*Article* **The Role of Salicylic Acid in Mitigating the Adverse Effects of Chilling Stress on "Seddik" Mango Transplants**

**Ibrahim Hmmam 1,\*, Amr E. M. Ali 1, Samir M. Saleh 2, Nagwa Khedr <sup>1</sup> and Abdou Abdellatif <sup>1</sup>**

<sup>1</sup> Pomology Department, Faculty of Agriculture, Cairo University, 4, El-Gamaa St., Giza 12613, Egypt; amr.ali@agr.cu.edu.eg (A.E.M.A.); nagwahamdy5@yahoo.com (N.K.); abdo.abdullatif@agr.cu.edu.eg (A.A.)

<sup>2</sup> Central Laboratory for Agricultural Climate (CLAC), Agriculture Research Center (ARC), 6,

Michael Bakhom St., Dokki, Giza 12411, Egypt; samir.saleh@arc.sci.eg

**\*** Correspondence: ibrahim.s.hmmam@agr.cu.edu.eg; Tel.: +20-1006985497

**Abstract:** Salicylic acid (SA) was sprayed on "Seddik" mango transplants at concentrations of 0, 0.5, 1, and 1.5 mM. Then, the mango transplants were subjected to 72 h of chilling stress at 4 ± 1 ◦C, followed by a six-day recovery under greenhouse conditions. Untreated transplants exposed to chilling stress represented the positive control, while those not exposed were the negative control. SA-pretreated mango transplants were compared to the positive and negative controls, evaluating physiological and biochemical changes. The SA concentration of 1.5 mM L−<sup>1</sup> was the most efficient in mitigating chilling injury (CI) in mango transplants by maintaining the integrity of the leaves' cell membrane and minimizing electrolyte leakage (EL), specifically after six days of recovery. SA increased photosynthetic pigment content, total sugar content, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and decreased proline and total phenolic content in the "Seddik" mango transplants' leaves. After exposure to chilling stress, the antioxidant enzymes' internal activities in SA-pretreated chilled mango transplants improved, especially on the sixth day of recovery, compared to the negative control; the transplants nearly attained normal growth levels. Thus, SA can protect plants against the adverse effects of chilling stress.

**Keywords:** antioxidant enzymes; chilling stress; climate; *Mangifera indica*; salicylic acid; Seddik; transplant
