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外源调节物质对干旱胁迫红椿苗木形态及光合生理的影响
高琦1, 刘亚敏1, 刘玉民,等1
西南大学 资源环境学院,三峡库区生态环境教育部重点实验室
摘要:
【目的】探明褪黑素(MT)、水杨酸(SA)和茉莉酸甲酯(MeJA)3种外源调节物质对干旱胁迫红椿苗木表观形态及光合生理的影响,筛选对红椿干旱损伤缓解效果最好的外源物质。【方法】以2年生红椿幼苗作为试验材料,通过盆栽控水试验,设置土壤湿度为45%,对红椿进行中度干旱胁迫(MD)处理,在此基础上分别外源施加0.1 mmol/L MT(MD+MT)、0.5 mmol/L SA(MD+SA)和0.4 mmol/L MeJA(MD+MeJA)进行3个缓解试验处理,同时设土壤湿度为70%的正常供水对照(CK),比较各处理红椿幼苗生长指标、表观形态、气孔和叶肉细胞形态、叶绿素含量、气体交换参数和叶绿素荧光参数的变化情况,运用隶属函数法综合评价3种外源物质的干旱缓解效果。【结果】①中度干旱胁迫(MD)会抑制红椿幼苗地径、株高和叶长等的生长,MD+SA处理可显著缓解干旱对地径和株高的抑制,但MD+MeJA处理对地径生长有抑制作用,MD+MT处理对株高生长有抑制作用。②中度干旱胁迫会损害红椿叶片的表观形态、气孔及叶肉细胞形态,MD+SA处理对红椿叶片脱落、叶色、气孔开闭程度及叶肉细胞形态有明显恢复效果,MD+MeJA处理对红椿叶片萎蔫情况和气孔开闭程度的恢复具有明显缓解效果。③中度干旱胁迫会显著抑制红椿的光合作用,MD+SA处理对干旱胁迫下红椿叶绿素含量、气孔参数和叶绿素荧光参数的抑制有缓解作用,MD+MeJA处理对气孔参数和叶绿素荧光参数有一定缓解作用,MD+MT处理仅对叶绿素荧光参数有缓解效果。④抗旱性综合评价结果显示,MD+SA、MD+MeJA和MD+MT处理抗旱性指标的隶属函数均值分别为0.55,0.52和0.45,表明MD+SA处理对红椿干旱损伤的缓解效果最好。【结论】干旱胁迫条件下,红椿表观形态受损,叶绿素含量下降,气体交换参数和PSⅡ反应中心等光合机构受损;MT、SA和MeJA 3种外源调节物质均可以缓解干旱胁迫下红椿的受损情况,且SA的调节效果最好。
关键词:  红椿  干旱胁迫  光合特性  外源物质
DOI:
分类号:
基金项目:重庆市林业科技攻关项目(ylky2018-05);中央林业改革发展资金科技推广项目(ylkt2019-04)
Effects of exogenous substances on morphology and photosynthetic physiology of Toona ciliata seedlings under drought stress
GAO Qi,LIU Yamin,LIU Yumin,et al
Abstract:
【Objective】The effects of three exogenous regulatory substances of melatonin (MT),salicylic acid (SA) and methyl jasmonate (MeJA) on apparent morphology and photosynthetic physiology of seedlings under drought stress were investigated,and the exogenous substances with best alleviating effect on drought damage of Toona ciliata were selected.【Method】The 2-year-old seedlings of Toona ciliata were used for pot experiment with controlled soil moisture at 45%.After moderate drought treatment,0.1 mmol/L melatonin (MD+MT),0.5 mmol/L salicylic acid (MD+SA) and 0.4 mmol/L methyl jasmonate (MD+MeJA) were exogenously applied.The normal water supply group with soil moisture of 70% was set as the control (CK).The changes in growth indexes,apparent morphology,stomatal and mesophyll cell morphology, chlorophyll content,gas exchange parameters and chlorophyll fluorescence parameters of Toona ciliata seedlings were compared among treatments.【Result】① Moderate drought stress inhibited the growth of ground diameter,plant height,and leaf length.MD+SA treatment significantly alleviated the effects of drought on ground diameter and plant height,MD+MeJA treatment inhibited the growth of ground diameter,and MD+MT treatment inhibited the growth of plant height.② Moderate drought stress damaged the apparent,stomatal and mesophyll cell morphology of leaves.MD+SA treatment had considerable recovery effect on leaf shedding,leaf color,stomatal opening and closing degrees and mesophyll cell morphology.MD+MeJA treatment had recovery effect on leaf wilting and stomatal opening and closing degrees.③ Moderate drought stress significantly inhibited the photosynthesis of Toona ciliata.MD+SA treatment alleviated chlorophyll content,stomatal parameters and chlorophyll fluorescence parameters under drought stress,MD+MeJA had alleviate effects on stomatal parameters and chlorophyll fluorescence parameters,while MD+MT only had alleviate effects on chlorophyll fluorescence parameters.④ A comprehensive evaluation of drought resistance showed that the mean membership functions of drought resistance indexes of MD+SA,MD+MeJA and MD+MT treatments were 0.55,0.52,and 0.45,respectively,indicating that MD+SA treatment had the best effect on alleviating drought damage of Toona ciliata.【Conclusion】Under drought stress,the apparent morphology,chlorophyll content,gas exchange parameters and photosynthesis such as PSⅡ reaction center were damaged.MT,SA and MeJA could alleviate the damage caused by drought stress,and SA was the best.
Key words:  Toona ciliata  drought stress  photosynthetic characteristics  exogenous substance