## 2 Results and Discussion
### Compatible Solutes  
Proline (Figure 5a) and glycine betaine (Figure 5b), which are compatible solutes whose levels increase significantly in leaves and roots under temperature stress, were found to be affected by temperature. The percentage increase in proline was at its highest at 30 \({}^{\circ}\)C (51.2%) and at its lowest at 35 \({}^{\circ}\)C (23.6%) compared with 25 \({}^{\circ}\)C. Proline activity was higher at 30 \({}^{\circ}\)C and lower at 35 \({}^{\circ}\)C compared with the optimal temperature. Additionally, the proline concentration increased in the early stages of seed germination before declining as the seed radicle emerged. Organic osmolytes' accumulation effectively contributed to osmotic adjustments and soluble sugar, maintaining turgidity and protecting cellular metabolism from salt toxicity [73]. The accumulation of both proline and soluble sugar contents indicates their active involvement in osmotic adjustment and temperature tolerance of moringa, as reported in different plant species [74; 75; 76]. Plants accumulate osmolytes, including polyamines, glycine betaine (GB), proline, and proteins, to maintain turgor pressure and osmoregulatory [77] mechanisms in response to abiotic stressors, which reduce the cytoplasmic osmotic potential and promote water absorption. Glycine betaine exhibited the highest percentage increases in leaves at 30 \({}^{\circ}\)C, whereas it increased by 22.5 percent at 35 \({}^{\circ}\)C. At all temperatures, glycine betaine levels increased significantly in roots, whereas the accumulation was lower in leaves. Higher glycine betaine concentrations were found in seeds germinated at temperatures below 30 \({}^{\circ}\)C, which suggests that this temperature regime is unfavorable for growth, resulting in the regulation of defensive mechanisms to cope with stress to allow seed germination to continue [78].  
Figure 5: Effect of temperature on (**a**) proline and (**b**) glycine betaine contents of _M. oleifera_ PKM-1 variety. Data represent the mean \(\pm\) standard deviation of three independent replicates. Different superscript letters within a column indicate significant differences (two-way ANOVA, post hoc Tukey’s test; \(p\leq\) 0.05).  
Nevertheless, post-seedling development might be influenced by delayed morphological advancement. As an osmoregulatory solute, glycine betaine (GB) is naturally synthesized in plants, particularly in the leaves [79]. When chloroplasts are exposed to high-stress conditions, GB can preserve the O\({}_{2}\)-generating apparatus [71]. Free proline accumulation in higher plants is a well-documented response to various abiotic stressors [80]. Enhanced production and reduced breakdown of proline and glycine betaine may result in an increased accumulation of these components under stress environments.
Additionally, these compounds engaged in stress signaling and modulating gene expression under stressful conditions [81]. Soluble carbohydrates function as osmoprotectants inside the cell [82], so elevations of their levels in moringa augment the ability of the plant to withstand a wide range of stresses. These compounds protect and stabilize enzymes and proteins, reduce the oxidation of lipid bilayers, work as free radical scavengers and cell redox balancers, provide sites for carbon and nitrogen storage, and are involved in cytosolic pH regulation. Exposure of sorghum embryos to drought or salt stress has resulted in enhanced sugar levels, which may assist in osmoregulation under stressful conditions [37; 49; 59].