盐胁迫对3种平欧杂种榛幼苗叶片解剖结构及离子吸收、运输与分配的影响

Effects of salt stress on leaf anatomical structure and ion absorption,transportation and distribution of three Ping′ou hybrid hazelnut seedlings

研究盐胁迫下3个品种平欧杂种榛幼苗叶片解剖结构和离子代谢特征,以揭示盐胁迫响应与适应机制及不同品种的耐盐性差异。以‘达维’、‘辽榛7号’、‘玉坠’2年生压条苗为材料,在盆栽条件下经轻度、中度、重度(分别为50、100、200 mmol/L NaCl)盐胁迫处理,设对照为0,研究幼苗叶片显微解剖结构参数和Na^(+)、K^(+)、Cl^(-)、Ca^(2+)含量的变化及其在根、茎、叶中的吸收、运输和分配特征。不同品种平欧杂种榛叶片厚度、上表皮厚度、下表皮厚度、栅栏组织和海绵组织厚度随着盐胁迫程度的增强呈现出先增加后降低的特点,轻度和中度胁迫下各参数显著高于对照。中度盐胁迫显著提高了各品种叶片结构紧密度。盐胁迫导致平欧杂种榛根、茎、叶Na^(+)和Cl^(-)含量明显高于对照。盐胁迫下,Na^(+)和Cl^(-)在叶中的绝对含量明显高于茎和根,但二者的增幅以根中最大,叶中最小,表明平欧杂种榛根系首先会吸收并截留一定数量的Na^(+)和Cl^(-),然后将其运输至茎和叶中。与对照相比,轻度和中度盐胁迫下根、茎对K^(+)和Ca^(2+)的吸收保持稳定或减少,叶对K^(+)和Ca^(2+)的吸收则有所增加,重度胁迫下根、茎、叶K^(+)含量以及茎、叶中Ca^(2+)含量显著减少。盐胁迫导致不同品种平欧杂种榛根、茎、叶K^(+)/Na^(+)比和Ca^(2+)/Na^(+)比显著降低。随着盐胁迫程度的增强,不同品种平欧杂种榛从根到叶以及从茎到叶的S_(K^(+),Na^(+))和S_(Ca^(2+),Na^(+))均表现为先升高后降低的趋势,盐胁迫对‘辽榛7号’和‘玉坠’从根到茎的S_(K^(+),Na^(+))影响不显著。盐胁迫下,平欧杂种榛叶片通过一系列形态结构的调整来适应盐渍化生境,在积累盐离子的同时,通过加强对K^(+)和Ca^(2+)的选择性吸收和运输能力来维持体内的离子平衡以及较高的K^(+)/Na^(+)和Ca^(2+)/Na^(+)比,进而维持盐胁迫下机体正常的生理代谢活动。盐胁迫下‘辽榛7号’表现出更强的形态与生理适应性,其耐盐性强于‘达维’和‘玉坠’。

This study investigated the leaf anatomical structure and ion metabolism characteristics of seedlings of three Ping′ou hybrid hazelnut varieties under salt stress,to reveal the salt stress response and adaptation mechanism,and the salt tolerance differences of different varieties.Three Ping′ou hybrid hazelnut varieties(Dawei,Liaozhen 7,Yuzhui)were selected as testing materials.The two⁃year⁃old seedlings were treated with control,mild,moderate and severe salt stress(0,50,100,and 200 mmol/L NaCl concentrations,respectively)in a pot experiment.Subsequently,the leaf microanatomic structure parameters and the variation of ions(Na^(+),K^(+),Cl^(-),Ca^(2+))content were analyzed.The absorption,transportation and distribution of these ions in roots,stems and leaves were investigated.With the increase of salt stress,the leaf thickness,upper epidermis thickness,lower epidermis thickness,palisade tissue and spongy tissue thickness of different Ping′ou hybrid hazelnut varieties increased first and then decreased,and these parameters under mild and moderate stress were significantly higher than those of the control group.The moderate salt stress significantly improved the leaf structure tightness of all varieties.Compared with the control,salt stress significantly increased the Na^(+) and Cl^(-) content in roots,stems and leaves of Ping′ou hybrid hazelnut.Under salt stress,the absolute contents of Na^(+) and Cl^(-) in leaves were significantly higher than those in stems and roots,however,the increase of the two was the largest in roots and the smallest in leaves,which indicated that the roots of Ping′ou hybrid hazelnut could absorb and intercept a certain amount of Na^(+) and Cl^(-) and then transport them to stems and leaves.Compared with the control,the absorption of K^(+) and Ca^(2+) by roots and stems remained stable or decreased under mild and moderate salt stress,while K^(+) content in roots,stems and leaves and Ca^(2+) content in leaves and stems decreased significantly under severe salt stress.Salt stress significantly reduced the K^(+)/Na^(+) and Ca^(2+)/Na^(+)ratios in roots,stems and leaves.With the increase of salt stress,the S_(K^(+),Na^(+))and S_(Ca^(2+),Na^(+))from root to leaf and from stem to leaf of different Ping′ou hybrid hazelnut varieties increased first and then decreased.The effects of salt stress on S_(K^(+),Na^(+)) from root to stem of Liaozhen 7 and Yuzhui were not significant.Under salt stress,the leaves of Ping′ou hybrid hazelnut could adapt to the saline habitat through a series of morphological structure adjustment.When accumulating salt ions,Ping′ou hybrid hazelnut could enhance the selective absorption and transportation capacity of K^(+) and Ca^(2+) to maintain the ion balance and high K^(+)/Na^(+) and Ca^(2+)/Na^(+) ratios,so as to maintain the normal physiological and metabolic activities under salt stress.The Liaozhen 7 showed stronger morphological and physiological adaptability to salt stress,and its salt tolerance was stronger than that of Dawei and Yuzhui.