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干旱胁迫对白花鬼针草异型瘦果萌发与幼苗生长的影响

闫小红,曾建军,周兵*,王宁,岳冬梅   

  1. (井冈山大学生命科学学院, 江西吉安 343009)
  • 出版日期:2019-11-10 发布日期:2019-11-10

Effects of drought stress on germination and seedling growth of heteromorphic achenes of Bidens alba.

YAN Xiao-hong, ZENG Jian-jun, ZHOU Bing*, WANG Ning, YUE Dong-mei   

  1. (School of Life Sciences, Jinggangshan University, Ji’an 343009, Jiangxi, China).
  • Online:2019-11-10 Published:2019-11-10

摘要: 白花鬼针草(Bidens alba)为菊科鬼针草属一年生草本入侵植物,具有瘦果异型性现象,而关于其生态学意义还不清楚。以白花鬼针草异型瘦果为研究对象,采用室内观测和生物测定的方法比较了其两种异型瘦果(中央瘦果和边缘瘦果)的形态特征差异及不同PEG-6000溶液模拟干旱胁迫下的萌发和幼苗生长差异,探讨了白花鬼针草异型瘦果的萌发策略及干旱适应性差异。结果表明:(1)白花鬼针草果序中中央瘦果和边缘瘦果在形态和萌发特性上存在较大差异。中央瘦果的总长、主体长及千粒重显著大于边缘瘦果,而其宽度显著小于后者。中央瘦果萌发相对缓慢,边缘瘦果萌发相对快速整齐。(2)与对照相比,5%~25%浓度的PEG-6000溶液对中央瘦果的最终萌发率、发芽势、发芽指数和活力指数表现为低促高抑的作用规律,而对边缘瘦果的4个指标基本上均表现为随着浓度升高而增强的抑制作用,且15%~25%浓度的溶液对两种瘦果4个指标的抑制作用均达到显著水平(P<0.05)。(3)与对照相比,PEG-6000溶液在5%浓度时对中央瘦果幼苗根长产生显著促进作用,而在20%~25%浓度时产生显著抑制作用(P<0.05);PEG-6000溶液分别在10%~25%和15%~25%浓度时对中央瘦果幼苗的苗高和鲜质量产生显著抑制作用,其在15%~25%浓度时对边缘瘦果幼苗的根长,5%~25%浓度时对边缘瘦果幼苗的苗高和鲜质量产生显著抑制作用(P<0.05)。可见,白花鬼针草中央瘦果和边缘瘦果形态上存在较大差异,具有不同的萌发策略,中央瘦果表现出更强的干旱适应性。这些特性有助于中央瘦果在扩散到新生境中的定殖及边缘瘦果在原生境中种群的延续。

关键词: NaCl胁迫, 离子稳态, 磁化作用

Abstract: Bidens alba, an invasive annual species from the genus Bidens in Asteraceae, has heteromorphic achenes. However, the ecological significance of heteromorphic achenes is still unknown. The differences of morphology, germination and seedling growth of the heteromorphic achenes under drought stress were compared by laboratory observation and bioassay. The differences of germination strategies and the adaptation of the heteromorphic achenes of B. alba to drought were examined. The results showed that: (1) There were significant differences in morphology and germination strategies between central achenes and peripheral achenes of B. alba. Total length, body length, and thousandgrain weight of central achenes were higher than those of peripheral achenes, but the width was reverse, central achenes germinated slowly, and peripheral achenes germinated fast and evenly. (2) Compared with the control, at 5%-25% of PEG-6000, germination rate, germination potential, germination index and vigor index of central achenes were enhanced at lower concentrations but inhibited at higher concentrations, and the solutions mostly showed increasing inhibition on the four indices of peripheral achenes withincreasing concentrations (P<0.05). (3) Compared with the control, seedling root length of central achenes was significantly promoted by PEG-6000 solutions at 5% concentration but inhibited at 20%-25% concentrations (P<0.05). Seedling height and fresh mass of central achenes was significantly inhibited at 10%-25% and 15%-25% concentrations respectively (P<0.05). The seedling root length of peripheral achenes was significantly inhibited at 15%-25% concentrations, and their seedling height and fresh mass was significantly inhibited at 5%-25% concentrations (P<0.05). Our results suggest that there were significant differences in the morphology and germination strategies between central achenes and peripheral achenes of B. alba. The centralachenes had stronger adaptation to drought. Those characteristics were helpful for the colonization of central achenes in new habitats and for population continuation of peripheral achenes in original habitats.

Key words: ionic homeostasis, magnetic effect, NaCl stress.