Comparison of the effects of cerium nitrate and different forms of cerium nanoparticles (CeO2 and Ce(OH)4), as a rare element, on reducing cold stress damages in Basil (Ocimum basilicum L.) plant.

Abstract

Low temperatures significantly challenge crop productivity, adversely affecting plant growth and development due to cold stress, which can damage crops such as Ocimum basilicum L., commonly known as basil. A recent study investigated the effects of treating basil plants with cerium nitrate, cerium oxide, and cerium hydroxide nanoparticles to alleviate cold stress. In this study, basil plants were sprayed with 20 µg/L concentrations of the different forms of cerium and then subjected to cold stress by being placed in a refrigerator at 3°C for 5 h. The results showed that cold stress resulted in an increase in lipoxygenase (LOX) enzyme activity and elevated levels of membrane lipid peroxidation, which are indicators of cold stress. Specifically, LOX enzyme activity rose by approximately 60%, the content of malondialdehyde increased by 70%, and other aldehyde levels nearly doubled. Measurement of carbonyl groups, which indicates protein oxidation, revealed that cold stress increased carbonyl groups in the cells by up to 86%, reflecting the severity of the cold stress on the plant. Additionally, the study found that, with the exception of catalase, the levels of compatible solutes and antioxidant enzyme activity increased under cold stress. Importantly, the application of cerium compounds reduced the severity of cold stress in basil plants. A comparison of the different forms of cerium demonstrated that cerium nanoparticles were more effective than cerium nitrate in mitigating cold stress and enhancing plant growth and defense mechanisms. Therefore, it is advisable to use cerium in its nanoparticle form for agricultural applications to combat stress. While cerium oxide nanoparticle form has been extensively studied, this research also examined the effects of cerium hydroxide nanoparticle form. The results indicated that the efficacy of these two nanoparticle forms in alleviating cold stress was quite similar; both reduced oxidative stress indicators, such as lipid peroxidation and protein oxidation, by approximately 50%. Previous studies have established that when used at low concentrations, cerium can significantly enhance plant growth and alleviate environmental stress factors. However, higher concentrations may be toxic to plants. Based on the findings regarding cerium content in basil plant tissue from this research, it is evident that cerium oxide nanoparticles are more effective than cerium hydroxide in promoting plant health and resilience. Based on this article's data and previous studies, cerium use is recommended as a new option for reducing environmental stressors in plants.