Interactions between Plasmopara helianthi, Glomus mosseae and two plant activators DL-b-amino-n-butyric acid (BABA) and CGA 245704 (acibenzolar-S-methyl (BTH)) in sunflower plants susceptible to downy mildew were studied in four experiments using different methods of treatment and pathogen inoculation. Both chemicals were applied as soil drenches and foliar sprays, whereas P.helianthi infection was obtained by root and cotyledon inoculations of the seedlings. Soil drenches at the rates of 50 and 100 mg Kg-1 soil of BABA and BTH given 1 and 3 days before P.helianthi inoculation, respectively to mycorrhizal plants, provided moderate protection against the pathogen (about 50-55%). Morphological changes and decrease in mycorrhizal colonization in roots of BTH-treated plants and in BTH-treated mycorrhizal plants were also observed. Delay in the emergence and reduction of the root systems were more evident at the highest concentration but decreased with time. These effects were absent with the BABA treatment. Foliar spray treatment of BABA and BTH, applied at 4000 and 200 mgml-1, respectively (1 day post-inoculation) to mycorrhizal plants provided good protection (about 80%) against P.helianthi foliar infections. No effects on mycorrhizal colonization or on root systems were observed. In vitro tests on the effect of the compounds on the mycorrhizal fungus showed that the germination of G.mosseae sporocarps increased with BABA treatment whereas it was greatly inhibited by BTH treatment.
Interactions between Plasmopara helianthi, Glomus mosseae and two plant activators in sunflower plants
TOSI, Laura;ZAZZERINI, Antonio
2000
Abstract
Interactions between Plasmopara helianthi, Glomus mosseae and two plant activators DL-b-amino-n-butyric acid (BABA) and CGA 245704 (acibenzolar-S-methyl (BTH)) in sunflower plants susceptible to downy mildew were studied in four experiments using different methods of treatment and pathogen inoculation. Both chemicals were applied as soil drenches and foliar sprays, whereas P.helianthi infection was obtained by root and cotyledon inoculations of the seedlings. Soil drenches at the rates of 50 and 100 mg Kg-1 soil of BABA and BTH given 1 and 3 days before P.helianthi inoculation, respectively to mycorrhizal plants, provided moderate protection against the pathogen (about 50-55%). Morphological changes and decrease in mycorrhizal colonization in roots of BTH-treated plants and in BTH-treated mycorrhizal plants were also observed. Delay in the emergence and reduction of the root systems were more evident at the highest concentration but decreased with time. These effects were absent with the BABA treatment. Foliar spray treatment of BABA and BTH, applied at 4000 and 200 mgml-1, respectively (1 day post-inoculation) to mycorrhizal plants provided good protection (about 80%) against P.helianthi foliar infections. No effects on mycorrhizal colonization or on root systems were observed. In vitro tests on the effect of the compounds on the mycorrhizal fungus showed that the germination of G.mosseae sporocarps increased with BABA treatment whereas it was greatly inhibited by BTH treatment.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
