| 摘要: |
| 【目的】探讨外源2,4-表油菜素内酯(2,4-epibrassinolide，EBR)对干旱胁迫下烤烟幼苗生长的调控效应与生理机制。【方法】以烤烟品种‘豫烟6号’为材料，采用Hoagland营养液水培法，研究不同质量浓度EBR(0，0.10，0.20和0.40 mg/L)对PEG 6000(质量分数15%)模拟干旱胁迫下烤烟幼苗生长、活性氧代谢、抗氧化酶活性和光合荧光特性的影响。【结果】干旱胁迫对烤烟幼苗造成了严重的氧化伤害和光抑制，添加不同质量浓度的EBR后，烤烟幼苗的总根长、总根表面积、根平均直径、根尖数、地上部和地下部鲜质量均明显提高；超氧化物歧化酶(SOD)、过氧化物酶(POD)和过氧化氢酶(CAT)活性显著提高，而超氧阴离子(O-·2)和丙二醛(MDA)含量显著下降；幼苗叶片的叶绿素相对含量(SPAD)、净光合速率(Pn)、蒸腾速率(Tr)、气孔导度(Gs)、气孔限制值(Ls)和水分利用效率(WUE)明显提高，而胞间二氧化碳浓度(Ci)显著降低；PSⅡ最大光化学效率(Fv/Fm)、PSⅡ实际光化学效率(ΦPSⅡ)和光化学猝灭系数(qP)显著提高，而非光化学猝灭系数(NPQ)显著降低。上述指标均以0.20 mg/L EBR处理的效果最为显著。【结论】在干旱胁迫下，外源EBR能够通过提高烤烟幼苗的抗氧化酶活性，减轻细胞膜氧化损伤，从而增强烟草幼苗对干旱胁迫的耐受性，并通过提高叶片对光能的捕获与转化能力，增强叶片光合效能，促进烟苗的生长。 |
| 关键词: 烤烟 油菜素内酯 干旱胁迫 抗氧化性能 光合特性 叶绿素荧光参数 |
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| 基金项目:国家自然科学基金项目（31700367）；河南省高等学校青年骨干教师培养计划项目（2016GGJS-062）；河南科技大学学科提升振兴A计划项目(13660002)；洛阳市烟草公司资助项目（LYKJ201803） |
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| Effects of brassinolide on growth,physiology and photosynthetic characteristics of flue-cured tobacco seedlings under drought stress |
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WANG Lijun,LI Dong,SHEN Hongtao,et al
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| Abstract: |
| 【Objective】This study explored the regulating effects and physiological mechanism of exogenous 2,4-epibrassinolide (EBR) on growth of flue cured tobacco seedlings under drought stress.【Method】This study adopted the method of nutrient solution hydroponics using 15% polyethylene glycol (PEG-6000) to simulate drought stress.Flue-cured tobacco (Nicotiana tabacum cv.‘Yuyan No.6’) was tested for response after foliar spraying with exogenous EBR at mass concentrations of 0,0.10,0.20,and 0.40 mg/L.Parameters including seedling growth,active oxygen metabolism,antioxidant enzyme activity and photosynthetic fluorescence characteristics were measured and analyzed.【Result】Drought stress caused serious oxidative damage and photoinhibition to tobacco seedlings.Exogenous EBR effectively alleviated damage of drought stress on tobacco seedlings,particular including significantly increasing total root length,total root surface area,average root diameter,root tip number,fresh weight of root and shoot,significantly increasing activities of superoxide dismutase (SOD),peroxidase (POD) and catalase (CAT),while significantly decreasing superoxide anion (O-·2) generation rate and malondialdehyde (MDA) content.The chlorophyll content (SPAD),net photosynthetic rate (Pn),transpiration rate (Tr),stomatal conductance (Gs),stomatal limitation (Ls) and water use efficiency (WUE) of leaves were enhanced,while intercellular carbon dioxide concentration (Ci) was significantly decreased.The maximal PSⅡ quantum yield (Fv/Fm),PSⅡ actual photochemical efficiency (ΦPSⅡ) and photochemical quenching coefficient (qP) were significantly increased,while non photochemical quenching coefficient (NPQ) was significantly reduced.Foliar application with 0.20 mg/L EBR had the largest growth promotion effects and drought stress alleviation.【Conclusion】Exogenous EBR enhanced the adaptability of seedlings to drought stress by improving antioxidant capacity and reducing oxidative damage of cell membrane,and stimulated tobacco seedlings to capture and convert solar energy for better seeding photosynthesis and growth. |
| Key words: flue-cured tobacco 2,4-epibrassinolide drought stress antioxidant capacities photosynthetic characteristics chlorophyll fluorescence characteristics |
