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Effects of NO (+ NO 2 ) pollution on growth, nitrate reductase activities and associated protein contents in glasshouse lettuce grown hydroponically in winter with CO 2 enrichment
Author(s) -
HUFTON CAROLINE A.,
BESFORD ROBERT T.,
WELLBURN ALAN R.
Publication year - 1996
Publication title -
new phytologist
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.742
H-Index - 244
eISSN - 1469-8137
pISSN - 0028-646X
DOI - 10.1111/j.1469-8137.1996.tb01917.x
Subject(s) - nitrate , nitrate reductase , horticulture , cultivar , chemistry , greenhouse , botany , biology , organic chemistry
summary Winter hydroponic growth of several lettuce cultivars under glass showed considerable inhibition (up to 47%) of growth after 6 wk exposure to concentrations of NO (+ NO 2 450 nl −1 in total) typical of emissions from propane burners used for direct heating and CO 2 enrichment. After a further 4 wk under similar conditions, however, these growth depressions were replaced by a swing into benefit so that, by harvest, pollutant‐exposed lettuces were bigger and had faster assimilation rates than those growing in clean CO 2 ‐enriched air. This adaptation may partly be explained by enhanced use of NO 2 ‐derived N by lettuce leaves, a consequence of increased nitrate reductase (NaR) activities and amounts of associated NaR proteins, despite adequate nitrate also being available in the hydroponic fluid. Rates of NaR activity in the roots, by contrast, were depressed by NO (+ NO 2 ) pollution. NaR activities were highest in early afternoon in clean or polluted air but these daily patterns did not coincide with the content of NaR‐associated proteins determined by ELISA. Other mechanisms of modulating NaR activity must therefore be responsible.