STUDIES ON INTERACTION DYNAMICS OF TRICHODERMA AND FUSARIUM OXYSPORUM IN RELATION TO WILT OF CHICKPEA
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Date
2022-08-11
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guntur
Abstract
In the present investigation on "Studies on interaction dynamics of Trichoderma and Fusarium oxysporum in relation to wilt of chickpea", 24 fields running across 12 villages in six mandals of Prakasam district, A.P were surveyed for the prevalence of Chickpea Fusarium wilt caused by Fusarium oxysporum f. sp. ciceri (Foc). The Fusarium wilt incidence ranged from 59.88% to 100% indicating impact of disease.
Twenty four each of Foc and Trichoderma isolates were collected from the surveyed villages and studied for variability along with one isolate each of Foc and Trichoderma collected from College Farm, Agricultural College, Bapatla.
Variability in Foc isolates was assessed for morphological characters such as macro and micro conidial length and width and cultural characters viz. medium pigmentation, texture, colony elevation, growth habit, colony margin and nature of mycelium. Based on the characters studied, 25 test isolates of Foc were segregated into different groups.
Variability in Foc pathogenicity was observed in pot culture as effect on seed germination and wilt incidence. All the isolates were found equally pathogenic in causing wilt, though variation existed in affecting seed germination.
SCAR marker with an amplicon size of ~207 bp specific to Foc was developed from Foc0-12 RAPD marker sequence of AF492451.1 clone available in genbank NCBI. Specificity and reliability of the SCAR marker was further confirmed by assessing F. moniliforme, other species of Fusarium and different other genera for which the result was negative.
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Variability assessment among the 25 test isolates of Trichoderma used in the present investigation was studied using the cultural and morphological characters. The 25 test isolates, accordingly were identified as T. longibrachiatum (4 No.s), T. pseudokoningii (1 No.s), T. virens (3 No.s), T. aureoviride (2 No.s), T. harzianum (4 No.s), T. asperellum (7 No.s) and T. viride (4 No.s). Molecular analysis of Trichoderma isolates using ITS primers revealed two clusters with 61% similarity.
Based on studies on in-vitro dual culture studies, volatile and non volatile metabolites of Trichoderma and volatile metabolites of Foc and compatibility with biorationals, Trichoderma isolate T 19001 was selected as the most potential isolate for biocontrol of Foc. T 19001 was found to be effective under green house conditions when integrated with panchagavya, by not only increasing germination, root length and shoot length of chickpea, but also significantly reduced the disease incidence over pathogen check.
Pooled analysis of the field experiment conducted during rabi 2018-19 and 2019-20 to assess the biocontrol potential of T 19001 in integration with biorationals revealed that seed treatment with T 19001 + Panchagavya @ 10% resulted in maximum disease control (35.9%) of chickpea wilt complex, yield (1586.5 kg/ha) and B:C ratio (2.40) and was on par with Tebuconazole seed treatment (1672.0 kg/ha and 2.42 B:C ratio). Beejaraksha and beejamrutha were inferior to panchagavya either alone or in integration with T 19001.
Studies on interaction dynamics of Foc and T 19001 in pot culture revealed that T 19001 could lower the population of Foc and thereby decreasing chickpea wilt incidence. Further, increased dose / cfu of Foc warrants increased dose / cfu of T 19001 indicating that dose of Trichoderma should depend on the cfu of Foc in soil for better disease management tactics.
Description
STUDIES ON INTERACTION DYNAMICS OF TRICHODERMA AND FUSARIUM OXYSPORUM IN RELATION TO WILT OF CHICKPEA