Water Transport In Schefflera Arboricola : Physiological and Anatomical Aspects

Schefflera arboricola (Araliaceae) was selected to study the effect of short term drought stress and other environmental factors on water transport. Effects of photosynthetic photon flux density, relative humidity, temperature, and soil water potential were studied. Leaf water potential was not affected under drought stress; even at very low transpiration rate. Constant xylem water potential in S. arboricola could be a strategy to avoid leaf abscission. Stem diameter fluctuation was affected by decreasing soil water potential. Hydraulic resistance for water flow between the soil and leaves decreased in the beginning and after that increased with decreasing soil water potential. Internal structures of well irrigated and water stressed plants were generally the same except new formed leaves. Cuticle thickness, xylem vessels' area were affected. Number of druses, in water stressed plants, were higher than well-irrigated plants. Optimal growth of S. arboricola can corroborate with irrigation control which should be in balance between frequency and dose. Stem diameter fluctuations could be an accurate indicator of water status and can be used for optimal irrigation control.