STUDIES ON EFFICACY OF BIOAGENTS, BOTANICALS AND FUNGICIDES ON SEED MYCOFLORA AND SEED QUALITY OF BLACK GRAM
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Date
2014
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ACHARYA N.G. RANGA AGRICULTURAL UNIVERSITY RAJENDRANAGAR, HYDERABAD
Abstract
Black gram (Vigna mungo L. Hepper) is one of the premium pulse crop amongst all
pulses and is also rich in phosphoric acid. Seed mycoflora known to affect the quality and
quantity of seeds and also decreases seed germination and vigour of the seedlings, seed quality
and causes seed rot, pre and post emergence seedling mortality and root rots. Seed borne fungal
pathogens declines seed viability and vigour both in storage and field conditions and
subsequently resulting in yield loss in field. Macrophomina phaseolina is one of the seed and
soil borne disease causing significant yield loss of up to 25 per cent which decrease the quality
and quantity of black gram seeds rendering the seeds unfit for consumption. Hence, detailed
investigations were carried out to study the occurrence of seed mycoflora of black gram and to
find out suitable detection method, in vitro and in vivo evaluation of bioagents, botanicals and
fungicides against M. phaseolina of black gram was conducted at Department of Plant
Pathology, College of Agriculture, Rajendranagar, Hyderabad during 2011 – 2012.
Sixty black gram seed samples of seven varieties viz., LBG 20, T 9, LBG 753, LBG 623,
LBG 17 (Ranga Reddy), WBG 26 (Warangal), LBG 752, LBG 623, LBG 20 (Guntur), T 9,
LBG 402 and LBG 623 (Krishna), T 9 and LBG 17 (Prakasam), LBG 20 (Srikakulum), East
Godavari and West Godavari) collected from black gram growing locations were analysed by
standard blotter and agar plate methods to detect the mycoflora associated with the black gram
seed samples.
Seven fungi of six genera viz., Aspergillus flavus, Aspergillus niger, Alternaria alternata,
Curvularia sp., Macrophomina phaseolina, Fusarium sp. and Rhizopus sp. were found
associated with different black gram varieties. The occurrence of M. phaseolina was found
predominant (32.1%), while incidence of Curvularia sp. was least (4.67%). The total percentage
incidence of mycoflora was high in var. WBG 26 collected from Warangal district (86%), while
it was low in variety T 9 (3%) of Krishna district by blotter method. The total seed mycoflora
ranged from 28.2 to 86% by blotter method. The occurrence of seed mycoflora was also similar
in agar plate method. The frequency of predominant seed mycoflora viz., M. phaseolina was
high in var. WBG 26 (25%) of Warangal district and least in var. T 9 (1%) of Krishna district.
The total seed mycoflora ranged from 9 to 62.5%.
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Out of two methods employed for detection of seed mycoflora, standard blotter was
found superior over agar plate method.
Among the three methods tested to prove pathogenicity of M. phaseolina on black gram
var. WBG 26, seed inoculation method was found superior in producing maximum seed rot and
seedling blight (90%) over seedling symptom test (80%) and spray inoculation (70%).
In vitro evaluation of fungicides against test pathogen M. phaseolina indicated that captan
and tebuconozole were found on par 99.7% and 99% over pyraclostrobin (80%). Botanical,
neem oil was also effective in inhibiting the test pathogen by 40.4%. Bioagents, Trichoderma
harzianum and T. viride were found to be superior in inhibiting the test pathogen by 99% and
71.2% respectively. The effective botanical (neem oil), bioagent (T. harzianum) and fungicide
(captan) were further tested for their efficacy against test pathogen under glass house conditions.
The results revealed that combined seed treatment with captan + neem oil + T. harzianum was
found to be superior in not only increasing the plant biometrics (shoot length) and seedling
emergence 64.5% and 93.65% respectively, but also resulted in reduction of pre and post
emergence mortality by 89.6% and 89.4%, respectively in black gram.
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Keywords
STUDIES, EFFICACY, BIOAGENTS, BOTANICALS, FUNGICIDES, SEED, MYCOFLORA, SEED, QUALITY, BLACK GRAM,