铅胁迫对玉米幼苗叶片光系统功能及光合作用的影响

通过同时测定玉米叶片的叶绿素荧光快速诱导动力学曲线和对820 nm光的吸收、分析叶片的气体交换过程以及叶绿体活性氧清除关键酶的活性,研究了不同浓度的铅(Pb)胁迫对玉米光系统Ⅰ(PSⅠ)、光系统Ⅱ(PSⅡ)的光化学活性和光合作用的影响,并分析了Pb胁迫下两个光系统的相互关系.结果表明:铅胁迫显著抑制了玉米地上部分和地下部分的生长、降低了叶片光合色素含量、并通过非气孔因素限制了光合作用、导致过剩激发能的增加;铅胁迫显著抑制了超氧化物歧化酶(SOD)和抗坏血酸过氧化物酶(APX)的活性、伤害了PSII反应中心、PSII的受体侧和供体侧(放氧复合体)以及PSI光化学活性.

The effects of Pb-stress on functions of photosystems and photosynthetic rate in maize seedling leaves

By simultaneously analyzing chlorophyll a fluorescence transient and light absorbance at 820 nm, gas exchange and activities of key scavenging enzymes of reactive oxygen species (ROS) in chloroplasts, we investigated the effects of Pb treatments with different concentration on photochemical activities of photosystem I (PSI) and photosystem II (PSII) and on photosynthesis in maize seedling leaves, and analyzed the interaction of PSI and PSII. The results showed that Pb treatments restrained growth significantly, decreased pigment content. The Pb treatments decreased net photosynthetic rate via non-stomatal limitations in the maize leaves, which increased the excess excitation energy. The Pb treatment also inhibited the activities of SOD and APX and damaged the reaction centers, donor and acceptor sides of PSII and the photochemical activity of PSI in maize leaves.