Detection and management of Burkholderia glumae (Kurita and Tabei), the cause of panicle blight in paddy (Oryza sativa L.)
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Date
2018-06
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G.B. Pant University of Agriculture and Technology, Pantnagar - 263145 (Uttarakhand)
Abstract
Rice (Oryzae sativa L.) is an important food grain crop grown in the major parts of the world. In the changing climatic conditions, crop production is affected by a number of bacterial and fungal diseases. The panicle blight of paddy caused by Burkholderia glumae is considered as one of the major emerging diseases of rice in the rice growing countries of world, including rice growing states of North India. Considering the devastating nature of B. glumae and modest knowledge about its chemical management, the present study was conducted with the following objectives; (i) isolation and identification through, cultural, morphological and molecular techniques, (ii) to detect the longevity in in-vitro storage and glass house conditions, (iii) to evaluate available antibiotics, copper compounds and bio control agents at in-vitro and field conditions. The pathogen was isolated from the infected plant parts viz., leaf, sheath, panicles and grains in semi selective king’s B medium. The bacteria was gram negative, rod shaped showing positive reaction to KOH, gelatin liquefaction, catalase, peroxides and negative to starch hydrolysis and hydrogen sulphide production. The pathogen giving 1.48kb ampilicon with genus specific primers, on mega blast analysis showed 91 per cent similarity with Burkholderia sp. Bacteria was recovered from 12 months old naturally infected seeds kept for storage in room temperature. Higher percentage of bacterium was recovered from freshly harvested seeds and the recovery rate steeply decreased with increase in the storage duration. On exploring the different growth stages for most susceptible stage of infection, boot leaf and panicle initiation stages were found to be equally susceptible with 93.33 per cent disease incidence. Through in-vitro screening Anand strain (A-1, Trichoderma viridae) was found most effective with 66.6 per cent inhibition followed by PBAT-2 (Pseudomonas fluorescens) 60 per cent inhibition. Amongst the antibiotics screened, streptomycin at 200ppm concentration with 40.19 per cent growth inhibition was found to be most effective. Amongst the copper compounds screened copper oxy chloride alone at 1000ppm was found to be most effective with 48.44 per cent growth inhibition. Amongst the consortium studied, copper oxy chloride with streptomycin sulphate showing 54.43 per cent inhibition was observed to be most effective. Under field conditions, at 45DAT, treatment containing foliar spray of PABT -2 was recorded with less disease incidence and less disease severity with combination seed treatment and foliar spray of ampicillin+ copper oxy chloride (100+250ppm). At 60 DAT, treatment containing ampicillin+ copper oxy chloride (100+250ppm) foliar spray alone, A-1 seed treatment alone, seed treatment +foliar spray of streptomycin sulphate + copper oxy chloride @ (100+250ppm and 200+500ppm) respectively were recorded with less disease incidence, combination of seed treatment and foliar spray of streptomycin sulphate + copper oxy chloride at (200+500ppm) was effective in reducing disease severity. Highest yield was observed in treatment combination of (ST+F) with copper oxy chloride, followed in (ST+F) of PBAT-1.
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