Evaluation of the pathogenic responses of some okra lines to cucumber mosaic virus

Abstract

A screenhouse experiment was carried out at the Crop production pavilion of the Faculty of Agriculture, University of Ilorin to evaluate the symptom and growth responses of some okra lines obtained from the National Horticultural Institute (NIHORT) Ibadan, Nigeria to a pepper isolate of cucumber mosaic virus (CMV, genus- Cucumovirus, Family - Bromoviridae). The lines evaluated were OLA99/3A, OLA99/7, OLA99/12-2, OLA99/R2-1 and OLA99/LB. The results showed all the lines as susceptible manifesting
disease symptoms, which included initial leaf mottling that later developed pale green to dark green mosaic pattern and in severe cases there were leaf rugose and stunting of plant some three to four weeks after inoculation. However, the degree of susceptibility was observed to vary with the lines. A tolerance rating system, based on cumulative mean losses incurred in selected growth and yield attributes, showed OLA99/LB as very tolerant and OLA99/3A as moderately tolerant. The others were judged as not tolerant to CMV infection. The results indicate the possibility of further breeding efforts leading ultimately to the production of resistant varieties.

Keywords: Okra lines, CMV, Pathogenicity, mock- and viral-inoculation,
tolerance rating