Seed dormancy and germination characteristics of two Rheum species in the Himalaya-Hengduan Mountains.
Seed dormancy and germination characteristics of two Rheum species in the Himalaya-Hengduan Mountains.
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喜马拉雅-横断山地区两种大黄种子休眠及萌发特性
DOI：
10.1016/j.pld.2017.05.009
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发表时间：
2017-08
期刊：
影响因子：
4.8
通讯作者：
Sun H
中科院分区：
文献类型：
--
作者：
Peng D;Chen Z;Hu X;Li Z;Song B;Sun H
种子休眠和萌发特性是决定植物繁殖成功的重要因素，并可能对植物分布产生重要影响。本研究旨在探讨喜马拉雅-横断山区两种大黄属特有植物（黄花大黄和亚历山大大黄）种子的休眠和萌发特性。为了确定休眠的类型，将两个物种（各一个种群）的新鲜种子在25/15和15/5 °C的光照下孵育，然后将干燥后熟（DAR）种子在含有或不含GA 3的水琼脂基质上孵育。为了确定温度和光对萌发的影响，将两个物种（各两个种群）的DAR种子在光照和黑暗中在几个温度下孵育，包括恒定和交替的温度。计算了基础温度（Tb）和50%发芽的热时间（θ50）。DAR释放生理休眠（PD），增加在15/5 °C下的最终萌发，并且将萌发温度的范围从较高拓宽到较低，指示两种大黄属物种的2型非深度PD。光照对两个种（各两个种群）的种子萌发没有显著影响。这两个物种的种子在中等温度（10-25 °C）下的发芽率明显高于（>80%）极端低温（5 °C）或高温（35 °C）。交替温度（25/15和15/5 °C）在光照和黑暗中均不显著增加两种植物的最终萌发，但在两种Rh中，它比相应的恒定温度在光照下更快地促进种子萌发。在15/5 °C时，alexandriumpopulations，尤其是。在次适温度下，萌发响应温度很好地描述了热-时间模型。在两个Rh中，估计的Tb值分别为1和0.9 °C。nobile居群;两个Rh.两种Rh的θ50（热时）分别为100和125 °Cd。两种Rh的Cd值分别为76.92和83.33 °。亚历山大种群。休眠类型和萌发对温度和光照条件的反应不能解释为什么这两种大黄分布在不同的生境。然而，这些研究结果反映了这两个大黄属物种的有利发芽策略，以适应相同的高山环境。
Seed dormancy and germination characteristics are important factors determining plant reproductive success, and may be expected to have a major influence on plant distribution. In this study, we aimed to explore the characteristics of seed dormancy and germination in two endemic Rheum species (Rheum nobile and Rheum alexandrae) in the Himalaya-Hengduan Mountains. To determine the type of dormancy, fresh seeds of the two species (one population each) were incubated in light at 25/15 and 15/5 °C, and then dry after-ripening (DAR) seeds were incubated on water agar substrate with or without GA3. To determine the effect of temperature and light on germination, DAR seeds of the two species (two populations each) were incubated both in the light and in the dark at several temperatures, including constant and alternating temperatures. Base temperature (Tb) and thermal times for 50% germination (θ50) were calculated. DAR released physiological dormancy (PD), increasing final germination at 15/5 °C and widening the range of germination temperatures from higher to lower, indicative of type 2 non-deep PD for the two Rheum species. Light had no significant effect on germination of seeds from the two species (two populations each). Seeds of the two species germinated significantly better (>80%) at medium temperatures (10–25 °C) than at extreme low (5 °C) or high (35 °C) temperatures. Alternating temperatures (25/15 and 15/5 °C) did not significantly increase the final germination of the two species either in the light and in the dark, but it promoted seed germination more quickly than corresponding constant temperatures in the light in both Rh. alexandrae populations, especially at 15/5 °C. Germination in response to temperature was well described by the thermal-time model at suboptimal temperatures. The estimated Tb values were 1 and 0.9 °C, respectively, in two Rh. nobile populations; 4 and 4.1 °C, respectively, in two Rh. alexandrae populations; θ50 (thermal time) were 100 and 125 °Cd, respectively in two Rh. nobile populations; 76.92 and 83.33 °Cd, respectively in two Rh. alexandrae populations. The dormancy type, and germination responses to temperature and light condition does not explain why the two Rheum species are distributed in contrasting habitats. However, these findings reflect an advantageous germination strategy of these two Rheum species to adapt to the same alpine environments.
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