关键词: 遮荫, 光合, 叶绿素荧光, 干物质积累

Abstract: Four winter wheat (Triticum aestivum L) varieties YangMai 158, YangMai 11, Nainong 9918 and Nainong 02Y393 were used to study the effect of shading between tillering and maturity on photosynthesis and chlorophyll fluorescence in flag leaves. Shading showed little impact on flag leaf SPAD value of shading-resistant variety Yangmai 158 and Nannong 02Y393 while decreased SPAD value of shading-sensitive variety Yangmai 11 and Nannong 9918 during the early grain filling stage. However, shading significantly increased leaf SPAD value at late grain filling stage for all varieties. Shading decreased flag leaf net photosynthetic rate (Pn), photosynthetic system II (PSII) actual photochemical efficiency (ΦPSII), photochemical quenching of chlorophyll fluorescence (qP) and dry matter accumulation, while increased leaf origianl fluorescence (Fo) and maximum photochemical efficiency (Fv/Fm). The low Pn of flag leaves was related to decrease in ΦPSII and qP, and thereafter, the dry matter accumulation in plant was decreased under shading between tillering and maturity in wheat.

Key words: shading, photosynthesis, chlorophyll fluorescence, dry matter accumulation