The use of legume trap crops for control of Striga hermonthica (Del.) Benth. in sorghum (Sorghum bicolor L. Moench) in northern Nigeria.

Two different field trials (one trial on sorghum intercropped with groundnut [Arachis hypogaea L.], and another trial on sorghum intercropped with bambara groundnut [Vigna subterranea L. Verdc.]) were conducted during the 1995 and 1996 rainy seasons at the Teaching and Research Farm of the Department of Crop Science, Faculty of Agriculture, University of Maiduguri, Maiduguri (11 degrees 51' N; 13 degrees 15' E) to evaluate the effect of intercropping resistant and susceptible sorghum varieties with the two legume crops for the control of Striga hermonthica (Del.) Benth, in sorghum. The sorghum varieties used for both trials were ICSV 1002, ICSV 1007 (resistant varieties) and War-warabashi (susceptible). Ex-Dakar variety of groundnut was used for the sorghum-groundnut trial, while a creamed brown eyed local bambara groundnut was used for the sorghum-bambara groundnut trial. There were six treatments with the groundnut trial and nine treatments with the bambara trial and all were laid out in a randomised complete block design (RCBD) replicated four times. In the sorghum-groundnut trial, the results show that the intercropping of sorghum with groundnut significantly reduced Striga infestation up to 50% in sorghum in both years. Both resistant varieties supported significantly fewer number of Striga on sorghum when intercropped with groundnut compared with the sole sown susceptible variety. In both years and the combined analyses of 1995 and 1996 data, however, there was no significant difference in grain yield of sorghum due to the treatments. In the sorghum-bambara groundnut trial, the results show that Striga shoot count at harvest in sole sown ICSV 1007 was significantly lower than the ICSV 1002 variety, while the susceptible variety supported significantly higher Striga shoot count than the resistant varieties in both years and the combined analyses. Alternating stands of sorghum and bambara groundnut within the same row, in general, reduced Striga shoot count in all the varieties with a range of 56%-91% reduction than intercropping with sorghum varieties in alternate rows with bambara groundnut with a range of 45%-96% reduction, or sole sorghum of each variety. This resulted in significantly higher grain yield of ICSV 1002 (1175.0 kg ha-1 in 1995, 814.8 kg ha-1 in 1996, and 994.9 kg ha-1 in the combined data) than ICSV 1007 (892.6 kg ha-1 in 1995, 666.7 kg ha-1 in 1996, and 779.6 kg ha-1 in the combined data) when both were planted in alternate stands in the same row with bambara groundnut. This studies have confirmed the potentials of groundnut and bambara groundnut as trap crops in the management of S. hermonthica in sorghum under a dried environment.