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<p>This study investigates the effects of temperature on germination and seedling growth across different rhubarb varieties, focusing on their distinct response patterns of endogenous hormones and non-structural carbohydrates (NSCs) under varying temperature conditions. The species included were Gansu-<i>Rheum palmatum</i> L. (<i>R. palmatum</i>- G), Gansu-<i>Rheum tanguticum</i> Maxim. et Balf. (<i>R. tanguticum</i>- G), Qinghai-<i>Rheum palmatum</i> L. (<i>R. palmatum</i>- Q), and Shaanxi-<i>Rheum officinale</i> Baill (<i>R. officinale</i>- S). Eight constant temperatures between 0 and 35&#xa0;°C and ten fluctuating day/night temperatures ranging between 15&#xa0;°C/10&#xa0;°C and 30&#xa0;°C/25&#xa0;°C were set as the experimental conditions. The findings demonstrated that 20&#xa0;°C was identified as the optimal germination temperature for all four varieties of rhubarb when subjected to constant temperature settings. Compared to a constant temperature of 20&#xa0;°C, the germination rate of <i>R. palmatum</i>- Q showed a slight increase when subjected to 30&#xa0;°C/20&#xa0;°C, although the difference was not statistically significant. Seeds maintained at a constant temperature of 30&#xa0;°C exhibited germination without subsequent seedling development, whereas seeds subjected to a fluctuating temperature regime of 30&#xa0;°C/25&#xa0;°C were capable of developing into seedlings after germination. The anticipated rankings of various models concerning germination temperature thresholds did not align with the actual observed values, and the rankings projected by the different models exhibited discrepancies among themselves. The peak daytime temperature may serve as a significant determinant for the levels of soluble sugars, starch, and endogenous hormones in relation to temperature fluctuations occurring between day and night. Variations in temperature can exert contrasting influences on germination rates and the ratios of endogenous hormones. Both soluble sugars and starch were negatively correlated with certain endogenous hormones. The mean annual temperature at the seed collection location and the level of abscisic acid (ABA) in seedlings following exposure to high temperatures cannot be used as reliable indicators of heat resistance. The distribution of soluble sugars and starch showed regularity in response to temperature fluctuation. Consequently, rhubarb species modulate NSCs and endogenous hormones to effectively coordinate their responses to external thermal stresses.</p>

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Differences in Seed Germination, Endogenous Hormones, and Non-structural Carbohydrates in Seedlings of Rhubarb Species Under Temperature Fluctuations

  • 期刊论文

  • 发表日期：

    2025年2月10日

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  • Duoyi Wang,
  • Yuanyuan Li,
  • Jing Gao,
  • Gang Zhang,
  • Zhongxing Song,
  • Zhishu Tang,
  • Nan Wang

摘要

This study investigates the effects of temperature on germination and seedling growth across different rhubarb varieties, focusing on their distinct response patterns of endogenous hormones and non-structural carbohydrates (NSCs) under varying temperature conditions. The species included were Gansu-Rheum palmatum L. (R. palmatum- G), Gansu-Rheum tanguticum Maxim. et Balf. (R. tanguticum- G), Qinghai-Rheum palmatum L. (R. palmatum- Q), and Shaanxi-Rheum officinale Baill (R. officinale- S). Eight constant temperatures between 0 and 35 °C and ten fluctuating day/night temperatures ranging between 15 °C/10 °C and 30 °C/25 °C were set as the experimental conditions. The findings demonstrated that 20 °C was identified as the optimal germination temperature for all four varieties of rhubarb when subjected to constant temperature settings. Compared to a constant temperature of 20 °C, the germination rate of R. palmatum- Q showed a slight increase when subjected to 30 °C/20 °C, although the difference was not statistically significant. Seeds maintained at a constant temperature of 30 °C exhibited germination without subsequent seedling development, whereas seeds subjected to a fluctuating temperature regime of 30 °C/25 °C were capable of developing into seedlings after germination. The anticipated rankings of various models concerning germination temperature thresholds did not align with the actual observed values, and the rankings projected by the different models exhibited discrepancies among themselves. The peak daytime temperature may serve as a significant determinant for the levels of soluble sugars, starch, and endogenous hormones in relation to temperature fluctuations occurring between day and night. Variations in temperature can exert contrasting influences on germination rates and the ratios of endogenous hormones. Both soluble sugars and starch were negatively correlated with certain endogenous hormones. The mean annual temperature at the seed collection location and the level of abscisic acid (ABA) in seedlings following exposure to high temperatures cannot be used as reliable indicators of heat resistance. The distribution of soluble sugars and starch showed regularity in response to temperature fluctuation. Consequently, rhubarb species modulate NSCs and endogenous hormones to effectively coordinate their responses to external thermal stresses.