Light-emitting diodes (LEDs) have recently been widely used as light sources for the cultivation of plants in controlled environments. However, before LEDs can be used as the sole light source, it is imperative that soybean ( Glycine max ) response to light quality be well characterized. The objective of the present work was to investigate how soybean seedlings respond to different blue (B) and red (R) photon flux ratios (PFR) using LEDs. Light treatments were comprised of 170 ± 5 μmol m −2 s −1 photosynthetic photon flux density with B:R ratios of 0B:100R%, 10B:90R%, 25B:75R%, 50B:50R%, 80B:20R%, 90B:10R%, and 100B:0R%. Our results suggest that with the increase in B PFR from 0 to 90%, both plant height and specific leaf area inclined to decline while stem diameter gradually increased. The plants exposed to 80B:20R% showed unexpectedly greater total root length, root surface area, root volume, number of root tip, plant dry mass, leaf dry mass, root dry mass, leaf mass fraction and root mass fraction than plants exposed to all other treatments. Plants grown with 0B:100R% had the highest content of chlorophyll b (Chl b ) and content of total chlorophyll [Chl ( a + b )] but possessed the lowest ratio of the content of chlorophyll a to the content of chlorophyll b (Chl a / b ). Plants grown with R alone also showed the lowest chlorophyll fluorescent parameters. The light-saturated CO 2 assimilation rate ( A sat ) and the light-saturated stomatal conductance ( g ssat ) for 0B:100R% were, respectively, 64.85% and 203.23% lower than those for 80B:20R%. However, plants grown with sole R accumulated higher soluble sugar and starch content during the daytime. Collectively, our results suggest that compared to R- or B-LED alone, an appropriate combination of R and B promotes plant growth and photosynthetic performance for soybean.

中文翻译：

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不同LED光照质量条件下大豆幼苗的植物生长及光合特性

发光二极管 (LED) 最近被广泛用作在受控环境中种植植物的光源。然而，在 LED 用作唯一光源之前，必须充分表征大豆（Glycine max）对光质量的响应。本工作的目的是研究大豆幼苗如何使用 LED 对不同的蓝色 (B) 和红色 (R) 光子通量比 (PFR) 做出反应。光处理包括 170 ± 5 μmol m -2 s -1 光合光子通量密度，B:R 比为 0B:100R%、10B:90R%、25B:75R%、50B:50R%、80B:20R%、 90B:10R% 和 100B:0R%。我们的研究结果表明，随着 B PFR 从 0% 增加到 90%，株高和比叶面积均呈下降趋势，而茎粗则逐渐增大。暴露于 80B 的植物：与暴露于所有其他处理的植物相比，20R% 显示出意外更大的总根长度、根表面积、根体积、根尖数量、植物干质量、叶干质量、根干质量、叶质量分数和根质量分数。0B:100R%生长的植物叶绿素b(Chl b)含量和总叶绿素含量[Chl ( a + b )]最高，但叶绿素a含量与叶绿素b含量(Chl一/二）。单独用 R 生长的植物也显示出最低的叶绿素荧光参数。0B:100R%的光饱和CO 2 同化率( A sat )和光饱和气孔导度( g ssat )分别比80B:20R%的低64.85%和203.23%。然而，使用单一 R 生长的植物在白天积累了更高的可溶性糖和淀粉含量。