Salicylic acid and its derivatives as one of the plant hormones produced by the plant naturally belong to the group of phenolic acids and consist of a ring linked to the group of hydroxyl and carboxyl group, and the starting ingredient to form the cinnamic acid. It is mainly manufactured within the plant in cytoplasmic cell. This acid was first discovered in Salix spp., which contains the Salicin compound by 9.5–11% and is present in the plant in the form of free phenolic acids or associated with amino compounds. Symbolized by the symbol SA called chemical ortha hydroxyl benzoic acid chemical formula is C7H6O3.
- salicylic acid
Salicylic acid and its derivatives as one of the plant hormones produced by the plant naturally belongs to the group of phenolic acids and consists of a ring linked to the group of hydroxyl and carboxyl group, and the starting ingredient to form is the cinnamic acid (Figure 1). It is mainly manufactured within the plant in cytoplasmic cell. This acid was first discovered in
Salicylic acid plays an important role in the growth and development of the plant for important physiological roles such as increasing the plant’s response to stress conditions (biotic and abiotic) by increasing the resistance of the plant to System Acquired Resistance (SAR) by stimulating or changing the internal paper dissection endogenous signaling to withstand a large number of stresses. Salicylic acid acts as a stimulant or transmitter of the cell to withstand environmental stress conditions such as dryness, coldness, heat, stress of heavy elements, and conditions of ammonia tension and also increases the plant’s ability to withstand salt stress salt particularly harmful sodium chloride compound NaCl .
It also has the ability to bind conjugate with some amino acids such as proline and arginine, which increase the plant’s effectiveness in resisting environmental stresses and at the same time maintain systemic acquired resistance .
The most important effects of salicylic acid are to stimulate the production of antioxidants. Antioxidant against the effect of free radicals from the group Reactive Oxygen species (ROS) when exposed to heat stress and stress Drought stress and prevents the oxidation of algebraic and oxytin and cytokinein and also has a role at the genetic level. It stimulates the genes of antioxidant enzymes such as manganese superoxide dismutase (Masud) .
Salicylic acid increases the plant’s response to tolerance and resistance to various diseases affecting plants as it is found that increasing its internal concentration activates the protective role of pathogenic pathogens . The SA also has many important physiological roles, such as stimulating the flowering, ion absorption, nutrient transfer, increasing the representation of CO2 gas, controlling the movement of stomata, photo materials, gas exchange, and protein synthesis. It also contributes to increasing the percentage of nucleic acids and amino acids and the accumulation of dry matter and speeds up the formation of various plant dyes and increasing their levels such as chlorophyll and carotene and prevents the representation of ethylene gas, and it is contrary to the work of ABA responsible for the fall of leaves. It also plays an important role in increasing metabolic rates, which contributes to the energy saving of the plant through alternative pathways accompanied by a change in the level of nucleic and amino acids within the plant .
2. Effect of salicylic acid in growth and yield
De Kock et al.  were the first to talk about the role of salicylic acid as a growth regulator during the past two decades, after which the interest in this compound has increased, and many studies have been conducted that showed a relationship between salicylic acid and the growth and development of plants. Among these studies is the finding of the cotton plant
Najafian  concluded that
Najafian  found that spraying SA acid at three levels (150, 300, and 450) mMol on
In a study on the response of the Indian mustard
In a study conducted in Pakistan on the
Abbas and Ibrahim reported  that the growth regulator SA was sprayed on
Al-Mohammadi and Al-Rawi also  observed a study on the effect of spraying on some of the growth catalysts on
3. Effect of salicylic acid in qualitative and medical qualities
The significant phylogenetic effects reflected by the salicylic acid act towards the growth and development of the plant and the improvement of its health made it a popular vehicle for those interested in agricultural production. This has already been shown to improve the qualities of many plants that occupy a high economic position. It also activates the roles of many enzymes and also has an important action towards syphilis and the bio-synthesis of ethylene gas (the maturation hormone and aging) and the movement of stomata and contributes to plant metabolism and transfer of ions [16, 17].
Through research and studies on the effect of salicylic acid treatment on the specific qualities of plants, Gharib  noted that the spray of the basil plants
Khandaker et al. showed  that spray of red
The addition of salicylic acid with three concentrations (30, 60, and 90 mg/l) resulted in a significant increase in the production of some plant antioxidants from blackwheat leaves when treated with concentrations of 60 and 90 mg/l compared with non-treated plants .
Majoul showed  a significant increase in the percentage of nutrients P, N, and the leaf content of chlorophyll when spraying the okra plants were measured at two levels of salicylic acid (78 and 155 mg/l) and in two steps compared to the comparison treatment.
The medicinal seeds of the