Abstract In the course of a breeding programme for high‐linolenic‐acid linseed (oilflax, Linum usitatissimum L.) doubled‐haploid lines (DH‐lines) of three F 1 hybrids were generated using an anther‐culture technique. A total of 82 DH‐lines were generated and multiplied in 1993, of which 39 were suitable for testing in a repeated field trial in 1994. Yield, fat content and fatty‐acid composition were determined. The yield of the DH‐lines was not significantly different from that of respective mid‐parent values. Fatty‐acid composition and fat content showed remarkable variation, and DH‐lines exceeded cross parents in some cases for both fat content and linolenic‐acid proportion. Superior DH‐lines surpassed mid‐parent linolenic‐acid‐content values by 4.5% and fat content by 1.9%. The results indicate that anther culture is a useful tool in linseed breeding.
Abstract Cucumber plants (Cucumis sativus L.) were grown under controlled conditions and fumigated with either O 3 , diluted automobile exhaust or a combination of both. The ratio of variable to maximum chlorophyll fluorescence (F v /F m ) was estimated as a measure of PSII activity Activities of the enzymes catalase, glutathione reductase and guaiacol-dependent peroxidase and contents of the antioxidants ascorbate and glutathione were assayed as potential indicators of oxidative stress. The behavior of catalase and of PSII are of particular diagnostic interest because they require continuous repair in light. Exposures of up to 13 days to moderate concentrations of the pollutant gases alone did not induce striking changes in any of the activities that were assayed. A lso when the plants were subjected to an additional stress treatment by exposing them to 4 short cold treatments (2h each at 0 - 4 °C in light on days 12-15 after sowing) which induced marked declines of the F v /F m ratio, the chlorophyll content and the catalase activity, these cold-induced symptoms of photodamage were not significantly enhanced by the fumigation treatments. However, increases of the activities of glutathione reductase and peroxidase observed during a period of recovery following the cold-exposures were markedly higher in O 3- fumigated plants, as compared to plants grown in filtered air or fumigated with car exhaust alone. The results emphasize that effects of moderate pollutant exposures may be latent or delayed over long time periods and that defence responses can be enhanced when plants are exposed to additional, naturally occurring stress situations.
Abstract Shoots of spruce ( Picea abies (L.) Karst.) seedlings grown in solution culture were fumigated with sulfur dioxide or ozone, or with a combination of both for 60 days. Dry weights of the shoots exposed to O 3 and SO 2 /O 3 were increased over the controls. Uptake rates of calcium, magnesium, potassium and nitrate from the nutrient solutions were altered in dependence on fumigation, time of exposure and stage of plant development. Uptake rates of all ions by the seedlings fumigated with SO 2 first increased, but later on decreased as compared to the control. Fumigation with O 3 , or O 3 in combination with SO 2 affected uptake of the various nutrients differently. The effects of the pollutants on the concentrations of calcium and magnesium in the various parts of the seedlings indicate that the changes are not only due to altered water and ion uptake but may be related to various effects in ion transport and plant metabolism.
