The effects of long‐term open‐air fumigation with SO₂ on a field crop of broad bean (Vicia faba L.) II Effects on growth components, leaf area development and elemental composition

Abstract

SUMMARYFaba bean erops (Vicia faba L.) were exposed to elevated SO, concentrations in three different years in an openair field exposure system for the controlled release of air pollutants. The treated crops were exposed to an average SO2 concentration of 165/fKm-' in 1985, 62/*g nn"^ in 1986 and 74/(g m"-' in 1988. The ambient SO., concentration was about \0 /ig m'''. Plant height, number of internodes and number of pods were not affected by SOj. The specific leaf area was reduced in the plants exposed to SO., at the end of the growing season. Leaf area de\-elopment was strongly affected during the pod-filling period in 1985 and 1988 as a result of leaf injury and defoliation in the fumigated plots. In 1986 a similar trend in leaf area reduction was observed in the early reproductive phase.N and Mg content of the different organs was unaffected by SO,. The S content was strongly elevated in the leaves and pods of the fumigated plants, and the Ca content of the leaves was reduced by SOj. Chlorophyll content of different leaf numbers was unaffected hy SO,.

Long-term effects of SO2 on plants, SO2 metabolism and regulation of intracellular pH

“…5B). In contrast to these results, in an earlier field experiment in 1985 a significantly lower Ca content in the leaves of the fumigated plants was observed (Kropff et a/., 1989b). This may be explained by the stronger injurious effect of S0 2 on leaf area in 1985 as a result of the higher S0 2 concentration.…”

A Mathematical Function for Crop Growth Based on Light Interception and Leaf Area Expansion

“…crop of Faba bean grown in an experiment to determine the effect of 80 2 fumigation on biomass growth (Kropff et al, 1989a). The experiment was done in 1985 with an average concentration of 165 p,g 80 2 m-3 in the fumigated treatment, and a background concentration of 16 p,g 80 2 m-3 in the control treatment.…”

Quantifying the direct effects of SO2 and O3 on forest growth

“…Here, short-term responses refer to effects that can be seen after short periods of exposure (hours to days), whereas long-term effects appear only after prolonged periods of exposure (weeks to months). Often the changes induced by the uptake of pollutants appear to be reversible, such as when photosynthesis is temporarily reduced because of build-up of toxic sulphite that results from the uptake of so2 (Kropff, 1989a, b;Kropff et al, 1989a;Lange et al, 1989 ); if the pollutant load is removed the amount of sulphite gradually decreases through detoxification, and the metabolism is able to recover. The maximum rate of detoxification determines whether cumulative effects occur with ongoing exposure; this rate depends on the detoxification capacity of the plant cell (possibly related to nutrient status) and on the speed of the biochemical reactions involved.…”