纳米氢氧化铜暴露对水培生菜生长变化的影响

研究以生菜(Lactuca sativa L.)为考察对象, 探讨纳米氢氧化铜nano-Cu(OH)₂]不同暴露浓度(0、1和50 mg/L)与时间(7d、14d、21d和28d)对水培生菜生长变化的影响。在生菜叶片涂抹nano-Cu(OH)₂过程中发现, 暴露初期(0—14d)Cu主要富集于生菜的老叶(靶器官)中, 且导致老叶失绿泛黄。同时, 老叶中的Cu会不同程度地向新叶(P<0.05)与根(P>0.05)中转移。在暴露后期(14—28d), nano-Cu(OH)₂胁迫对生菜产生不可逆的损伤致使生菜老叶干枯变黄脱落。虽然老叶的脱落阻断了Cu在生菜体内进一步的富集, 但前期累积在老叶中的Cu会继续向新叶与根中转移。在28d的nano-Cu(OH)₂暴露期间, 生菜主要通过调控体内超氧化物歧化酶(SOD)和过氧化物酶(POD)的含量来抵御Cu的胁迫伤害, 且nano-Cu(OH)₂暴露对生菜生长表现出低浓度促进和高浓度抑制的效应。研究表明, nano-Cu(OH)₂对生菜的主要致毒机理来源于它溶出的Cu离子。

NANO-CU (OH)2 EXPOSURE ON LETTUCE GROWTH IN HYDROPONIC CULTURE

Nano-Cu(OH)₂, one of the most used nano-pesticide formulations, can be applied to replace pesticide. However, the hazardous effects of nano-Cu(OH)₂ on biological plant are still unclear. This study investigated the effects of various concentrations of nano-Cu(OH)₂ on the growth of lettuce (Lactuca sativa L.) in hydroponic culture for 4 weeks. Cu dominantly accumulated in the old leaves (target organs) of lettuce during the first 2 weeks, which resulted in greenness loss and yellow-turning of old leaves. Meanwhile, the Cu partially transferred from old leaves to new leaves (P<0.05) and root (P>0.05). Nano-Cu(OH)₂ stress caused irreversible damage to old leaves of lettuce during the last 2 weeks, reflected by the drying and yellow-shedding old leaves. Again, the Cu continually transferred from old leaves to the new leaves or roots of lettuce. Lettuce mediated the content of SOD and POD to resist the hazardous damage caused by Cu stress. Low concentration of nano-Cu(OH)₂ promoted the growth of lettuce, and high concentrations of nano-Cu(OH)₂ and Cu2+ inhibited the growth and development of lettuce. The results indicated that the underling toxicity of nano-Cu(OH)₂ on lettuce growth was derived from the free Cu ions. The study provides a new perspective of potentially hazardous effects of nano-Cu(OH)₂ on lettuce, and scientific basis for the safe use of nano-Cu(OH)₂.