| Selenium is an essential trace element for humans and animals,and also plays an important regulatory role in plant growth and development.Rice is an important food crop in China,and increasing the selenium content in rice through selenium application to rice is the safest way to supplement selenium.In this study,we selected Ha Japonica Rice 11 as the test material and investigated the effects of selenium nanoparticles and sodium selenite on rice seed germination and on the growth and development of early rice seedlings under root application and foliar spraying,based on the significant differences in phenotypic traits,and studied the effects of sodium selenite hydroponics on rice leaves The effects of sodium selenite hydroponics on the differential metabolites of rice leaves were investigated based on significant differences in phenotypic traits to provide a reference for the study of selenium enrichment and tolerance mechanisms in rice.The main findings were as follows:Nano-selenium and sodium selenite showed inhibition of germination growth of rice seeds.Under different concentrations of nano-selenium treatment,the lowest germination potential was reached at 400 mg/L nano-selenium treatment with a 39.6%reduction compared to the control and at 800 mg/L nano-selenium treatment with an11.9% reduction compared to the control,both reaching significant differences.Under different concentrations of sodium selenite treatment,the germination potential and germination rate of Ha Japonica Rice 11 rice seeds were lower than the control,showing a gradual decrease,and at 400 mg/L sodium selenite treatment,the germination potential and germination rate reached the lowest value,90.9% and 81.2% lower than the control,respectively,both of which reached a significant difference.Significant differences were found in root length of rice seedlings at 80 mg/L nano-selenium foliar spray,seedling length and fresh weight at 40 mg/L nano-selenium foliar spray,and dry weight at 40 mg/L and 80 mg/L nano-selenium.The malondialdehyde content showed a phenomenon of low concentration inhibition and high concentration promotion,and the malondialdehyde content of seedling leaves reached the maximum under 400 mg/L nano-selenium treatment,which was 125.5%higher than that of the control.There were significant differences in the root length of rice seedlings with foliar spraying of 80 mg/L and 400 mg/L sodium selenite,and no significant differences in seedling length,dry weight and fresh weight of rice seedlings with foliar spraying of sodium selenite.The malondialdehyde content of the seedlings showed inhibition at low concentration and inhibition at high concentration,and the maximum malondialdehyde content of the seedling leaves was reached at 400 mg/L sodium selenite treatment,which was 49.9% higher than that of the control group.The SOD activity of rice seedlings treated with 200 mg/L selenium nanoparticles showed a maximum SOD activity of 50.7% higher than that of the control group.The root application of sodium selenite to rice seedlings showed a low concentration inhibition and high concentration promotion of SOD activity,POD activity showed a gradual promotion,CAT activity and APX activity showed a low concentration promotion and high concentration inhibition of leaf SOD activity.Under400 mg/L sodium selenite treatment,SOD,POD,CAT and APX increased by 23.7%,increased by 13.6%,decreased by 51% and decreased by 39.1% compared with the control,all reaching significant differences.Primary and secondary metabolites were identified in rice with root application of400 mg/L sodium selenite and control rice using a broad targeted metabolism technique.A total of 1598 rice metabolites were identified,with 637 differential metabolites distributed across 81 KEGG pathways.The differences in these metabolites and metabolic pathways provide important information for exploring the metabolic mechanism studies in rice during the stress phase.In summary,both sodium selenite and selenium nanoparticles at concentrations above 40 mg/L inhibited the germination of rice seeds.Leaf spraying of selenium nanoparticles showed an inhibitory effect on the growth of rice seedlings.The antioxidant enzyme activity of rice increased with root application of sodium selenite.Differential metabolites such as amino acids and their derivatives,triterpenoids and flavonoids played important roles in rice resistance to high selenium stress,providing important information for exploring the metabolic mechanism of rice during the stress phase. |
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