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.
|出版ステータス||Published - 2003 1月|
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