Time filter

Source Type

Manici L.M.,Italian Agricultural Research Council | Kelderer M.,Laimburg Research Center for Agriculture and Forest | Caputo F.,Italian Agricultural Research Council | Mazzola M.,U.S. Department of Agriculture
Plant Pathology

This study aimed to elucidate the relationship between plant hosts and root-colonizing fungi recovered from apple orchard soils that had been replanted over multiple generations. Functional relationships of three groups of filamentous fungi (Ceratobasidium sp., Cylindrocarpon-like group and Fusarium acuminatum) with apple rootstocks were evaluated in plant growth bioassays. The Cylindrocarpon-like group and Ceratobasidium sp. showed a relationship with the host plant varying from pathogenic to commensal through to mutualistic for the latter group, while that of F. acuminatum tended to be mutualistic. Seven fungal isolates of each group, which induced the highest plant growth in bioassays, were evaluated for auxin (IAA) and gibberellin (GA3 and GA4) production in culture filtrate. All isolates of F. acuminatum as well as most of those of the Ceratobasidium sp. and Cylindrocarpon-like groups produced IAA in culture filtrate. IAA production was evaluated for additional isolates of endophytic fungal species from fruit tree orchards and the functionality of IAA was confirmed by growing in vitro micropropagated plantlets of apple rootstock on MS medium supplemented with fungal culture filtrate. Findings from this study may explain the difficulty in defining the precise role of diverse root-colonizing fungal populations in replant disease aetiology of fruit tree orchards. However, the results demonstrate the presence of a positive and widely available biotic component of the orchard soil biology that may be exploited for the benefit of tree growth and production. © 2014 British Society for Plant Pathology. Source

Manici L.M.,Italian Agricultural Research Council | Kelderer M.,Laimburg Research Center for Agriculture and Forest | Caputo F.,Italian Agricultural Research Council | Nicoletti F.,Italian Agricultural Research Council | And 2 more authors.
Canadian Journal of Plant Science

Replant disease of fruit tree orchards has a multifactorial etiology, mainly due to the decline in soil biodiversity along with an increase in root rot pathogens, which can be principally countered with appropriate cropping practices. Therefore, a study on the impact of cover crops on plant health of young fruit trees in long-term orchards was performed. Bioassays were performed over two consecutive growing cycles using soil from a multigeneration apple orchard affected by replant disease. First, a cycle was performed with three cover crops (alfalfa, barley, marigold) and apple rootstock plantlets; at the end, the above-ground part of the plant was removed and root residues left in the soil. In the second cycle, an apple orchard planting was simulated upon the first experimental design. Changes of diversity and composition of root inhabiting fungi and rhizospheric bacteria were evaluated as well as apple plant growth response to the pre-plant treatments. Results suggest that one cycle with alternate plants was sufficient to induce changes at the rhizosphere level, despite soil microbial resilience caused by the same long-term soil management. Rhizospheric bacteria were generally affected by plant genotype. Findings suggest that all three different cover crops can harbor almost all fungal species that colonize apple in replanted orchards (Fusarium spp., Pythum spp., binucleate Rhizoctonia sp., Cylindrocarpon- like-fungi and a several nonpathogenic saprophytic fungi named ‘‘other’’), but their infection frequency varied according to the host plant. A single pre-plant break treatment did not overall differ significantly in plant growth of subsequent apple tree; however, break with marigold, which increased abundance of nonpathogenic root inhabiting fungi more than other cover crops, gave significantly higher plant growth than obtained after barley. This study provides evidence about cover- crop potential to increase soil diversity in long-term permanent cropping systems and to manipulate root colonizing fungi involved in crop health. © 2015, Agricultural Institute of Canada. All rights reserved. Source

Discover hidden collaborations