## 4 Discussion  
### Plant Yielding  
In the conducted studies, drought stress reduced plant yield. An effective method of improving the yields was the application of SA and MA (for Control with an optimal water regime) and SA, MA, and CA (for PEG 7.5%). Dry matter yielding indicates the efficiency of photosynthesis--acid application had a positive effect on dry matter yielding for the control (SA, MA), PEG 5% (MA), and PEG 7.5% (SA, MA).  
One more significant component of plant physical control is water use proficiency, which is the proportion of the dry matter accumulated to the volume of water used. Effective wheat cultivars have higher water use productivity in drought situations [32]. The improved water use proficiency is basically due to the accumulation of dry matter by using a lower volume of water due to the closing of the stomata and decreased transpiration rate [33]. A reduced water use proficiency was seen in potatoes (_Solanum tuberosum_ L.) when presented with water shortage in the early period; it eventually brought about reduced biomass and yield [34]. Also, in our work, we observed the decreasing tendency of biomass production under drought stress.  
One significant physiological process impacted by the drought is photosynthesis [35]. It is predominantly impacted because of decreased leaf development, malfunctioning of the photosynthetic systems, and leaf death. Closing of the stomata during drought periods lessens the CO\({}_{2}\) accessibility, which makes the plant more vulnerable to photo injury [36]. The decreased water accessibility negatively affects photosynthetic pigments, harms the photosynthetic processes, and impedes the activities of significant enzymes, causing impressive losses in plant development and yield. Additionally, drought impedes the course of photosynthesis by damaging the photosynthetic pigment, lessening the action of Photosystem II and debilitating the recovery limit of RuBP [37]. Lettuce is relatively sensitive to water deficits throughout its growth cycle, which places grave repercussions on nutrient and CO\({}_{2}\) assimilation and photosynthetic functions, which are necessary to maintain optimum yielding [38; 39]. In the studies that were conducted, plants subjected to drought stress significantly decreased in yield (about 30-50%) compared to the control plants. This may confirm the theory that stomata closure in plants is the primary response to restrict transpiration, thus affecting photosynthesis at the expense of yield [40]. These results agree with [PERSON] et al. [41] and [PERSON] et al. [38] on lettuce under water stress. Furthermore, water plays a fundamental role in nutrient assimilation [42]. However, insignificant organic acid (maleic, salicylic, and citric) caused a propensity to increase plant yielding (9.9%, 3.9%, and 3.9%), respectively, when stress worsened. According to previous studies, the exogenous application of abscisic acid, salicylic acid, brassinolide, and jasmonic acid can further develop crop efficiency during drought [43]. Plant hormones like cytokine are catalysts that direct the drought's negative influence on different plants, including maize, lettuce, tomato, and rice. Soluble sugars, soluble protein content, superoxide dismutase, peroxidase, and catalase activities in the leaves were increased by uniconazole in the stress from drought [44]. Salicylic acids and exogenously applied substances further develop drought resistance and improve plant development and final harvest. An improvement in the catalase operation of wheat was seen through salicylic acid application during water scarcity [45]. The utilisation of salicylic acid and its subsidiaries in foliar and seed treatment applications expanded the drought resilience system in lettuce exposed to drought stress [46]. Also, studies by [PERSON] et al. [47] show that applying salicylic acid improved proline accumulation.