Response of nitrogen metabolism in beans (Phaseolus vulgaris L.) after exposure to ozone and nitrogen dioxide, alone and in sequence

Abstract

summary Bush bean (Phaseolus vulgaris L.) plants were exposed to low levels of ozone (O3) and/or nitrogen dioxide (NO2) in open‐top chambers during the growing seasons of 1988 and 1989. Treatments consisted of charcoal‐filtered (CF) air, and CF air enriched with either O3 (50–60 nll −1), NO2 (30–40 nll−1) or both gases. A daily sequential exposure, O2 followed by NO2, was used in each year in the combined treatment: O2 was added for 8 h d−1 from 08.00 h until 16.00 h, and NO2 for 16 h d−1 from 16.00 h until 08.00 h. Growth variables and key enzymes of N assimilation in leaves were investigated during vegetative growth and at anthesis. Pollutant effects varied between years. No significant effects were found in 1988. In 1989 NO2, alone or in sequential exposure with O3+, increased leaf dry weight and total biomass until anthesis. Moreover, there was a parallel increase in the extractable activity of both nitrate and nitrite reductase in the NO2 treatments during vegetative growth, while glutamine synthetase and glutamate dehydrogenase were only increased by sequential exposure to O3+ NO2. In contrast, during anthesis the activities of nitrite reductase and glutamine synthetase were lowest in leaves sequentially exposed to O3+ NO2. Ozone alone had very little effect on N metabolism but suppressed growth during anthesis. At pod maturity, the lowest leaf dry weight and leaf area occurred in plants exposed to the sequential combination of O3+ NO2, but yield (pod weight) was not significantly affected by any of the pollutant treatments. It is concluded that chronic exposure especially to the sequence O3−NO2 reduced the capacity of the plants for N assimilation. The observed shift in nitrogen metabolism during the plants' development may have contributed to the adverse effects of the sequential treatment O3+ NO2 on growth variables at the end of the exposure period.

Response of arbuscular mycorrhizal mungbean plants to ambient air pollution

“…This may be considered as a reflection of more vigorous growth of FA plants through out the experimental period. These results are also inline with the previous studies carried out in North America (Kats, et al, 1985;Amundson, et al, 1987), Europe (Adaros, et al, 1991 ;Bender, et al, 1991;Pleijel, et al, 1991), Japan (Nouchi, et al, 1995) and Pakistan, (Wahid, et al, 1995a(Wahid, et al, , 1995. The difference in growth between UFA and AA plants may be considered due to dust particles.…”

Effects of NO (+ NO2) pollution on growth, nitrate reductase activities and associated protein contents in glasshouse lettuce grown hydroponically in winter with CO2 enrichment

“…Increases in activity in tlie leaf of both NaR (Murray & We! !burn, 1985;Rowland et al, 1987;Bender, Weigel & Jager, 1991;Theone et al, 1991) and NiR (We!lbum et al, 1980;Besford & Hand, 1989) after fumigation with NO, are analogous to the effects of increasing nitrate supply to the roots, and further support for the concept that NO., acts by supplying the substrate nitrate which induces NaR and NiR activity (see Wellburn, 1990). Increased NiR activity is also associated with increased amounts of NiR protein (Besford & Hand, 1989) which were detected by western blotting.…”

Ecological ramifications of the direct foliar uptake of nitrogen

“…The primary hypotheses presented have proposed antioxidant compounds in the apoplast facilitating rapid uptake (Ramge et al 1993;Teklemariam and Sparks 2006;Eller and Sparks 2006;Haberer et al 2006) and regulation of the transport and consumption of the apoplastic endpoint products (NO 2 -, NO 3 -, and NH 4 ? ) by downstream enzymatic activity (Zeevaart 1976;Murray and Wellburn 1985;Rowland et al 1987;Bender et al 1991;Thoene et al 1991;Hur and Wellburn 1994;Hufton et al 1996;Wellburn 2002;Eller and Sparks 2006). Eller and Sparks (2006) suggested the uptake of NO 2 to leaves could be predicted with fidelity using a correlative model considering stomatal conductance, apoplastic ascorbate, and leaf nitrate reductase activity.…”