Response of Wheat Fungal Diseases to Elevated Atmospheric CO2 Level

Infection with fungal pathogens on wheat varieties with different levels of resistance was tested at ambient (NC, 390 ppm) and elevated (EC, 750 ppm) atmospheric CO2 levels in the phytotron. EC was found to affect many aspects of the plant-pathogen interaction. Infection with most fungal diseases was usually found to be promoted by elevated CO2 level in susceptible varieties. Powdery mildew, leaf rust and stem rust produced more severe symptoms on plants of susceptible varieties, while resistant varieties were not infected even at EC. The penetration of Fusarium head blight (FHB) into the spike was delayed by EC in Mv Mambo, while it was unaffected in Mv Regiment and stimulated in Mv Emma. EC increased the propagation of FHB in Mv Mambo and Mv Emma. Enhanced resistance to the spread of Fusarium within the plant was only found in Mv Regiment, which has good resistance to penetration but poor resistance to the spread of FHB at NC. FHB infection was more severe at EC in two varieties, while the plants of Mv Regiment, which has the best field resistance at NC, did not exhibit a higher infection level at EC. The above results suggest that breeding for new resistant varieties will remain a useful means of preventing more severe infection in a future with higher atmospheric CO2 levels

Urban inequalities Social geography and demography in seventeenth century York

Includes appendices C-F on fiche in a pocket attached to inside back coverSIGLEAvailable from British Library Document Supply Centre-DSC:D211601 / BLDSC - British Library Document Supply CentreGBUnited Kingdo

Development of a physical model of a typical nineteenth-century English canvas painting

The chemical and mechanical degradation of typical nineteenth-century English canvas paintings has recently been examined. A physical model of such a painting was developed, consisting of fine Ulster linen, rabbitskin glue size, and lead white/oil ground layers. The model painting composite was artificially aged and its validity assessed by comparison with archival specimens prepared by Roberson in the nineteenth century. The failure mechanisms and selected mechanical properties of the model and the archival specimens were compared. The development of such model systems will lead to a better understanding of physical deterioration processes in paintings on canvas supports and to improved approaches to conservation