Biological control of tomato collar rot induced by <i>Sclerotium rolfsii</i> using <i>Trichoderma</i> species isolated in Bangladesh

<p>This study evaluated three <i>Trichoderma</i> strains (<i>T. harzianum</i> TR05, <i>T. virens</i> TR06 and <i>T. asperellum</i> TR08) originating from Bangladesh as potential biological control agents against collar rot of tomato under greenhouse conditions. After seed treatment with TR05, a disease incidence of collar rot (5.36%) was lower than for TR06 (34.2%) and TR08 (20.8%). Germination percentage of tomato was highest for TR05 (90.3%). In soil treatment, inoculation with TR08 resulted in the lowest disease incidence (9.78%), and the disease incidence was statistically no different from that for TR05 (16.4%). Thus, TR05 and TR08 have potential as biological control agents of collar rot in tomato.</p

Arbuscular mycorrhizal fungal community of wheat under long-term mineral and organic amendments in semi-arid Mediterranean Turkey

<p>A minimal amount of information is currently available concerning arbuscular mycorrhizal (AM) fungal associations with crops in semi-arid zones on Leptosols in Turkey. Therefore, using molecular ecological techniques, we studied the effects of different management practices (without fertilization, chemical fertilization, farmyard manure, and plant compost amendments) on AM fungal communities associated with wheat roots. Experiments were conducted in a field established in 1996 in southern Mediterranean Turkey where soil productivity is low owing to unfavorable climatic effects and soil characteristics. We determined 201 partial sequences of AM fungal nuclear ribosomal large subunit genes. The higher AM fungal richness was found in the control treatment without fertilization and plant compost treatments compared with the chemical fertilization and farmyard manure treatments. Clones related to <i>Rhizophagus</i> were found in all treatments and accounted for 37% of the total AM fungal clones, whereas those of <i>Funneliformis</i> were dominant under chemical fertilization. Redundancy analysis based on the frequency of operational taxonomic units revealed that AM fungal communities were divided into three groups, namely, the control treatment, the chemical fertilization treatment, and the organic treatments (farmyard manure and plant compost treatments). Although different organic amendments supported relatively similar AM fungal communities, plant compost induced higher AM fungal richness than farmyard manure fertilization.</p

Native <i>Trichoderma</i> strains isolated from Bangladesh with broad spectrum antifungal action against fungal phytopathogens

<p>Nineteen <i>Trichoderma</i> isolates, collected from different locations in Bangladesh, were characterised through phenotypic, biochemical and molecular means. Besides, they were assessed for their antifungal action <i>in vitro</i>. The isolates were divided into three groups: <i>T. asperellum</i>, <i>T. virens</i> and <i>T. harzianum</i>. A dual culture assay and a culture filtrate assay against 6 phytopathogens revealed that 9 of the 19 isolates showed significant antifungal activities. The isolate <i>T. harzianum</i> TR05 showed the highest inhibition against <i>Fusarium oxysporum</i>, <i>Rhizoctonia solani</i>, <i>Fusarium circinatum and Phomopsis vexans</i>, followed by <i>T. asperellum</i> TR08 and <i>T. virens</i> TR06. TR08 had the highest inhibition against <i>Sclerotium rolfsii</i> and <i>Pythium aphanidermatum</i>, followed by TR05 and TR06. These findings were in agreement with their activities of extracellular hydrolytic enzymes, including chitinase, β-1,3-glucanase, and proteinase. Our results suggest that isolates TR05, TR06 and TR08 have the potential to be effective biocontrol agents against the phytopathogenic fungi.</p