## 4 Discussion
### Nutrient Uptake  
Drought stress significantly affected the deterioration of plant nutrient management. Nitrogen is a mobile macronutrient that plays a pivotal role in photosynthesis pigments (chlorophyll) and molecular compounds, such as proteins (structural components of enzymes) [48]. Drought stress significantly decreases nitrogen content in plants (30%), which may be attributable to the inhibition of key enzymatic enzymes, such as nitrate reduc-stage [49; 50] and nutrient-uptake proteins (AMT1, NRT1) [51]. These findings agree with those reported by [PERSON] et al. [52]. Phosphorus is integral to cell energy (ATP), water use efficiency, and enhanced root proliferation [53; 54]. The results of our research correspond positively with previous studies by [PERSON] et al. [55], who reported a significant decrease in phosphorus status with increasing drought stress intensity. Potassium primarily activates key enzymes in respiration and photosynthesis, including regulating the stomatal aperture [33]. In our work, reducing K uptake by plants grown under water stress may inhibit ATP production, further decelerating varied ATP-dependent processes [56]. [PERSON] [57] also reported that K significantly helps maintain water balance and the transport of nutrients via the xylem and phloem. K application due to drought stress alleviates the negative impact of water shortages and keeps up with plant efficiency. The plants take up more potassium in the cytoplasm during drought-stress situations. Subsequently, plants' increased demand for K under stress is to keep up with the CO2 fixation during photosynthesis. Under stress, the increase in ROS in plants can be due to decreased CO2. The photosynthesis cycle was impeded and carbohydrate metabolism was likewise impacted through ROS formation when plants were exposed to stress conditions. A lower photosynthesis rate was found in plants grown under drought stress with a lower K status [58]. K increment by acid application (especially MA) more than the control could improve the regulation of the stomatal opening [59; 60], which could enhance the photosynthesis process. Calcium is an immobile nutrient in plant tissues that facilitates cellular stability, cell elongation, and division [61]. We observed that calcium content significantly decreased (average 50-60%) with increasing drought stress. This may highlight decreased cell membrane stability, whereas growth and development are severely inhibited. In addition, this could have caused problems with the selective uptake of other ions. Magnesium is an essential central ion in chlorophyll that helps enhance the green pigments to trap light energy for photosynthesis [62]. In the stroma, light reactions are enhanced by magnesium and the activation of Rubisco in facilitating CO2 assimilation [63]. In our studies, drought stress significantly reduced the Mg uptake by plants, which could implicate a decrease in chloroplast size and electron transfer in Photosystem II [64]. The synergistic effect of K and Mg in plants has been extensively highlighted in their role in activating key enzymes, ion homeostasis, and pH stabilisation [65]. The significant reduction in potassium and magnesium content may highlight the plant's exposure to varied consequences, including photosynthetic damage [66]. An appreciable amount of these cations could help improve growth, as seen in the case of maleic acid, which increased Mg content at PEG 7.5%. Meanwhile, drought stress reduces the content of Na in plant tissues. Sodium has been reported to maintain mesophyll structure [67] and osmotic adjustment [68]. [PERSON] et al. [69] found a higher sodium content in lettuce leaves under drought stress. According to [PERSON] et al. [70], plants accumulate salt ions by reducing the osmotic potential to facilitate water absorption by the roots. Furthermore, it has been established that Na+ may confer a similar role in osmotic balance in potassium-deficient plants [71]; nevertheless, it may be toxic in excess.