||Growth Response in Radish to Sequential and Simultaneous Exposures of NO2 and SO2.
Hogsett, W. E. ;
Holman, S. R. ;
Gumpertz, M. L. ;
Tingey, D. T. ;
||Corvallis Environmental Research Lab., OR. ;Northrop Services, Inc., Corvallis, OR.
Nitrogen dioxide ;
Sulfur dioxide ;
Raphanus sativus ;
Air pollution effects(Plants)
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Sequential and simultaneous exposures of radish Raphanus sativus L. cv. Cherry Belle to 0.8 microliters per liter nitrogen dioxide (NO2) and 0.8 microliters per liter sulphur dioxide (SO2) were conducted under both day- and night-time conditions to examine the effects on growth and development. Plants were exposed for 2 h per week over the four-week growing period. Frequent harvests at regular intervals were utilised for determination of the growth analysis functions. Sequential exposure to the two pollutants had no effect on growth compared with the charcoal-filtered air controls. The simultaneous exposure to the gases significantly reduced plant growth. The relative growth rate was reduced throughout the growing period apparently influenced by a reduced net assimilation rate. The partitioning of the available assimilate was altered to favor leaf growth at the expense of hypocotyl development. Night-time simultaneous exposures also altered growth progress but to a lesser degree than exposures during the day.