盐分和水分胁迫对芦荟幼苗渗透调节和渗调物质积累的影响

用不同浓度NaCl和等渗聚乙二醇(PEG 6000)处理芦荟(Aloe vera L.)幼苗,10 d后测定叶片相对生长速率和厚度、叶片中主要有机溶质、无机离子含量及渗透调节能力.结果表明,-0.44、-0.88 MPa NaCl和PEG处理使芦荟叶片的相对生长速率和叶片厚度明显下降,且盐胁迫对幼苗生长的抑制和叶片含水量降低的效应明显高于等渗的水分胁迫,其叶片渗透调节能力随处理渗透势的降低而增加, -0.88 MPa PEG胁迫的芦荟幼苗的渗透调节能力高于等渗盐分胁迫.在主要渗透调节物质可溶性糖、有机酸、K 、Ca2 和Cl-中,-0.88 MPa PEG处理下含量比相同渗透势的NaCl处理下显著增加的是有机溶质,因此推断有机溶质含量高是PEG胁迫下渗透调节能力较强的主要因素.

Effects of Salt and Water Stresses on Osmotic Adjustment and Osmotica Accumulation in Aloe vera Seedlings

Aloe seedlings were treated with different concentrations of NaCl and iso-osmotic PEG6000 solutions for 10 d, and relative growth rate, leaf thickness, content of main organic solutes, inorganic ions and osmoregulation ability of leaves were determined. The results showed that exposure to - 0.44,- 0.88 MPa NaCl and PEG lowered the relative growth rate(Fig.1A) of aloe leaves and made their thickness smaller (Fig.1B). The growth of seedlings and water content in leaves (Fig.2A) under salt stress were decreased more than that under iso-osmotic water stress. The osmoregulation of aloe seedlings increased with the extent of lowering of osmotic potential of treatment solution and was stronger under -0.88 MPa PEG treatment than under NaCl treatment with the same osmotic potential(Fig.2B). The main osmoregulatory substances of aloe seedlings were soluble sugars,organic acids,K +,Ca 2+ ,and Cl -(Fig.3A). Organic solute contents of -0.88 MPa PEG-treated seedling leaves were dramatically more than that of -0.88 MPa NaCl-treated ones (Fig.3B). Strong osmotic adjustment ability of aloe under PEG stress was mainly caused by accumulation of organic solutes.