【摘要】 [目的]通过对干旱胁迫下藜开花期基本光合特性的研究,初步探讨其耐旱机理。[方法]9月上旬选择典型晴天,对开花期的藜功能叶进行有关光合参数的测定。[结果]开花期藜的光合日变化呈单峰型,峰值出现在中午12:00左右,光合"午休"现象消失,与其营养生长期藜具有明显的午休现象不同。蒸腾速率呈双峰型,在上午8:00左右蒸腾速率达到最大,然后开始渐渐下降,到下午14:00左右达到谷底。在自然条件下藜的光饱和点(LSP)为1 300μmol CO2/(m2.s)左右,光补偿点(LCP)为37μmol CO2/(m2.s)左右,表观量子效率(AQY)为0.348 9。[结论]开花期藜的光合速率的限制因素主要是非气孔限制,光强也不再是控制气孔开闭的主要因素,温度和空气湿度成为控制气孔开闭的主要因素。更多还原

【Abstract】 [Objective]The purpose was to discuss drought resistance mechanism of Chenopodium album L.by studying the photosynthetic characteristic of it under drought-strss at flowering stage.[Method]The photosynthetic parameters of the functional leaves of Chenopodium album L.were measured on the days with clear sky at flowering stage.[Results]The photosynthesis curve of C.album presented in a single peak and no a remarkable noon inhibition at flowering stage.Its peak occurred at about 12:00 and there was remarkable different from the vegetative stage had a noon inhibition.The transpiration of C.album presented varied in a double peak manner thus suffering a remarkable noon inhibition.It′s first peak occurred at about 8:00,then the transpiration rate descend and reached the bottommost point at 14:00,its second peak appeared at about 17∶00.With natural condition the light saturation and compensation points of C.album were about 1 300 μmol CO2/(m2·s) and 37 CO2 μmol/(m2·s)respectively;the apparent quantum yield was about 0.348 9.[Conclusion]The major reason for the noon inhibition of Pn was not the stomatal regulation.Light intensity was not the major factor and temperature,atmosphere humidity become the major factors.更多还原