النشر العلمي

  • Variability in Striga hermonthica (Del.) Benth, Populations in Gadarif Area, Eastern Sudan

   Field surveys were conducted during the rainy season, 2008/2009, in Gadarif area, Eastern Sudan, to investigate variability within S. hermonthica populations. Five locations; Galabat, Sumsum, Gadarif, Butana and El Fau were selected at random in S. hermonthica endemic area. Variability among S. hermonthica populations was determined by measuring morphological and floral characters. Data on S. hermonthica morphology were collected and subjected to descriptive analysis and analysis of variance. Means were separated for significance using Duncan's Multiple Range Test (at p £ 0.5). Data on floral characters were subjected to descriptive analysis and compared with the taxonomic key. The results of the surveys revealed that, S. hermonthica was pre-dominant on sorghum genotypes in Gadarif area. S. hermonthica populations showed significant differences in morphological characters. However, differences in flower shape, size and colour were often not significant. Average Striga height ranged between 49.7and76.6 cm, leaves production ranged between 42.4 and 81.7, number of internodes ranged between 21.3 and 41.4 and density ranged between 17.4 and 33.8 plant/m2. Average of capsules per plant ranged between 42.2 and 109.5, seeds per parasite ranged between 29516.5 and 76626.7 and Striga shoot dry weight ranged between 1.01 and 9.02 g. The average of ribs per calyx ranged between 5.3 and 5.7, flower cross ranged between 1.8 and 2 cm, length of corolla tube ranged between 1.7 and 1.9 cm, width of bracts ranged between 2.2 and 2.5 cm and spikes had pink flowers that turn dark at drying. The variability in morphological and floral characters revealed by this study could be attributed to a multitude of variables including initial size of Striga seed bank, Striga species, strains or variants, crop genotype, management and climatic and edaphic condition including, spacing, soil fertility and moisture status.

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/span>Striga strains or variants, crop genotype, management, climatic, population density and edaphic condition including soil fertility, moisture status and pH.

 

span style='color:black'>) and sorghum root extract concentration (6.3 and 25g/L). Much remains to be learnt about the action of 2,4-D. It appears to have a potential for Witchweed management. However, further research is needed to clear the basic principles of 2,4-D actions on Witchweed.

 

published in Sudan University of Science and Technology Journal of agricultural and Veterinary Sciences. 16 (2):119-132

  • Effects of Sorghum (Sorghum bicolor [L.] Moench) Root Exudates and Extracts on Early Developmental Stages of Striga hermonthica (Del.) Benth

   Two types of laboratory experiments (in vitro and in vivo) were undertaken at the Faculty of Agricultural Sciences, University of Gezira, Sudan, to investigate the effects of sorghum (Sorghum bicolor [L.] Moench) root exudates and root extracts on early developmental stages of Striga hermonthica (Del.) Benth. collected from different locations in Sudan. Collection of seeds was made in S. hermonthica endemic areas in Gadarif, Gezira and Kordofan. A total of fifteen Striga populations were collected. Twelve S. hermonthica populations, one each, were collected from under sorghum and three S. hermonthica populations, one each, were collected from under millet. The fifteen S. hermonthica populations were arranged in completely randomized design with three replicates. Striga seeds and/or germilings were examined under a binocular for germination, haustorium initiation, attachment and penetration 24, 72, 144, 192 hour after initial incubation, respectively. Data were collected and subjected to analysis of variance procedure. Means were separated for significant using Duncan's Multiple Range Test (P £ 0.5). The results revealed that root exudates and extracts of all plants induced seed germination and haustorium initiation in S. hermonthica. However, the highest germination, haustorium initiation, attachment and penetration attained by each of S. hermonthica population, were on their respective hosts. These findings suggest the existence of both inter-and intra-crop specificity. Moreover, the results confirmed the existence of two strains of S. hermonthica, one specific to sorghum and the other, to millet.

Keywords: Witchweed, variability, virulence, specificity, strain, sorghum.

/span>Striga strains or variants, crop genotype, management, climatic, population density and edaphic condition including soil fertility, moisture status and pH.

 

span style='color:black'>) and sorghum root extract concentration (6.3 and 25g/L). Much remains to be learnt about the action of 2,4-D. It appears to have a potential for Witchweed management. However, further research is needed to clear the basic principles of 2,4-D actions on Witchweed.

 

published in Sudan University of Science and Technology Journal of agricultural and Veterinary Sciences. 16 (2): 95-108

  • Reduction in Growth and Yield of Sorghum Caused by Striga hermonthica (Del.) Benth in the Sudan Gezira

   Field surveys were conducted during the rainy season, 2008/2009, in the Gezira, Central Sudan, to estimate reduction in growth and yield attributes of host caused by the root parasitic weed, S. hermonthica (Del.) Benth. Five locations; Hasaheisa, Abu-Haraz, Hag-Abdalla, Barakat and Wad-Rabia; were selected at random in S. hermonthica endemic areas in Gezira, Central Sudan. Reduction on host growth was estimated by measuring number of plants / m2, plant height, number of leaves and number of internodes. Yield losses were measured by determining head size, head weight, head length and 1000 seeds weight. Data on growth reduction and yield were collected and subjected to descriptive analysis and analysis of variance (ANOVA). Means were separated for significant by the Duncan's Multiple Range Test (P ≤ 0.05). The results showed that, all sorghum genotypes in the study area were infested by the parasite. S. hermonthica parasitism, significantly, reduced plant height by up to 89.1%, number of leaves by up to 25.3%, number of internodes by up to 21% and length of the 3rd Internode  by up to 63.1%. Also, Striga, significantly, decreased head size by 27.4- 92.1%, head weight by 20.5- 90.9%, head length by 13.8- 68% at and 1000 seeds weight by 5.1- 28.8%. Moreover, there were significant differences in growth and yield of sorghum between host genotypes, between and within locations. Variability in the damage caused by the parasite could be attributed to a multitude of variables including initial size of Striga seed bank, Striga strains or variants, crop genotype, management, climatic, population density and edaphic condition including soil fertility, moisture status and pH.

span style='color:black'>) and sorghum root extract concentration (6.3 and 25g/L). Much remains to be learnt about the action of 2,4-D. It appears to have a potential for Witchweed management. However, further research is needed to clear the basic principles of 2,4-D actions on Witchweed.

 

published in Sennar University Journal. 3 (1): 90-122

  • Variability and host specificity of witchweed [Striga hermonthica (Del.) Benth.] populations on millet [Pennisetum glaucum (L.) R. Br.] Moench

   Field surveys and greenhouse experiments were conducted during season 2009/10 in the Sudan to investigate variability and host specificity of witchweed [Striga hermonthica (Del.) Benth.] populations. Field surveys were conducted in S. hermonthica endemic areas in Gadarif, Gezira and Kordofan to collect seeds from Striga plants growing under their respective hosts. A total of fifteen S. hermonthica populations were collected. Twelve S. hermonthica populations, one each, were collected from under sorghum and three S. hermonthica populations, one each, were collected from under millet. A greenhouse experiment was undertaken at the horticulture nursery, Faculty of Agricultural Sciences, University of Gezira, Wad Medani, Sudan, to test the infectivity of seeds of witchweed populations on millet, cultivar Ashana, which is known for its differential response and to study virulence of parasitism on this cultivar. The fifteen S. hermonthica populations were arranged in a randomized complete block design with three replicates. Growth and harvest attributes on the parasite and crop were measured. Data were collected and transformed as necessary to √x+0.5 and subjected to the analysis of variance procedure. Means were separated for significance using Duncan's Multiple Range Test (at p £ 0.5). The greenhouse experiment showed that emergent S. hermonthica, capsules per plant and shoot dry weight were highest on the respective host. It is noteworthy that some of the Striga, sorghum populations, displayed limited emergence on millet and produced seeds. S. hermonthica populations significantly reduced growth and yield of millet. However, the magnitude of the damage attained, by each 

published in Gezira Journal of Agricultural Sciences. 12 (2): 14-34

  • Effects of 2,4-D , DMBQ and sorghum root extract on haustorium induction and attachment of witchweed [Striga hermonthica (Del.) Benth.] to roots of Sorghum bicolor (L.) Moench

     Two types of experiments were conducted during 2006 in Wad Medani, Sudan in the laboratory. In vitro experiments were carried out to study the effects of 2,4-D at 2.5-100M, 2,6-dimethoxy-ρ-benzoquinone at 2.5 and 10.0 M and sorghum root extract at 6.3 and 25 g/L on haustorium induction of witchweed. In vivo experiments were carried out to study the effects of 2,4-D at 2,5-100M for pre-conditioning and soaking pre-conditioned witchweed seeds at the same rate for 10-120 min on attachment of haustorium to sorghum seedling roots. Treatments were arranged in a completely randomized design with three replicates. Witchweed germilings were examined for haustorium induction and attachment 4 and 15 days after treatment. Data were collected, transformed to arcsine as required and subjected to the analysis of variance procedure. The results revealed that haustorium induction and attachment to sorghum seedling roots was suppressed with increased 2,4-D concentration(2.5-100M) and soaking period (10-120 min) of pre-conditioned seeds. However, haustorium induction increased with increased 2,6-dimethoxy-ρ-benzoquinon (2.5 and10.0 M) and sorghum root extract concentration (6.3 and 25g/L). Much remains to be learnt about the action of 2,4-D. It appears to have a potential for Witchweed management. However, further research is needed to clear the basic principles of 2,4-D actions on Witchweed.

published in Gezira Journal of Agricultural Sciences. 12 (2): 1-13

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