Citrus rootstock characterization against citrus canker and evaluation of antibiotics effect against Xanthomonas axonopodis pv. citri

Citrus canker (X. axonopodis pv. citri) widespread bacterial disease which limits citrus productivity and causes quality deterioration. Citrus canker is mostly a leaf-spotting and fruit rind-blemishing disease, but under highly favorable conditions, infections cause defoliation, shoot dieback, and fruit drop. Citrus rootstocks exert a high degree of influence to scions in fruit production and plant susceptibility to diseases including citrus canker. Keeping in view the importance of citrus rootstock present study was planned to evaluate the performance of citrus rootstocks against citrus canker and antibiotics response to control X. axonopodis pv. citri. Eleven exotic citrus rootstocks were selected to evaluate against canker which was inoculated by grafting. Disease index was observed after 9 months of inoculation. Five different commercially available antibiotics were selected for the Invitro treatment, applied at 300, 400 and 500ppm. Inhibition zone was observed at four time points (24, 48, 72 and 96 hours). Kirumakki showed maximum resistance followed by Rangpur Poona nucellar and X639 while Rough lemon was highly susceptible. In Invitro evaluation maximum inhibition zone was expressed by Kanamycin sulphate at 500 ppm followed by Streptomycin sulphate. Lincomycin showed minimum inhibition zone as compared with control (Distilled water, No inhibition). Biochemical analysis exhibited that the disease index (%) decrease with increase of total phenolics contents and total protein contents. Whereas disease index had increasing trend with TSS. This study concludes that according to rootstocks evaluation Kirumakki and Rangpur Poona nucellar showed resistant performance while, on other hand Kanamycin Sulphate having maximum inhabitation against canker.