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A Kinetic Analysis of Phosphate Absorption by Excised Roots of Millet, Barley, and Alfalfa
Author(s) -
Noggle J. C.,
Fried Maurice
Publication year - 1960
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1960.03615995002400010017x
Subject(s) - absorption (acoustics) , hordeum vulgare , chemistry , poaceae , dissociation (chemistry) , phosphate , reaction rate constant , agronomy , zoology , botany , biology , kinetics , biochemistry , materials science , physics , quantum mechanics , composite material
A kinetic analysis was made of P absorption at steady state by excised roots of millet, barley, and alfalfa. Short‐time absorption studies indicated that the rate of P absorption is greater for millet than barley and greater for barley than alfalfa. The specific reaction rate constants for the metabolic turnover of the two carriers of P are of the same order of magnitude for the three plant species. They are approximately 1 × 10 ‐2 moles of P per mole of combined carrier per second. The apparent dissociation constant for carrier “a” is approximately 9 × 10 ‐4 for all three plant species, but the value for carrier “b” varies from 3 × 10 ‐6 for millet and alfalfa to 8 × 10 ‐6 for barley. The major difference between species is in concentration of carrier. These values are 2 × 10 ‐7 , 3 × 10 ‐8 , and 1 × 10 ‐8 moles per g. of millet, barley, and alfalfa roots, respectively.