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Title: Studies on biochemical basis of resistance against late blight of potato and its management through fungicides, bio- fungicides, and plant extracts
Keywords: Applied Sciences
Agriculture & related technologies
Plant pathology
Issue Date: 2014
Publisher: University of Agriculture, Faisalabad Pakistan
Abstract: Present studies were carried out to screen potato lines/cultivars against late blight, determine the effects of late blight on mineral nutrients and phenolic contents of susceptible and resistant potato cultivars, and manage late blight of potato. Out of 61 varieties/lines tested under natural disease conditions none of the variety/line was found to be immune, highly resistant or resistant to late blight of potato. Thirteen varieties/lines exhibited moderately resistant, thirteen exhibited moderately susceptible, twenty five showed susceptible, and ten showed highly susceptible response. Total phenols detected one month pre and post disease appearance in 50 lines/cultivars. After infection with late blight disease, total phenols significantly increased in all the diseased plants more than the increase in healthy plants of same age. We found an increase in nitrogen, phosphorus, magnesium, copper, and zinc contents of healthy plants of susceptible varieties/lines whereas, potassium, calcium, sodium and iron contents higher in the healthy plants resistant cultivars/lines. Upon disease appearance nitrogen, sodium, potassium, calcium, copper, zinc, and iron contents increased invariably in all plants of both susceptible and resistant cultivars/lines. On the other hand, phosphorus and magnesium contents increased in susceptible cultivars/lines but decreased in resistant cultivars/lines. Control efficiency of Ridomil Gold and Neem (Azadrachta indica) leaf extract, as protective and curative was more pronounced on moderately resistant cultivar (Shanan) as compared to highly susceptible (Karoda). By sowing moderately resistant cultivars and spraying Neem leaf extract or Garlic extract @3% or moderately resistant varieties/lines combined with half the recommended dose of fungicides can protect the crop efficiently. Fungicide application (Ridomil Gold or Melody Dew) should be done at the appearance of disease just for once or twice to reduce the damage to environment and creation of resistance in the pathogen. Our study suggests that resistant cultivars should be exploited with fungicide use to enhance the disease control and disease losses.
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