Abstract
Xanthomonas oryzae pv. oryzae (Xoo) which causes bacterial leaf blight (BLB) disease is one of
the most destructive pathogen of rice. BLB incites more than 70% yield losses in epidemic
conditions thus deteriorating the rice industry and export revenue. The use of conventional
synthetic bactericides causes remarkable environmental hazards such as water and air pollution.
This study was focused at the management of bacterial leaf blight disease through the application
of antibiotics because unjudicious use of bactericides results in the development of resistance in
bacteria. The objectives were to evaluation of rice germplasm against BLB, biochemical
characterization of the pathogen and its in-vitro management. There were very limited studies on
the phenotypic evaluation of BLB disease and biochemical analyses of its causal organism.Twelve rice cultivars were screened against the disease in randomized complete block design.
The isolated pathogen was subjected to Gram staining and microscopic examination.
Biochemical characterization of the pathogen was done by methyl red, indole production, citrate
utilization and voges-proskaure tests. Three antibiotics (Kanamycin, Streptomycin and
Ampicilin) were used at three concentrations (0, 50, 100 and 150 ppm) against the pathogen.
Among all the screened cultivars, none was highly resistant and resistant. Maximum disease
severity (89.01%) was depicted by the variety Super Basmati. All isolate were Gram negative
and these showed positive response in case citrate utilization test indicating that citrate
permeases enzyme is abundant. In-vitro results showed that Kenamycin is the most effective
against pathogen at all concentrations than Ampicilin and Streptomycin. It is concluded that none
of the screened cultivars showed resistance against Xoo, so the Basmati varieties may be sown
with appropriate antibiotic like Kenamycin. It is recommended to devise effective breeding
programs for the development of resistance rice cultivars against this economically important
disease.
Aysha Khan, Safdar Ali, Muhammad Sajid, Muhammad Ahmad Zeshan, Rana Binyamin, Nadeem Ahmed, Muhammad Usman Ghani. (2021) Phenotypic evaluation of rice germplasm against Xanthomonas oryzae pv oryzae and its in-vitro management through antibiotics, Asian Journal of Agriculture and Biology, Volume-09, Issue-2.
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