采用水培法研究了不同浓度(24、120 和 240 μmol· L^-1 ) Pb 胁迫条件下花芽甜麦菜( Sonchus lingiaus)、碧绿粗苔菜心(Brassica chinensis var. utilis)和空心菜( Ipomoea aquatica)生长和部分生理指标(包括游离脯氨酸含量及SOD、POD 和 CAT 活性)以及 Pb 吸收量的变化,并通过隶属函数法对 3 种叶菜的 Pb 抗性进行了综合比较。 结果表明:Pb 胁迫对 3 种叶菜单株地上部分鲜质量总体上影响不明显。 随 Pb 胁迫浓度的提高,3 种叶菜地上部分和地下部分 Pb 含量逐渐升高,且地下部分 Pb 含量均高于地上部分,Pb 转运系数则显著降低(P<0. 05);按 Pb 含量由高至低依次为空心菜、碧绿粗苔菜心、花芽甜麦菜。 在 Pb 胁迫条件下,花芽甜麦菜中游离脯氨酸含量均略低于对照但差异不显著(P>0. 05),空心菜中游离脯氨酸含量均显著高于对照,而碧绿粗苔菜心的游离脯氨酸含量仅在 120 和240 μmol· L^-1 Pb 胁迫条件下显著高于对照。 随 Pb 胁迫浓度提高,3 种叶菜 SOD 活性呈逐渐增加的趋势,但总体上与对照差异不显著;经 Pb 胁迫处理后,3 种叶菜的 CAT 活性或高于或低于对照,但在 240 μmol· L^-1 Pb 胁迫条件下花芽甜麦菜的 CAT 活性显著低于对照、碧绿粗苔菜心和空心菜的 CAT 活性显著高于对照;Pb 胁迫后 3 种叶菜的POD 活性未表现出明显的规律。 经过综合评价,3 种叶菜对 Pb 的抗性由大至小依次为碧绿粗苔菜心、空心菜、花芽甜麦菜。 经过主成分分析,确定 3 种叶菜的游离脯氨酸含量、SOD 和 CAT 活性为 Pb 胁迫的响应因子。

 

Changes of growth and some physiological indexes and Pb absorption amount in three leaf vegetables (including Sonchus lingiaus, Brassica chinensis var. utilis and Ipomoea aquatica) were studied by water culture method under Pb stress with different concentrations (24, 120 and 240 μmol· L-1 ), and Pb resistance of three leaf vegetables was compared comprehensively by subordinate function method. The results show that effect of Pb stress on fresh weight of above-ground part of individual of three leaf vegetables is not obvious generally. With rising of Pb concentration, Pb contents in above- and under- ground parts both increase gradually, and Pb content in under-ground part is higher than that in above-ground part, while the translocation coefficient of Pb decreases significantly (P<0. 05). The order of Pb content in three leaf vegetables from high to low is I. aquatica, B. chinensis var. utilis, S. lingiaus. Under Pb stress condition, free proline content in S. lingiaus is slightly lower than that in the control without significant  difference (P>0. 05), while that in I. aquatica is significantly higher than that in the control. But that in B. chinensis var. utilis only under high concentration (120 and 240μmol· L^-1 ) of Pb stress is significantly higher than that in the control. SOD activity of three leaf vegetables appears an gradually increasing trend with enhancing of Pb stress concentration, but generally has no significant difference with that in the control. CAT activity of three leaf vegetables is higher or lower than that of the control after Pb stress, but only under 240 μmol· L^-1 Pb stress that of S. lingiaus is significantly lower than that of the control and that of B. chinensis var. utilis and I. aquatica is significantly higher than that of the control. POD activity of three leaf vegetables has no obvious regularity after Pb stress. According to the comprehensive evaluation of physiological indexes, the order of Pb resistance of three leaf vegetables from strong to weak is B. chinensis var. utilis, I. aquatica, S. lingiaus. It can be determined that the response factors of three leaf vegetables to Pb stress are free proline content and activities of SOD and CAT by the principal component analysis.