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The effects of oxides of nitrogen and carbon dioxide enrichment on photosynthesis and growth of lettuce ( Lactuca sativa L.)
Author(s) -
CAPORN SIMON J. M.
Publication year - 1989
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.1469-8137.1989.tb00710.x
Subject(s) - lactuca , photosynthesis , fumigation , carbon dioxide , stomatal conductance , nitrogen , chemistry , horticulture , botany , biology , organic chemistry
summary The response of glasshouse crops to the nitrogen oxide pollutants which may be generated during enrichment with O 2 has been studied in controlled environments. Lettuce ( Lactuca sativa L. cv. Ambassador) was grown in air containing either low CO 2 , (380μmol mol −1 ), high CO 2 , (1200 μmol mol −1 ), or high CO 2 plus oxides of nitrogen? (NO x )‐ Carbondioxide enrichment increased the rate of emergence and expansion of leaves and the growth of Young plants. Addition of NO x (2μmol mol −1 NO and c. 0.5 μmol mol −1 NO 2 ) to CO 2 ‐enriched air significantly reduced the yield, compared with the ‘clean, high CO 2 treatment, without producing visible symptoms of toxicity. Fumigation of single plants in high CO 2 , with NO x rapidly inhibited photosynthesis per unit leaf area. This did not appear to be due to a reduction in stomatal conductance. Removal of NO x from the atmosphere caused a rapid and complete recovery in the rate of photosynthesis. Studies were made of the effects of growing Plants for long periods in atmospheres containing high CO 2 and NO x on the photosynthetic capacity of single leaves when measured in NO x ‐free air. The decrease in photosynthetic rate as the fourth leaf aged occurred earlier in plants grown in CO 2 ‐enriched air than in those from the low CO 2 treatment. Leaves which developed in the CO 2 ‐enriched air containing NO x did not suffer any long‐term damage to photosynthetic activity in comparison with those of the ‘clean’ high CO 2 . In mature leaves the principal long‐term effect of enrichment (with or without NO x was to reduce the rate of photosynthesis in saturating CO 2 . In contrast, there was less effect on the rate of Photosynthesis in low CO 2 . The absence of a long‐term effect of NO x , on the photosynthetic capacity suggested that photosynthesis by the lettuce crop will be inhibited only during the transient periods of NO x accumulation in the glasshouse.