Karine Vandermeiren

Ozone sensitivity of Phaseolus vulgaris in relation to cultivar differences, growth stage and growing conditions

Exposure of Phaseolus vulgaris cv. Lit to ambient ozone caused a 14% pod yield reduction in 1994. This yield loss was assessed by comparing plants that were protected against ozone by treatment with EDU (ethylenediurea) with unprotected plants, both cultivated in pots with a continuous water supply. The plants had experienced an AOT40 of 8135 ppb.h during their growth. However, plant response to ozone depends on a large number of environmental and plant-specific conditions. Visible injury increased mainly after flowering and was much less severe on soil-grown bean cultivars (Lit, Stella and Groffy) not receiving additional water. Ozone fumigations in closed chambers before or after flowering proved that the growth stage during which the plants are exposed also plays a very important role with regard to injury development. Plants seem to be more susceptible during the generative growth stage and the relative cultivar sensitivity was related to the developmental stage during fumigation. However with regard to yield effects the timing of the ozone exposure seems to be less important.

Effects of air filtration on spring wheat grown in open-top field chambers at a rural site. I. Effects on growth, yield and dry matter partitioning

Spring wheat, Triticum aestivum, was grown in open-top field chambers and exposed during the whole life cycle to filtered and non-filtered ambient air. The relatively low ambient pollution level did affect plant growth but had no effect on the overall grain yield of the two spring wheat cultivars Echo (1987) and Pelican (1988). A reduced root growth was found in both years which could be attributed mainly to the deposition of NO2 and SO2. Effects on crop development most likely due to ozone were limited to the 1987 growing season during which the ambient ozone concentrations were enhanced compared to 1988. This resulted in a slightly increased grain harvest index, a reduced 1000-grain weight, straw yield and a greater reduction in root growth. Visible damage resembling ozone injury appeared both years during seedling growth.

Accumulation of atmospheric deposition of As, Cd and Pb by bush bean plants.

Bush bean (Phaseolus vulgaris) was exposed to atmospheric deposition of As, Cd and Pb in a polluted and a reference area. The atmospheric deposition of these elements was significantly related to the concentrations in leaves, stems and pods at green harvest. Surprisingly there was also a clear relation for As and Pb in the seeds at dry harvest, even though these seeds were covered by the husks. Root uptake of accumulated atmospheric deposits was not likely in such a short term experiment, as confirmed by the fact that soil pore water analysis did not reveal significant differences in trace element concentrations in the different exposure areas. For biomonitoring purposes, the leaves of bush bean are the most suitable, but also washed or unwashed pods can be used. This means that the obtained relationships are suitable to estimate the transfer of airborne trace elements in the food chain via bush bean.

Impacts of Ground-Level Ozone on Crop Production in a Changing Climate

Ozone (O3) is a naturally occurring chemical present in both the stratosphere (the ‘ozone layer’, 10–40 km above the earth) and in the troposphere (0–10 km above the earth). While stratospheric O3 protects the Earth’s surface from solar UV radiation, tropospheric O3 is the third most important greenhouse gas (after CO2 and CH4) (Denman et al. 2007; Solomon et al. 2007). It contributes to greenhouse radiative forcing, causing a change in the balance between incoming solar radiation and outgoing infrared radiation within the atmosphere that controls the Earth’s surface temperature. Besides its role as a direct greenhouse gas, O3 has been identified as one of the major phytotoxic air pollutants. The adverse effects of O3 on plants were first identified in the 1950s (Hill et al. 1961), and it is now recognized as the most important rural air pollutant, affecting human health and materials, as well as vegetation (WGE 2004).

A comparison of two stomatal conductance models for ozone flux modelling using data from two Brassica species

In this study we tested and compared a multiplicative stomatal model and a coupled semi-empirical stomatal-photosynthesis model in their ability to predict stomatal conductance to ozone (gst) using leaf-level data from oilseed rape (Brassica napus L.) and broccoli (Brassica oleracea L. var. italica Plenck). For oilseed rape, the multiplicative model and the coupled model were able to explain 72% and 73% of the observed gst variance, respectively. For broccoli, the models were able to explain 53% and 51% of the observed gst variance, respectively. These results support the coupled semi-empirical stomatal-photosynthesis model as a valid alternative to the multiplicative stomatal model for O3 flux modelling, in terms of predictive performance.

Response to the environment: Carbon dioxide

Publisher Summary In this review, the authors report the effects of CO 2 on potato phenology, physiology and yield. And explains how the effects are caused, their interactions with other variables and how the acquired information can be integrated into predictive models. A detailed assessment of the number of leaves, LAI and plant height, in combination with intermediate biomass measurements during the European CHIP experiments, made it clear that the influence of elevated CO 2 concentrations on plant growth was very dependent on the developmental stage of the crops. On the whole, elevated CO 2 induces an increase in growth rate that will lead to a biomass increase at full canopy, but at the same time, the active growing period is reduced, and there is an earlier onset of senescence that counteracts final biomass accumulation. The balance between these processes and changes in assimilate partitioning (influenced, e.g., by source–sink imbalance) is responsible for the final yield response. Doubling of the ambient CO 2 level results in tuber yield (dry matter) increases ranging from 0% to 60%. The physiological and morphological responses of potato to elevated CO 2 have been discussed, as have some of the interactions with other environmental factors.