Na_2CO_3胁迫下羊草苗的胁变反应及其数学分析

STRAIN RESPONSES IN NaCO_3-STRESSED LEYMUS CHINENSIS SEEDLINGS AND THEIR MATHEMATICAL ANALYSIS

将羊草(Leymus chinensis L.)苗培养在含有1.25—30 mmol/Na_2CO_3的营养液中,胁迫处理6天,然后测定其相对生长抑制率等9项胁变指标。结果表明:在Na_2CO_3胁迫作用下羊草苗生长受到明显抑制,植物休内Na^+含量急剧上升,而K^+含量逐渐下降,脯氨酸、柠檬酸大量积累,电解质外渗率上升,叶绿素含量下降,两种光合羧化酶的活力均降低,但由于1,5-二磷酸核酮糖羧化酶(RuBPCase)活力下降的幅度明显大于磷酸烯醇式丙酮酸羧化酶(PEPCase),所以,导致两酶活力比(PEPCase/RuBPCase)明显变大。对实验数据进行数学分析的结果显示:所测定的9项胁变指标与胁强(Na_2CO_3摩尔浓度的自然对数)间均具有可用关系式:Y=Ym/[1+Ke^(-(ax^2+bx))]+C(Y为胁变值;Ym为最大胁变值;X为胁强,即No_2CO-3摩尔浓度的自然对数;K、a、b、c均为参数)或其变换式来表示的S型或倒S型曲线关系。

The seedlings of Leymus chinensis were Na_2CO_3-stressed for 6 days by planting in various culture solutions containing 1.25—30mmol/L Na_2CO_3.Nine strain indexes, such as the relative growth inhibition rate etc.,were determined.The growth was obviously inhibited;the Na+ content was rapidly increased and K^+content was gra dually decreased;great amount of proline and citric acid was accumulated;the leakage rate of electrolyte was elevated;the content of chlorophyll was reduced;the activities of both photosynthetic carboxylases RuBPCase and PEPCase were reduced and the ratio of PEPCase activity/RuBPCase activity became great eventually,as the reductio of RuBPCase activity was much more than PEPCase.Mathematice an- alyses of the experimental data for relationships between the strain indexes and str- ess(in natural logarithm of molar concentrations of Na_2CO_3)revealed sigmoidal or inverted sigmoidal relationships which can be expressed by the equation Y=Y_m/ [1+Ke^(-(ax^2+bx))]+C or its varied forms(Y.strain value;Ym.maximum strain value;X.stress value viz.In molar concentration of Na_2CO_3;K,a,b,C.parameters).