目的:探讨头花蓼四倍体和二倍体光合生理特性的差异。方法:采用LI-6400XT便携式光合仪测定人工诱变培育的四倍体头花蓼品种和二倍体头花蓼品种的各项光合生理参数,探究两者的光合特性变化规律。结果:四倍体和二倍体头花蓼的叶片净光合速率(Pn)日变化都呈双峰型曲线,并有“午休”现象,但四倍体全天Pn高于二倍体。2个头花蓼品种的气孔导度(Gs),蒸腾速率(Tr),日变化趋势与Pn日变化趋势基本一致,而胞间CO2浓度(Ci)日变化趋势与Pn日变化趋势完全相反;四倍体Gs,Tr,水分利用率(WUE)整体水平高于二倍体,而四倍体Ci低于二倍体。头花蓼光补偿点(LCP)为二倍体[67.83μmol·(m2·s)-1]>四倍体[41.43μmol·(m2·s)-1],光饱和点(LSP)为二倍体[1 225μmol·(m2·s)-1]<四倍体头[1 370μmol·(m2·s)-1],最大净光合速率(Pnmax)为二倍体[5.36μmol·(m2·s)-1]<四倍体[8.83μmol·(m2·s)-1],表观量子效率(AQY)为二倍体[0.01μmolphotons·(m2·s)-1]<四倍体[0.02μmolphotons·(m2·s)-1]。结论:四倍体头花蓼的光合性能较二倍体增强。 Objective: To investigate the differences of photosynthetic characteristics between tetraploid and diploid of Polygonum capitatum. Methods: The photosynthetic physiological parameters of tetraploid tetraploid and diploid Polygonum capitatum cultivated by artificial mutagenesis were measured by LI-6400XT portable photosynthetic apparatus, and the changes of their photosynthetic characteristics were investigated. Results: The diurnal changes of net photosynthetic rate (Pn) of tetraploid and diploid Polygonum capitatum showed a bimodal curve with “noon break” phenomenon, but the tetraploid Pn was higher than that of diploid . The changes of diurnal variation of stomatal conductance (Gs), transpiration rate (Tr) and daily diurnal variation of Pn of two Polygonum capitatum cultivars were basically the same as that of Pn, while the diurnal variation trend of daily intracellular CO2 concentration (Ci) Ploidy Gs, Tr, water use efficiency (WUE) overall level higher than diploid, and tetraploid Ci lower than diploid. LCP was diploid [67.83μmol · (m2 · s) -1]> tetraploid [41.43μmol · (m2 · s) -1] and light saturation point (LSP) was two The maximum net photosynthetic rate (Pnmax) was diploid [5.36μmol · (m2 · s) -1] The apparent quantum yield (AQY) was diploid [0.01 μmolphotons · (m2 · s) -1]