BACKROUND Although changes in photosynthetic traits (PTs) during the long-term genetic improvement of soybean [Glycine max (L.) Merr.] yield have been studied, detailed information on whether PTs responses to environmental stress have improved and their correlations with seed yield are still unknown. Our objectives were to describe the changes in soybean PTs (leaf area index (LAI), leaf chlorophyll content (Chl), net photosynthetic rate (PN ), stomatal conductance (gs ) and transpiration rate (E) during decades of genetic improvement and to detect whether the responses of the PTs of 13 different soybean cultivars released in various decades to increasing fertilizer application rates (FRs) differed. RESULTS All the PTs of soybean increased significantly as the year of cultivars released increased under different FR treatments, indicating that PTs have improved during decades of genetic breeding. Medium FR (nitrogen) treatment (150 kg ha -1 ) increased PTs values, to different extents, at all the investigated growth stages. LAI, Chl and PN of old and middle cultivar group at the full bloom (R2), full seed (R6) and beginning maturity (R7) stages decreased significantly under the high FR treatment (300 kg ha-1 ) compared with the medium FR treatment. The former had no or promotive effects on any of the PTs of new cultivar group. Thus, the photosynthetic capacities of the new cultivars are more tolerant to high FR-related stress than older cultivars CONCLUSIONS: The photosynthetic capacities and the tolerance levels to high FR-related stress of soybean released in different years improved after long-term genetic breeding. This article is protected by copyright. All rights reserved.

中文翻译：

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几十年遗传改良过程中大豆 [Glycine max (L.) Merr.] 光合性状的变化及其对受精率增加的反应


背景虽然已经研究了大豆 [Glycine max (L.) Merr.] 产量长期遗传改良过程中光合性状 (PT) 的变化，但关于 PT 对环境胁迫的反应是否有所改善及其与种子产量的相关性的详细信息仍然未知。我们的目标是描述几十年遗传改良过程中大豆 PT（叶面积指数 (LAI)、叶片叶绿素含量 (Chl)、净光合速率 (PN )、气孔导度 (gs ) 和蒸腾速率 (E)）的变化，并检测不同年代释放的 13 个不同大豆品种的 PT 对增加施肥量 (FR) 的响应是否存在差异。 结果 在不同 FR 处理下，随着释放品种年份的增加，所有大豆的 PT 均显着增加，表明 PT 发生了变化。经过几十年的遗传育种，中等FR（氮）处理（150 kg ha -1 ）不同程度地提高了老、中品种组在盛花期的所有生长阶段的PTs值。与中FR处理相比，高FR处理（300 kg ha-1）下的（R2）、饱满种子（R6）和开始成熟（R7）阶段显着减少，前者对任何PT没有或有促进作用。新品种群。因此，新品种的光合能力比老品种更能耐受高FR相关胁迫。结论：经过长期遗传育种，不同年份大豆的光合能力和对高FR相关胁迫的耐受水平有所提高。本文受版权保护。版权所有。