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Investigation on seed mycoflora of greengram [ Vigna radiata (L.) Wilczek.] and their management

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Title Investigation on seed mycoflora of greengram [ Vigna radiata (L.) Wilczek.] and their management
 
Creator Deshmukh, Amol Jagannath
 
Contributor Sabalpara, A.N.
 
Subject Unable to Generate Tags nau-53866 deshmukh a. j..pdf
 
Description Greengram [Vigna radiata (L.) Wilczek] is one of the im portant pulse crop grown extensively in Gujarat. It suffers from a number of seed borne pathogens causing heavy qualitative and quantitative losses. This is one of the important constraints in greengram production specially during Kharif season in south Gujarat. Looking to the seriousness of the problem, the present investigation on seed mycoflora of greengram and their management was carried out.
Mainly four types of broad symptoms viz., bold healthy, bold discolored, shrivelled and small seeds were observed in the collected seeds of all the three varieties i.e. GM-3, GM-4 and K-851. Only single type of specific symptom like bold green healthy seeds was observed in bold healthy seed lot, five types of specific symptoms viz., mosaic, brown lesion, black lesion, red to dark red spot and whole brownish coloured seeds were observed in bold discoloured seeds, six types of specific symptoms viz., apparently green, mosaic, brown lesion, black lesion, red to dark red spot, and whole brownish coloured seeds in the shrivelled seeds and only apparently green seeds were observed in small seeds.
Study on the confirmation of the fungi associated with various types of symptoms revealed that red to dark red spots on the greengram seeds found to be due to Colletotrichum sp., while black lesions was due to Alternaria sp. and brown lesions on the seed occurred due to Macrophomina sp. The development of mixture of yellow and green coloured pattern on greengram seeds resulted in presence of sterile unidentified fungi, while a group of seed
infecting mycoflora looked responsible for development of whole brownish coloured discolouration.
The isolation of seed mycoflora from the seed samples revealed the association of nine different fungi and were identified as Macrophomina phaseolina (Tassi) Goid (I.T.C.C. No.7811.10), Alternaria alternata (Fr.) Keissler (I.T.C.C. No. 7820.10), Colletotrichum capsici (Syd.) Butler & Bisby (I.T.C.C. No. 7813.10), Nigrospora sphaerica E. W. Masson (I.T.C.C. No. 7819.10), Chaetomium sp. (I.T.C.C. No. 7815.10), Aspergillus sp. (I.T.C.C. No. 7818.10), Rhizopus oryzae Went & Prins. Geerl. (I.T.C.C. No. 7817.10), sterile aseptate (I.T.C.C. No. 7814.10) and sterile septate fungus (I.T.C.C. No. 7816.10).The pathogencity was proved by seed inoculation method with
positive results in reducing seed germination by all isolated fungi. Moreover, mixture of all the fungi and three fungi individually viz., M. phaseolina, A. alternata and C. capsici also proved to be act as a primary source of infection by transmitting the pathogen inoculums from seed to seedling and seedling to plant to cause leaf spot, leaf blight, anthracnose or root rot diseases.
The results on the frequency of associated fungi in seeds of greengram revealed, ectophytic association of nine different fungi viz., Aspergillus sp., M. phaseolina, A. alternata, C. capsici, N. sphaerica, R. oryzae, Chaetomium sp. , non sporulating sterile aseptate fungi and sterile septate fungal mycelia and endophytic association of only four fungi viz., Aspergillus sp., M. phaseolina, A. alternata and C. capsici more or less frequently in all variet y seeds viz., GM-3, GM-4 and K-851. Comparatively higher association of A. alternata (16-24%), C. capsici (4-8%) and Aspergillus sp. (16-24%) was found in GM-3 followed by GM-4 and K-851. Cultivar K-851 was found highly associated with M. phaseolina (16-24%) followed by GM-3 and GM-4.
Detection and location of endophytic fungi in infected seeds of greengram revealed that the fungus, C. capsici represented deep seated nature in seeds of greengram in seed coat, cotyledon and embryo. A. alternata and M. phaseolina were present i n seed coat and cotyledon. Presence of Aspergillus sp. was only in seed coat.
Impact of seed infecting fungi on seed health status in naturally infected seeds evealed that naturally infected small seeds were responsible for higher loss of seed weight followed by shrivelled and bold discoloured seeds. Higher loss of seed germination and seedling vigour was recorded in shrivelled seeds followed by bold discoloured and small seeds.
The study on the assessment of the prevalence of seed infecting fungi in relation to harvesting time and stage with respect to qualitative and quantitative losses revealed that single time delayed harvesting at 90 DAS was responsible in causing higher losses in qualitative pod formation, seed weight, seed quality and comparatively maxi mum frequency of fungal association with
seeds. Two times harvesting at 68 and 75 DAS by mature pod picking revealed minimum losses followed by single time harvesting at 68 and 75 DAS. Moreover, single time delayed harvesting coupled with high temperature, relative humidity and rainfall caused maximum qualitative losses of pods. Greater influence of weather parameters along with the harvesting time and stage on the prevalence of seed infecting fungi was observed to cause
qualitative and quantitative losses.
Experiments conducted on the management of seed borne fungal diseases through seed biopriming revealed that seed biopriming with T. harzianum, T. viride or P. aeruginosa @10 gm talc base formulation/kg seeds proved very effective not only to get better seed germination, seedling vigour, plant growth, root growth, root nodules, yield parameters and yield but also to manage significantly leaf spot (A. alternata), Leaf blight (M. phaseolina) and anthracnose (C. capsici).
Experiments conducted on the management of seed borne fungal diseases through fungicidal seed treatment revealed that dry seed treatmemt with either mix formulation of carbendazim + mancozeb or thiophanate methyl or carbendazim @ 2.5 g/kg seeds proved very effective not only to get better seed germination, seedling vigour, plant growth, root growth, yield parameters and yield but also to manage significantly leaf spot (A. alternata), Leaf blight (M. phaseolina) and anthracnose (C. capsici).
 
Date 2016-05-28T09:41:14Z
2016-05-28T09:41:14Z
2012
 
Type Thesis
 
Identifier http://krishikosh.egranth.ac.in/handle/1/66418
 
Language en
 
Format application/pdf
 
Publisher NAU