Allelopathic Mechanisms in Camellia oleifera–Arachis hypogaea L. Intercropping

Tree-crop intercropping is of great significance in food security, land protection, and sustainable agriculture. However, the mechanisms of allelopathy between plant species during intercropping are still limited. This study focuses on the allelopathic effects in the intercropping between Camellia oleifera and Arachis hypogaea L. in southern China. We use different parts of the C. oleifera extract to evaluate their impact on peanut seed germination. The results showed that it has inhibitory effects on peanut germination and growth, with the fruit shell having the strongest inhibitory effect. Three main allelopathic substances affecting A. hypogaea germination and growth were identified using gas chromatography–mass spectrometry (GC-MS) analysis, namely, 2,4-di-tert-butylphenol, hexanal, and benzaldehyde. Transcriptomics and metabolomics analyses revealed their effects on glutathione metabolism pathways and specific gene expression. In summary, this study reveals the allelopathic interaction mechanism between C. oleifera and A. hypogaea, which helps to better understand the role of allelopathy in intercropping practices between trees and crops.