Does defoliation induce chemical and morphological defenses in the leaves of silver birch seedlings under changing climate?

CHEMOECOLOGY - Tập 18 - Trang 85-98 - 2007
Liisa Huttunen1, Pekka Niemelä1, Riitta Julkunen-Tiitto2, Susanne Heiska2, Riitta Tegelberg3, Matti Rousi4, Seppo Kellomäki1
1Faculty of Forest Sciences, University of Joensuu, Joensuu, Finland
2Faculty of Biosciences, University of Joensuu, Joensuu, Finland
3Department of Biological and Environmental Sciences, Plant Biology, University of Helsinki, Helsinki, Finland
4Finnish Forest Research Institute, Punkaharju Research Station, Punkaharju, Finland

Tóm tắt

We examined the effects of defoliation con-currently with elevated temperature and CO2 on some chemical and morphological characteristics in the leaves of silver birch seedlings (Betula pendula). We also analyzed the consequent changes in the palatability of leaves for adult blue alder leaf beetles (Agelastica alni). Under the different climatic treatments, the seedlings were subjected to three fertilizer treatments (0 kg, 130 kg and 270 kg N ha−1) and defoliation treatments (0%, 25% and 50% of the total leaf area). In each climatic treatment, fertilization increased the nitrogen content in the leaves, but decreased total concentrations of soluble phenolics, detected by high-performance liquid chromatography (HPLC), and insoluble condensed tannins. Defoliation, both independently and in combination with elevated temperature and CO2, decreased the concentrations of the phenolics. Compared to the intact controls, the leaves of the defoliated seedlings were smaller and tougher. Under elevated temperature, the beetles consumed a smaller amount of the leaves of plants subjected to the high fertilization, while under ambient climatic conditions, fertilization increased the feeding. The total leaf consumption was higher under the ambient climatic conditions than under elevated temperature, elevated CO2 or the combination of elevated temperature and CO2.