Root activity in 'carabao' mango (Mangifera indica L.) trees by radiotracer technique using 32P [radioactive phosphorus; study conducted in the Philippines]
1981
Mercado, E.L.
The zones of most active roots of 24 yr-old, grafted 'carabao' mango planted in Ibaan loan were determined with the use of radioactive isotope, 32P. Each tree received a total dose of 5 mci 32P contained in glass ampoules inserted and crushed in holes dug around the tree at different combinations of soil depths (15, 30, 60 cm) and lateral distance from the trunk (100, 200, 300 cm). With a Geiger-Muller counter, activities of leaf samples were assessed 15, 30, 45 and 60 days after 32P placement. The zone of highest root activity, in terms of 32P uptake, occurred at a depth and distance of 30 and 100 cm, respectively. The second peak of uptake was at the same depth and 200 cm from the trunk. Roots 15 cm deep were active when close to the trunk (100 cm). Lowest activity was at 60 cm depth, for all lateral distances. Uptake of 32P was higher from the leaves at the top one-third zone of the tree than from the leaves of bottom one-third zone.
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