采用营养液培养法,研究了不同浓度(1、3、5 和 7 g· L^-1 ) NaHCO₃对喜盐鸢尾(Iris halophila Pall.)和马蔺[I.lactea var. chinensis (Fisch.) Koidz.]株高、叶数、叶宽、根长和根数的影响,并采用石蜡切片法观察了 NaHCO₃胁迫后二者叶及根解剖结构的变化。 结果表明:用 1 ~ 7 g· L^-1 NaHCO₃处理 4 周,喜盐鸢尾和马蔺的生长指标均持续增加,但各指标的周增长量差异较大且总体上随 NaHCO3浓度提高而降低。 在 1 和 3 g· L^-1 NaHCO₃胁迫条件下,二者所有指标的周增长量均随胁迫时间延长而增加;而在 5 和 7 g· L^-1 NaHCO₃胁迫条件下,随胁迫时间延长,二者的株高和叶数及马蔺叶宽的周增长量均逐渐降低,二者根数及喜盐鸢尾叶宽的周增长量则逐渐增加,但二者根长的周增长量在第 1 至第 3 周逐渐增加、第 4 周则有所降低。 多数情况下二者大部分指标的周增长量均低于对照,仅在 1和 3 g· L^-1 NaHCO₃胁迫条件下部分时间段喜盐鸢尾株高、叶数、叶宽、根长和根数的周增长量高于对照;且总体上看,喜盐鸢尾各指标的周增长量均大于马蔺,二者地下部各生长指标的周增长量大于地上部。 观察结果表明:二者的解剖结构有一定差异,马蔺叶肉细胞层数多于喜盐鸢尾;用 7 g· L^-1 NaHCO₃处理 28 d,二者根和叶片的解剖结构均未有明显的损伤性变化,仅表现为根系和叶片表皮细胞壁加厚、根皮层内大部分薄壁细胞破裂形成通气组织。研究结果显示:较低浓度 NaHCO3对喜盐鸢尾和马蔺的生长无明显抑制作用,但较高浓度 NaHCO₃则能延缓二者的生长,且对地上部的影响大于地下部;喜盐鸢尾和马蔺对 NaHCO₃胁迫均有较强的耐性,且前者的耐性大于后者。

 

By means of nutrient solution culture method, effects of different concentrations (1, 3, 5 and7 g· L^-1) of NaHCO3 on seedling height, number and width of leaf, length and number of root of Iris halophila Pall. and I. lactea var. chinensis ( Fisch.) Koidz. were studied, and anatomical structure change of leaf and root of two plants after NaHCO₃ stress was observed by paraffin section method. The results show that growth indexes of I. halophila and I. lactea var. chinensis all increase continuously during the process of 1-7 g· L^-1 NaHCO₃ stress for four weeks, but weekly increment of growth indexes has larger differences and generally decreases with rising of NaHCO₃ concentration. Under conditions of 1 and 3 g · L^-1 NaHCO3 stress, weekly increment of all growth indexes of two plants increases with prolonging of stress time. While, under conditions of 5 and 7 g· L^-1 NaHCO₃ stress, with prolonging of stress time, weekly increment of seedling height and leaf number of two plants and leaf width of I. lacteal var. chinensis all decreases gradually, and weekly increment of root number of two plants and leaf widthof I. halophila all increases gradually, but weekly increment of root length of two plants all increases in the first to the third week and decreases in the fourth week. Weekly increment of most indexes of two plants is lower than those of the control in most cases, only that of seedling height, leaf number and width, root length and number of I. halophila is higher than those of the control in some time period under conditions of 1 and 3 g· L^-1 NaHCO₃ stress. And basically, weekly increment of growth indexes of I. halophila is higher than that of I. lactea var. chinensis, and that of growth indexes of their under- ground part is higher than that of their above-ground part. The observation result shows that there is a certain difference in their anatomical structure, and layer number of mesophyll cells of I. lactea var. chinensis is more than that of I. halophila. After 7 g· L^-1 NaHCO3 stress for 28 d, there is no obvious injure change in anatomical structure of root and leaf of two plants, only appearing that the wall of epidermal cells of root and leaf is thickened, and most parenchyma cells in root cortex are ruptured to form. aerenchyma. It is suggested that NaHCO₃ stress with lower concentrations has no obvious inhibition to growth of I. halophila and I. lactea var. chinensis, but NaHCO₃ stress with higher concentrations may retard their growth, and the effect on their above-ground part is greater than that on their under-ground part. Both I. halophila and I. lactea var. chinensis have stronger resistance abilitiy to NaHCO₃ stress, and the resistance of the former is larger than that of the latter.