蒋英 郭红伟

摘    要：為探讨丝瓜幼苗对铜的耐受范围，以‘美秀丝瓜品种为试材，借助营养液沙培的方式，研究不同浓度的铜胁迫（Cu2+ 0，5，15，30，50 μmol·L-1）对丝瓜幼苗光合色素、光合参数及渗透调节物质含量的影响。结果表明：随着铜浓度的增加，丝瓜幼苗叶片叶绿素a、叶绿素、类胡萝卜素含量呈先升后降的趋势，均于铜浓度5 μmol·L-1时达到最大值;净光合速率、气孔导度和胞间CO2浓度均呈现逐渐降低的变化趋势，其中铜浓度5 μmol·L-1处理的净光合速率、蒸腾速率和胞间CO2浓度均与对照差异不显著，但其他处理均显著低于对照，蒸腾速率呈先升后降的趋势且于铜浓度5 μmol·L-1达到最大值;可溶性糖含量呈现先升高再降低的单峰变化规律，且在铜浓度5 μmol·L-1时值最大;游离脯氨酸含量呈现显著上升的趋势。综上，铜浓度不高于5 μmol·L-1时，能提高丝瓜幼苗光合色素含量，保持较高的净光合速率，同时通过渗透调节物质的调节保护叶片细胞免受重金属铜毒害。

关键词：丝瓜;铜胁迫;光合色素;光合参数;渗透调节

中图分类号：S642.4          文献标识码：A          DOI 编码：10.3969/j.issn.1006-6500.2021.07.002

Abstract： To explore the tolerance range of Luffa cylindrical seedlings to copper，the effects of different concentrations of copper stress （Cu2+ 0，5，15，30，50 μmol·L-1） on photosynthetic pigment， photosynthetic parameters and osmotic adjustment substance content of Luffa cylindrica seedlings were studied by using 'Meixiu' varieties as test materials in the method of nutrient solution sand culture. The results showed that， the contents of chlorophyll a， chlorophyll and carotenoid were increase first and then decrease following with the increased copper concentration， which the maximum value were all appeared at the copper concentration of 5 μmol·L-1. With the increase of copper concentration， the net photosynthetic rate， stomatal conductance and intercellular CO2 concentration of Luffa cylindrica seedlings decreased gradually，in which the treatment of 5 μmol·L-1 copper concentration had no significant difference with the control but the other treatments were significant lower than the control; the transpiration rate was rising first and then decreasing， and the maximum value was appeared at the copper concentration of 5 μmol·L-1; following with the copper concentration， the soluble sugar content of Luffa cylindrica seedlings showed a single peak change and the maximum value was obtained at the copper concentration of  5 μmol·L-1， while the  free proline content was significantly increased. In summary， when the copper concentration was not higher than 5 μmol·L-1， the photosynthetic pigment content of Luffa cylindrica could be increased，the net photosynthetic rate were maintained at the level consistent with the control， and the leaf cells were protected from the heavy metal copper toxicity by the regulation of osmotic regulators.

Key words： Luffa cylindrica; copper stress; photosynthetic pigment; photosynthetic parameters; osmotic regulation

铜是高等植物生长发育必需微量元素之一，是超氧化物歧化酶、多巴胺-β-加氧酶、细胞色素氧化酶等多种酶的重要组分[1]，同时铜又参与作物产量、品质、形态建成等众多生理代谢过程，是植物生长发育过程中必不可少的营养元素。但环境中铜含量过高时会导致植物体遭受铜毒害，如根系生长不良、根系变短、根条数减少、株高下降、叶片失绿、分蘖减少、种子发芽率降低、PSⅡ反应中心的电子浓度下降[2]，细胞器功能受损[3]，产量降低、品质下降、品种退化[4]。……