RESPONSE OF FIVE CULTIVARS OF SUNFLOWER (Helianthus annus) TO ROOT-KNOT NEMATODE (Meloidogyne spp) INFECTION

Abstract

Sunflower is well known for its allelopathic compounds which confers certain resistance to some pathogens on the plant. The susceptibility of sunflower cultivars to root-knot nematodes and response to control was investigated on the field. Five cultivars of Helianthus annus L, namely France lever, Isanka, Peredovicks, Pwk E5 and Sigco 445 were examined for their susceptibility to Meloidogyne spp, Alternaria leaf spot and virus mosaic. They exhibited different degrees of susceptibility to Alternaria leaf spot, Meloidogyne spp and virus mosaic. Most parameters of growth and yield that is; mean plant height, mean number of leaves, weights of head and seeds at harvest also differ significantly (p<0.05) among the cultivars. France lever appeared to be the least affected by the diseases and consequently exhibited superiority over others in most growth and yield parameters. The highest concentration of Eucalyptus officinalis powder reduced significantly (p<0.05) the pathogenic effect of Meloidogyne spp and other field pathogens on the plants which received them. The cultivars were examined quantitatively for the various phytochemical compounds present in them and France lever contains the highest degree of bio-active compounds, this explains the resistance ability of the cultivar, even under inoculated untreated conditions. Thus France lever is highly recommended for cultivation with the objective of vegetable oil production.