Allelopathic effects of potato root exudates on Andrographis paniculata seedings under cinnamic acid stress
In order to confirm the viability of the potato-Andrographis paniculata rotation mode,and to investigate the effect mechanism of potato root exudates on phenolic acid allelochemicals in the potato-A.paniculata rotation system,the seeds of A.paniculata were used as materials to explore the effects of potato root exudates on seed germination,root border cell morphology,and root tip antioxidant enzyme activity of A.paniculata under cinnamic acid stress.The results were as follows:(1)Cinnamic acid of 0.4 mmol·L-1 significantly inhibited the germination and growth of A.paniculata seeds.Adding different concentrations of potato root exudates had a certain mitigation effect on all gerimation indexes.When the concentration of root exudate was 25 mg·mL-1,the allelopathic effect index of each index reached its maximum value,indicating that the mitigation effect was the strongest at this time.Each germination index showed significant differences compared to the cinnamic acid group(P＜0.05).(2)Cinnamic acid strongly damaged the root border cells of A.paniculata seedlings and significantly reduced the number and viability of root border cells.Adding potato root exudates could effectively alleviate this damage.After root exudates treatment,the number and viability of cells at the root border of A.paniculata increased significantly,and the apoptosis rate and thickness of the mucilage layer decreased significantly(P＜0.05).(3)Cinnamic acid caused strong stress damage to the root tip of A.paniculata,which led to an imbalance of the antioxidant enzyme system and decreased root activity.After the treatment of potato root exudates,the activities of superoxide dismutase,peroxidase,catalase,and malondialdehyde content in the root tip of A.paniculata decreased significantly,and the root activity increased significantly(P＜0.05),indicating that the degree of damage to the root tip decreased.In conclusion,potato root exudates can reduce the degree of oxidative damage to the root tip of seedlings by reducing the allelopathic stress of root marginal cells,improve the tolerance of A.paniculata to cinnamic acid during germination and the seedling stage,and alleviate the allelopathic inhibition of cinnamic acid on the growth characteristics of A.paniculata seedlings.The results provide a theoretical reference for the rationality of the potato-A.paniculata rotation mode.
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