Indian Institute of Spices Research (ICAR), Marikkunnu P. O., Calicut, Kerala, 673 012, India E-mail: dibypaul@yahoo.co.in
*Corresponding author: Microbiology Group, M. S. Swaminathan Research Foundation, Taramani Institutional Area, CPT Campus, Chennai, 600113.
Six strains of Pseudomonas fluorescens, which had been found efficient in root-rot suppression in black pepper (Piper nigrum L.) caused by Phytophthora capsici were tested for their ability in rejuvenating Phytophthora infected black pepper cuttings. Among the treatments, which had only bacterial application, IISR-6 ensured survival of 67% of the infected cuttings where as only 22% of the untreated plants survived 3 months after treatment, The combined application of IISR-51, IISR-6+IISR-13 and I1SR-51+IISR-11 with Metalaxyl -Mancozeb resulted in 100% survival of the infected plants, showing an additive effect. Experiments conducted for root-proliferation activity of the P. fluorescens showed that the bacterial strains helped increase the root biomass of the plants (30–135%). All the strains increased the root length and root area in the treated plants (12–127%, 43–200%, respectively). Strains were also found to produce plant growth hormones, viz. IAA & GA.
Black pepper, root-rot, Phytophthora capsici, Pseudomonas fluorescens, rejuvenation, root proliferation
