Effects of Intercropping Pearl Millet with Some Legumes on Striga hermonthica Emergence and Millet Growth

Abstract

Striga spp, pose a severe problem to agriculture. They impose significant losses in yields of staple food crops in sub-Saharan Africa and thus a genuine threat to food security. Furthermore, they are difficult to control by conventional methods. Green house experiment was undertaken during the season 2015/2016, at the College of Agricultural Studies, Sudan University of Science and Technology, Shambat, Khartoum North to determine the effects of intercropping pearl millet (Sudan Brawn and Wad-Elbashir cv.) with cowpea, green gram, and cluster bean on Striga millet strain incidence and pearl millet growth. Treatments were arranged in Complete Randomized Block Design (CRBD) with three replicates. The results showed that Striga emergence on millet cultivars displayed a progressive increase with seed bank size. Striga number was generally lower in the intercrops than in the sole millet. Sole millet displayed highest Striga number. Cowpea intercropped with millet cultivars (Wad–Elbashir and Sudan Brown) at seed bank size of 32 and 64mg/pot, reduced Striga emergence by 57.1 -100%. Intercrops cluster bean with millet cultivars at Striga seed bank size of 32 mg/pot completely suppressed Striga emergence throughout the experiment. However, at Striga seed bank size of 64 mg/pot intercropping cluster bean with millet decreased Striga number by 28.3-70.9%. Green gram intercropped with millet cultivars, irrespective of seed bank size caused considerable reductions of Striga number (14.8-76.7%). All intercrops reduced Striga dry weight, in comparison to the sole millet. Cowpea, cluster bean and green gram, irrespective of Striga seed bank size and millet cultivars reduced Striga dry weight by (70.4-72.6%), (40.9-82.1%) and (36.4-81.2%), respectively. At 90 DAS, intercropping cowpea with Wad-Elbashir cultivar, at Striga seed bank size of 32mg/pot increased significantly millet height by 82.4%, as compared to the sole millet. Intercropped Sudan Brown cultivar with cowpea and cluster bean at Striga seed bank size of 32mg/pot increased millet height by 35.7 and 35.1%, respectively. Intercropped Wad-Elbashir cultivar with V cowpea, irrespective of Striga seed bank size, increased number of leaves (32.3-72.0%). At Striga seed bank size of 32mg/pot number of leaves in Sudan Brown cultivar increased significantly when intercropped with cowpea by192.8%, as compared to the sole millet. However, intercropping with cluster bean at Striga seed bank size of 64mg/pot, the number of leaves increased (46.7%), but not significantly. Intercropping with cowpea and cluster bean, irrespective of Striga seed bank size and millet cultivars, decreased number of tillers, but not significantly, as comparison to the sole millet. However, intercropping millet cultivars with green gram displayed complete reduction in number of tillers. All intercrops did not reduce stem diameter of millet cultivars, as compared to the sole crop. Intercropping Wad–Elbashir with cluster bean, at Striga seed bank size of 64mg/pot, decreased chlorophyll content significantly (34.4%), as compared to the corresponding control. All intercrops reduced Sudan Brown chlorophyll content, but not significantly. At Striga seed bank size of 32mg/pot, intercropping Wad-Elbashir cultivar with cowpea and cluster bean increased millet dry weight by 31.3 and 62.5%, respectively, as compared to the sole millet. However, at Striga seed bank size of 64/pot, Wad-Elbashir dry weight increment by 54.1 and 41.6% when intercropped with cowpea and green gram, respectively. Intercropping Sudan Brown cultivar with cowpea, cluster bean and green gram, at Striga seed bank size of 32 and 64 mg/pot, displayed non- significant reductions in millet dry weight and the observed reductions were (19.0-31.7), (22.4-27.6) and (32.8-39.7%), respectively, in comparison to the un-infested control.