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cje ›› 2012, Vol. 31 ›› Issue (09): 2197-2202.

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Effects of drought stress on the photosynthesis and growth of Cyclobalanopsis glauca seedlings: A study with simulated hierarchical karst water supply.

ZHANG Zhong-feng1,2, YOU Ye-ming3, HUANG Yu-qing1, LI Xian-kun1, ZHANG Jin-chi2, ZHANG De-nan4, HE Cheng-xin1**   

  1. (1Guangxi Institute of Botany, Guangxi Zhuangzu Autonomous Region and the Chinese Academy of Sciences, Guilin 541006, Guangxi, China; 2College of Forest Resources and Environment, Nanjing Forestry University, Nanjing 210037, China; 3College of Forestry, Beijing Forestry University, Beijing 100083, China; 4College of Life Sciences, Guangxi Normal University, Guilin 541002, Guangxi, China)
  • Online:2012-09-10 Published:2012-09-10

Abstract: Based on the geological characteristics of karst environment, a simulated hierarchical columniation of water supply (soil layerepikarst layerrock layer) was built up, and a gradient of soil moisture content (severe drought, medium drought, suitable soil moisture, and saturated soil moisture corresponding to 30%-40%, 50%-60%, 70%-80%, and 90%-100% of field moisture capacity, respectively) was installed to investigate the photosynthesis and growth of 2-year-old Cyclobalanopsis glauca seedlings under the simulated karst environment. The results showed that soil drought stress decreased the growth of the seedlings basal diameter and branch significantly (P<0.01), but had less effects on the basal diameter growth when the water in epikarst layer was available. The photosynthesis-light response curve of the seedlings fitted the nonrectangular hyperbola model well, meaning an agreement between the model and the actual response of the seedlings photosynthesis, and the light response curve under different soil moisture conditions had the similar variation trend. The maximum net photosynthetic rate (Pmax) and the apparent quantum yield (AQY) of the seedlings under different soil moisture conditions were in the order of saturated soil moisture > suitable soil moisture > medium drought > severe drought. Soil drought stress decreased the light saturation point (LSP) and increased the light compensation point (LCP), but the LSP and LCP changed irregularly when the water in epikarst layer was available.

Key words: mid-subtropical planted coniferous forest, light-use efficiency, photochemical reflectance index, environmental factors, water conditions.