Translocation
Translocation of Organic Solutes Plants synthesize food materials by photosynthesis and store the same in the form of starch grains in the chloroplasts found in mesophyll cells. Then the found material is converted into simple sugars; then it is transported to regions where it is required – stem apex, young flower buds fruits and storage organs are the sites to which the organic food is translocated. The site of synthesis and the site of need are separated by time and space. The structures found between these sites play a significant role in translocation.
Structures responsible for translocation
Girdling experiments involving the removal of a ring of cortex including phloem cells below leaves prevent the flow of food materials towards roots which accumulate at the upper rim o the rig and shows swelling. Radioactive tracers like 14CO2 sucrose phosphates supplied to lead are found to be translocated through sieve tube elements. While mealy bugs pierce their stylets into sieve tubes and suck the sap, the white bugs have specialized in feeding on the sieve tube sap. Thus various studies reveal that the food material is translocated through sieve tubes.
Rate of translocation Using radio active tracers at the source of supply like leaves, it is possible to measure the rate of translocation. Such experiments have shown that, the organic food material is translocated at the rate of 100-200 cm per hour which is relatively 1000 times faster than the rate of passive diffusion. However, not all plants exhibit the same rate of transport and it varies from plant to plant; added to this various factors also contribute to the rate of movement. Direction of movement:
Food material always moves from the leaves of different regions of the plant body organic solutes found in the leaves nearer to the stem apex move upwards, and leaves found at the base move down wards. But the substances in the leaves found in between, move in
Structures responsible for translocation
Girdling experiments involving the removal of a ring of cortex including phloem cells below leaves prevent the flow of food materials towards roots which accumulate at the upper rim o the rig and shows swelling. Radioactive tracers like 14CO2 sucrose phosphates supplied to lead are found to be translocated through sieve tube elements. While mealy bugs pierce their stylets into sieve tubes and suck the sap, the white bugs have specialized in feeding on the sieve tube sap. Thus various studies reveal that the food material is translocated through sieve tubes.
Rate of translocation Using radio active tracers at the source of supply like leaves, it is possible to measure the rate of translocation. Such experiments have shown that, the organic food material is translocated at the rate of 100-200 cm per hour which is relatively 1000 times faster than the rate of passive diffusion. However, not all plants exhibit the same rate of transport and it varies from plant to plant; added to this various factors also contribute to the rate of movement. Direction of movement:
Food material always moves from the leaves of different regions of the plant body organic solutes found in the leaves nearer to the stem apex move upwards, and leaves found at the base move down wards. But the substances in the leaves found in between, move in