Susceptibility of Sudanese Wheat Cultivars to Striga hermonthica (Del.) Benth

Striga hermonthica (Del.) Benth, an obligate root parasitic plant, constitutes a major constraint to cereals production and a threat to agriculture and food security in sub-Saharan Africa. The present investigation was undertaken at the College of Agricultural Studies, Sudan University of Science and Technology at Shambat to determine the effects of the reaction of local Sudanese wheat cultivars to S. hermonthica (sorghum and millet strains) under laboratory conditions and to study the effects of Striga on growth and yield of wheat under greenhouse conditions. Treatments were arranged in a Randomized Complete Block Design (RCBD), with four replicates. Striga sorghum and Striga millet applied with Elnilean root exudates (20µl) and Wadi-Elnile root exudates displayed 58, 53.7, 69.5 and 67.7% emergence, respectively. On Wadi-Elnile, Striga sorghum strain showed very low emergence at the lowest seedbank size (2 mg/pot). Increasing Striga seedbank size to 4, 8, 16 and 32 mg/pot increased Striga emergence to 1, 3, 27 and 31 plants/pot, respectively. However, a further increase in seedbank size to 64 mg/pot decreased emergence considerably. A further increase in Striga seedbank size to 16, 32 and 64 mg/pot increased emergence to 3, 7 and 16 plants/pot, respectively. Striga, sorghum strain, at seedbank size of 2-8 mg/pot caused a slight non-significant increase in Wadi-Elnile height. However, increasing seedbank size to 16-64 mg/pot reduced height by 34.1-38.5% as compared to Striga free control. Striga, millet strain, at the lowest seedbank size (2-8 mg/pot) caused a slight non-significant decrease 4.7-8.9% in height, in comparison to Striga free control. Increasing Striga seedbank to 16, 32 and 64 mg/pot reduced height significantly by 14.1, 29.0 and 35.5%, respectively. On Elnilean, Striga sorghum strain, at seedbank size of 16, 32 and 64 mg/pot reduced chlorophyll content by 25.6, 27.5 and 44.1%, respectively, in comparison to Striga free control. Striga, millet strain, at seedbank of 2-32 mg/pot had no significant effects on chlorophyll content. The results revealed that Sudanese wheat cultivar is susceptible to S. hermonthica. Striga emergence and Striga dry weight, irrespective of wheat cultivar and Striga strain, progressively increased with seedbank size. However, the influence on wheat height, chlorophyll contents and number of grains varied with the parasite seedbank size, strain and crop cultivar.