Abstract
The present experiment was conducted at University of Pune for biocontrol of soil-borne plant pathogen Sclerotium rolfsii by incorporating arbuscular mycorrhizal fungi (Glomus fasciculatum) and conventional system of cultivation with different spacing pattern (15 and 30 cm) in field. Both mycorrhizal inoculation and 30 cm spacing pattern significantly increased growth and yield as compared to control or 15 cm spacing pattern. The pathogenic mycorrhizal groundnut plants in 30 as well as 15 cm spacing pattern showed better growth in terms of plant height, leaf and pod number, fresh and dry weight of whole groundnut plant in comparison to non-mycorrhizal pathogenic ones and the plant growth was better in 30 spacing than 15 cm. The colonization by AM fungi in both spacing pattern was higher in absence of pathogen S. rolfsii. However, pathogen’s presence decreased the mycorrhizal colonization considerably in 30 and 15 cm. The disease severity and incidence were recorded to be lowered when inoculated with mycorrhiza in pathogenic groundnut plants as compared to non-mycorrhizal pathogenic ones in both spacing pattern and incidence and severity was significantly lower in 30 cm as compared to 15 cm. Therefore, it was observed from our results that for management of soil-borne pathogens inoculation of AM fungi and spacing patterns are necessary.
Highlights
Groundnut (Arachis hypogaea L.) is very important crop of developing countries which contributes around 95% of world production (Nautiyal, 2002)
S. rolfsii were re-isolated from the seedling of groundnut and the potato dextrose agar (PDA) cultures were identical to original isolate
In 15 cm spacing pattern the incidences of stem rot disease caused by S. rolfsii was 33.33%, 46.66%, 60% respectively in pathogenic mycorrhizal groundnut plants (Gf+Sr) as compared to pathogen infected non-mycorrhizal control groundnut plants by 53.33%, 70%, 83.33% in (C+Sr) after 30, 60 and 90 days of sowing respectively (Tab. 2)
Summary
Groundnut (Arachis hypogaea L.) is very important crop of developing countries which contributes around 95% of world production (Nautiyal, 2002). In India, the state of Maharashtra is among chief producer of groundnut crop in the country. (teleomorph Athelia rolfsii) is among those fungal soil-borne root pathogens which causes severe stem-rot in groundnut plant. There are reports that AM colonization of root systems helps in reducing disease severity caused by soil-borne pathogens such as Sclerotium, Rhizoctonia, Fusarium or Pythium (Mulongoy et al, 1992; Azcón-Aguilar and Barea, 1996), known to be phenomenon of “bioprotection”. Bioprotection ensures disease resistance and helps in development of ecofriendly environment for sustainable agricultural practices today, as chemical measures against soil-borne fungi is often considered to be hazardous and costly. In AM association various mechanisms are employed for biocontrol of plant pathogens such as improvement in nutritional status of the host plant (Karagiannidis et al, 2002), competition for host photosynthates (Xavier and Boyetchko 2004), competition for infection/colonization sites (Azcón-Aguilar and Barea, 1996), morphological changes in the roots system (Gutjahr et al, 2009), root damage compensation (Singh et al, 2000), microbial changes in the mycorhizosphere (Li et al, 2007) and activation of plant defence mechanism (Garcia-Garrido and Ocampo, 2002)
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