Comparative study of morphology, morphometrics, reproductive fitness on carrot discs and pathogenicity on musa genotypes of Radopholus Similis Philippine populations

Abstract

Comparative studies were conducted on three Radopholus similis populations collected in Quezon, Laguna and Davao, Philippines from 2008 to 2010. For the first time, morphological and morphometrical characteristics of the Philippine R. similis populations were studied and showed differences for the major body regions. Consequently, reproductive fitness of the three populations on a single carrot disc at 28°C was elucidated and found different from each other. The Davao population showed high nematode density (Pf = 8,447) and reproduction ratio (Rf = 422.4) 8 weeks after inoculation (WAI) indicating greater percentage of reproductive females and found most pathogenic. Ten Musa genotypes including the resistant reference cultivars Pisang Jari Buaya and Yangambi Km5, and susceptible Grande Naine showed various degrees of response to R. similis populations. Cuarenta Dias and Latundan showed high to moderate resistance and tolerance to R. similis based on nematode counts and root damage, respectively. The most pathogenic Davao population caused significant reduction in roots weight and necrosis on the susceptible genotypes, Bungulan, LakatanDavao, Morado and M. balbisiana. Although nematode morphology and morphometrics failed to correlate the pathogenicity of R. similis, the reproductive fitness could help underpin selection and breeding of Musa for nematode resistance