Hu Guifang, He Xinyue, Wang Ning, Liu Jun'e, Zhou Zhengchao
School of Geography and Tourism, Shaanxi Normal University, Xi'an 710119, China.
Plants (Basel). 2024 Feb 29;13(5):693. doi: 10.3390/plants13050693.
Global warming is increasing the frequency and intensity of heat waves and droughts. One important phase in the life cycle of plants is seed germination. To date, the association of the temperature and water potential thresholds of germination with seed traits has not been explored in much detail. Therefore, we set up different temperature gradients (5-35 °C), water potential gradients (-1.2-0 MPa), and temperature × water potential combinations for nine native plants in the Loess Plateau region to clarify the temperature and water combinations suitable for their germination. Meanwhile, we elucidated the temperature and water potential thresholds of the plants and their correlations with the mean seed mass and flatness index by using the thermal time and hydrotime models. According to our findings, the germination rate was positively correlated with the germination percentage and water potential, with the former rising and the latter decreasing as the temperature increased. Using the thermal time and hydrotime models, the seed germination thresholds could be predicted accurately, and the germination thresholds of the studied species varied with an increase in germination percentage. Moreover, temperature altered the impact of water potential on the germination rate. Overall, the base water potential for germination, but not the temperature threshold, was negatively correlated with mean seed mass and was lower for rounder seeds than for longer seeds. This study contributes to improving our understanding of the seed germination characteristics of typical plants and has important implications for the management and vegetation restoration of degraded grasslands.
全球变暖正在增加热浪和干旱的频率及强度。植物生命周期中的一个重要阶段是种子萌发。迄今为止，萌发的温度和水势阈值与种子性状之间的关联尚未得到详细探究。因此，我们为黄土高原地区的九种本土植物设置了不同的温度梯度（5 - 35°C）、水势梯度（-1.2 - 0 MPa）以及温度×水势组合，以阐明适合其萌发的温度和水分组合。同时，我们通过热时间模型和水分时间模型阐明了这些植物的温度和水势阈值以及它们与平均种子质量和平整度指数的相关性。根据我们的研究结果，发芽率与发芽百分比和水势呈正相关，随着温度升高，前者上升而后者下降。利用热时间模型和水分时间模型，可以准确预测种子萌发阈值，且所研究物种的萌发阈值随发芽百分比的增加而变化。此外，温度改变了水势对发芽率的影响。总体而言，萌发的基础水势而非温度阈值与平均种子质量呈负相关，且圆形种子的基础水势低于长形种子。本研究有助于增进我们对典型植物种子萌发特性的理解，对退化草地的管理和植被恢复具有重要意义。
