Premium
Growth requirement for N as a criterion to assess the effects of physical manipulation on nitrate uptake fluxes in spinach
Author(s) -
Steege Margreet W. Ter,
Stulen Ineke,
Wiersema Peter K.,
Paans Anne J. M.,
Vaalburg Wim,
Kuiper Pieter J. C.,
Clarkson David T.
Publication year - 1998
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 - 10.1034/j.1399-3054.1998.1030205.x
Subject(s) - nitrate , spinacia , spinach , chemistry , nitrogen , nitrate reductase , nutrient , zoology , biochemistry , biology , organic chemistry , chloroplast , gene
The effects of physical manipulation of hydroponically grown plants of spinach ( Spinacia oleracea L., cvs Subito and Glares) on nitrate uptake fluxes were studied in a long‐term experiment (3 days), and in short‐term label experiments (2 h) with 13 N‐nitrate and 15 N‐nitrate. In the long‐term experiment, net nitrate uptake rate (NNUR) was measured by following the nitrate depletion in the uptake solution, which was replaced at regular intervals. In the short‐term experiments, NNUR and nitrate influx were measured by simultaneous application of 13 N‐nitrate and 15 N‐nitrate. Plants were gently transferred into the labelled uptake solution, as is usually done in nutrient uptake studies. In addition, a more severe physical manipulation was carried out, including blotting of the roots, to mimic pretreatments which involve more handling of the plants prior to uptake measurements. Nitrate influx was measured immediately after physical manipulation and after 2 h of recovery. To assess the impact of the physical manipulation the experimentally determined nitrate uptake fluxes were compared with the N demand for growth, defined as relative growth rate (RGR) times plant nitrogen concentration (PNC) of parallel plants, which were left undisturbed. Nitrate influx and efflux were both subject to changes after physical manipulation of the plants. Physical handling, however, did not always result in an alteration of NNUR, which complicates the determination of the length of the recovery period. The impact of the handling and the time course of the recovery depended on the severity of the disturbance and were independent of the light conditions during the experiments. Even after a gentle transfer of the plants, recovery, in most cases, was not complete within 2 h. The data emphasise the need for minimal disturbance of plants during the last hours prior to nutrient uptake measurements.