,*中国科学院大学资源与环境学院, 北京 101408Effects of soil-burial depths on the relationship between seed mass and seed emergence
Zu-Xing WANG, Wei-Ming HE,*College of Resources and Environment, University of Chinese Academy of Sciences, Beijing 101408, China通讯作者: 通信作者Corresponding author (weiminghe@ibcas.ac.cn)
编委: 李敏
收稿日期:2019-06-24接受日期:2019-09-5网络出版日期:2019-10-20
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Corresponding authors:
Received:2019-06-24Accepted:2019-09-5Online:2019-10-20
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摘要
种子出苗对种间关系和群落组成具有重要影响。种内研究表明种子质量与种子出苗之间存在正相关关系, 但这种关系很少在物种水平进行检验, 尤其是在不同土壤埋藏深度条件下。为此, 该文开展了一个因子实验(10种植物和5种土埋深度(0、1、2、4和8 cm))以检验是否在不同土层中“种子质量-种子出苗之间的正相关关系”始终存在。该文在不同土埋深度播种50粒种子(重复5次), 连续30天观测种子出苗, 并提出了一个耐土埋性指标。结果表明: (1) 10种植物的最适出苗深度为0-2 cm土层; 6种植物的最大出苗率发生在1 cm土埋深度。(2)种子质量与耐土埋性之间存在显著的正相关关系, 种子质量越大耐土埋性越强, 适宜出苗的土层越深。(3)当土层较深(4或8 cm)时, 种子出苗率和持续出苗时间随种子质量增加而增大, 种子出苗率与持续出苗时间之间存在正相关关系; 这些关系在较浅土层(0、1或2 cm)并不存在。这些结果有助于进一步理解种子大小与出苗之间的关系, 以及种子出苗过程中的策略。
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Abstract
Aims Seed emergence is a key stage of plant life history and thus of important impacts on interspecific relationships and community composition. Increasing evidence has shown that seed mass determines (or strongly affects) seed emergence within a species, but it has seldom been tested across species at different depths of soil burial. Accordingly, the purpose of this study was to examine the influence of soil burial depths on the relationship between seed mass and seed emergence. Methods We performed a full-factorial experiment. Two factors included plant species (i.e. Achillea millefolium, Achnatherum sibiricum, Chenopodium glaucum, Centaurea maculosa, Medicago falcata, Poa pratensis, P. secunda, Solidago canadensis, Stipa bungeana and Vulpia octoflora) and soil burial depth (i.e. 0, 1, 2, 4 and 8 cm). Each combination was replicated five times, totaling 250 pots (10 species × 5 burial depths × 5 replicates). For each species, seed mass was determined prior to sowing at a given soil burial depth. We watered the pots and recorded seed emergence every day for 30 days. We determined the first date of seed emergence, and calculated the overall seed emergence, the tolerance to soil burial, and T50 (i.e. the number of days in the presence of 50% emergence). Seed mass and seed emergence were analyzed using an analysis of variance, and the relationships between two variables were tested using correlation analyses. Important findings We found that: (1) The optimum soil burial depth for seed emergence varied among the species, and for most of tested species this optimum depth ranged from 0 to 2 cm (i.e. shallow soil); six species had the maximum seed emergence at 1 cm soil burial depth, and no species had the maximum seed emergence at 4 or 8 cm. (2) There was a positive correlation between seed mass and the tolerance to soil burial across the 10 tested species, specifically, the tolerance to soil burial and the optimum depths increased with seed mass. (3) At deeper soil burial depths (i.e. 4 or 8 cm), there were significantly positive correlations among seed mass, seed emergence, and T50; in contrast, such correlations did not occur at shallower burial depths (i.e. 0, 1 or 2 cm).
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引用本文
王祖幸, 何维明. 土埋深度影响物种水平的种子质量-种子出苗关系. 植物生态学报, 2019, 43(10): 899-908. DOI: 10.17521/cjpe.2019.0154
WANG Zu-Xing, HE Wei-Ming.
种子出苗是植物生活史中极为重要的一个阶段(Harper & Benton, 1966; Harper, 2010; Ahmed et al., 2015)。这个阶段对植物种群数量增长、种间竞争、群落组成、食物链等具有重要的调控作用(Stanton, 1984; Bani-Aameur & Sipple-Michmerhuizen, 2001; Ye et al., 2016)。种子出苗代表着由对环境条件耐受性最强阶段(种子休眠)向最脆弱、最敏感阶段的高风险转变(Harper & Benton, 1966; Harper, 2010), 极易受到众多外界环境因素, 如温度、光照、土壤含水量、氧气含量和土壤埋藏深度等(Wu et al., 2015; Amini et al., 2016; Gao et al., 2018; Ye et al., 2019b)的影响。因此, 研究种子出苗过程及其驱动因素具有重要的生态学意义。
种子出苗受遗传和环境的共同影响(Baskin & Baskin, 1998; Li et al., 2006)。种子大小是植物相对稳定的一个内在特征, 它与种子传播、萌发、出土和幼苗竞争等过程密切相关(武高林和杜国祯, 2008)。比如, 较大种子总体上比较小种子具有更高的出苗率(Winn, 1988), 幼苗具有更大的竞争力和更高的存活力(Simons & Johnston, 2000; Li et al., 2006)。当然也有相反的报道(Dolan, 1984)。种子质量是衡量种子大小的重要指标, 种子质量与耐土壤埋藏能力之间存在正相关关系(Chen & Maun, 1999; Chen et al., 2002)。较大质量种子往往储存更多的物质和能量, 因而可能从更深的土壤中顺利出苗(聂春雷和郑元润, 2005; Li et al., 2006; Guo et al., 2009; Müller et al., 2018)。也有研究发现种子大小与出苗率之间没有直接的相关性(何玉惠等, 2008)。
种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(Baskin & Baskin, 1998)。换言之, 土壤埋藏深度是决定种子命运的关键性因素。一方面, 适当深度的土壤埋藏有助于为种子创造适宜的温度、水分等出苗条件(Baskin & Baskin, 1998; Li et al., 2006; Guo et al., 2009)。另一方面, 埋藏过深会对种子出苗产生阻碍或抑制(Baskin & Baskin, 1998; 李柱等, 2004; Li et al., 2006; Guo et al., 2009)。种子出苗率随埋藏深度的增加而逐渐减小(Amini et al., 2017), 这与种子出苗前储存物质逐渐耗尽有关(Javaid & Tanveer, 2014; Amini et al., 2016)。最适宜种子出苗的埋藏深度往往位于较浅土层, 并随土埋深度的增加而降低(Amini et al., 2017; Wang et al., 2018)。
前人对于种子质量与出苗关系的研究多从同一物种角度出发, 种子质量大小的变异来源于种群内个体间的差异(Guillemin & Chauvel, 2011; Amini et al., 2016), 较少研究将物种间种子质量的差异作为研究对象(Müller et al., 2018)。换言之, 以前的研究主要集中在同种植物不同大小种子与其萌发/出苗关系的研究, 很少在物种水平检验种子质量-种子出苗的关系。天然植物群落由多种不同植物组成(Crawley, 1997)。事实上, 种间种子质量差异大于种内种子质量差异(Baskin & Baskin, 1998)。研究物种间种子质量差异对出苗过程的影响, 有助于在物种水平上理解源自种内种子性状间关系的一般性格局。更重要的是, 较少研究将种子质量与出苗之间的关系在不同土层深度的框架下考虑。综上所述, 我们的研究目标是在物种水平检验“种子质量-种子出苗关系”随土壤埋藏深度变化的一般性格局。为此, 本项研究选择草原中的10种优势或常见植物为对象, 将它们的种子(存在质量梯度)分别置于0、1、2、4和8 cm的土壤埋藏深度, 连续30天观察种子出苗, 以期回答如下两个科学问题: (1)土壤埋藏深度是否改变物种水平“种子质量-种子出苗关系”?(2)种子出苗率与出苗速率之间是否存在权衡关系?
1 材料和方法
1.1 实验物种
本实验选择草原中的10种优势或常见植物作为研究对象(表1)。选择典型的植物群落, 在秋天收集群落中优势/常见物种(表1)的种子。每个物种的种子均来自不少于30株大小相近的个体。将收集的种子风干并小心分拣以去除小枝、叶或花序; 然后将所有种子存放在冰箱中低温保存6个月。预备实验表明: 低温保存6个月后种子具有很高的萌发率。实验于翌年3月正式进行。实验开始之前, 从每个物种中挑选50粒饱满种子称质量, 重复5次, 取平均值作为每个物种的单粒种子质量。饱满种子的活力很高, 10种植物中任何一种植物的种子活力都高于80%。此外, 还开展了一个预备实验。当种子被放置在培养皿中的湿润滤纸上培养时, 所有植物的种子萌发率都高于60%。有几种植物种子在土壤中的萌发率明显低于在培养皿中的萌发率。
Table 1
表1
表1本实验选择的10种不同植物
Table 1
| 物种 Species | 科 Family | 生长型 Growth form | 生活型 Life form |
|---|---|---|---|
| 羽茅 Achnatherum sibiricum | 禾本科 Gramineae | 禾草 Grass | 多年生 Perennial |
| 长芒草 Stipa bungeana | 禾本科 Gramineae | 禾草 Grass | 多年生 Perennial |
| Vulpia octoflora | 禾本科 Gramineae | 禾草 Grass | 一年生 Annual |
| 草地早熟禾 Poa pratensis | 禾本科 Gramineae | 禾草 Grass | 一年生 Annual |
| Poa secunda | 禾本科 Gramineae | 禾草 Grass | 多年生 Perennial |
| 野苜蓿 Medicago falcata | 豆科 Leguminosae | 非禾草 Forb | 多年生 Perennial |
| 灰绿藜 Chenopodium glaucum | 藜科 Chenopodiaceae | 非禾草 Forb | 一年生 Annual |
| 千叶蓍 Achillea millefolium | 菊科 Compositae | 非禾草 Forb | 多年生 Perennial |
| 加拿大一枝黄花 Solidago canadensis | 菊科 Compositae | 非禾草 Forb | 多年生 Perennial |
| Centaurea maculosa | 菊科 Compositae | 非禾草 Forb | 二年生 Biennial |
新窗口打开|下载CSV
1.2 实验设计
本实验为两因素完全因子设计。两个因素包括: 物种(10个水平)和土埋深度(5个水平)。物种代表遗传因素而土埋深度代表环境因素。每种处理重复5次。因此, 本实验共需250个实验盆。实验盆为圆柱形, 底部直径12 cm, 顶部直径18 cm, 高17 cm。实验于中国科学院植物研究所温室内进行, 温室内的温度和相对湿度为20-25 ℃和50%-60%, 白天光合有效辐射保持在1 200 μmol·m-2·s-1以上。将事先准备的250个实验盆分成5组, 每组50个。第1组盆内装入16 cm深的土壤, 第2组盆内装入15 cm深的土壤, 第3组盆内装入14 cm深的土壤, 第4组盆内装入12 cm深的土壤, 第5组盆内装入8 cm深的土壤。所用土壤来自研究所附近荒坡的表层自然土壤, 过筛去杂质后, 100 ℃条件下烘48 h杀死土壤中可能存在的种子。在每个盆的土壤表面均匀撒播50粒种子, 然后在第2组、第3组、第4组和第5组盆内分别覆盖1、2、4和8 cm厚的土壤。即, 5组盆中的种子分别被0、1、2、4和8 cm厚的土壤覆盖, 以模拟自然条件下不同土埋深度的种子。
本实验从3月14日开始, 到4月13日结束。实验中定期浇适量的水以维持足够的土壤水分含量, 以幼苗露出土壤表面作为出苗的标志, 每天检查种子的出苗情况, 记录后将幼苗及时拔除。首次出苗时间指每盆中第1株幼苗出土时距离实验开始的天数; 出苗率为花盆中露出土层表面的幼苗株数占该花盆使用种子粒数的百分比, 每种植物的种子出苗率由每个土埋深度下5个重复的平均值来表示。T50为花盆中占出苗总数50%的幼苗出土所对应的播种后天数, T50越小说明种子出苗速度越快, 反之越慢。另外, 为了量化土壤埋藏深度对种子出苗率的影响, 我们提出了一个新的反映种子忍耐土壤埋藏深度的指标——耐土埋性(tolerance to soil burial, TSB), 具体计算方法如下:
$TSB =\sum C_{i} \times R_{i}$
式中, Ci是耐受系数, 在土壤深度1、2、4和8 cm时分别等于1、2、4、8。Ri是在i cm土壤深度种子的出苗数占所有土壤深度总出苗数的比值。这一指数同时考虑了遗传(物种)和环境(土埋)两方面因素; TSB值越大, 表示种子耐土壤掩埋性越强。
1.3 统计分析
用一元方差分析检验种子质量在物种间的变化, 并采用Turkey检验法进行多重比较。用二元方差分析揭示物种和土埋深度对首次出苗时间和出苗率的影响。用相关分析量化种子质量与耐土埋性、种子质量与出苗率、种子质量与T50、出苗率与T50的关系。所有统计分析在SPSS 19.0中完成。2 结果
2.1 种子质量
10种植物的单粒种子质量逐个增大, 长芒草(Stipa bungeana)种子质量分别为加拿大一枝黄花(Solidago canadensis)、千叶蓍(Achillea millefolium)、草地早熟禾(Poa pratensis)、Vulpia octoflora、Poa secunda、灰绿藜(Chenopodium glaucum)、Centaurea maculosa、野苜蓿(Medicago falcata)和羽茅(Achnatherum sibiricum)种子质量的102、46、20、16、15、12、3、3和2倍(图1)。物种间种子质量存在显著差异(F = 1017, p < 0.001)。具体而言, Vulpia octoflora与草地早熟禾、Poa secunda的种子质量间无显著差异(p > 0.05); Centaurea maculosa与野苜蓿之间种子质量无显著差异(p > 0.05); 其他任何两种植物的种子质量均存在显著差异(p < 0.05)(图1)。因此, 10种植物的种子质量形成一个梯度。图1
新窗口打开|下载原图ZIP|生成PPT图110种植物的单粒种子质量(平均值±标准误差)。不同小写字母表示种子质量在种间差异显著(p < 0.05)。Am, 千叶蓍; As,羽茅; Cg, 灰绿藜; Cm, Centaurea maculosa; Mf, 野苜蓿; Pp, 草地早熟禾; Ps, Poa secunda; Sb, 长芒草; Sc, 加拿大一枝黄花; Vo, Vulpia octoflora。
Fig. 1The mass per seed of the ten species used in the experiment (mean ± SE). Different lowercase letters indicate significant differences in mass per seed among species (p < 0.05). Am, Achillea millefolium; As, Achnatherum sibiricum; Cg, Chenopodium glaucum; Cm, Centaurea maculosa; Mf, Medicago falcata; Pp, Poa pratensis; Ps, Poa secunda; Sb, Stipa bungeana; Sc, Solidago canadensis; Vo, Vulpia octoflora.
2.2 种子出苗
2.2.1 首次出苗时间种子质量(F = 40.49, p < 0.001)、土埋深度(F = 48.26, p < 0.001)以及两者交互作用(F = 4.95, p < 0.001)显著影响种子首次出苗时间。总体上, 种子首次出苗时间随着土壤深度增加而延长(图2), 例如, 长芒草种子首次出苗时间随土壤深度的增加依次为: 6、7、8、9和10天; 草地早熟禾种子首次出苗时间随土壤深度的增加分别为7、9、10和21天(8 cm土埋时出苗率为0, 所以没有首次出苗时间)。种子质量的增大可使较深土埋种子的首次出苗时间提前。
2.2.2 最大出苗率
种子质量(F = 43.91, p < 0.001)、土埋深度(F = 190.32, p < 0.001)以及两者交互作用(F = 17.15, p < 0.001)显著影响种子出苗率。不同植物的种子出苗率存在较大差异, 羽茅、灰绿藜和加拿大一枝黄花种子最大出苗率相对较低, 分别为22%、8%和19%; 而千叶蓍、草地早熟禾、Poa secunda和Vulpia octoflora具有较高的最大出苗率, 分别为82%、77%、75%和89%; 长芒草、野苜蓿和Centaurea maculosa则介于两者之间, 分别为47%、51%和61% (图2)。
10种植物的种子出苗主要集中于0、1和2 cm的土埋深度; 种子最大出苗率出现在1 cm土埋深度的物种有6种(羽茅、灰绿藜、Centaurea maculosa、草地早熟禾、Poa secunda和长芒草); 在0 cm土埋深度有3种(千叶蓍、加拿大一枝黄花和Vulpia octoflora); 在2 cm土埋深度有1种(野苜蓿); 没有任何物种的最大出苗率出现在4和8 cm的土埋深度 (图2)。
2.2.3 耐土埋性
图1和图2表明, 加拿大一枝黄花的种子((0.06 ± 0.002) mg)仅在0-1 cm土壤深度时出苗; 千叶蓍((0.14 ± 0.004) mg)在0-2 cm土壤深度时出苗; 草地早熟禾((0.33 ± 0.011) mg)、Poa secunda ((0.43 ± 0.017) mg)、Vulpia octoflora ((0.41 ± 0.009) mg)和羽茅((3.14 ± 0.102) mg)在0-4 cm土壤深度下出苗; 灰绿藜((0.57 ± 0.043) mg)、Centaurea maculosa ((1.97 ± 0.054) mg)、野苜蓿((2.02 ± 0.044) mg)和长芒草((6.57 ± 0.260) mg)在0-8 cm土壤深度下出苗。
单粒种子质量与种子耐土埋性呈现显著的正相关关系(r = 0.797, p = 0.006)(图3), 即种子出苗对土埋的耐受性随物种种子质量的增加而逐渐加强。换言之, 物种间种子质量的差异可以在一定程度上用来预测种子对土壤掩埋的耐受性大小。这一结果与图2中的结果一致, 质量较大种子能在较深土壤掩埋(4和8 cm)下出苗。
2.3 种子质量、出苗率和T50间的相互关系
在0、1和2 cm土埋条件下, 单粒种子质量与出苗率之间无显著相关关系(p > 0.05)(图4A、4C、4E); 在4和8 cm土埋条件下, 两者之间存在显著正相关关系(r = 0.863, p = 0.001; r = 0.882, p < 0.001)(图4G、4I)。种子质量与T50的关系和种子质量与出苗率的关系非常相似, 在0、1和2 cm较浅土埋条件下, 单粒种子质量与T50之间无显著相关性(p > 0.05)(图4B、4D、4F); 在较深土埋条件(4和8 cm)下, 两者之间有显著正相关关系(r = 0.751, p = 0.012; r = 0.793, p = 0.006)(图4H、4J)。这些结果表明, 当土壤埋藏较深时, 种子质量较大的物种比质量较小的物种具有更长的出苗时间。
当土壤埋藏较浅(0、1和2 cm)时, 种子出苗率与T50之间无显著相关性(p > 0.05)(图5A、5B、5C); 当土壤埋藏较深(4和8 cm)时, 种子出苗率与T50之间存在显著正相关关系(r = 0.559, p = 0.093; r = 0.930, p < 0.001)(图5D、5E)。
图2
新窗口打开|下载原图ZIP|生成PPT图210种植物的种子出苗率随5种不同土埋深度和时间的变化(平均值±标准误差)。
Fig. 2Changes in the seed emergence of 10 different plant species with five different soil burial depths and time (mean ± SE).
图3
新窗口打开|下载原图ZIP|生成PPT图3种子质量与耐土埋性的关系。图中的10个点分别代
Fig. 3Relationship between seed mass and the tolerance to soil burial. Each point represents 10 species (mean ± SE). r represents the correlation coefficient between two variables, and the p represents probability.
3 讨论
在自然条件下, 植物群落是由不同种类的植物组成的。虽然不同植物有不同特性, 但它们长期生长在相同环境中, 可能会形成趋同的适应对策(Crawley, 1997)。我们发现, 种子质量和土埋深度共同影响植物种子出苗, 不同植物种子出苗所需的适宜土层深度存在差异。更有趣的是, 土埋深度显著影响物种水平上种子质量、出苗率及T50间的相互关系。这些结果丰富了人们在物种水平上对种子大小-种子出苗关系的认识, 同时为理解种子出苗多少与出苗快慢之间的权衡关系提供了实验证据。3.1 土埋深度对“种子质量-种子出苗关系”的影响
我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素。这与以前大量的种内研究结果(Winn, 1988; Baskin & Baskin, 1998; Li et al., 2006; Guo et al., 2009; Müller et al., 2018)一致。有利于不同物种种子出苗的适宜土埋深度各不相同, 较浅的土壤埋藏深度对于种子出苗更加有利(Wang et al., 2018)。我们发现, 10种植物种子出苗的最适土壤条件都在较浅土层, 特别是在1 cm的土层; 土壤表面撒种或是较深土层播种会在一定程度上降低种子的出苗率。这些结果与Harper和Benton (1966)的研究结果相一致。最适出苗的土埋深度与种子出苗所需的氧气、光照、温度和水分等条件有关(Kondo & Sato, 2007)。本实验中有3个物种在土壤表层播种时拥有最高的出苗率, 这与以前类似研究的结果(杨慧玲等, 2007; Guo et al., 2009; Zhu et al., 2014)不同。产生不同结果的可能原因与物种自身繁殖特性及栽培基质有关, 如千叶蓍和加拿大一枝黄花, 其种子质量较小且以风媒传播为主, 这种繁殖特性决定了它们在土壤表层时出苗率最大。再者, 较多前人的研究以沙子作为实验基质, 其浅层的保水性能差于土壤, 从而可能在一定程度上因无法提供连续而充足的水分供应而降低了种子的出苗率。最适宜种子出苗的土埋深度在物种间存在明显差异, 这说明土埋深度在调节种子出苗时机方面具有重要作用。这种意义已经被最新的研究所证实(Ye et al., 2019a)。目前对这方面的机理研究依然不足, 这将是未来研究的一个重点。然而, 许多研究表明植物种子质量与出苗率之间没有相关性(Chen & Maun, 1999; Chen et al., 2002; Paz et al., 2005)。这一结论是基于选择同种植物不同个体的种子作为质量梯度得出的, 而不是基于不同物种间种子质量与出苗率的关系, 也没有将两者的关系在不同土壤埋藏深度下进行对比分析(Peng, 2001; Müller et al., 2018)。本实验通过探究10种不同植物种子质量与出苗率在5个不同土壤埋藏深度下的相关性, 发现在较深土埋条件下, 单粒种子质量同出苗率间存在正相关关系, 但这种相关关系在较浅土埋条件下不存在。这一发现表明, 土壤埋藏深度强烈影响物种水平的“种子质量-种子出苗关系”。在较深土埋条件下, 具有较大质量种子的物种其出苗率要高于种子质量较小的物种, 这可能与较大种子储存有更多的营养物质及种子自身存在生物量分配的权衡有关(Baskin & Baskin, 1998)。在较深埋藏条件下, 种子出苗过程中较大比例的能量储备将被耗尽, 它们对未来生长的初始投资较少, 而将更多的生物量分配给地下部分的生长(Seiwa et al., 2002)。较小种子可能由于分配给地下茎生长的能量较少而不能支撑幼苗从较深土层中出苗(Wang et al., 2018)。综上所述, 在较浅土层中种子的出苗可能是一个随机过程, 受种子大小等自身特征的影响相对较小; 而在较深土层中种子出苗可能是一个定向过程, 受自身遗传特征的影响相对较大, 其出苗过程在一定程度上受种子大小的调控。
图4
新窗口打开|下载原图ZIP|生成PPT图4不同土埋深度下种子质量与出苗率、T50间的关系。每个小图中的10个点分别代
Fig. 4Illustrations of seed mass vs. seed emergence and seed mass vs. T50 at five different soil burial depths. The ten data points per panel represent the different plant species (mean ± SE).
图5
新窗口打开|下载原图ZIP|生成PPT图5不同土埋深度下种子出苗率与T50之间的关系。每个小图中的10个点分别代
Fig. 5Relationships between seed emergence and T50 at five different soil burial depths. Each point per panel represents one tested plant species (mean ± SE).
种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(Baskin & Baskin, 1998; Gardarin et al., 2010)。特别指出的是, 以前研究的种子质量梯度来自于种内不同个体, 而本实验中种子质量梯度来自于不同物种。通过分析每种植物种子在不同土埋深度下的出苗情况可以看出, 土埋深度对于具有较小种子物种(加拿大一枝黄花、千叶蓍、草地早熟禾、Vulpia octoflora和Poa secunda)出苗的负面效应大于较大种子物种(灰绿藜、Centaurea maculosa、野苜蓿、羽茅和长芒草)。这说明种子质量越大, 越能突破深层土壤的阻碍而出苗。这与Chen和Maun (1999)、Ren等(2002)的研究结果相似。因此, 种子质量与耐土埋性之间的正相关格局适用于同种和不同种植物。不同植物具有不同的生活习性和繁殖策略(Harper, 2010)。例如, 加拿大一枝黄花的种子远远小于很多植物的种子, 而且出苗率也很低, 这可能与加拿大一枝黄花是入侵性植物有关, 其种子质量较小有利于在空气中传播, 所以加拿大一枝黄花通过降低单粒种子的质量来产生更多的种子, 以此增加其成功入侵的几率(Noble, 1989; Moles & Westoby, 2006)。我们的结果和前人的结果共同表明, 无论是种间还是种内, 种子质量大小都能有效指示其忍耐土壤埋藏的能力。
3.2 种子出苗率与出苗速率之间的权衡关系
权衡关系是生态对策理论的基本内容(Harper, 2010)。比如, 种子大小与种子数量之间存在权衡关系(Baskin & Baskin, 1998), 个体大小与个体数量之间存在权衡关系(Harper, 2010)。在种子生态学领域, 对“出苗率与出苗速率之间关系”的研究较少, 尤其是在物种水平。因此, 探讨跨物种的“种子出苗率与出苗速率间的关系”对理解植物群落构建和属性具有重要意义(Crawley, 1997)。我们发现, 对于10种植物中的绝大多数物种而言, 它们的首次出苗时间均随着土埋深度的增加而延长, 这种现象与Chen和Maun (1999)、刘桂霞等(2007)的研究结果完全吻合。产生这种格局的可能原因是随播种深度的增加, 土壤对种子的机械阻挡作用和不适宜的水分、氧气含量、温度和光照等对种子的出苗过程造成了不利影响, 从而导致出苗过程较慢。例如, 胜红蓟(Ageratum conyzoides)的种子为光敏感型, 埋藏过深会导致光照强度和光质发生变化, 从而影响胜红蓟种子的出土过程(钟军弟等, 2017)。在本实验中, 我们采用T50来反映种子出苗速度。我们发现, 在较深土埋处理中, 种子质量与T50、出苗率与T50间均存在正相关关系; 在较浅土层中这些正相关性均不存在。这些结果表明, 在较深土埋条件下, 种子质量较大的物种比质量较小的物种具有更长的出苗时间, 出苗过程相对比较缓慢。出苗较为缓慢在一定程度上与种子的耐土埋性有关, 种子质量越大其耐土埋性较高, 越能在较深土埋条件下出苗, 但较深的土壤厚度使得萌发的幼苗穿透土壤到达表层的时间相对较长。基于这些结果, 我们认为T50的增大在一定程度上取决于幼苗出土前所需要经历的时间, 也就是较长的种子首次出苗时间。种子中储备的物质和能量可通过缓慢的释放过程为地下幼苗的生长提供持续的营养供给(Baskin & Baskin, 1998)。在此, 我们初步推测, 在较深土壤埋藏条件下, 较大种子的物种可能通过生物量分配权衡和缓慢而持续地出苗最终实现较高的出苗率。遗憾的是, 我们并不知道产生这种格局的确切原因。
鉴于权衡关系在生态学理论和实践中的重要性, “出苗率与出苗速率间的关系”值得进一步深入研究。为此, 未来的研究可重点考虑以下几个方面。第一、同时研究种内和种间的这种关系。第二、基于物种库开展多物种(比如几十种甚至上百种植物)这种关系的研究。第三、同时考虑多种群落类型。第四、在全球变化背景下开展这方面的研究。
4 结论
本研究在物种水平上探究了种子质量-种子出苗关系随土壤埋藏深度变化的格局。基于我们的实验数据, 可以得到以下初步结论。(1)对种子质量较大的植物而言, 其种子能在较深土层出苗。(2)在较深土埋条件下, 物种间种子质量与出苗率存在显著正相关关系, 出苗速率随物种间种子质量的增大而减慢。(3)出苗率和出苗速率之间存在一定的负相关关系, 即较深土埋下出苗率较高的种子其出苗速度较慢。物种间种子出苗快慢的权衡策略可能是群落中植物种子适应不同埋藏深度的一种有效方式。参考文献 原文顺序
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Common ragweed (Ambrosia artemisiifolia L.) is one of the annual plants that were described recently as invasive weeds in Europe. This species is described as an invasive plant that produces seeds that are highly variable. Its production of variably sized seeds is regarded as promoting its spread in different environments. Experiments were carried out to determine the influence of the seed weight and temperature on germination and the influence of the seed weight and burial depth on seedling emergence. The seeds were divided into a number of classes of weight and the seed weight effect on germination was evaluated by Petri dish assays. In another experiment, the seeds were buried at different depths in a clay soil/sand mix to estimate the burial effect on germination and seedling emergence. The germination level of A. artemisiifolia was high overall, between 76.8% and 94.2%. The seed germination was modified by temperature but it was not influenced by the seed weight. The amounts of germination and seedling emergence were greater for the seeds on the soil surface and decreased with an increasing burial depth, from 2 to 8 cm. No germination or emergence was observed for the seeds that were buried at 10 and 12 cm. The lightest seeds were more sensitive to burial. A greater level of seedling emergence for those seeds that were placed near the soil surface could explain the success of this species in open habitats, where the probability of deeper burial is low. After high seed production, the management of A. artemisiifolia in fields could be partly achieved through soil tillage, burying seeds below 10 cm, and not carrying out deep soil tillage the following year.
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Emex spinosa and Emex australis are invasive dicotyledonous weeds. The effects of various environmental factors on the germination of these weeds were investigated under laboratory and glasshouse conditions. Germination response of both species was lower at warmer temperature, and maximum germination was recorded at 20/12 degrees C (day/night). Light stimulated germination in both species, but considerable germination also occurred under darkness. More than 80% of E.spinosa seeds germinated at pH between 6 and 9, whereas E.australis seeds germination was considerably decreased at pH 9. Emex spinosa was fairly tolerant to salinity as compared with E.australis and germination (21%) of E.spinosa occurred even at 200mm NaCl. Both species were sensitive to osmotic stress, but E.spinosa tolerated more osmotic stress than E.australis. Temperature above 20/12 degrees C (day/night) and low osmotic potential increased time to start germination and mean germination time (MGT), as well as decreased germination index (GI) of both species. Darkness resulted in increased MGT and decreased GI in both species when compared with 10h photoperiod. Salt stress strongly increased time to obtain 50% germination and reduced GI of both species. In both species, an increasing burial depth decreased emergence percentage and emergence index and increased time to start emergence, although some seed emerged even at 10cm burial depth. It was concluded that both species can germinate over a wide range of environmental conditions. However, E.australis was more sensitive under adverse environmental conditions compared with E.spinosa. This information on germination ecology may aid in developing tools and strategies for management.
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In this study, we conducted experiments to accumulate practical information on the propagation and establishment of a population of Cardiocrinum cordatum var. glehnii by seed sowing. C. cordatum var. glehnii seeds require approximately 19months from seed dispersal to cotyledon emergence in the field. However, the period from seed dispersal to radicle emergence was shortened to approximately 7–8months by the temperature transition of 25/15°C (60days)→15/5°C (30days)→0°C (120days)→15/5°C (i.e., 15/5°C represents alternating temperature treatment wherein the seeds were placed at 15°C for 12h during the day and then at 5°C for 12h during the night). More than 90% of the seeds, which were stored dry at 5°C for 12months and sown in pots in the field, showed cotyledon emergence, whereas in seeds stored dry at 25°C, dry at room temperature, and non-dry at room temperature, cotyledon emergence was decreased by less than 1%. More than 88% of the seeds that were stored dry at 5°C and sown in the field in October 2002 immediately after collecting, November, and from April to July 2003 showed cotyledon emergence in spring 2004. However, seeds sown in August, September, and October 2003 showed cotyledon emergences of 57.6%, 0%, and 0% in spring 2004, respectively. Seeds collected in October 2002 and sown until July 2003 in the field received adequate high temperature in summer, moderate temperature in autumn, and cold temperature in winter; therefore, the percentage of cotyledon emergence was high in spring 2004. On the other hand, seeds sown in August 2003 or later could not receive enough high temperature; thus, cotyledons emerged from only a few seeds.
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A greenhouse experiment was conducted to test the effects of sand burial depth and seed mass on seedling emergence and growth of Nitraria sphaerocarpa. Seeds of Nitraria sphaerocarpa were sorted into three size-classes (large, medium, small) and artificially buried at 0, 1, 2, 3, 4, 5 and 6cm depths in plastic pots filled with unsterilized sand. In the seven treatments, the percent emergence, seedling mass and seedling height, significantly affected by both burial depth and seed size, were highest at the optimal burial depth of 2cm burial depth, and decreased with increasing burial depth in each seed size-class. Although seedling mass was usually greatest for large seeds and least for small seeds at each burial depth, little difference was observed in seedling height at shallow burial depths of 0–3cm. In each seed size-class, with increasing burial depth, both root-mass ratio and aboveground stem-mass ratio decreased, while belowground stem-mass ratio increased. In each burial depth, with decreasing seed size, belowground stem-mass ratio increased, while root-mass ratio decreased.
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羊柴 (Hedysarum leave)、柠条 (Caragana korshinskii)、籽蒿 (Artemisia sphaerocephala)与油蒿 (Artemisia ordosica)为鄂尔多斯高原广泛分布的植物种，也是该地区飞播选用的主要植物种。由于飞播为鄂尔多斯高原植被恢复的重要手段，而飞播后植物种子的出苗率与土壤水分及沙埋密切相关。因此，上述植物种子萌发与出苗对水分和沙埋反应的研究对当地退化生态系统的恢复具有重要意义。通过温室控制实验，对4种植物萌发特性及出苗与水分和沙埋深度的关系进行研究，阐明了种子萌发最适合的水分条件和沙埋深度。结果表明，4种植物种子萌发与出苗最适宜的供水量都接近于当地种子萌发时期的平均降水量, 最适宜的沙埋深度为0.5～1 cm, 过多的水分和过深的沙埋会降低种子萌发与出苗，反映了4种植物对沙区环境的生态适应。4种植物最适宜的供水量均为123 ml，羊柴、柠条、籽蒿和油蒿的最适沙埋深度分别为：0.5、1.0、0.5和0.5 cm。根据实验结果及当地气候特点，鄂尔多斯地区的飞播时间应由6月初提前至5月中下旬，以提高飞播植物的出苗率。
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羊柴 (Hedysarum leave)、柠条 (Caragana korshinskii)、籽蒿 (Artemisia sphaerocephala)与油蒿 (Artemisia ordosica)为鄂尔多斯高原广泛分布的植物种，也是该地区飞播选用的主要植物种。由于飞播为鄂尔多斯高原植被恢复的重要手段，而飞播后植物种子的出苗率与土壤水分及沙埋密切相关。因此，上述植物种子萌发与出苗对水分和沙埋反应的研究对当地退化生态系统的恢复具有重要意义。通过温室控制实验，对4种植物萌发特性及出苗与水分和沙埋深度的关系进行研究，阐明了种子萌发最适合的水分条件和沙埋深度。结果表明，4种植物种子萌发与出苗最适宜的供水量都接近于当地种子萌发时期的平均降水量, 最适宜的沙埋深度为0.5～1 cm, 过多的水分和过深的沙埋会降低种子萌发与出苗，反映了4种植物对沙区环境的生态适应。4种植物最适宜的供水量均为123 ml，羊柴、柠条、籽蒿和油蒿的最适沙埋深度分别为：0.5、1.0、0.5和0.5 cm。根据实验结果及当地气候特点，鄂尔多斯地区的飞播时间应由6月初提前至5月中下旬，以提高飞播植物的出苗率。
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This paper studied the effects of sand-burying on the seed germination and seedling emergence of six dominance plants in Keerqin Sandy Land. Six treatments of artificially sand-burying to depths 0, 2, 4, 6, 8, 10 and 12 cm were designed. The results showed that the seed germination of Agriophyllum squarrosum was significantly different (P &lt; 0.05) between different treatments, but that of Artemesia halodendron was only significantly different (P&lt; 0.05) between 2 cm and other burial depths. For other four plants, their seed germination was significantly different (P &lt; 0.05) only between 0 cm and other burial depths. Sand-burying significantly affected the seedling emergence of all plant species. The emergence rate decreased with increasing burial depth. Higher emergence percentages were obtained at 2 and 4 cm burial depths. The species with larger seeds emerged from deeper depth, and the maximum burial depth of seedling emergence was Sophora flavescdens &gt; Atraphaxis manshurica &gt; or = Agriophyllum squarrosum &gt; Hedysarum fruticosum &gt; Bassia dasyphylla &gt; Artemesia halodendron.
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Seed germination constitutes an important event in the life cycle of plants. Two related seed traits affect fitness: seed size and the timing of seed germination. In three sets of experiments, we (1) partition the sources of seed-size variance in Lobelia inflata into components attributable to fruit size, relative fruit position, and parental identity; (2) examine the influence of pregermination conditions and seed size on time to germination; and (3) assess the fitness consequences of seed size and germination timing under seminatural, harsh conditions. Seed-size variance is attributable to both parental identity and fruit position within an individual. Distal fruits produce larger but fewer seeds. No significant correlation exists between fruit size and seed size, but a trade-off is found between the number and size of seeds contained in a fruit after correcting for fruit size. The timing of germination is influenced by seed size, light conditions before winter, and winter duration. Germination timing influences survival, and despite small seed size in this species (2 × 10 g/seed), seed size has a persistent and significant association with both final plant size and the probability of survival to autumn.
DOI:10.2307/1938318URL [本文引用: 1]
DOI:10.1111/ere.2019.34.issue-1URL [本文引用: 3]
DOI:10.2307/1941651URL [本文引用: 2]
URLPMID:18419094 [本文引用: 1]
Seed size and seedling recruitment strategy are of importance in the life-history strategy of plant. In this paper, the current ecological researches at home and aboard on the relationships between seed size and seedling growth were reviewed from the aspects of the effects of seed size on seed germination and seedling emergence, the relationships between seed size and seedling growth traits, and the relationships between seed size and seedling survival and competition ability. Some suggestions on future researches in this field were put forward. There were likely different relationships between seed size and seedling growth in different microenvironments and vegetation types, and the effects of seed size on seedling growth could result in different contributions of different seed-size species to the seedling recruitment of vegetation. The large-scale community level and the small-scale intra- and inter-species level researches on this issue should be strengthened, which would have significance for the recruitment and renewing of natural vegetation.
URLPMID:18419094 [本文引用: 1]
Seed size and seedling recruitment strategy are of importance in the life-history strategy of plant. In this paper, the current ecological researches at home and aboard on the relationships between seed size and seedling growth were reviewed from the aspects of the effects of seed size on seed germination and seedling emergence, the relationships between seed size and seedling growth traits, and the relationships between seed size and seedling survival and competition ability. Some suggestions on future researches in this field were put forward. There were likely different relationships between seed size and seedling growth in different microenvironments and vegetation types, and the effects of seed size on seedling growth could result in different contributions of different seed-size species to the seedling recruitment of vegetation. The large-scale community level and the small-scale intra- and inter-species level researches on this issue should be strengthened, which would have significance for the recruitment and renewing of natural vegetation.
DOI:10.1614/WS-D-14-00093.1URL [本文引用: 1]
URLPMID:18260444 [本文引用: 1]
This paper studied the effects of different depth sand burying on the caryopsis germination, seedling emergence and growth of Bromus inermis Leyss., a perennial gramineous grass dominated on Othidag sandy land. The results showed that the maximum burying depth for B. inermis caryopsis germination and seedling emergence was 12 cm and 8 cm, respectively. Below the thresholds, the percentages of caryopsis germination and seedling emergence decreased with increasing depth of sand burying. All the 1- and 2-week-old seedlings of B. inermis could survive when the sand burying depth was up to 33% of their height, and their biomass was no less than the unburied seedlings. When the burying depth increased to 66% of their height, 70% of 1-week-old seedlings and 25% of 2-week-old seedlings could survive, but their growth was impaired. No seedlings could survive when they were wholly buried in sand. When buried by sand, the seedlings allocated more biomass for the development of their aboveground part, which might be an important adaptation strategy of B. inermis to sand burying.
URLPMID:18260444 [本文引用: 1]
This paper studied the effects of different depth sand burying on the caryopsis germination, seedling emergence and growth of Bromus inermis Leyss., a perennial gramineous grass dominated on Othidag sandy land. The results showed that the maximum burying depth for B. inermis caryopsis germination and seedling emergence was 12 cm and 8 cm, respectively. Below the thresholds, the percentages of caryopsis germination and seedling emergence decreased with increasing depth of sand burying. All the 1- and 2-week-old seedlings of B. inermis could survive when the sand burying depth was up to 33% of their height, and their biomass was no less than the unburied seedlings. When the burying depth increased to 66% of their height, 70% of 1-week-old seedlings and 25% of 2-week-old seedlings could survive, but their growth was impaired. No seedlings could survive when they were wholly buried in sand. When buried by sand, the seedlings allocated more biomass for the development of their aboveground part, which might be an important adaptation strategy of B. inermis to sand burying.
DOI:10.1016/j.scitotenv.2019.05.087URLPMID:31100667 [本文引用: 1]
Sand burial plays important role in the life history of species in sandy areas of arid and semi-arid temperate regions, by affecting seed germination, seedling growth and survival and plant community. However, few studies have focused on the effects of sand burial on the dynamics of seed dormancy in such areas. In this study, seed germination characteristics of Allium tenuissimum, a dominant perennial herb in the dune ecosystem in Ordos Plateau in northern China, was investigated. Dormancy dynamics were monitored for seeds buried at sand depths of 0, 2 and 5?cm in the natural habitats for 13?months. Freshly matured seeds of A. tenuissimum were conditionally dormant and germinated to high percentages at high but not low temperatures. Germination percentages were increased by incubation at summer temperature (15/25?°C) and dry storage, but GA3 and cold stratification had no significant effects. These results suggested that seeds of A. tenuissimum were conditionally dormant, and incubation under warm, wet (but not cold, wet) conditions and dry after-ripening resulted in complete dormancy releasing. Seeds buried at 2 and 5?cm in the field for 13?months exhibited seasonal changes in germination, with an increase in spring and summer followed by decrease in autumn and winter. However, seeds on the soil surface (0?cm) gradually came out of dormancy beginning in January, and germinated percentage was highest in July, after which remained high. The peak of nondormancy for seeds buried in the field was in the summer, which corresponds to the period of highest annual precipitation. Sand burial helped mediate seeds dormancy dynamics of A. tenuissimum via seasonal dormancy cycling. Our finding contributes to a better understanding of how timing of seedling establishment is controlled in a semiarid dune ecosystem in temperate climate.
DOI:10.1111/jvs.2017.28.issue-1URL [本文引用: 1]
DOI:10.1016/j.scitotenv.2018.10.208URLPMID:30463160 [本文引用: 1]
Sand burial is a common phenomenon in inland semi-arid and arid areas, affecting plant growth and even plant community structure. Precipitation regime, including the variation of precipitation intensity and frequency, also drives community structure and functions in such areas. However, few studies have focused on the combined effect of sand burial and changed precipitation regime on community function, specifically its role in carbon storage. A 2-yr field experiment with factorial treatments of precipitation (control, slight enhancement and strong enhancement) and sand addition (control and 5?cm sand addition) was conducted to test the responses of plant and soil carbon content in a semi-arid typical steppe in N China. Results showed that sand burial had no significant effect on plant carbon density, but significantly changed the allocation of plant carbon from aboveground to belowground; these responses differed among species and life forms in the community. Precipitation enhancement had no significant effects on plant carbon and its allocation, perhaps because effects of precipitation on plants are due more to precipitation frequency than to precipitation intensity per event. Sand burial and precipitation enhancement decreased soil carbon, especially soil organic carbon, and promoted soil carbon to be distributed deeper down the soil profile. These findings will help to understand how sand deposition affects plant and soil carbon storage and their allocation in plant communities under a changing precipitation regime, and more generally, to understand carbon storage dynamics in early-successional sandy ecosystems in the context of global change.
[本文引用: 1]
[本文引用: 1]
DOI:10.1007/s11104-013-1892-9URL [本文引用: 1]
Seed germination and seedling emergence are vulnerable to water stress in arid environments. When precipitation is low and unpredictable during the early growing season, seeds near the sand surface often suffer from hydration/dehydration during germination. We investigated the responses of seedling emergence and survival of a sand dune grass with high sand stabilization value to amount and frequency of precipitation and depth of burial in sand.
Effects of amount and frequency of precipitation, burial and hydration/dehydration on seedling emergence of Leymus secalinus, were examined using standard procedures.
Seedling emergence was affected by amount and frequency of monthly precipitation and depth of burial, and it decreased as precipitation frequency decreased with same amount of precipitation. Highest emergence percentage was obtained with 100 or 150 mm precipitation at 1-4 cm depth. Hydration/dehydration treatments decreased germination and increased dormancy percentage. Young seedlings with root lengths of 0-1 mm desiccated up to 30 days revived after rehydration.
Seedling emergence of L. secalinus is adapted to 150 mm monthly precipitation with frequency of 10-30 times per month, 1-4 cm burial depth and dehydration interval of 1-2 days. Alteration of amount and/or frequency of precipitation caused by climate change could markedly affect seedling emergence and population regeneration of this species.
DOI:10.1002/ajb2.1984.71.issue-9URL [本文引用: 1]
Soil temperature and moisture regulate seed dormancy cycling of a dune annual in a temperate desert
1
2018
... 种子出苗是植物生活史中极为重要的一个阶段(
Seed mortality in the soil is related to seed coat thickness
1
2010
... 种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(
Effects of the seed weight and burial depth on the seed behavior of common ragweed (Ambrosia artemisiifolia).
1
2011
... 前人对于种子质量与出苗关系的研究多从同一物种角度出发, 种子质量大小的变异来源于种群内个体间的差异(
Impacts of burial and insect infection on germination and seedling growth of acorns ofQuercus variabilis.
5
2009
... 种子出苗受遗传和环境的共同影响(
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
... ;
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
... ;
5
... 种子出苗是植物生活史中极为重要的一个阶段(
... ;
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
... 种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(
... 权衡关系是生态对策理论的基本内容(
The behaviour of seeds in soil: The germination of seeds on the surface of a water supplying substrate
2
1966
... 种子出苗是植物生活史中极为重要的一个阶段(
... ).种子出苗代表着由对环境条件耐受性最强阶段(种子休眠)向最脆弱、最敏感阶段的高风险转变(
小叶锦鸡儿种子大小变异对萌发和幼苗生长的影响
1
2008
... 种子出苗受遗传和环境的共同影响(
小叶锦鸡儿种子大小变异对萌发和幼苗生长的影响
1
2008
... 种子出苗受遗传和环境的共同影响(
Germination ecology of Emex spinosa and Emex australis, invasive weeds of winter crops.
1
2014
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
Effects of temperature, light, storage conditions, sowing time, and burial depth on the seed germination of Cardiocrinum cordatum var. glehnii(Liliaceae).
1
2007
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
Effects of sand burial depth and seed mass on seedling emergence and growth of Nitraria sphaerocarpa.
6
2006
... 种子出苗受遗传和环境的共同影响(
... ;
... ;
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
... ;
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
播种深度对心叶驼绒藜出苗的影响
1
2004
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
播种深度对心叶驼绒藜出苗的影响
1
2004
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
播种深度和种子来源对羊草种苗出土的影响
1
2007
... 权衡关系是生态对策理论的基本内容(
Seed germination ecology of doveweed (Murdannia nudiflora) and its implication for management in dry-seeded rice.
1
2015
... 种子出苗是植物生活史中极为重要的一个阶段(
Effects of environmental factors and burial depth on seed germination and emergence of two populations of Caucalis platycarpos.
2
2017
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
... ).最适宜种子出苗的埋藏深度往往位于较浅土层, 并随土埋深度的增加而降低(
播种深度和种子来源对羊草种苗出土的影响
1
2007
... 权衡关系是生态对策理论的基本内容(
Seed size and plant strategy across the whole life cycle
1
2006
... 种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(
Effect of environmental factors on seed germination and emergence of Lepidium vesicarium
3
2016
... 种子出苗是植物生活史中极为重要的一个阶段(
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
... 前人对于种子质量与出苗关系的研究多从同一物种角度出发, 种子质量大小的变异来源于种群内个体间的差异(
Germination and seedling survival of argan (Argania spinosa) under experimental saline conditions.
1
2001
... 种子出苗是植物生活史中极为重要的一个阶段(
Impact of seed burial depth on the emergence and growth of annual forage legumes
4
2018
... 种子出苗受遗传和环境的共同影响(
... 前人对于种子质量与出苗关系的研究多从同一物种角度出发, 种子质量大小的变异来源于种群内个体间的差异(
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
鄂尔多斯高原4种主要沙生植物种子萌发与出苗对水分和沙埋的响应
1
2005
... 种子出苗受遗传和环境的共同影响(
10
... 种子出苗受遗传和环境的共同影响(
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
... ).换言之, 土壤埋藏深度是决定种子命运的关键性因素.一方面, 适当深度的土壤埋藏有助于为种子创造适宜的温度、水分等出苗条件(
... ).另一方面, 埋藏过深会对种子出苗产生阻碍或抑制(
... 前人对于种子质量与出苗关系的研究多从同一物种角度出发, 种子质量大小的变异来源于种群内个体间的差异(
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
... 种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(
... 权衡关系是生态对策理论的基本内容(
... 在本实验中, 我们采用T50来反映种子出苗速度.我们发现, 在较深土埋处理中, 种子质量与T50、出苗率与T50间均存在正相关关系; 在较浅土层中这些正相关性均不存在.这些结果表明, 在较深土埋条件下, 种子质量较大的物种比质量较小的物种具有更长的出苗时间, 出苗过程相对比较缓慢.出苗较为缓慢在一定程度上与种子的耐土埋性有关, 种子质量越大其耐土埋性较高, 越能在较深土埋条件下出苗, 但较深的土壤厚度使得萌发的幼苗穿透土壤到达表层的时间相对较长.基于这些结果, 我们认为T50的增大在一定程度上取决于幼苗出土前所需要经历的时间, 也就是较长的种子首次出苗时间.种子中储备的物质和能量可通过缓慢的释放过程为地下幼苗的生长提供持续的营养供给(
Effects of sand burial depth on seed germination and seedling emergence of Cirsium pitcheri.
4
1999
... 种子出苗受遗传和环境的共同影响(
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
... 种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(
... 权衡关系是生态对策理论的基本内容(
鄂尔多斯高原4种主要沙生植物种子萌发与出苗对水分和沙埋的响应
1
2005
... 种子出苗受遗传和环境的共同影响(
1
... 种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(
Seed germination and storage of woody species in the lower subtropical forest
2
2002
... 种子出苗受遗传和环境的共同影响(
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
Plant Ecology. 2nd edn. Blackwell Science, Oxford
3
1997
... 前人对于种子质量与出苗关系的研究多从同一物种角度出发, 种子质量大小的变异来源于种群内个体间的差异(
... 在自然条件下, 植物群落是由不同种类的植物组成的.虽然不同植物有不同特性, 但它们长期生长在相同环境中, 可能会形成趋同的适应对策(
... 权衡关系是生态对策理论的基本内容(
Comparative ecology of seed mass in Psychotria(Rubiaceae): Within- and between-species effects of seed mass on early performance.
1
2005
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
六种牧草种子大小和播种深度对出苗的影响
1
2001
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
六种牧草种子大小和播种深度对出苗的影响
1
2001
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
Effect of sand burial depth on seed germination and seedling emergence of Calligonum L. species.
1
2002
... 种子质量与耐土埋性之间存在较强的正相关关系, 较大种子意味着储存有更多的能量, 因而具有较大质量种子的物种更可能在较深的土壤埋藏条件下出苗(
Effects of burying depth and seed size on seedling establishment of Japanese chestnuts, Castanea crenata.
1
2002
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
Variation in seed traits of Lobelia inflata(Campanulaceae): Sources and fitness consequences.
1
2000
... 种子出苗受遗传和环境的共同影响(
Seed variation in wild radish: Effect of seed size on components of seedling an adult fitness
1
1984
... 种子出苗是植物生活史中极为重要的一个阶段(
Effects of sand burial disturbance on establishment of three desert shrub species in the margin of oasis in northwestern China
3
2018
... 种子萌发后能否顺利出土不仅与自身储存的物质和能量有关, 还取决于它在土壤中的位置(
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
... 然而, 许多研究表明植物种子质量与出苗率之间没有相关性(
Ecological and evolutionary consequences of seed size in Prunella vulgaris.
2
1988
... 种子出苗受遗传和环境的共同影响(
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
植物种子大小与幼苗生长策略研究进展
1
2008
... 种子出苗受遗传和环境的共同影响(
植物种子大小与幼苗生长策略研究进展
1
2008
... 种子出苗受遗传和环境的共同影响(
Factors affecting seed germination and seedling emergence of Asia minor bluegrass (Polypogon fugax).
1
2015
... 种子出苗是植物生活史中极为重要的一个阶段(
沙埋对无芒雀麦种子萌发和幼苗生长的影响
1
2007
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
沙埋对无芒雀麦种子萌发和幼苗生长的影响
1
2007
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
a). Sand burial helps regulate timing of seed germination of a dominant herb in an inland dune ecosystem with a semiarid temperate climate
1
2019
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
Differential plant species responses to interactions of sand burial, precipitation enhancement and climatic variation promote co-existence in Chinese steppe vegetation
1
2016
... 种子出苗是植物生活史中极为重要的一个阶段(
Experimental sand burial and precipitation enhancement alter plant and soil carbon allocation in a semi-arid steppe in north China
1
2019
... 种子出苗是植物生活史中极为重要的一个阶段(
不同埋藏深度对白花鬼针草、假臭草和胜红蓟种子出苗及生长的影响
1
2017
... 权衡关系是生态对策理论的基本内容(
不同埋藏深度对白花鬼针草、假臭草和胜红蓟种子出苗及生长的影响
1
2017
... 权衡关系是生态对策理论的基本内容(
Effects of amount and frequency of precipitation and sand burial on seed germination, seedling emergence and survival of the dune grass Leymus secalinus in semiarid China.
1
2014
... 我们的结果表明, 在物种水平, 种子质量依然是决定种子出苗的一个重要内在因素.这与以前大量的种内研究结果(
The effect of seed size and maternal source on individual size in a population of Ludwigia leptocarpa(Onagraceae).
1
1984
... 种子出苗受遗传和环境的共同影响(
