外源褪黑素对淹水胁迫下竹叶花椒的生理调控效应OA

To determine the optimal concentration of melatonin,this study analyzed its regulatory effect on the physiological indicators of Zanthoxylum armatum under waterlogging stress by exogenously applying different con-centrations of melatonin.The experiment was conducted using a potted method,with Zanthoxylum armatum seed-lings as the test material.A non-waterlogging control group(CK)and four waterlogging stress treatments(one day,two days,three days,and six days of waterlogging)were set up.Meanwhile,for each waterlogging treatment,three melatonin concentrations(0 μmol/L,400 μmol/L,and 800 μmrol/L)were applied through exogenous root irrigation to explore the effects of different combinations of waterlogging duration and melatonin concentration on the morphological characteristics,physiological and biochemical indicators of Zanthoxylum ar-matum.The results showed that in terms of phenotype,when waterlogging lasted for more than two days,obvious waterlog-ging damage symptoms appeared in both the aboveground parts and root systems of Zanthoxylum armatum plants;after me-latonin treatment,the damage was alleviated,and the 400 pmol/L melatonin treatment showed the best mitigation effect.In terms of physiological indicators,compared with CK,under waterlogging stress,the activities of alcohol dehydrogenase(ADH)and pyruvate decarboxylase(PDC)in the roots of Zanthoxylum armatum showed an increasing trend,and the ac-tivities of peroxidase(POD),catalase(CAT),and ascorbate peroxidase(APX)in the leaves of Zanthoxylum armatum first increased and then decreased with the extension of waterlogging time.Meanwhile,the superoxide dismutase(SOD)ac-tivity,malondialdehyde(MDA)content,relative electrical conductivity,and proline(PRO)content increased continuous-ly with the prolongation of waterlogging time,while the relative water content of leaves decreased continuously.In terms of regulatory effects,both 400 μmol/L and 800 μmol/L melatonin could effectively regulate the above-mentioned physiological indicators.Among them,400 μmrol/L melatonin not only significantly reduced the ADH activity,PDC activity,relative electrical conductivity,and MDA content,but also significantly increased the activities of SOD,POD,CAT,and APX,as well as the relative water content of leaves and PRO content.In conclusion,400 μmol/L is the optimal melatonin concen-tration for regulating the waterlogging tolerance of Zanthoxylum armatum in this experiment.It synergistically enhances the waterlogging tolerance of Zanthoxylum armatum seedlings by regulating physiological metabolic pathways,including modu-lating respiratory enzyme activities,balancing the intracellular redox status,and stabilizing the osmotic adjustment system.