外源褪黑素对盐胁迫下金盏菊幼苗生长、光合及生理特性的影响

为探讨褪黑素（melatonine,MT）对盐胁迫下金盏菊幼苗生理机制的影响,采用盆栽砂培法研究不同浓度外源褪黑素（0、50、100、200 μmol/L MT）对不同程度盐胁迫（0、100、200 mmol/L NaCl）下金盏菊幼苗生长、光合作用及生理特性的影响。结果表明,100、200 mmol/L NaCl胁迫严重限制了金盏菊幼苗的生长,叶绿素含量、光化学荧光效率及光合作用强度降低,MDA、H₂O₂含量升高加剧了脂质过氧化程度,诱导POD酶活性升高的氧化应激反应及脯氨酸含量增加。经外源褪黑素处理能有效缓解盐胁迫对金盏菊幼苗的伤害,其中100 μmol/L MT处理下株高、茎围、地上部和根系干重较对照分别平均提高了17.35%、17.64%、32.14%和19.83%;叶绿素含量和F_v/F_m增幅分别达71.96%和4.13%,光合作用参数P_n、G_s和T_r平均分别提高了88.74%、97.21%和58.88%,而C_i降幅达18.07%;MDA和H₂O₂含量降幅达33.77%和64.29%,POD、CAT酶活性及可溶性蛋白、脯氨酸含量平均分别提高了118.02%、67.29%、55.47%和56.30%。盐胁迫条件下,MT处理能有效提高抗氧化酶活性及降低脂质过氧化水平,促进可溶性蛋白和脯氨酸积累,改善光合荧光特性,最终表现为促进金盏菊幼苗生长。

Effects of Exogenous Melatonin on the Growth,Photosynthesis and Physiological Characteristics of Calendula officinalis Seedlings under Salt Stress

To explore the effect of melatonine (MT) on the physiological mechanism of Calendula officinalis seedlings under salt stress, a pot-sand culture method was used to study different concentrations of exogenous melatonin (0, 50, 100, 200 μmol/L MT) effects on the growth, photosynthesis and physiological characteristics of C. officinalis seedlings under different levels of salt stress (0, 100, 200 mmol/L NaCl). The results showed that 100 and 200 mmol/L NaCl stress severely restricted the growth of C. officinalis seedlings, reduced chlorophyll content, photochemical fluorescence efficiency and photosynthesis intensity. The content of MDA and H₂O₂ increased, which intensified the degree of lipid peroxidation, induced POD enzyme activity and proline content increased. Treatment with exogenous melatonin could effectively alleviate the damage of salt stress to marigold seedlings. The plant height, stem circumference, shoot and root dry weight under 100 μmol/L MT treatment increased by 17.35%, 17.64%, 32.14% and 19.83%, respectively compared with the control. Chlorophyll content and F_v/F_m increased by 71.96% and 4.13%, respectively. The photosynthesis parameters P_n, G_s and T_r increased by 88.74%, 97.21% and 58.88%, respectively, while C_i decreased by 18.07%. The content of MDA and H₂O₂ reduced by 33.77% and 64.29%, POD, CAT enzyme activity, soluble protein, and proline content increased by 118.02%, 67.29%, 55.47% and 56.30%. Under salt stress conditions, MT treatment could effectively increase the activity of antioxidant enzymes and reduce the level of lipid peroxidation, promote the accumulation of soluble protein and proline, improve photosynthetic fluorescence characteristics, and ultimately promote the growth of C. officinalis seedlings.