Impact of cover crop in pre-plant of apple orchards: relationship between crop health, root inhabiting fungi and rhizospheric bacteria

Abstract

. 2015. Impact of cover crop in pre-plant of apple orchards: relationship between crop health, root inhabiting fungi and rhizospheric bacteria. Can. J. Plant Sci. 95: 947Á958. 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., Cylindrocarponlike-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 covercrop potential to increase soil diversity in long-term permanent cropping systems and to manipulate root colonizing fungi involved in crop health.Key words: Alfalfa, barley, marigold, root rot fungal complex, Pythium spp., replant disease, Cylindrocarpon-like fungi, Rhizoctonia sp., permanent cropping systems Manici, L. M., Kelderer, M., Caputo, F., Nicoletti, F., De Luca Picione, F. et Topp A. R. 2015. Impact d'une culture abri sur les vergers de pommiers avant la plantation: liens entre la sante´des arbres, les champignons peuplant les racines et les bacte´ries de la rhizosphe`re. Can. J. Plant Sci. 95: 947Á958. La maladie de la replantation des arbres fruitiers se caracte´rise par une e´tiologie multifactorielle re´sultant principalement d'une baisse de la biodiversite´du sol et d'une hausse de la population des agents pathoge`nes responsables du pourridie´, hausse que l'on peut dans une large mesure combattre en adoptant les mesures agricoles ade´quates. Da...

Cover cropping system and mulching can shape soil microbial status in fruit orchards

“…Corroborating with the current results, cover crops benefit fruit orchards by improving soil microbial growth and activity, and different fruit orchards intercropped with cover crops can alter the rhizosphere microbial community (Manici et al, 2015).…”

Potential of Some Medicinal and Fodder Crops to Alleviate Soil Sickness in the Old Prunus persica var. Persica (L.) Batsch and Malus domestica Borkh. Tree Monocultures

“…A positive effect of marigold species on the allelopathic and biochemical characteristics of soil was shown in our previous studies (Didyk and Mashkovska, 2006). According to the results obtained by Manici et al (2015) marigold used as a pre-plant in apple orchards demonstrated the highest stimulative effect on apple rootstock plantlets growth as well as the increase in the abundance of nonpathogenic root inhabiting fungi more compared to the other tested cover crops. Besides, marigolds (Tagetes spp.)…”

“…It is a major challenge in the sustainable management of fruit orchards, because of its complex effect on soil biological, biochemical, agrochemical and physical characteristics. When properly fit cover crops not only alter allelopathic and biochemical regime of the "sick" soil but also enrich the soil with additional organic matter, which stimulates microorganisms involved in mineralization processes and suppresses phytopathogenic and phytotoxic strains (Manici et al, 2015;Zhou et al, 2019). The changes in soil microbial community affect further detoxification and mineralization processes and contribute to the restoration of the balance of nutrients.…”

“…Europe), marigold (Tagetes patula L. cv. Disco Marinetta) on the soil microbial community colonizing apple trees in orchards suffering SS was studied by Manici et al (2015). All studied cover crops showed the potential to increase soil microbial diversity in long-term permanent cropping systems and to manipulate root colonizing fungi involved in crop health.…”

“…The most effective in this respect was marigold, which increased the abundance of nonpathogenic root inhabiting fungi and stimulated the growth of young apple seedlings more than other cover crops. The author concludes that the appropriate use of a cover crop pre-plant can reduce the inoculum of soil-borne pathogens and give an effective advantage in the early post-plant stage, during which young fruit trees are most susceptible to root rot fungal pathogens (Manici et al, 2015). Tongy Zhou et al (2019) demonstrated that the incorporation of cover crops (mixed herbs or red clover) into the soil in apple orchards improved the chemical composition and had a positive influence on microbial communities.…”