## Results and Discussion
### Nitrate and Chlorophyll a Contents, Phenolic Composition and Total Phenolic Content

Table 3: Analysis of variance and mean comparisons for protein, nitrate and chlorophyll a contents, target phenolic acids and total polyphenols in green and red perilla grown under increasing NaCl concentration in the nutrient solution. Significant genotype variation was demonstrated in terms of perilla pigmentation expressed in total chlorophyll a concentration (Table 3). When averaged over salinity treatments the highest chlorophyll a concentration was recorded in red compared to green perilla leaves (Table 3). Sodium and chloride concentrations in the nutrient solution interfere with multiple aspects of plant biochemistry/physiology including chlorophyll biosynthesis. In the current experiment, salinity-induced degradation of chlorophyll as well as inhibition of its synthesis [37], presumably a consequence of Na\({}^{+}\) induced Mg\({}^{2+}\) deficiency, has been driven by an extreme ratio of Na\({}^{+}\)/Mg\({}^{2+}\)[38]. Nutritional and functional properties of perilla leaves are associated with the high concentration of secondary metabolites, in particular polyphenols [1; 22]. Moreover, the quantitative and qualitative variations of bioactive molecules (phenolic acids) depend on several preharvest factors, including species/genotypes, environmental conditions, developmental and physiological stage as well as the biotic and abiotic elicitors [22; 38]. The major phenolic compound recorded in both green and red perilla leaves was rosmarinic acid, a caffe acid derivate (synthesized through the phenylpropanol pathway) representing more than 93% of the total target polyphenols determined by HPLC-DAD (Table 3). Increasing the nutrient solution salinity from 1 to 30 mM NaCl enhanced the functional quality of leaves by increasing rosmarinic acid and total polyphenol levels (Table 3). Similar beneficial effects of salinity (30 mM NaCl) on total phenolic compounds and major polyphenols (chlorogenic acid, cynarin and luteolin) of artichoke and cardoon leaves were reported previously by [PERSON] and co-workers [24]. Elicitation effect of salinity on rosmarinic acid is very important, particularly in light of clinical and pre-clinical studies that have attributed to rosmarinic acid present in Lamiaceae species, such as perilla, widely ranging therapeutic and health-promoting (anticancer, neuroprotective, antiatherogenic, antibacterial, antiviral and antidiabetic) properties [39; 40; 41; 42]. The application of 10 mM NaCl to the nutrient solution elicited an increase in total polyphenols synthesis and accumulation in both green and red perilla compared to the non-saline control treatment, thus contributing added value to this product for human diet. Further increase of the nutrient solution salinity (20 and especially 30 mM NaCl) however had a negative effect on total phenolics content (Table 3). A putative mechanism involved in the decrease of total polyphenols at 20 and especially 30 mM NaCl is that the antioxidant system of red and green perilla did not efficiently support reactive oxygen species (ROS) scavenging and cellular water homeostasis [22] as demonstrated by the sharp decrease in plant growth parameters and crop productivity (especially in green perilla). In addition to the positive effect of a chemical eustressor such as salinity, enhancing the production of polyphenols (rosmarinic and caffe acids and flavonoids) by chemical elicitors such as chitosan, jasmonic acid and its ester, methyl jasmonate has been previously demonstrated effectively by several authors on culinary, medicinal and aromatic plants belonging to the family of Lamiaceae (e.g., _Ociumbassicium_ and _Salvia officinalis_; [43; 44; 45]). Regarding the effect of perilla genotypes, the content of sinapic acid as well as total polyphenols were 10 and 1.5-fold higher respectively in red than green perilla (Table 3). The strong effect of genetic material on target and total polyphenols has been previously demonstrated in other vegetable species such as potato [46], tomato [47], artichoke [48; 49] and garlic [50].