## 3 Results and Discussion  
### Fe Deficiency Impact on Physiological Traits  
Since Fe is a cofactor of many redox proteins, it is considered as a noble element contributing to crucial metabolic function in plants [25]. Therefore, the exploration of metabolic changes observed under low Fe supply has recently gained great concern, especially with the novel priming approach adopted for the improvement of plants performance. In a previous investigation [20], deficient plants of _S. carnosa_ primed with SA and/or H\({}_{2}\)O\({}_{2}\) were shown to increase their root growth, in comparison with the unprimed ones, with a more evident effect observed in SK cultivar. This tolerant behavior was elucidated as a challenge of _S. carnosa_ plants to improve Fe acquisition capacity through a more efficient exploration of the soil, in association with increased rhizosphere acidification and photosynthetic capacity. Similar behavior was previously described in other tolerant genotypes subjected to Fe constraint [5, 25, 26, 27]. Nevertheless, no previous work was focused on the priming effect with SA on the secondary metabolism under low Fe supply, especially in _S. carnosa_ plants. In this work, we investigate the potential relationship between SA and secondary metabolites generated under this environmental constraint.  
As described Table 2, Fe deficiency decreased DW in shoots of _S. carnosa_ plants grown from unprimed seedlings, when compared to the control (C). Nevertheless, the application of SA under control conditions (C+SA) or under low Fe supply (D+SA) repaired the harmful effect of Fe constraint via increasing the biomass production in both varieties. Indeed, shoot and root DW in addition to root/shoot ratio parameters were notably increased unprimed plants (C+SA) with respect to C plants. Regarding _S. carnosa_ leaf photosynthetic pigments, our results showed that Fe deficiency differently affected their levels (Table 2). Interestingly, the addition of SA (D+SA) treatment remediated the harmful impact of Fe stress for Chlorophyll a content, particularly in SK cultivar (+54% of the respective control D). However, a notable increase was noted for Chlorophyll b independent of cultivar, when compared to control plants.  
Fe deficiency decreased the bivalent Fe content in _S. carnosa_ tissues. In harmony with growth and total Fe status results [20], the reduction rate was more pronounced in KA compared to SK, particularly in shoots (ca. 56 and 44%, respectively), as compared to C plants. Interestingly, a notable rise of bivalent Fe content was noted in plants primed with SA. The degree of increase was more important in shoots when compared to roots (275 and 170% of the respective control), respectively in SK and KL, as presented in Table 2.  
Thus, outcomes suggest that the different efficiency level noted in Fe deficient plants of _S. carnosa_ primed with SA was not only related to the adequate modulation of the photosynthetic machinery and the acidification capacity [20], but also to the improved bivalent Fe immobilization from roots to shoots. This fact may be considered a novel _S. carnosa_ approach based on the enhancement of root assimilation of this element that is not very accessible under Fe-scarce conditions, essentially in calcareous soils.  
With this regard, recent investigations proved that the effectiveness of pretreatment seeds approach significantly depends on genotypic, seed physiology, and pretreatment agent type [16; 26]. In addition, the bivalent Fe content decrease could be explained by the chlorophyll content reduction, as previously reported in several plants [16; 26]. The critical function of Fe\({}^{2+}\) in the regeneration of chlorophyll precursors was previously confirmed by [PERSON] et al. [27].