💡 In plants, transpiration, along with root pressure, affects the rate of water flux across both the root and xylem vessels. Increasing the rate of transpiration can sometimes enhance the uptake and placements of elements in the xylem. This enhancement depends on four factors:
📌 Research Highlights:
▶ Plant age: Seedlings and younger plants are less affected by increased transpiration due to their smaller leaf surface area. The importance of transpiration increases as the age and size of plant mature.
▶ Time of day: 90% of total transpiration occurs through the stomata, tiny openings on the leaf’s surface. Transpiration rates and nutrient uptake are higher during the light period.
▶ External concentration: An increase in the concentration of elements in the nutrient medium can enhance the effect of transpiration rates.
▶ Type of element: The effect of transpiration rate on nutrient uptake and transport is usually absent, or minor, for K, nitrate and P, but it may be significant for Na or Ca. As a rule, transpiration enhances the uptake and translocation of uncharged molecules to a greater extent than that of ions.
🎯 The distribution of an element that is transported in the xylem but not the phloem should be related solely to transpiration rates and duration of transpiration. A good example of this is with the manganese inside a single maple tree. The ‘sun leaves’ (high transpiration rates) have higher concentrations of manganese that the ‘shades leaves’ (low transpiration rates).
📷 Image: Enhancement of nutrient uptake depends of four key factors.