, and stopped two weeks before harvesting. Further, spraying with salicylic acid at concentration of 0.01 mM was the best concentration on enhancing chlorophyll content, fresh weight yield, phosphorus and potassium concentrations, in addition, alleviation of free nitrate accumulation in lettuce tissues. Concerning the effect of pH value, it was noticed that pH value 7 was better than pH value 4 on enhancing chlorophyll content, fresh weight yield, phosphorus and potassium concentrations, while pH value 4 was better than pH 7 on alleviation of free nitrate accumulation in plant tissues.