Chemical and physical defence in early and late leaves in three heterophyllous birch species native to northern Japan
Chemical and physical defence in early and late leaves in three heterophyllous birch species native to northern Japan
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DOI：
10.1093/aob/mch022
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发表时间：
2004-02-01
期刊：
影响因子：
4.2
通讯作者：
Koike, T
中科院分区：
文献类型：
--
作者：
Matsuki, S;Sano, Y;Koike, T
岳桦（Betula ermanii，B.）maximowicziana和B.阔叶变种japonica具有异叶（即早叶和晚叶），是日本北方典型的先锋种。方法以2年生幼苗为材料，在一个生长季节内，在全光照条件下生长，研究其早期和晚期叶片对食草动物的化学和物理防御作用。将每株幼苗的三周龄叶收获三次（5月、7月和10月）。总酚和缩合单宁含量测定化学防御和叶韧性和毛状体密度进行了评估物理防御。在5月的早期叶片落叶也进行了研究早期叶片的贡献，随后growth.Key结果化学和物理防御在早期大于晚叶B。Platyphylla和B. ermanii，而B则相反。maximowicziana。B的毛状体密度与其较弱的化学防御相反。maximowicziana很高。在B。Platyphylla和B. ermanii，相对生长速率（RGR）较大的生长季节早期。去除早叶对生长的负面影响仅在B中显著。结论B. Platyphylla和B. Ermanii在早期而不是后期的叶子上投资防御，因为早期的叶子对随后的生长至关重要。相反，B. maximowicziana更强烈地保护其晚叶，因为其RGR在整个生长季节保持在相同水平。(C)2004年《植物学年鉴》（Annals of Botany Company）
Background and Aims Betula ermanii, B. maximowicziana and B. platyphylla var. japonica have heterophyllous leaves (i.e. early leaves and late leaves) and are typical pioneer species in northern Japan. Chemical and physical defences against herbivores in early and late leaves of these species were studied.Methods Two-year-old seedlings were grown under full sunlight in a single growing season. Three-week-old leaves of each seedling were harvested three times (May, July and October). Total phenolics and condensed tannin content were determined for chemical defence and leaf toughness and trichome density were assessed for physical defence. Defoliation of early leaves in May was also performed to study the contribution of early leaves to subsequent growth.Key Results Chemical and physical defences were greater in early than late leaves in B. platyphylla and B. ermanii, whereas the reverse was true in B. maximowicziana. In contrast to its weak chemical defences, the trichome density in B. maximowicziana was very high. In B. platyphylla and B. ermanii, the relative growth rates (RGR) were greater early in the growing season. Negative effects on growth of removal of early leaves were significant only in B. platyphylla.Conclusions B. platyphylla and B. ermanii invest in defence in early rather than late leaves, since early leaves are crucial to subsequent growth. In contrast, B. maximowicziana more strongly defends its late leaves, since its RGR is maintained at the same level throughout the growing season. (C) 2004 Annals of Botany Company.