Salicylic acid mediated multi-pronged strategy to combat bacterial blight disease (Xanthomonas axonopodis pv. punicae) in pomegranate

Abstract

Pomegranate bacterial blight disease caused by Xanthomonas axonopodis pv. punicae is one of the most serious threat to the pomegranate industry in India. So far, the chemicals used to control this pathogen alone are less effective. In this article, an attempt was made to supplement chemical control through improving the systemic acquired resistance of plant using nutrients such as nitrogen (N) and salicylic acid (SA) as elicitor. The study revealed that foliar application of SA at the rate of 300 ppm increased above-ground dry mass of plant by 64.97%, improved chlorophyll content of leaves and resulted higher concentration of macro-elements and micro-elements, particularly Mn and Zn, in leaves. It also significantly increased the activities of nitrate reductase (NR), superoxide dismutase (SOD), catalase and peroxidase. However, the maximum response of SA was recorded when it was sprayed after soil application of N at 100% of the recommended dose. As a consequence, this combination recorded the least bacterial blight infection with average severity of 11.58% followed by without-N application under challenge inoculation of the pathogen. However, sustainable production cannot be realized without N application. The integration of this strategy for activation of defence mechanism of plant with the bactericide streptocycline resulted in further reduction of bacterial blight disease incidence and severity under field condition to very low levels (3.84% and 18.57% respectively).