Combined whole-season effects of elevated ozone and carbon dioxide concentrations on a simulated wheat leaf rust (Puccinia recondita f. sp. tritici) epidemic
A. Von Tiedemann et Kh. Firsching, Combined whole-season effects of elevated ozone and carbon dioxide concentrations on a simulated wheat leaf rust (Puccinia recondita f. sp. tritici) epidemic, Z PFLANZENK, 105(6), 1998, pp. 555-566
Citations number
32
Categorie Soggetti
Plant Sciences
Journal title
ZEITSCHRIFT FUR PFLANZENKRANKHEITEN UND PFLANZENSCHUTZ-JOURNAL OF PLANT DISEASES AND PROTECTION
A complete growth season with the physical climate and ozone pollution from
1 April to 31 July as recorded at a field site in Northern Germany, averag
ed over several years, was simulated in climate chambers and combined eithe
r with a current (370-400 mu l l(-1)) or enriched (620-650 mu l l(-1)) CO2
atmosphere. Wheat, grown from seedling emergence to maturity under the diff
erent physico-chemical climates, was inoculated with leaf rust (Puccinia re
condita f. sp. tritici) at tillering stage and a rust epidemic was induced
by repeated re-inoculations with the newly Formed inoculum. Ozone significa
ntly reduced disease severity, uredospore production and increased the late
nt period of leaf rust on young planes, consequently inhibiting the epidemi
c spread on upper leaves of mature plants. Inhibiting effects of ozone on l
eaf rust development were not reflected by the early infection stages such
as spore germination, germ tube growth, formation of infection hyphae, haus
torial mother cells and haustoria, which remained largely unaffected by the
ozone treatments. However, ozone induced a significantly higher extent of
hypersensitive responses of the infected leaf tissue. Additionally, plants
exposed to elevated ozone turned senescent much earlier than plants without
this stress which prematurely degraded the growth conditions for the funga
l pathogen. Enrichment with CO2 increased the rotal carbohydrate content in
leaves but this had only minor effects on the disease. Thus, elevated CO2
only poorly compensated for the disease-inhibiting effects of ozone. The co
mpensation of ozone effects on wheat leaf rust by elevated CO2 is much smal
ler than known compensatory effects of both gases on plans productivity.