淹水胁迫对美国流苏幼苗生理特性和叶片结构的影响

Physiological Characteristics and Leaf Structure of Chionanthus virginicus Seedlings under Flooding Stress

以美国流苏2年生实生苗为材料,测定不同程度淹水处理(对照、轻度淹水、渍害、涝害)及其不同胁迫时间下幼苗生理指标和叶片结构特征,分析淹水胁迫对美国流苏幼苗生理生化和叶片结构的影响,探讨其耐涝性及其生理机制,为引种和栽培应用提供理论依据。结果表明:(1)美国流苏叶片过氧化物酶(POD)活性在轻度淹水和涝害处理下呈“下降-上升-下降”趋势,在渍害处理下呈先降后升趋势;在各淹水处理下,叶片超氧化物歧化酶(SOD)活性均呈先升后降趋势,相对电导率呈上升趋势,丙二醛(MDA)不同程度积累。在轻度淹水处理下,叶片可溶性糖(SS)、可溶性蛋白质(SP)含量呈先升后降趋势;在渍害和涝害处理下,叶片SS含量呈上升趋势,SP含量呈先降后升趋势。(2)随着淹水胁迫程度的加深,叶片厚度总体呈上升趋势,上、下表皮厚度总体呈下降趋势,栅栏组织厚度、海绵组织厚度、组织结构紧密度(CTR)和栅海比(P/S)总体呈先降后升趋势,组织结构疏松度(SR)总体呈先升后降趋势。(3)淹水胁迫使叶绿体形态膨胀变圆,多数不贴细胞壁,边缘降解,嗜锇颗粒和淀粉粒膨胀增多,基粒片层空泡化;随着淹水胁迫加剧,细胞核与叶绿体降解,淀粉粒大量聚集,细胞死亡。(4)叶片上表皮厚度与SOD、POD活性分别呈极显著和显著正相关关系;栅栏组织厚度与MDA和SS含量呈极显著正相关关系,与SP含量呈显著正相关关系;叶片厚度与叶片相对电导率、MDA、SS、SP含量均呈极显著正相关关系;海绵组织厚度与叶片相对电导率和SS含量呈显著正相关关系。研究发现,轻度淹水和渍害处理对美国流苏幼苗叶片生理特性和结构影响较小,幼苗能通过调节生理指标和叶片结构来适应胁迫,表现出一定的耐涝性;而涝害处理下,幼苗生理指标和叶片结构发生明显变化,植株大量死亡。

To analyze the effects of flooding stress(control,mild waterflooding,waterflooding and waterlogging)on physiology,biochemistry and leaf structure of Chionanthus virginicus seedlings,and to explore their waterlogging tolerance and physiological mechanism,so as to provide theoretical basis for the introduction and cultivation application of C.virginicus,we used two years old seedlings of C.virginicus as materials to determine the changes of physiological indexes and leaf structure characteristic of C.virginicus seedlings under different degrees of flooding and different stress time points.The results showed that:(1)the POD activity of C.virginicus leaves showed a“decline-rise-decline”trend under mild waterflooding and waterlogging,and showed a first decrease and then increase trend under waterlogging.Under each waterlogging treatment,SOD activity increased first and then decreased,while relative conductivity increased,and MDA accumulated in different degrees.Under mild waterlogging,the contents of SS and SP increased first and then decreased.Under waterflooding and waterlogging,the content of SS increased,and the content of SP decreased first and then increased.(2)With the increase of stress degree,the thickness of leaves increased,the thickness of top and lower epidermis decreased,palisade tissue thickness,spongy tissue thickness,CTR and P/S decreased first and then increased,and SR increased first and then decreased.(3)Under waterlogging stress,the chloroplasts were enlarged and rounded,most of them did not stick to the cell wall,the margins degraded,osmophilic grains and starch grains expanded and increased,and the grana lamellae were vacuolized.The intensification of stress resulted in the degradation of nuclei and chloroplasts,the accumulation of starch granules and cell death.(4)Leaf top epidermis thickness had very significantly positive correlation with SOD activity and significantly positive correlation with POD activity.The Palisade tissue thickness had very significantly positive correlation with the contents of MDA and SS,and significantly positive correlation with the content of SP.Leaf thickness had very significantly positive correlation with relative conductivity,MDA,SS and SP contents.The spongy tissue thickness had significantly positive correlation with the relative conductivity and SS content.In conclusion,mild waterflooding and waterflooding had little effect on C.virginicus seedlings.The seedlings could adapt to stress by adjusting physiological indexes and leaf structure,and had certain waterlogging tolerance.Under waterlogging treatment,the physiological indexes and leaf structure of seedlings changed obviously,and the plants died a lot.