D. JAGADISH BABU, A. JOHN PETER, A. BABU, S. MAIYAPPAN, K.C. KUMHAR AND V. BHADRA MURTHY
Abstract
Laboratory studies were carried out to evaluate the growth and bio-efficacy of three Trichoderma isolates from tea ecosystem of Dooars region in North Bengal viz., KBN-24, KBN-1/14 (ITCC Nr 7765) and KBN-29 (ITCC Nr 7764) in comparison with commercially available Trichoderma viride TV1-TNAU (ITCC Nr 6914), and Trichoderma harzianum TH-IIHR (ITCC Nr 6888). The in vitro antagonistic activity of all the five isolates against four economically important tea pathogens was carried out using dual culture technique. Isolates KBN-29 and KBN-1/14 recorded significant growth inhibition of Curvularia sp and Fusarium sp as compared to KBN-24, TV1-TNAU and TH-IIHR. The isolate KBN-29 also significantly inhibited the growth of Colletotrichum sp as compared to other tested isolates. However, TH-IIHR recorded significant growth inhibition in Pestalotiopsis theae followed by KBN-29 isolate. The strain KBN-29 was identified as best antagonist based on the z-score 3.139 followed by KBN-1/14 (0.4079), KBN-24 (-0.4550), TH-IIHR (-0.6925) and TV1-TNAU (-2.3994). When the isolates were allowed to grow in potato dextrose agar (PDA), the maximum growth was recorded in KBN24 (1.13 cm-d) followed by KBN29 (1.08 cm-d). Since KBN29 was shortlisted as the best bio-control agent for the management of select tea pathogens based on z-score, it was allowed to grow on potato dextrose medium, yeast molasses medium (YMM) and Sabourauds dextrose broth (SDB) to find out the best media for mass multiplication. Maximum sporulation (2.4X108 mL-1) and dry mass (5.56 g-L) yield was recorded in PDB. Yeast molasses medium (YMM) and Sabourauds dextrose broth (SDB) recorded 2.3X108 mL-1 and 2.2X108mL-1 of spore count along with 5.46 g-L and 5.36 g-L of dry mass, respectively.