Screening of indigenous Trichoderma isolates for abiotic stress and evaluation against collar rot of lentil
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Date
2016
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Department of Plant Pathology, BAU, Sabour
Abstract
Lentil (Lens culinaris), a Rabi season crop belongs to family Fabaceae and sub-family
Paplionaceae. It is a rich source of protein for vegetarians containing about 20-30% protein. It contributes about 6.0 percent share in global pulse production. India is a leading producer of lentil with a total production of 0.94 m tonnes, covering an area of about 1.59 m ha with average productivity of 591 kg/ha. As far as Bihar is concern, lentil covers 0.17 m ha with production of 0.17 m tonnes and average productivity of 1031 kg/ha. Plant diseases play a direct role in the destruction of natural resources in agriculture. In particular, soil-borne pathogens including
Sclerotium rolfsii cause significant losses to the crop. Yield loss due to Sclerotium rolfsii ranges between 20-60 % in various hosts. It has spread during the last few years due to changes introduced in farming, with detrimental effects on crops of economic importance. More specific the effect of a chemical on an organism, the greater the probability of decreasing the effect through genetic shifts in the population, whereas fungicides of broad spectrum produce undesirable consequences on non-target organisms. In contrast, the use of micro-organisms that antagonize plant pathogens (biological control) is risk-free and environmentally safe.
Trichoderma is being the most important fungal bio-agent widely used for plant disease management. Abiotic and biotic environmental parameters may have negative influence on the bio-control efficacy of Trichoderma strains; therefore it is very important to generate information about the effects of environmental factors on the different activities of Trichoderma strains with respect to bio-control. Some of the mechanisms used by Trichoderma to alter the drought response include drought avoidance through morphological adaptations, drought tolerance through physiological and biochemical adaptations, and enhanced drought recovery. The root colonization by Trichoderma increases the growth of roots and of the entire plant, thereby increasing plant productivity and yield. Recently, antagonists of phytopathogenic fungi have been used to control plant diseases, and 90% of such applications have been carried out with different
strains of the fungus Trichoderma. In the study eleven Trichoderma isolates have been isolated from different fields of agro ecological zone III-A of Bihar. All Twelve Trichoderma isolates were screened for abiotic stresses viz., heat stress, salt tolerant capacity, pH tolerance and antagonistic potential by dual inoculation test with Sclerotium rolfsii, Rhizoctonia solani and
Fusarium oxysporum f. sp. lentis. In all in-vitro tests, isolate Tvb1 was found to be the most efficient and can tolerate up to 45⁰C temperature, 2000 mM salt concentration, pH up to 11 and suppressed 89.2% Sclerotium rolfsii, 90.2% Rhizoctonia solani and 92.3% Fusarium oxysporum f.sp. lentis followed by Thg1 at 30⁰C. At increased temperature of 35⁰C, Tvb1 antagonised S. rolfsii by 40.43 %, R. solani by 40.82 % and F. oxysporum f. sp. lentis by 42.12 % followed by
Thg1. Both the isolates, Tvb1 and Thg1 were found statistically more efficient (P≤0.)01 antagonists than Trichoderma viride (TC) isolated from commercial formulation against tested pathogens at both temperatures (30⁰and 35⁰C). The most efficient Trichoderma isolate Tvb1and Thg1 were molecularly characterizes as Trichoderma asperellum after the amplification of 18S rRNA gene and sequencing. For the evaluation of most efficient Trichoderma spp., T. asperellum
Tvb1 and Thg1 were evaluated in pot culture against S. rolfsii with lentil. In this experiment it was found that T. asperellum Tvb1 decreased the disease incidence most efficiently (P≤0.)and05 correspondingly increased the yield (pod/plant by 37.97 %, Number of seed/plant by 54.13 % and weight of seeds/plant by 55.56 %) in comparison to inoculated plants with S. rolfsii. Application of Tvb1 also delayed wilting in lentil plants by twelve days compare to inoculated plants with pathogen (S. rolfsii). It was also found that Tvb1 efficiently (P≤0.)enhanced05 the plant vigour index (germination %, shoot and Root length) and yield of lentil plants in comparison to un-inoculated untreated plants. However, T. asperellum Tvb1 needs to be evaluated in the field conditions and may be used against different soil borne pathogens especially against S. rolfsii causing collar rot disease in lentil under abiotic stressed soils.
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