In this study, Zinnia elegant plug seedlings with 3-4 leaves were used to analyze assimilation product distribution, photosynthesis, water use efficiency and chlorophyll fluorescence parameters under high temperature stress. The results showed that under high temperature stress, plant height of Zinni-a elegant with different concentrations(10, 20, 30, 40 mg/L) of S3307 were reduced and stem diameters were increased, however, dry weight of shoot and root, root-shoal ratio in dry weight were higher than those of the control, and photosynthetic rate and water use efficiency of those treatments were increased as well. The treatment of S3307 significantly slowed down the inhibition of high temperature stress on photo-synthetic system Ⅱ of seedlings, alleviated the decrease of maximum photochemical efficiency ( Fv/Fm) , actual photochemical efficiency under light ( φPS Ⅱ ), photochemical quench (qP) and the increase of no photochemical quench(NPQ) and prevented the damage of high temperature on photosynthetic apparatus. Among them, the treatment effect of 30 mg/L S33O07 is the best.%以百日草3～4叶期的穴盘苗为试验材料,分析了高温胁迫下不同浓度(10,20,30,40 mg/L)烯效唑(S3307)对百日草幼苗的同化产物分配、光合作用、水分利用率、叶绿素荧光参数等指标的影响.结果表明:高温胁迫下S3307处理的百日草幼苗的株高降低,茎粗增加,地上部冠干重、地下部根干重及其根冠比均大于对照,并且S3307处理还提高了百日草幼苗的净光合速率、叶片水分利用率,显著减缓了高温胁迫对百日草幼苗光合系统Ⅱ(PSⅡ)的抑制作用,使百日草幼苗PSⅡ最大光化学效率(Fv/Fm)、实际光化学效率(ΦPSⅡ)、光化学猝灭系数(qP)下降缓慢,非光化学猝灭系数(NPQ)升高幅度增大,从而使光合机构免受高温胁迫的伤害.以30 mg/L的S3307处理效果最佳.
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