Biology of Xanthomonas axonopodis pv. glycines causing bacterial pustule of soybean and identification of resistance sources
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Date
2021-12-09
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Palampur
Abstract
The investigation on “Biology of Xanthomonas axonopodis pv. glycines causing
bacterial pustule of soybean and identification of resistance sources” was undertaken
during 2019-21 in the Department of Plant Pathology, CSK HPKV, Palampur. The
occurrence of bacterial leaf pustule was recorded only at four locations viz. Utrala,
Mahakal, Nagri and Palampur of district Kangra on Hara Soya variety with per cent
disease index of 11.11 per cent. Morpho-cultural characteristics of the bacterium
indicated that the bacterium was rod shaped and produced circular, yellow colored
colonies on nutrient agar medium. The nutrient agar medium was found to be the best
for Xag growth. The biochemical characteristics of the bacterium revealed that it was
Gram negative and showed positive reaction for starch hydrolysis, gelatin
liquefaction, KOH solubility, H2S production and acid production by carbon sources
while negative reaction for acid production by nitrogen source. The optimum
temperature and pH for the growth of pathogen were 30oC and 7.0, respectively.
Bacterium culture of 4 days old and inoculum load of 106
cfu/ml resulted in the
maximum disease development i.e. 72.0 and 78.67 per cent disease severity
respectively under artificial inoculation conditions. Pin prick inoculation method was
found to be the most effective as it resulted in the highest disease severity of 77.67 per
cent after 30 days of inoculation. Among five leguminous plants, only horse gram was
found to be another host of bacterial pustule. Out of fifty germplasm lines, six
genotypes viz. Him Soya, EC 7048, MAUS 732, RSC 11-22, DSb 37 and MAUS
1566 were found to be resistant and two [EC 250591 and VLS 59] were moderately
resistant against Xag