Allelopathic Effects Of Camellia Oleifera Litter On Peanut Seed Germination

The allelopathic effects between plants have a significant impact on the comprehensive benefits of agroforestry systems.Camellia oleifera peanut intercropping,as a common agroforestry system,is widely used to improve the agricultural ecological environment and increase economic benefits.However,the allelopathic effects of C.oleifera litter on undergrowth peanuts in the composite system have not been established and may result in allelopathic inhibition,leading to a decrease in germination rate and delayed emergence,thereby affecting the overall growth of peanuts.This study used peanuts as the test plant,C.oleifera branches,shells,leaves,and roots as the target litter,and the aqueous extract of C.oleifera litter as the exposure medium.GC-MS,targeted metabonomics,and transcriptome techniques were employed for exploring the impact of C.oleifera litter on peanut seed germination at different concentrations(0.01,0.02,0.04,0.08 g/mL).Through identification of allelochemicals,screening of key allelochemicals,and verification of key allelochemical pathways,Clarify the molecular mechanism of allelopathic effects.The main research findings are as follows:(1)A peanut germination exposure experiment was conducted in the water extract of C.oleifera litter to investigate the allelopathic effects of branches,shells,leaves,and roots on peanut seed germination.The experimental results showed that all four types of litter at different concentrations inhibited seed germination and growth,with a comprehensive allelopathic effect index ranging from-0.059 to-0.296.As the concentration increased,the germination rate,germination potential,germination index,radicle length,root length,and seed fresh weight decreased significantly.The inhibitory effects of different litters on peanut seed germination are different,in descending order:C.oleifera shell(-0.206)>leaves(-0.181)>roots(-0.171)>branches(-0.147).(2)Identify the water extracts of C.oleifera branches,shells,leaves,and roots by GC-MS,and screen out key allelochemicals.The research results showed that a total of 171 compounds(with a matching degree greater than 90%)were detected in the water extract of C.oleifera litter.Of these compounds,2,4-ditert-butylphenol and benzaldehyde were detected in all four types of C.oleifera litter,while hexanal was present in three types.(3)Selecting 2,4-ditert-butylphenol,hexanal,and benzaldehyde screened as target allelochemicals,conducting germination exposure experiments on peanut seeds to verify the effects and differences of allelochemicals on peanut seed germination.The experimental results showed that all three allelopathic substances inhibited seed germination and growth,with a comprehensive allelopathic effect index of-0.011 to-0.217.As the concentration increased,the germination index,radicle length,root length,and seed fresh weight significantly decreased.The inhibitory intensity of seed germination varies significantly among different allelochemicals,with 2,4-ditert-butylphenol(-0.148)>benzaldehyde(-0.103)>hexanal(-0.078)in descending order.(4)The metabolomics results show that common differential metabolites(DEMs)are amino acids and their metabolites.In transcriptome,K-means cluster analysis found that GARP-G2 like,AP2/ERF-ERF,LH,NAC,bZIP,WRKY,GRAS,bZIP,GARP-ARR-B,and other plant transcription factor families played an important role in stress response.During the stress response process of peanut plants,DEGs and DAMs in the glutathione metabolism pathway were significantly enriched.The key differentially expressed genes APN,GPX,and RNR in the glutathione metabolic synthesis pathway were downregulated in different treatment groups,while the expression levels of L-glutamate metabolites and GCL,NADPH,and PRDX 6 genes were upregulated.This study found that in the C.oleifera peanut agroforestry complex system,C.oleifera litter significantly inhibited peanut seed germination.The allelopathic intensity of different types of C.oleifera litter varied,with C.oleifera shell exhibiting a significant allelopathic inhibitory effect.2,4-ditert-butylphenol,hexanal,and benzaldehyde are key allelochemicals that have a certain inhibitory effect on peanut seed germination,and the inhibitory effect of 2,4-ditert-butylphenol is the most significant.Under allelopathy,APN,GPX,RNR,GCL,NADPH,and PRDX 6 genes are key factors regulating the glutathione metabolism pathway.The above results provide data support for the allelopathic response mechanism of plants,and at the same time,they also provide the scientific basis for how to more effectively manage the types and quantities of C.oleifera litter in optimizing the management process of agroforestry systems.