EVALUATION OF ORGANIC PRODUCTS ON THE VIABILITY OF THE SCLEROTIA OF RICE SHEATH BLIGHT PATHOGEN, Rhizoctonia solani Kuhn.
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Date
2018
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Acharya N.G. Ranga Agricultural University
Abstract
The present investigation was carried out to study the effect of organic products on the mycelial growth and viability of sclerotia of Rhizoctonia solani Kuhn. Rice sheath blight pathogen R. solani was isolated from the diseased samples obtained from Agricultural Research Station, Nellore and pathogenicity was proved by using detached leaf technique.
The organic amendments viz., neem, groundnut, karanj, sunflower, gingelly and castor cakes were screened against R. solani by poisoned food technique. All the amendments tested at 5, 10 and 15 per cent concentrations were significantly superior to control in checking the mycelial growth of the fungus. Among the tested organic amendments, groundnut cake showed 100 per cent inhibition at 15 per cent concentration followed by neem cake (86.66%) inhibition. The least inhibition was recorded with castor cake (44.44%).
Among the six organic amendments tested against sclerotial viability only two viz., neem and groundnut cakes were found to be effective in inhibiting the sclerotial germination at higher incubation periods i.e. 24 h. Rest of the amendments tested were ineffective in inhibiting sclerotial germination even though they were effective in inhibiting the mycelial growth. Neem cake and groundnut cake were also effective in inhibiting sclerotial germination when applied to soil.
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Bioefficacy of six plant extracts viz., Azadirachta indica, Calotropis indica, Datura stramonium, Lantana camara, Allium sativum, Pongamia glabra Vent. against R. solani were screened by poisoned food technique among which leaf extract of A. indica was found to be most effective in inhibiting the growth of R. solani (85.18%) followed by clove extract of A. sativum (72.59%). It was found that higher the concentrations of extracts, greater will be the inhibition of mycelial growth of R. solani.
Among the six plant extracts tested against sclerotial viability only two viz., clove extract of A. sativum and leaf extract of A. indica were found to be effective in inhibiting the sclerotial germination even at lower incubation periods i.e. 5 min, both in soil application and in vitro. While L. camara and D. stramonium inhibited sclerotial germination at higher incubation periods i.e. 18 h and 24 h. Rest of the plant extracts tested were ineffective in inhibiting sclerotial germination even though they were effective in inhibiting the mycelial growth.
Natural preparations used in organic farming viz., cow urine, panchagavya, beejamrutham, jeevamrutham and modified panchagavya were tested against R. solani using poisoned food technique. All the natural preparations at different concentrations were significantly superior to control in checking the mycelial growth of the fungus. Among the tested preparations, jeevamrutham and beejamrutham showed 100 per cent inhibition on the mycelial growth.
The above natural preparations were also screened against sclerotial viability of test pathogen, in which all except cow urine were found to be effective in inhibiting sclerotial germination under in vitro. Beejamrutham and panchagavya were found to be effective in inhibiting sclerotial germination even at lower incubation period of 6 h. While jeevamrutham and modified panchagavya inhibited sclerotial germination at higher incubation periods i.e. 18 h and 24 h. Cow urine was ineffective in inhibiting sclerotial germination even though it was effective in inhibiting the mycelial growth. Panchagavya and jeevamrutham were found to be effective in inhibiting the sclerotial germination when applied to soil.
The efficacy of seed treatment with different organic products viz., neem cake, groundnut cake, leaf extract of A. indica, clove extract of A. sativum, panchagavya, jeevamrutham and beejamrutham on the viability of sclerotia admixtured with the seed was tested, in which all the treatments showed significantly highest sclerotial inhibition except neem cake (83.33%) and groundnut cake (76.66%).
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The seed admixtured with sclerotia was treated with different organic products as mentioned above, and the effect of sclerotia on germination and seedling growth was tested by paper towel method. All the seeds germinated in paper towel method. All the tested organic products showed increased seedling growth (root length and shoot length) except groundnut cake when compared to control in paper towel method.
The efficacy of organic products viz., neem cake, groundnut cake, leaf extract of A. indica, clove extract of A. sativum, panchagavya, jeevamrutham and beejamrutham through detached leaf technique was observed. Symptoms were not observed on the leaf bits treated with neem leaf extract, panchagavya, garlic and jeevamrutham and found to be effective.
Description
D5727
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