【摘要】 以高淀粉玉米品种郑单21为材料,借助叶绿素荧光快速诱导动力学曲线和820nm光吸收曲线,研究了灌浆期土壤干旱胁迫对玉米籽粒产量和叶片光系统I(PSI)及光系统II(PSII)活性的影响。两年的研究结果均表明,干旱胁迫显著降低叶片光合速率(P<0.05)和籽粒产量(P<0.05)。JIP-test分析发现干旱胁迫导致叶绿素荧光快速诱导动力学曲线中的K点和J点上升,表明PSII放氧复合体(OEC)和QA之后的电子传递链受到抑制,且PSII受体侧受抑制的程度大于供体侧。此外,干旱胁迫也显著地抑制PSI的最大氧化还原活性(ΔI/Io),阻碍光合电子从PSII向PSI的传递,破坏了PSI和PSII的协调性。我们认为干旱胁迫抑制PSI和PSII活性并破坏二者的协调性,是导致Pn和籽粒产量下降的重要原因之一。更多还原

【Abstract】 At grain filling stage, the effects of drought stress on photosynthetic acivities of photosystem I (PS I) and photosystem II (PS II) in leaves of maize (Zhengdan 21, a cultivar with high starch content) were studied by simultaneously analyzing chlorophyll a fluorescence transient and light absorbance at 820 nm. The results, obtained from two years experiments, demonstrated that the drought stress significantly reduced photosynthesis (P<0.05) and grain yield (P<0.05) of the maize. The K and J steps at fluorescence transient were increased by drought stress, which indicated the inhibition of oxygen-evolving complex (OEC) and electron transport chain after QA in PS II. The acceptor side of PS II was damaged more severely than the donor side of PS II. Furthermore, the maximal oxidation-reduction activity of PS I (ΔI/Io) was also significantly decreased by the drought stress, which inhibited the photosynthetic electron tranport from the PS II to PS I, destructing the coordination between PS I and PS II. We suggest that the inhibition of PS I and PS II and the destruction of the coordination between PS I and PS II by the drought stress is one of the main reasons to cause the decrease in photosyntheis and grain yield of maize.更多还原