Correct option is A
For maintaining hydraulic conductance, trees need to balance the diameter of the xylem vessels with other factors such as the strength of the stem. Here’s why the correct answer is the strength of the stem:
Hydraulic conductance refers to the ability of the plant’s vascular system (especially the xylem) to conduct water. For efficient water transport, trees generally need to have larger diameter vessels to allow for higher water flow rates. However, larger vessels are more prone to cavitation (formation of air bubbles that block water flow), which can be a problem for the tree's water transport system.
To mitigate the risks associated with larger vessel diameters, trees often face a trade-off between vessel diameter and the strength of the stem. Larger vessels may compromise the mechanical strength of the stem because they reduce the proportion of structural tissue, which provides support to the plant. This trade-off means that trees need to carefully balance the size of their water-conducting vessels with the need for stem strength to avoid structural failure while maintaining efficient water transport.
Information Booster:
Stem Strength: The mechanical strength of the stem is determined by the lignin content in xylem fibers and other supportive tissues.
While larger vessels increase hydraulic conductance, they reduce the strength of the stem.
Therefore, a balance must be struck between the diameter of xylem vessels and the need for structural integrity to avoid the risk of breaking or buckling under mechanical stress.
Xylem Vessels: The diameter of xylem vessels directly impacts the flow rate of water.
Larger vessels allow more water to flow but also make the plant more susceptible to cavitation and embolism, leading to a need for the plant to balance vessel size and strength.
