tailieunhanh - Báo cáo lâm nghiệp: "Interactive effects of irradiance and water availability on the photosynthetic performance of Picea sitchensis seedlings: implications for seedling establishment under different management practices"

Tuyển tập các báo cáo nghiên cứu về lâm nghiệp được đăng trên tạp chí lâm nghiệp Original article đề tài:"Interactive effects of irradiance and water availability on the photosynthetic performance of Picea sitchensis seedlings: implications for seedling establishment under different management practices" | Ann. For. Sci. 62 2005 413-422 413 INRA EDP Sciences 2005 DOI forest 2005037 Original article Interactive effects of irradiance and water availability on the photosynthetic performance of Picea sitchensis seedlings implications for seedling establishment under different management practices Kevin Black Phill Davis Joseph Mc Grath Pat Doherty Bruce Osborne Botany Department University College Dublin Belfield Dublin 4 Ireland Received 26 July 2004 accepted 3 March 2005 Abstract - The impact of water availability on the photosynthetic performance of three year old commercially obtained Sitka spruce Picea sitchensis seedlings under exposed and shaded conditions was evaluated to provide a physiological understanding of the factors controlling seedling performance under conventional and continuous cover forestry CCF management scenarios. Decreases in photosynthesis in response to water deficits under exposed and shaded conditions were associated with reductions in both stomatal Gs and mesophyll conductance Gm and an increase in the proportion of electrons consumed in non-photosynthetic pathways. After re-watering photosynthesis of plants subjected to higher irradiances was inhibited for up to 6 days due to high photorespiratory activity and damage to photosystem II. Waterlogged seedlings grown under both exposed and shaded conditions showed smaller decreases in photosynthesis that were also associated with an altered Gs and Gm but no changes in chlorophyll fluorescence related parameters were observed. We conclude that the performance of seedlings will be more susceptible to management-related or environmentally-induced water deficits in exposed sites typical of temperate latitudes and may therefore be improved in CCF systems. continuous cover forestry irradiance water availability photosynthesis Résumé - Interactions entre intensité lumineuse et disponibilité en eau sur la performance photosynthétique de plants de Picea sitchensis implications sur le .

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