PATHOGENIC POTENTIAL AND MANAGEMENT OF SEED MYCOFLORA OF PIGEONPEA [Cajanus cajan (L.) MILLSP.]
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Date
2015-05
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Plant Pathology Dept., N.M.C.A., NAU, Navsari
Abstract
Seed infecting fungi are important constraints for the pigeonpea crop grown during Kharif season. Investigation was carried out on certain aspects related to seed health including isolation of pigeonpea seed infecting fungi, symptomatology induced by seed infecting fungi, impact of seed infecting fungi on seed health status in respect of seed germination and seedling vigour, effect of culture filtrates of seed infecting-fungi on seed germination and seedling growth, effect of seed infection on seed quality, screening of known antagonists as bio-priming agent and phyto-extracts to control seed borne fungi in vitro, management of seed infecting fungi through seed treatment with chemicals. Investigation was carried out during 2014 at Department of Plant Pathology N. A. U., Navsari.
Infected seeds samples of pigeonpea collected from field grown pigeonpea crop of farmer’s fields of Navsari district and Pulse Research Station Farm, N. A. U., Navsari, revealed the
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varieties of symptoms viz; discoloured seeds, shrivelled, damaged, inert matter and healthy seeds. Isolation of seedinfecting fungi was done by standard blotter method and PDA plate method. Isolation by both methods revealed the association of Alternaria alternata, Fusarium oxysporum, Fusarium moniliforme, Fusarium udum, Drechslera sp., Curvularia lunata, Rhizoctonia sp., Aspergillus niger and Aspergillus flavus. In pathogenicity test, highest per cent pre-emergence mortality was observed in seeds inoculated with Aspergillus niger (58.00% & 57.50%) in in vitro and in vivo test, respectively. Whereas, highest post-emergence mortality was recorded in Aspergillus niger (64.29%) in in vitro and Fusarium oxysporum (68.18%) in in vivo test.
All nine different fungi significantly hampered seed health status as evident from artificial inoculation of seed. Overall, fungi induced 6.18 to 42.26, 9.28 to 57.80 and 20.48 to 60.61 per cent reduction in seed germination, shoot length and root length over healthy seeds, respectively. Seed inoculation with Aspergillus niger significantly reduced the germination (56.00%), minimum shoot length (4.00 cm), root length (5.25 cm) and seedling vigour index (518.20).
Seeds inoculated with culture filtrate of Aspergillus niger revealed significantly the lowest seed germination (43.00%), minimum shoot length (3.30 cm), root length (4.70 cm) and seed vigour index (344.20) over control.
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Highest reduction in seed protein (58.17%) and TSS content (52.00%) was observed in discoloured seeds while, decrease lipid content (55.25%) in shrivelled seeds over control.
Seed bio-priming with Trichoderma viride recorded highest seed germination (88.00%), shoots length (9.03 cm), root length (11.17 cm) and gave highest seedling vigour index (1777.46). While, seed treated with Neem seed extract @ 1 % gave highest seed germination (78.67%), shoots length (7.97 cm), root length (9.20 cm) and highest seedling vigour index (1350.00) in phyto-extracts.
Seeds treated with metalaxyl 8% + mancozeb 64% @ 0.2 % gave highest germination (93.33%), shoot length (11.23 cm), root length (13.67 cm) and seedling vigour index (2323.73).
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