抄録
Cedrela odorata L. originates from mesic habitats of the Central and South American forest, whereas Khaya senegalensis (Desr.) A. Juss. is native to xeric habitats (hot, dry savanna vegetation) of tropical Africa. In order to estimate drought resistance of C. odorata and K. senegalensis seedlings, transpiration rate (E), stomatal conductance (gs), chlorophyll fluorescence traits and shoot growth in a progressive mild drought were examined under greenhouse conditions. Withholding watering from container-grown plants resulted in a range of soil water potentials (Ψs). As days of drought progressed, E decreased in both species as a result of stomatal limitations. However, K. senegalensis plants generally maintained higher E and gs than C. odorata plants almost throughout the period of soil drying. Chlorophyll fluorescence measurements before and after drought for both species indicated that photosystem II was negatively influenced by soil drying, with C. odorata being more affected than K. senegalensis. The correlation coefficient for E and Ψs; E and Fv ⁄ Fm; gs and Ψs; gs and Fv ⁄ Fm were higher in K. senegalensis than C. odorata under the same period of drought treatment. Drought restricted shoot growth more in C. odorata than K. senegalensis. These findings suggest that K. senegalensis exhibited stronger drought resistance, whereas C. odorata followed a drought-avoiding strategy (greater leaf shedding) and was more conservative in its water use.
