【摘要】 盆栽条件下对碱茅在等渗的盐（ＮａＣｌ）及渗透胁迫（ＰＥＧ模拟）下的生长，水分含量，离子（Ｋ＋、Ｎａ＋）吸收与选择性以及渗透反应进行了比较研究。结果表明，在－０．０１～－１．５ＭＰａ渗透势范围内，随渗透势降低植株的干重及水分含量均迅速降低，ＰＥＧ胁迫比等渗的ＮａＣｌ胁迫下降幅更大。ＮａＣｌ及ＮａＣｌ＋ＰＥＧ胁迫下，随溶液渗透势的降低（或ＮａＣｌ浓度的增大）植株Ｎａ＋浓度，Ｎａ＋／Ｋ＋及对Ｋ＋（相对于Ｎａ＋）的选择性均迅速增大，而Ｋ＋浓度未显著变化。植株Ｎａ＋主要是被动吸收的结果，而Ｋ＋则是主动的选择性吸收的结果。植株渗透势随胁迫溶液渗透势降低而线性降低，ＮａＣｌ胁迫下植株渗透势约比等渗的ＰＥＧ胁迫下低－０．１４～－０．２０ＭＰａ。ＮａＣｌ胁迫下，当渗透势高于－０．９ＭＰａ时，植株渗透势的降低（渗透反应）主要可归于由Ｎａ＋积累引起的渗透调节与脱水；渗透势－０．９～－１．５ＭＰａ时，渗透调节可解释植株渗透反应的７２％～７８％（其中，由Ｎａ＋引起的渗透调节占总渗透调节的５６％～７３％），脱水可解释２２％～２８％。ＰＥＧ胁迫下，当溶液渗透势高于－０．７ＭＰａ时，植株的渗透反应主要是脱水引起的；渗透势－０．７～－１．５?更多还原

【Abstract】 The dry matter, moisture content,ion(K&Na)uptake and selectivity, and osmotic response ofshoots in pottedPuccinellia tenuiflora were compartatively investigatedd under isosmotic salinity and osmoticstress which were simulated by the solutions of NaCl , polyethylene glycol(PEG 6000)and NaCl+PEG witharange of osmotic potentials , respectively。 The dry matter and moisture content of shoot were significantlyreduced as the osmotic potential decreased from-0.01～-1. 5 MPa in the three stress solutions,withPEG solution causing a more rapid decrease than the is osmotic NaCl solution。 Moreover , it was found thatNa concentration and the selectivety of K over Na in shcot were rapidly increased , and K/Na ratio in shootswas evidently decreased in NaCl and NaCl+PEG sofutions , whereas no or only little changes wereoberserved6oth in Na concentration of shoot in PEG solution and in K concentration of shoot in the threesolutions as the osmotic potentials of solutions decreased. The osmotic potential of shoot was linearlyreduced with the decreased osmotic potentials of the solutions under the three stresses , and the decrease ofthe potential in shoot was approximately-0.14～-0. 20 MPa lower in the plants growing in NaCl than inPEG,Under NaCl stress,the decrease of the osmotic potential of Shoot was essen tially due to both theosmoregulation caused by Na accumulation and dehydrationins in shoot in the solutions with osmoticpotentials higher than-0.9MPa,when the osmotic potential of solution was lower(-0.9～-1. 5MPa ),the total osmoregulation caused by the solute accumulation and dehydration in shoot accounted for 72%～78%and 22%～28%,respectively,wherein the osmoregulation caused by Na accumulatinn accounted for56%～73%of the total osmoregulation value。 In contrast, under PEG stress,the decrease of osmoticpotential of shoot could be mainly attributed to the dehydration in the solution with osmotic potential higherthan-0. 7MPa, when this potential of solution was lower(-0.7～1.5MPa),only 20%～38%of thedecrease of the potential in shoot was due to dehydration,and the other part of that to the osmoregulation by solute accumulation in shoots。更多还原