以荷花(Nelumbo nucifera Gaertn.)品种‘太湖红莲’(‘Taihu Honglian’)和‘荷塘情深’(‘Hetang Qingshen’)为实验材料,以MDA 含量、相对电导率、脯氨酸含量、可溶性糖含量、SOD 活性和POD 活性为指标,对经过5 ℃低温锻炼10 h 后2 个品种地下茎对0 ℃低温胁迫(0、2、4、6、8 和10 h)的生理响应差异进行了分析,并比较了低温锻炼对2 个荷花品种抗寒性的影响。结果表明:在低温胁迫条件下,随低温胁迫时间的延长(0 ~10 h),经低温锻炼的荷花品种‘太湖红莲’和‘荷塘情深’地下茎的MDA 含量和相对电导率总体上呈逐渐升高的变化趋势,可溶性糖含量均呈“升—降—升”的变化趋势,SOD 活性基本呈“升—降 — 升 —降”的变化趋势,而POD 活性则呈先上升后微幅波动的变化趋势;二者的脯氨酸含量变化趋势有一定差异,其中,前者的脯氨酸含量逐渐上升,而后者的脯氨酸含量则先升后降。经低温锻炼后,在低温胁迫条件下2 个荷花品种的6 项生理指标均与对照组(未进行低温锻炼)有一定差异;其中,品种‘太湖红莲’地下茎的MDA 含量和相对电导率在低温胁迫的4 ~10 h 均显著低于对照组,品种‘荷塘情深’地下茎的相对电导率在低温胁迫的2 ~8 h 显著低于对照组,但其MDA 含量则与对照组无显著差异;2 个品种地下茎的脯氨酸含量和可溶性糖含量总体上显著高于对照组,而二者的SOD 活性和POD 活性也总体上高于对照组。综合分析结果显示:低温锻炼有助于减轻低温胁迫对荷花地下茎膜系统的伤害、增加细胞内渗透调节物质的含量、提高抗氧化酶活性,在一定程度上提高了荷花的抗寒性;经低温锻炼后品种‘太湖红莲’抗寒性的增幅大于品种‘荷塘情深’。

Taking cultivar ‘Taihu Honglian’and ‘Hetang Qingshen’of Nelumbo nucifera Gaertn. As experimental materials, and taking MDA content, relative electrical conductivity, contents of proline and soluble sugar, and activities of SOD and POD as indexes, after cold acclimation at 5 ℃for 10 h, difference in physiological response of rhizome of two cultivars to low temperature stress at 0 ℃for 0, 2, 4, 6, 8 and 10 h was analyzed, and effect of cold acclimation on cold resistance of two cultivars was compared. The results show that under low temperature stress, MDA content and relative electrical conductivity of rhizome of cultivar ‘Taihu Honglian’and ‘Hetang Qingshen’after cold acclimation totally appear gradually increasing trend with prolonging of low temperature time (0-10 h), their soluble sugar contents appear the “increasing-decreasing-increasing”trend, SOD activities basically appear the “increasing-decreasing-increasing-decreasing”trend, while POD activities appear the trend of firstly increasing and then slightly fluctuating; there is a certain difference in change trend of proline content of two cultivars, in which, proline content of cultivar ‘Taihu Honglian’ increases gradually, while that of cultivar ‘Hetang Qingshen’ increases firstly and then decreases. After cold acclimation, there is a certain difference in six physiological indexes of two N. nucifera cultivars under low temperature stress with those of the control group (without cold acclimation), in which, both MDA content and relative electrical conductivity of rhizome of cultivar ‘Taihu Honglian’ under low temperature stress for 4-10 h are significantly lower than those of the control group, relative electrical conductivity of rhizome of cultivar ‘Hetang Qingshen’ under low temperature stress for 2-8 h is significantly lower than that of the control group and its MDA content has no significant difference with that of the control group; contents of proline and soluble sugar in rhizome of two cultivars are totally significantly higher than those of the control group, and their SOD and POD activities are totally higher than those of the control group. The comprehensive result shows that cold acclimation is benefit to relieve damage to membrane system of rhizome of N. nucifera, increase osmoregulation substance content and enhance antioxidant enzyme activity, therefore, cold resistance of  N. nucifera can be enhanced at a certain degree. And increasing range of cold resistance of cultivar ‘Taihu Honglian’ is higher than that of cultivar ‘Hetang Qingshen’ after cold acclimation.