EFFECT OF PLANT GROWTH REGULATORS AND SIGNAL MOLECULES ON PATHO-PHYSIOLOGICAL FUNCTIONS RELATED TO BACTERIAL BLIGHT OF POMEGRANATE
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Date
2017-03
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K.R.C. COLLEGE OF HORTICULTURE, ARABHAVI (UNIVERSITY OF HORTICULTURAL SCIENCES, BAGALKOT)
Abstract
The present investigation entitled “Effect of plant growth regulators and signal molecules on patho-physiological functions related to bacterial blight” was carried out both under greenhouse condition and in field conditions at College of Horticulture, Bagalkot during 2014-16. Different phytohormones and signal molecules like auxins, gibberellins, paclobutrazol, ethylene, salicylic acid, chitosan and nitric oxide were studied in present investigation to know their effect on physiological response and disease resistance against bacterial blight under field condition. Among these treatments, foliar spray of GA3 at 50 ppm resulted in enhancing vegetative growth like plant height (2.24 m), plant spread (N-S-2.88 m, E-W-3.05 m) and plant canopy (10.49 m3), whereas, foliar spray of ethrel at 200 ppm enhanced early flowering and helped in inducing highest per cent of hermaphrodite flowers (91.18), with increased fruit setting (72.20%) and maximum yield (16.34 t/ha) in both seasons. Ethrel treatment also found effective for reducing the disease severity. Quality traits like total phenols, anthocyanins, TSS, total sugars and reducing sugars found superior in both ethrel and GA3 treatments.
Enzyme assay and gene expression studies of PR proteins and defense related genes were analyzed to understand the defense mechanism involved during host-pathogen interaction under greenhouse condition. Accordingly, different enzymes like POD, PPO, PAL and chitinase were upregulated in paclobutrazol, salicylic acid, ethrel and 2,4-D treatment upon pathogen inoculation at different time intervals. Higher expression of pathogenesis related genes, PR1, PR3, PR4 and defense related genes, phenylalanine ammonia-lyase (PAL), catalase and callose synthase-3 (CS-3) were found higher in 2,4-D, paclobutrazol, salicylic acid and ethrel treatment. Thus, phytohormone mediated plant defense responses and understanding its biochemical and molecular basis of plant–pathogen interaction enabled to develop effective strategies towards managing bacterial blight, a devastating disease of pomegranate.
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TH597
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