Interaction of leaves and roots ofRuppia maritimain the uptake of phosphate, ammonia and nitrate

✍ Scribed by G. B. Thursby; M. M. Harlin

• Book ID: 104753433
• Publisher: Springer-Verlag
• Year: 1984
• Tongue: English
• Weight: 730 KB
• Volume: 83
• Category: Article
• ISSN: 0025-3162
• DOI: 10.1007/bf00393086

✦ Synopsis

Leafy shoots of Ruppia maritima were incubated in twocompartment chambers, with the roots in one compartment and the leaves in the other. Rates of phosphate and ammonia uptake were compared when roots and leaves were supplied with these nutrients separately and simultaneously. Uptake of phosphate and ammonia by leaves was redueed when these nutrients were supplied to the roots, but uptake by roots was not affected by the availability of these nutrients to leaves. This response suggested root-toshoot translocation predominated. Vma x for leaf uptake of phosphate was decreased by 31% when roots were supplied with phosphate simultaneously. Leaf uptake of ammonia was not affected by the availability of ammonia to roots unless the plants were starved for nitrogen. Vmax for plants starved for nitrogen was two times greater than for unstarved plants. When roots and leaves of starved plants were exposed simultaneously to ammonia, Vma x for ammonia uptake by leaves did not change but Ks increased by 97% to a value similar to that for unstarved plants. Ammonia supplied to leaves or roots inhibited nitrate uptake by leaves by an average of 52%. Ammonia supplied to leaves, however, had no influence on the rate of nitrate uptake by roots. * Contribution No. 579 of the Environmental Research Laboratory, US Environmental Protection Agency. Use of product names does not imply endorsement by USEPA