Influence of intereropping of sorghum (sorghum bicolor L. moench) with hyacinth bean (lablab purpureous l.) on striga hermonthica control and sorghum growth and yield

Striga hermonthica (Scrophulariaceae), a root parasitic weed, is a major constraint to cereal production in Sudan. Available control measures are relatively expensive. An integration of simple cultural practices was thought to give an economically acceptable solution under subsistence farming conditions. The aim of this work was to evaluate the efficiency of intercropping sorghum with hyacinth bean on Striga control and sorghum growth and yield. Under field conditions, sowing of hyacinth bean, in alternating holes with sorghum on the same day, reduced Striga population density, biomass and number of capsules per plant by 88, 83 and 52% in comparison to sole sorghum, respectively. Sowing of hyacinth bean on the same day as sorghum was more effective in suppressing the parasite than delayed planting for one or two weeks. Urea at 190 kg/ha applied to sole sorghum reduced Striga population density, Striga biomass and number of capsules per plant by 57, 73 and 94%, respectively. Unrestricted Striga parasitism reduced number of heads, straw and grain yield of sorghum significantly. Urea applied to sole sorghum increased the number of heads and straw yield by more than 2-folds. Intercropping, without urea, increased straw yield by over 100% and number of sorghum heads by 55 -170 %. Urea, at 190 kg/ha, applied to intercropped sorghum increased straw yield by 24-100% and grain yield by 38-200% in comparison to the respective intercropping treatment without urea. Laboratory observations on the subterranean stages of Striga growth in root chambers revealed that hyacinth bean sown alone or in mixture with sorghum induced 40 _ 47% Striga seed germination in comparison to 55% germination on sole sorghum. Attachment of Striga seed was high on sole sorghum (14.9%) but low (2.6%) on intercropped sorghum. Intercropping sorghum with hyacinth bean reduced Striga attachment to sorghum, Striga growth, seed production and ability to debilitate the host. Delayed intercropping reduced efficiency of controlling the parasite, but decreased competition between hyacinth bean and sorghum. Intercropping technique is suitable for subsistent farming especially on localized infestations