NaCl胁迫对2个菊属野生种幼苗体内K^＋、Na^＋和Cl^-分布及生长的影响

Effects of NaCl stress on organ compartmental allocation of K^+,Na^+ and Cl^- and growth of two Dendranthema species seedlings

采用营养液水培,研究了不同浓度NaCl处理下耐盐性不同的2个菊属物种幼苗的生长变化及体内K+、Na+、Cl-在器官间的区域化分布和吸收、运输特性,以揭示其耐盐差异机制。结果表明,NaCl胁迫下,2个物种的新生叶面积比率减小,受害叶面积比率增加,叶电解质外渗率增加;大岛野路菊受胁迫影响较轻。2个物种体内Na+和Cl-含量随NaCl浓度的升高而增大,且地上部的Na+、Cl-积累量大于根系,成熟叶是2个物种Na+、Cl-积累的主要器官。新生叶、茎的K+含量也随NaCl浓度的升高而增加。与耐盐性强的大岛野路菊相比,NaCl胁迫下萨摩野菊各器官积累的Na+和Cl-量均显著高于前者,其生长对其体内含有的Na+和Cl-比大岛野路菊更为敏感。除高盐胁迫下的根以外,大岛野路菊各器官的K+/Na+均显著高于萨摩野菊。大岛野路菊根向茎运输的SK,Na值远高于萨摩野菊,茎向中位成熟叶运输的SK,Na值较低,高盐胁迫时茎向上位新生叶运输的SK,Na值较高。说明NaCl胁迫下大岛野路菊对Cl-、Na+的累积能力弱、维持K+、Na+平衡的能力强,且根系对Na+的截留能力强,茎向上位新生叶运输Na+的选择性较低,是其耐盐性强的主要原因,而茎向中位成熟叶运输Na+的选择性较高是其对盐胁迫的适应。多元回归分析结果还表明,Cl-对萨摩野菊的影响强于Na+。

In order to disclose the salt tolerant mechanisms of Dendranthema,the absorption,transportation and organcompartmentalized distribution of K ＋,Na ＋ and Cl-under different concentrations of NaCl stress were compared in seedlings of two Dendranthema species via hydroponics method.Under NaCl stress,both species showed decrease in ratio of newly developed leaf area while increase in ratio of injured leaf area per plant,and relative electricity conductivity in leaves increased too.Dendranthema crassum was lesser affected by NaCl stress than D.ornatum did.The Na ＋ and Cl-contents increased with the increase of NaCl concentration,and accumulations of Na ＋ and Cl-were more in organs above the ground than those in roots in both species.Similarly,K ＋ content elevated with increase of NaCl concentration in newly developed leaves and stem.Mature leaves seemed to be the main storage organ for Na ＋ and Cl-.Compared with salt tolerant D.crassum,the salt sensitive D.ornatum showed more Na ＋ and Cl-accumulation in all organs,and its growth was more susceptible to the contents of accumulated Na ＋ and Cl-.The ratios of K ＋ /Na ＋ in all organs except root of D.crassum under severe NaCl stress were higher than those in corresponding organs of D.ornatum.D.crassum had a higher transportation selectivity of K ＋ /Na ＋（designated as SK,Na） from root to stem,whereas a lower SK,Na from stem to middle mature leaves under same salt stress.However a higher SK,Na from stem to upper newly developed leaves was observed under high NaCl stress.All these data indicated that D.crassum could maintain a better K ＋ /Na ＋ ratio rather than to accumulate Cl-and Na ＋,constrain Na ＋ in the root,and keep lower SK,Nafrom stem to upper newly developed leaves,all of which are good explanations for its salt tolerance.Higher SK,Na from stem to middle mature leaves probably represented a kind of accommodation to salt stress of D.crassum.Based on multiple-linear regression analysis,the growth of D.ornatum was affected more evidently by Cl-than by Na ＋.