盐、碱胁迫对药用植物碱地肤生长及其茎叶离子含量的影响

Effects of salt and alkali stresses on growth and ions accumulation in shoot of medicinal plant Kochia sieversiana

对碱地肤(Kochia sieversiana)幼苗进行盐胁迫或碱胁迫动态处理,通过动态监测碱地肤的生长及无机离子含量等指标的变化情况,探讨了碱地肤生长及离子积累的动态特点.结果表明:随着盐、碱胁迫的延长,碱地肤含水量、鲜重和干重等生长指标均不同程度地受到影响,且碱胁迫影响更大.盐、碱胁迫均抑制碱地肤的生长,碱胁迫抑制更为严重.碱地肤并非肉质化植物,其在长时间的渗透胁迫和高pH下仍能保持高含水量,此特殊现象可能是决定碱地肤具有高度抗盐碱特性的生理特点之一.随着盐、碱胁迫的延长,碱地肤植株对K^+,Na^+吸收不存在拮抗竞争,且在144h的盐、碱胁迫下仍保持着较低的b_(Na^+)/b_(K^+)比值,这种排Na^+、吸K^+的特殊吸收机制对碱地肤的抗盐、碱性具有重要意义.此外,与盐胁迫相比,碱胁迫下其b_(Na^+)/b_(K^+)比值更低,这可能是碱地肤适应高pH盐碱生境的重要原因之一.

In this study,seedlings of Koch ia sieversiana （Pall.）C. A. Mey were exposed to the dynamic treatment.salt stress and alkali stress. The dynamic characteristics of K. sieversiana growth and ions accumulation were investigated by determining and analyzing the growth index, the concentrations of ions and so on. The results showed that the growth indexes, such as water content, dry weight, fresh weight and so on,in K. sieversiana,were affected to various degrees with increasing stress time under salt and alkali stresses, and alkali stress was greater than salt stress. Clearly, both salt and alkali stresses inhibited the growth of K. sieversiana, and the inhibition of alkali stress was more serious than salt stress. K. sieversiana is not a kind of succulence plant, whereas it could still keep high water content under long-time osmotic stress and high pH condition, which may endow it with high saline- alkali tolerance as a primary physiological characteristic. There is no antagonism competition between absorption of K^＋ and Na^＋ in K. sleversiana with increasing stress time under salt and alkali stresses, and it could still low value of bNa^＋/bK^＋ under 144 h alkali stress. This kind of special absorption mechanism of K^＋ and Na＋ may have great significance in saline-alkali tolerance of K. sieversiana. Moreover,the value of bNa^＋/bK^＋ is lower under alkali stress than salt stress,which may be one of the important reasons for adaption to saline-alkaline habitat contained high pH in K. sieversiana.