Identification of Bangladeshi rice varieties resistant to ufra disease caused by the nematode Ditylenchus angustus

摘要

The rice stem nematode Ditylenchus angustus causes "Ufra" disease in rice resulting in substantial yield losses. Although it is predominant in deep water rice in South and Southeast Asia, this nematode also infects irrigated and rainfed low land rice. This study evaluated rice genotypes (irrigated, rainfed, deep water and landraces) for resistance to the Bangladeshi population of D. angustus. The experiment was executed using artificial inoculation, in both rainfed and irrigated ecosystems. The rice varieties were first scored at 28 days post inoculation (dpi), and ranked based on the postinfectional reactions and severity of symptoms on a 0-16 rating scale. The susceptibility of the varieties was also evaluated at a later time point, i.e. 55 dpi, based on the percentage of tiller infections, using a disease index scoring system ranging from 0 to 9. Both screening methods showed a similar ranking of the varieties for susceptibility/resistance against this nematode. The experiment was initially conducted in plastic pots, and the promising varieties were analyzed further in field conditions. Out of the 85 varieties, one landrace named 'Manikpukha' proved to be highly resistant, while 6 other varieties showed resistance and 13 varieties showed moderately resistant responses under both pot and field conditions. The promising varieties found in the present investigation can be used in rice breeding programs as well as for further detailed studies to develop a sustainable ufra management strategy. (C) 2015 Elsevier Ltd. All rights reserved.