Variability in antagonistic activity and root colonizing behaviour of Trichoderma Isolates

Subhendu Jash, Sitansu Pan

Abstract


Antagonistic activity and root colonizing behaviour of 10 Trichoderma isolates collected from different agro-ecological zone of West Bengal were evaluated. Of these, T. viride from Bishnupur (red and lateritic zone) and T. roseum of Alipurduar (terai zone) were most prominent showing superior antagonistic effects and fast growth; both overgrew Rhizoctonia solani after 3 days of incubation in dual culture. Production of volatile and non-volatile substances was highest for T. viride of Falakata (terai) origin as evidenced by the greatest mycelial growth inhibition in R. solani, followed by T. roseum from Alipurduar. The highest growth stimulation of the antagonist by both exudates and extract of Bengal gram (Cicer arietinum Linn.) roots was found in T. harzianum of Kalyani (new alluvial zone) source. This isolate, however, was not only antagonistic to the pathogen, but also colonized the rhizosphere and maintained high population growth (224 x 106 cfu g–1 of soil at 30 days after sowing). Conversely, very low rhizosphere colonizing ability was found in T. roseum collected from Bardhaman’s old alluvial zone. Colonization of non-rhizospheric soil by Trichoderma isolate was very low compared to that of rhizosphere (81.33 x 106 cfu g–1 of soil at 20 days after sowing for T. virens from Kalimpong hill zone). Significantly, the isolates showing high antagonism were not always highly rhizosphere competent.


Keywords


Antagonistic activity; Cicer arietinum; Root exudates; Rhizosphere; Non-rhizosphere colonization.

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A KAU publication [CODEN: JTAGEI; ISSN 0971-636X; eISSN 0973-5399]