To study the effects of enhanced UV-B radiation on biomass, chlorophyll content and photosynthetic indices of soybean ( Glycine max Merr. ) , simulated treatments with enhanced UV-B radiation under field condition were applied and related indices were measured in this research. The results showed that, enhanced UV-B radiation inhibited the growth and development during flowering period(21. 8% for plant height and 77. 0% for dry weight) and seed-filling period(18. 9% for plant height and 20. 8% for dry weight). The UV-B radiation made the flavonoids content and malondialdehyde ( MDA) content increase during branching period(61. 7% and 35. 2% respectively) and flowering period (28. 9% and 37. 4% respectively). The net photosynthetic rate was inhibited by 23. 2%,35. 9% and 20. 8% during the three periods, respectively. The stomatal conductance was also inhibited and the intercellular CO2 concentration was increased. The enhanced UV-B radiation mainly inhibited the content of chlorophyll during branching period(19. 4%),but no significant effect on ΦPSⅡ was found. In conclusion,enhanced UV-B radiation showed significant inhibition effects on net photosynthetic rate, stomatal conductance and CO2 assimilation rate, and the growth and biomass accumulations in soybean were finally decreased.%为明确UV-B辐射增强对大豆生物量、叶绿素含量以及光合特性的影响,在田间条件下模拟UV-B辐射增强,对大豆相关指标进行了测定与分析. 结果表明:UV-B辐射增强对大豆生长具有抑制作用,花期株高、干质量分别降低21 . 8%、77 . 0%,鼓粒期分别降低18 . 9%、20 . 8%;总体使大豆叶片的类黄酮、MDA含量增加,其中分枝期分别增加61 . 7%、35 . 2%,花期分别增加28 . 9%、37 . 4%,鼓粒期二者增加均不显著;使大豆分枝期、花期和鼓粒期的净光合速率分别降低23 . 2%、35. 9%和20. 8%,气孔导度降低,胞间CO2 浓度升高;对叶绿素含量有一定的影响,主要使分枝期叶绿素含量降低19. 4%,但对ΦPSⅡ影响不显著. 综合分析,UV-B辐射增强对大豆的影响主要体现在抑制叶片净光合速率,降低气孔导度,使得CO2 利用率下降,最终抑制了大豆生物量.
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