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Acclimatization of K + uptake to changes in root temperature: experiments with oilseed rape and barley in flowing solution culture
Author(s) -
MACDUFF J. H.,
HOPPER M. J.,
WILD A.
Publication year - 1987
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.1987.tb01852.x
Subject(s) - hordeum vulgare , brassica , nitrogen , acclimatization , chemistry , horticulture , nutrient , zoology , agronomy , poaceae , botany , biology , organic chemistry
Changes in the net uptake rate of K + and in the average tissue concentration of K + were measured over 14 d in response to changes in root temperature with oilseed rape ( Brassica napus L. cv. Bien venu) and barley ( Hordeum vulgare L. cv. Atem). Plants were grown in flowing nutrient solutions containing 2.5 mmol m −3 K + and were acclimatized over 49 d (rape) or 28 d (barley) to low root temperature (5°C) prior to steady–state treatments at root temperatures between 3 °C and 25 °C, with common air temperature. Uptake of K + was monitored continuously over 14 d and nitrogen was supplied as NH 4 + + NO − 3 or NH + 4 or NO − 3 . Unit absorption rates of K + increased with time and with root temperature up to Day 4 or 5 following the change in root temperature. Thereafter they usually approached steady‐state, with Q 10 ≃ 2.0 between 7 °C and 17°C, although rates became similar between 7 °C and 13°C. Uptake of K + by rape plants was invariably greater under NO − 3 nutrition compared with NH + 4 . The percentage K + in the plant dry matter increased with temperature from 2% at 3 °C to 4% at 25 °C in rape, but there was less effect of temperature on the average concentrations of K + in the plant fresh weight or plant water content. Concentrations of K + in the leaf water fraction of rape plants decreased with increasing root temperature, but in barley they increased with increasing root temperature. Concentrations of K + in the root water fraction were relatively stable with respect to root temperature. The results are discussed in terms of compensatory changes in K + uptake following a change in root temperature and the relationships between growth, shoot: root ratio and K + composition of the plant.