ISSN:
1573-2932
Keywords:
Ozone
;
Plant Biochemistry
;
Stomatal Conductance
;
Oxides of Nitrogen
;
Antioxidants
;
Calcium and Signal Transduction
Source:
Springer Online Journal Archives 1860-2000
Topics:
Energy, Environment Protection, Nuclear Power Engineering
Notes:
Abstract Urban air basins produce many pollutants, such as oxides of nitrogen (NOx) and ozone, which move into rural areas. NOx itself has been shown not to be especially phytotoxic except at high levels. More problematical is the conversion of NOx into inorganic nitrogen that the plant can utilize. In ecosystems which are nitrogen- limited, excess nitrogen can radically increase plant growth by stimulating the nitrogen-handling metabolic pathways which then alters "normal" carbon (C) metabolism. On the other hand, ozone alters plant productivity by inducing a decline in growth, speeding developmental events to senescence, lowering reproductive rates, and impairing resistance to other stresses. Three major metabolic events induced by ozone exposure have been well studied: 1) increased turnover of antioxidant systems, 2) production of symptoms similar to tissue wounding, especially ethylene production; and 3) decline in photosynthesis. In order to understand the effect upon productivity of any pollutant, one must understand the mechanisms by which that effect is generated. Those mechanisms must not be merely descriptive statements, but must be firmly modeled with predictions. Any model will be highly complex; however here, the focus will be upon C metabolism. Both a closure of the stomata and a decline in the ability to fix CO2 within the chloroplast can alter the photosynthetic rate of leaves. Yet the movement of C throughout the plant (translocation) seems also to be altered by pollutants. The loss of carbohydrate to roots and growing shoot tips has a profound effect upon the plant's ability to respond normally to the integrated effects of the total environment; loss may cause the most pronounced and long lasting dilemma for plants.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1023/A:1005208306712
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