Mitigating Cd stress in alfalfa: the role of melatonin and nano-calcium oxide in enhancing photosynthesis and antioxidant defense
Abstract Background Heavy metal contamination, particularly cadmium (Cd), is a significant threat to agricultural productivity and food security. Melatonin, as a key biostimulant, plant growth regulator and stress resistance hormone, along with nano-calcium oxide (nCaO), can enhance plant resilience...
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| Main Authors: | , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
BMC
2025-08-01
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| Series: | BMC Plant Biology |
| Subjects: | |
| Online Access: | https://doi.org/10.1186/s12870-025-07157-7 |
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| Summary: | Abstract Background Heavy metal contamination, particularly cadmium (Cd), is a significant threat to agricultural productivity and food security. Melatonin, as a key biostimulant, plant growth regulator and stress resistance hormone, along with nano-calcium oxide (nCaO), can enhance plant resilience to stress. However, few studies have investigated the combined effects of melatonin and nCaO in mitigating Cd stress in plants. This study examined the effects of the combined application of melatonin (100 µM) and nCaO (100 mg kg-1) on alfalfa (Medicago sativa L.) seedlings. Results Under Cd stress, alfalfa seedlings exhibited a 43% reduction in shoot length, 50% in root length, and 60% in chlorophyll content, while increased MDA, hydrogen peroxide (H2O2) and O2 •– accumulation. However, the combined application of melatonin and nCaO significantly alleviated Cd toxicity, enhancing shoot and root growth by 46% and 49%, respectively. Photosynthetic efficiency improved by 70%, while chlorophyll content and Fv/Fm ratio increased by 68% and 81%, respectively. This treatment also reduced Cd accumulation in roots and shoots by 47% and 75%, while increasing calcium uptake by 84% in roots and 63% in shoots. Antioxidant enzyme activities (SOD, POD, CAT, and APX) were upregulated by 59%, 42%, 62%, and 49%, respectively, mitigating oxidative damage. The effect of combined treatment on ultrastructural analysis revealed restored chloroplast integrity and stomatal functionality under Cd stress. Conclusion The combined application of melatonin + nano calcium oxide shows great promise for ecologically acceptable alleviation of Cd stress in alfalfa by lowering its absorption. |
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| ISSN: | 1471-2229 |