Premium
Ammonia compensation points in two cultivars of Hordeum vulgare L. during vegetative and generative growth
Author(s) -
HUSTED S.,
MATTSSON M.,
SCHJOERRING J.K.
Publication year - 1996
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.1365-3040.1996.tb00008.x
Subject(s) - hordeum vulgare , ammonia , shoot , chemistry , hydroponics , nitrogen , horticulture , anthesis , zoology , botany , cultivar , analytical chemistry (journal) , poaceae , biology , environmental chemistry , biochemistry , organic chemistry
The NH 3 compensation point (χ NH3 ) in Hordeum vulgare cvs Golf and Laevigatum was determined at different growth stages under controlled environmental conditions. The plants were grown to maturity in hydroponics under N limitation. When plants were exposed to NH 3 at realistic ambient levels ranging from 0 to 25 nmol NH 3 mol −1 air at an air temperature of 20°C, a significant ( P < 0.001) linear correlation between the NH 3 flux and the atmospheric NH 3 mole fraction was observed, showing a constant conductivity to NH 3 exchange irrespective of the NH 3 level. For both cultivars a marked decrease in χ NH3 was observed in the period from tillering to anthesis. In cv. Golf, χ NH3 decreased from 6.4 ± 1.1 to 3.0 ± 0.4 nmol NH 3 mol −1 air, while χ NH3 in cv. Laevigatum dropped from 4.2 ± 0.3 nmol NH 3 mol −1 air to below the detection limit (< 0.9 nmol NH 3 mol −1 air). The NH 3 compensation points increased again during senescence, peaking at 5.3 ± 0.8 nmol NH 3 mol −1 air for cv. Laevigatum. The modern and high‐yielding cv. Golf had significantly higher ( P < 0.01) NH 3 compensation points than the old and primitive cv. Laevigatum. Golf also had higher shoot NH 4 + and total nitrogen concentrations than Laevigatum. During generative growth the ratio between NH 3 and water vapour conductivities increased 10‐fold, suggesting a shortening of the diffusive path length for NH 3 compared to H 2 O during leaf senescence.