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Paper Details

Morphological and biochemical characterization of antagonist Pseudomonas isolates

N. SRINIVASA1, H. RYMBAI*, A.M. RAJESH1, P. GANESHAMOORTHI1, B. RAMANUJAM2 AND K.R. YATHISH3

Journal Title:International Journal of Agricultural Sciences
Abstract


The morphological and biochemical characterization of phylloplane and rhizosphere Pseudomonas isolates collected from different places were determined. The Pseudomonas isolates antagonistic activity against Alternaria solani, were also tested to determine their capacity to inhibit fungal infection on tomato. The result showed that among the seven isolates of Alternaria solani on potato dextrose agar, isolate HES AL-1 recorded maximum growth coupled with distinct sporulation and colony characteristics. Based on morphological and biochemical characterization of the twelve bacterial antagonists, ten genuses belong to Pseudomonas while two were of Flourescent Pseudomonas. It was also confirmed that the growth of all the seven isolates of Alternaria solani was significantly inhibited by the antagonists Pseudomonas in potato dextrose agar (PDA) conditions. Out of twelve Pseudomonas isolates, five isolates viz., S4B7P (27.74), S1B8P (27.33), S2B10P (25.47), S3B3PF (23.07) and S1B1P (19.69) which showed higher mean inhibition percentage on all the isolates of Alternaria solani were identified as potential antagonistic against Alternaria solani. Further, in pot culture under green house conditions, among the five promising isolates of Pseudomonas isolates, S1B8P isolate and S3B3PF isolate expressed the minimum mean per cent disease incidence (PDI) in all the three methods of inoculation. While, among the three methods of inoculation tested, pre inoculation of Pseudomonas antagonists followed by Alternaria solani showed the minimum PDI (20.68). Therefore, foliar application of Pseudomonas antagonists before inoculation with pathogens may reduce the incidence of early blight in tomato.

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