© 2003 Heron Publishing—Victoria, Canada
Variations in transpiration rate and leaf cell turgor maintenance in saplings of deciduous broad-leaved tree species common
in cool temperate forests in Japan
Takami Saito (1, 2, 3), Tadashi Tanaka (4), Hiromi Tanabe (5), Yoosuke Matsumoto (6) and Yasushi Morikawa (7)
1. Graduate School of Human Science, Waseda University, Saitama 359-1164, Japan / 2. Department of Biology, Graduate School of Science, Osaka University, 1-16 Machikaneyama-Cho, Toyonaka, Osaka 560-0043, Japan / 3. Author to whom correspondence should be addressed (>takami@bio.sci.osaka-u.ac.jp) / 4. Forestry and Forest Products Research Institute of Yamanashi Prefecture, Yamanashi 400-0502, Japan / 5. Laboratory of Forest Ecology, Chiba University, 648 Matsudo, Matsudo City 271-8510, Japan / 6. Forestry and Forest Products Research Institute, Ibaragi 305-8687, Japan / 7. Faculty of Human Science, Waseda University, Saitama 359-1164, Japan / Received September 5, 2001; accepted February 8, 2002; published online December 2, 2002
Summary
To clarify mechanisms underlying variation in transpiration rate among deciduous broad-leaved tree species, we measured diurnal
changes in stomatal conductance (gs) and leaf water potential, and calculated the maximum transpiration rate (Emax), leaf-specific hydraulic conductance (Ks–l) and difference between the soil water potential and the daily minimum leaf water potential (Ψs – Ψl,min). Pressure–volume (P–V) measurements were made on leaves. Saplings of eight broad-leaved tree species that are common in Japanese cool temperate
forests were studied. Maximum transpiration rate varied significantly among species. There was a statistically significant
difference in Ψs – Ψl,min, but not in Ks–l. Species with large Emax also had large Ψs – Ψl,min and gs. The results of the P–V analyses showed that species with a large Ψs – Ψl,min maintained turgor even at low leaf water potentials. The similar daily minimum leaf pressure potentials (Ψp) across all eight species indicate that Ψp values below this minimum are critical. Based on these results, we suggest that the leaf cell capacity for turgor maintenance
strongly affects Ψs – Ψl,min and consequently Emax via stomatal regulation.
Keywords:
hydraulic conductivity, pressure–volume curve, soil–plant–atmospheric continuum (SPAC), stomatal conductance.
