SELECTION OF NATIVE TRICHODERMA ISOLATES FOR THE MANAGEMENT OF SOIL-BORNE DISEASES IN TEA (CAMELLIA SINENSIS)

摘要

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 cmd) followed by KBN29 (1.08 cm^). 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 Sabouraud's dextrose broth (SDB) to find out the best media for mass multiplication. Maximum sporulation (2.4X108 ml/1) and dry mass (5.56 gmt) yield was recorded in PDB. Yeast molasses medium (YMM) and Sabouraud's dextrose broth (SDB) recorded 2.3X108mL-> and 2.2X108mL-' of spore count along with 5.46 gL and 5.36 gL of dry mass, respectively.