Soil properties, but not plant nutrients (N, P, K) interact with chemically induced resistance against powdery mildew in barley

Abstract

± ZusammenfassungChemically induced resistance is a promising method of plant protection against diseases, which can be triggered by systemically acting chemical inducers such as BTH (benzo(1,2,3)thiadiazole-carbothioic-acid-S-methylester). BTH is commercially distributed as a 50 % formulation, called Bion . The uncertain success of Bion application in controlling infection by powdery mildew is a major obstacle in using induced resistance for plant protection in agriculture. This study aimed to investigate the effect of soil properties, selected macronutrients (N, P, and K), and addition of organic matter on induced resistance and to identify possible factors responsible for the high variability of BTH effect under field conditions. A pot experiment under open-air conditions was set up using the pathosystem Hordeum vulgare cv. Ingrid / Blumeria graminis f. sp. hordei race A6. The different soils strongly affected the resistance of barley plants against powdery mildew after BTH treatment. The infection of barley by powdery mildew was lower than on all other soils when grown on an acid forest soil which was limed up to pH 4.9, even after BTH treatment. A reproducible induction of pathogen resistance by BTH was shown only on a mineral soil (Kleinlinden) with a negligible C content. Application of N, P, and K did not consistently affect the induction of resistance by BTH. The addition of green manure and compost led to an enhanced variability of resistance induction on the soil ªKleinlindenº. Possible effects of soil microflora on resistance induction are discussed.Bodeneigenschaften, aber nicht Pflanzennährstoffe (N, P, K) interagieren mit der chemisch induzierten Resistenz gegen Gerstenmehltau in Gerste Chemisch induzierte Resistenz ist eine viel versprechende Methode im Pflanzenschutz, welche durch systemisch wirkende Substanzen wie BTH (Benzo(1,2,3)-thiadiazolcarbothion-Säure-S-Methylester) induziert werden kann. BTH ist die wirksame Komponente des kommerziell erhältlichen Produkts Bion . Allerdings ist die Wirksicherheit von Bion im Feld gering, wodurch die Anwendung des Produkts im Pflanzenschutz eingeschränkt ist. Das Ziel der vorliegenden Arbeit war es, den Einfluss verschiedener Böden, ausgewählter Makronährstoffe (N, P und K) und des Zusatzes von organischem Material zum Boden auf die induzierte Resistenz zu untersuchen und Faktoren zu identifizieren, die für die unsichere BTH-Wirkung im Feld verantwortlich sind. Dafür wurden Gefäûexperimente unter freilandähnlichen Bedingungen durchgeführt. In diesen wurde das Pathosystem Hordeum vulgare cv. Ingrid / Blumeria graminis f. sp. hordei Stamm A6 verwendet. Es wurde ein starker Einfluss des Bodens auf die Resistenz der Gerste gegen Gerstenmehltau nach BTH-Behandlung ermittelt. Die Mehltauinfektion von Gerste, welche auf einem sauren Waldboden kultiviert wurde, der auf einen pH-Wert von 4,9 aufgekalkt worden war, war niedriger als auf allen anderen Böden, selbst nach BTH-Behandlung. Eine reproduzierbare Induktion der Pathogenresistenz durch BTH konnte nur auf ein...

Induction of Pathogen Resistance in Barley by Abiotic Stress

“…Therefore, this phenomenon is often named chemically-induced resistance (cIR) when describing the systemic resistance after application of a synthetic compound. In a recent paper, we demonstrated the high variability of chemically-induced resistance using various soils and nutrient regimes in pot experiments (Wiese et al, 2003). Even if the same soil is used, variations in soil water potential may occur.…”

Control of foliar diseases in barley: towards an integrated approach

“…But not all studies have found an effect of nitrogen on the efficacy of induced resistance. Wiese et al (2003) could find no effect of nitrogen on resistance induced by ASM against powdery mildew on barley in field trials. Instead, they found that resistance induced by ASM was most profoundly affected by the organic matter content of the soil, with soils containing low organic matter content exhibiting the greatest induction of resistance.…”

“…In soils with low organic matter content and hence low microbial activity, any rhizobacteria-induced resistance would be much less, allowing ASM induced resistance to be expressed. The suggestion of Wiese et al (2003) that induction of resistance in field-grown barley by the soil microbial population might affect the ability of the plant to respond to ASM is interesting in the light of recent work on barley responding to the elicitor combination ASM + BABA + cis-jasmone (Walters et al 2011b). Here, the authors found that if plants were already infected with R. commune, their ability to respond to the elicitor combination was significantly compromised.…”

Induced resistance: destined to remain on the sidelines of crop protection?

“…Instead, they found that resistance induced by ASM was most profoundly affected by the organic matter content of the soil, with soils containing low organic matter content exhibiting the greatest induction of resistance. The authors suggested that high microbial activity in soils with high organic matter content may have led to a high degree of resistance, possibly induced by rhizobacteria and which could not be further enhanced by ASM (Wiese et al 2003). In soils with low organic matter content and hence low microbial activity, any rhizobacteria-induced resistance would be much less, allowing ASM-induced resistance to be expressed.…”

“…However, not all studies have found an effect of nitrogen on the efficacy of induced resistance. Wiese et al (2003) could find no effect of nitrogen on resistance induced by ASM against powdery mildew on barley in field trials. Instead, they found that resistance induced by ASM was most profoundly affected by the organic matter content of the soil, with soils containing low organic matter content exhibiting the greatest induction of resistance.…”