Effects of Foliar Application of Nano-Se on Photosynthetic Characteristics and Se Accumulation in Paeonia ostii

Fengdan (Paeonia × suffruticosa Andrews), a woody oil crop abundant in unsaturated fatty acids, notably linolenic acid, holds promise in agriculture. However, selenium deficiency in Chinese soil poses a challenge to its growth. This study investigated the impact of Selenium nanoparticles (SeNPs) on Fengdan’s physiological traits and selenium enrichment. Employing a randomized complete block design, five SeNPs spraying levels were tested on Fengdan cultivar Feng Dan. Results showed substantial enhancements in photosynthetic parameters with Se application, particularly at 6.00 g/ha (S3) and 8.25 g/ha (S4). Moreover, Se application improved protein, soluble sugar, and proline solubility, along with increased activities of SOD and POD, while decreased MDA content. Se content in Fengdan organs notably increased with SeNPs concentration, especially in the testa, leaf, and kernel. In conclusion, comprehensive SeNPs fertilizer application positively affected Fengdan’s growth, photosynthesis, and selenium enrichment. The most effective treatments were observed at 6.00 g/ha (S3) and 8.25 g/ha (S4). This study offers valuable insights into selenium enrichment strategies for oil crops, stressing the significance of Se application dosage and organ specificity in biological Se enrichment.