Screening of cotton varieties for resistance to root knot and reniform nematodes and determination of efficient assessment parameters
1984
Barron, C.M. (University of the Philippines at Los Banos, College, Laguna)
None of the varieties screened showed resistance to both Rotylenchulus reniformis and Meloidogyne incognita. Two varieties (Deltapine 55 and T-120-76) and one variety (Hoisefilly) appeared moderately resistant, respectively to R. reniformis and M. incognita. The rest of the varieties showed moderately susceptible and susceptible reactions to both nematodes. Except percentage reduction in top weight and number of nematodes recovered from 250 cc soil, linear correlations between resistance ratings and each of the assessment parameters used in both experiments were significantly positive. The most efficient parameters for determining resistance to R. reniformis and M. incognita were the following: necrosis rating (for R. reniformis), root gall rating (for M. incognita), percentage reduction in root weight, number of nematodes recovered from 1 g of roots, number of egg masses/g of roots, and number of egg/egg mass
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