## 4 Discussion
These data partially confirm our results since, in our case, the CO\({}_{2}\) concentration and photosynthetic rate in the SM treatment were significantly lower and the stomata opening was slightly lower compared to the combinational application of SM + EBLS (Figure 3A-C). WUEi provides information on how efficiently water is used by plants (high internal utilization in terms of CO\({}_{2}\) assimilation and low losses by transpiration since it is defined as the ratio between photosynthetic rate and stomatal conductance). Our data showed that a significantly higher WUEi value was found in the SM + EBLS and the control compared to the SM- and EBLS-treated plants (Figure 3D). [PERSON] et al. (2020) [5] found that the type of organic fertilization (cow or goat manure applications) influenced the WUEi in olive plants. Other researchers quoted that WUEi was affected by the K supply [40; 41], N fertilization, and AMF inoculation [42]. Thus, in our study, it seems possible that the differences in the nutrient availability and uptake by plants among the treatments (Tables 2, 4 and 5) could be responsible for the differences in the photosynthetic rates of the plants, which afterwards influenced the WUEi. The differences in the K uptake among the treatments (Table 4) did not significantly influence the stomata opening (Figure 3B), as it happened in other studies [5; 41]. Thus, the significant differences in the WUEi values should be mainly attributed to the differences in the photosynthetic rates (Figure 3A). The main leaf translocated sugars were sucrose and mannitol, while the main non-translocated sugars were fructose and glucose. Overall, the translocated sugars were significantly lower in the control compared to the SM + EBLS-treated plants, while the opposite tendency was observed for the non-translocated sugars, which were significantly lower in the SM + EBLS treatment compared to the control (Table 6). [PERSON] and [PERSON] (2005) [PERSON] and [PERSON] (2005) concluded that soluble carbohydrates in wheat plants varied in response to the N supply, while in potato plants, low rates of N fertilization led to a lower accumulation of total soluble sugars compared to those that were properly fertilized [PERSON] and [PERSON] (2005). In another study [PERSON] and [PERSON] (2005), the effect of P on carbohydrates was investigated, and it was found that the P nutrition of pepper plants clearly influenced carbohydrate production, while in other cases, it was found that the foliar K nutrition influenced the accumulation of translocated sugars and the ratio of translocated/non-translocated sugars in olive leaves [PERSON] and [PERSON] (2005). In our study, significantly lower foliar N levels were determined in the control and EBLS-treated plants compared to those treated with SM + EBLS (Table 4). In addition, the lowest leaf K concentrations, both for the basal and apical leaves, were observed in the control plants (Table 4). These differences in the N and K uptakes by olive plants might have shown their impact on the differences determined as follows: (i) in the accumulation of translocated sugars among the treatments (Table 6) and (ii) in the ratio of translocated/non-translocated sugars, as also explained by other researchers. However, further research on this topic will be needed under field conditions to better clarify the impact of nutrient uptake on the accumulation of translocated and non-translocated sugars.