ETHYLENE MEDIATED RESISTANCE AGAINST BACTERIAL BLIGHT IN POMEGRANATE AND ITS INFLUENCE ON PHENOLOGICAL CHARACTERS
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Date
2021-06
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University of Horticultural Sciences Bagalkot. (College of Horticulture, Bagalkot).
Abstract
Bacterial blight in pomegranate is a major disease caused by Xanthomonas
axonopodis pv. punicae, which has resulted in significant economic losses in terms of
both quality and quantity. The ineffectiveness of most chemicals in controlling this
disease has shifted grower attention to the quest for a new molecule and hence the use
of plant growth regulators and signaling molecules is a novel approach to control the
disease as well as improving quality and quantity attributes of pomegranate. Hence,
the aim of present study was to determine the impact of plant hormone ethylene on
bacterial blight of pomegranate and also its effect on phenological characters. Result
shown that, in present study, among all cultivars, foliar application of ethrel at
300ppm shown higher pathogen load (9371.62-folds) and disease severity (28.64%) in
Bhagwa cultivar. Application of ACC deaminase producing bioagents like
Pseudomonas putida and Trichoderma asperellum resulted in reduction of disease
severity as well as ethylene levels (ACC oxidase) in plants under greenhouse
condition. Field study revealed that foliar application of ethrel (200ppm) at different
growth and developmental stages enhanced production of productive flowers
(38.17%), yield (15.24 t/ha), colour of pomegranate but meanwhile it also shown
higher disease severity on leaves (6.65%), fruits (5.17%) and twigs (0.57%). Among
different hormones applied, ethrel application shown maximum disease severity
(33.2%) and salicylic acid shown lowest disease severity (15.08%) under greenhouse
condition. Hence, it is evident from present study that ethylene is a negative regulator
of disease resistance and application of ethylene deaminase producing bioagents like
Pseudomonas putida and Trichoderma asperellum decreased the bacterial blight
disease severity and also ethylene levels (ACC Oxidase) in plants, meanwhile
ethylene application increased number of productive flowers, yield and quality
attributes of pomegranate.