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Changes in NO 3 − and K + uptake by four species in flowing solution culture in response to increased irradiance
Author(s) -
Macduff J. H.,
Wild A.
Publication year - 1988
Publication title -
physiologia plantarum
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.351
H-Index - 146
eISSN - 1399-3054
pISSN - 0031-9317
DOI - 10.1111/j.1399-3054.1988.tb00628.x
Subject(s) - lolium perenne , lolium multiflorum , irradiance , perennial plant , poaceae , zoology , brassica , horticulture , biology , nitrogen , botany , chemistry , physics , quantum mechanics , organic chemistry
Net rates of NO 3 − and K + uptake were compared for oilseed rape ( Brassica napus L. cv. Jet neuf), perennial ryegrass ( Lolium perenne L. cv. S23), Italian ryegrass ( Lolium multiflorum Lam. cv. Augusta) and wheat ( Triticum aestivum L. cv. Fen‐man) in flowing solution culture during a 4‐day sequence of low‐low‐high‐high natural irradiance. Concentrations of NO 3 − (10 μ M ) and K + (2.5 μ M ) in solutions were maintained automatically and hourly variation in net uptake of these ions was measured. During the 2 days of low irradiance (<1 MJ m −2 day −1 ) the uptake rates of both ions by all species were low at <1 mmol NO 3 − , m −2 h −1 and <0.4 mmol K + m −2 h −1 . Uptake increased in each species during the first day of high irradiance (7.90 MJ m −2 day −1 ) to >4 mmol NO 3 − m −2 h −1 and >1.4 mmol K + m −1 h −1 . These higher rates were maintained throughout the following night. The lag‐time between maximum irradiance and the onset of the highest acceleration in uptake was greater for NO 3 − (5–8 h) than for K + (≤1 h) in rape, wheat and Italian ryegrass. Uptake of NO 3 − , by perennial ryegrass showed an almost constant acceleration for 18 h following maximum irradiance. In all species the measured maximum inflows (uptake rate per unit root length) of both ions were greater than theoretical maximum potential inflows to a non‐competing infinite‐sink root in soil, by factors of 7 and 36, respectively, for NO 3 − and K + , averaged over all species.