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Muhammad Jamil - One of the best experts on this subject based on the ideXlab platform.
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Striga hermonthica max2 restores branching but not the very low fluence response in the arabidopsis thaliana max2 mutant
New Phytologist, 2014Co-Authors: Qing Liu, Muhammad Jamil, Yanxia Zhang, Radoslava Matusova, Tatsiana Charnikhova, Maryam Amini, Monica FernandezaparicioAbstract:Seed germination of Striga spp. (witchweeds), one of the world's most destructive parasitic weeds, cannot be induced by light but is specifically induced by strigolactones. It is not known whether Striga uses the same components for strigolactone signaling as host plants, whether it has endogenous strigolactone biosynthesis and whether there is post-germination strigolactone signaling in Striga. Strigolactones could not be detected in in vitro grown Striga, while for host-grown Striga, the strigolactone profile is dominated by a subset of the strigolactones present in the host. Branching of in vitro grown Striga is affected by strigolactone biosynthesis inhibitors. ShMAX2, the Striga ortholog of Arabidopsis MORE AXILLARY BRANCHING 2 (AtMAX2) - which mediates strigolactone signaling - complements several of the Arabidopsis max2-1 phenotypes, including the root and shoot phenotype, the High Irradiance Response and the response to strigolactones. Seed germination of max2-1 complemented with ShMAX2 showed no complementation of the Very Low Fluence Response phenotype of max2-1. Results provide indirect evidence for ShMAX2 functions in Striga. A putative role of ShMAX2 in strigolactone-dependent seed germination of Striga is discussed.
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Striga hermonthica parasitism in maize in response to n and p fertilisers
Field Crops Research, 2012Co-Authors: Muhammad Jamil, Fred Kanampiu, Tatsiana Charnikhova, H. Karaya, Harro J BouwmeesterAbstract:Parasitism by the parasitic weed, Striga hermonthica (Striga), constitutes a major biological constraint to maize production in sub-Sahara Africa. Nutrient deficiency is known to aggravate Striga infestation and in a number of plant species it was recently shown that this may be due to increased secretion of Striga germination stimulants into the soil. The present study was designed to observe the connection between soil fertility, secretion of germination stimulants and Striga infection in maize under greenhouse and field conditions. The experiments were conducted during two successive cropping seasons (2008 and 2009). The greenhouse study showed that maize secretes a number of so far unidentified strigolactones that induce Striga seed germination and the amount of these strigolactones increases upon N and P deficiency. The increased secretion of germination stimulants under N and P deficiency resulted in increased Striga infection in pot experiments. The on-station and on-farm field trials in Western Kenya also showed reduction in Striga infestation with the application of mineral nutrients but the results were less consistent than in the greenhouse. Increasing levels of N showed a fair reduction of Striga in the field especially during the first year, whereas P application did not have much effect in contrast to the greenhouse study where both N and P clearly reduced Striga infection. The likely explanation for this discrepancy is that availability of mineral nutrients under field conditions is less predictable than under greenhouse conditions, due to a number of factors such as soil texture and structure, pH, salinity, drought, leaching and runoff. Hence, further studies are needed on the importance of these factors before a fertiliser application strategy can be formulated to improve control of Striga in maize in the field.
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The relationship between strigolactones and Striga hermonthica infection in cereals
2012Co-Authors: Muhammad JamilAbstract:Cereal production in Africa is under increasing constraint due to the obligate, out-crossing, hemiparasitic weed Striga hermonthica (Del.) Benth, a member of the Scrophulariaceae family. Striga parasitizes roots of cereals like sorghum, pearl millet, maize and upland rice. It has infested about 40% of the African agricultural land, resulting in severe yield losses or even complete crop failure worth US billion per annum. The subsistence farmers or approximately 300 million African people lose about 20-80% of their crop because of this weed. This considerable damage by Striga is due to the fact that existing control measures are often ineffective. Since much of the damage occurs underground during the early stages of parasitism, there is a need to develop control strategies that target the weed prior to attachment and emergence. A crucial step in the lifecycle of Striga is the induction of germination by strigolactones, signalling molecules secreted by the roots of its host. These strigolactones could be an important target to control this weed at the pre attachment phase. Control methods targeted at the germination and attachment phase, based on low strigolactones, might prove to be more effective and result in reduced infestation of this weed in cereal crops. In present thesis we studied the relationship between strigolactones and Striga infection in cereals and explored opportunities for lowering Striga damage at the germination or attachment phase. To this end different aspects like strigolactone biosynthetic inhibitors, genetic variation for strigolactone production, and the effect of fertilizers on strigolactone production were investigated in laboratory studies and – when possible - in the field in Kenya and Mali. The first investigation was on the use of carotenoid inhibitors to see the possibilities of strigolactone reduction in the roots of plants by blocking carotenoid biosynthesis. We postulated in this study that the (mild) inhibition of carotenoid biosynthesis by carotenoid inhibitors, could lead to a reduced production of strigolactones and decreased Striga germination and infection. Very low concentrations of four different carotenoid inhibitors (fluridone, norflurazon, clomazone and amitrole) were applied to rice either through irrigation or through foliar spray. Irrigation application of all carotenoid inhibitors and spray application of amitrole significantly decreased strigolactone production. Application of carotenoid inhibitors caused 61-75% reduction in Striga germination and 65-94% reduction in Striga attachment. The study shows thatthe reducing effect of carotenoid inhibitors (which, in much higher concentrations are widely used as herbicides) on strigolactone secretion and subsequent Striga germination and attachment may be developed into an attractive Striga control technology. Another experiment was aimed at assessing the pre-attachment Striga resistance based on low strigolactone production. We hypothesized that low strigolactones producing crop cultivars might possess pre-attachment Striga resistance due to less germination. For this purpose a set of 18 upland cultivars of NERICA and their parents were screened for strigolactones production and Striga infection parameters like germination, attachment, emergence and Striga dry biomass. NERICA 1 and CG14 produced significantly less strigolactones and showed less Striga infection while NERICAs 7, 8, 11 and 14 produced the highest amounts of strigolactones and showed the most severe Striga infection. This study shows that genetic variation for pre-attachment Striga resistance exists in NERICA rice due to variation in strigolactones. This could be highly relevant for breeding programs aimed at the development of Striga resistant cultivars. In another similar study we hypothesized that variation in strigolactone production in rice might be interconnected with the tillering phenotype and that this link could affect Striga infection. In this study the genetic variation was tested in a series of rice varieties collected from all over the world for strigolactone production, tillering phenotype and Striga infection. Rice cultivars like IAC 165, IAC 1246, Gangweondo and Kinko produced high amounts of the strigolactones, displayed low amounts of tillers and induced high Striga germination, attachment, emergence as well as Striga biomass. In contrast to this, rice cultivars such as Super Basmati, TN 1, Anakila and Agee showed low production of strigolactones and also low Striga germination and infection but high tillering. These results show that genetic variation in strigolactone production results in variation in tillering and also in Striga infection. The tillering phenotype could possibly be used as an easy indicator of the strigolactone production in a breeding programme for Striga resistance. Some experiments were also designed with the aim to quantify the relationship between strigolactones and Striga germination and attachment and to explore the mechanism responsible for the reported reduction in Striga parasitism in the field after fertilizer application. Different levels of nitrogen and phosphorous were applied under greenhouse conditions using rice, maize and sorghum. For maize and sorghum, a parallel study was carried out under field conditions in Kenya and Mali to study the translation of greenhouse results to the field. Application of N and P effectively suppressed Striga infection in the greenhouse in all three crop species and the reduction strongly correlated with reduced secretion of strigolactones into the rhizosphere and the Striga germination induced by these exudates. Although the field results with maize in Kenya were less consistent than in the greenhouse, especially with respect to P effect, still there was a trend that fertilizer application reduced Striga infection. These results show that the positive effect of fertilizer against Striga is at least partly due to a reduction in strigolactone production and as a consequence of that lower Striga germination and subsequent attachment. Overall it can be concluded that there is a good correlation between strigolactones andStriga germination, attachment and biomass. We found this using strigolactone biosynthesis inhibitors, genetic variation and using fertilizer application. These technologies can hence be exploited as an important tool to target Striga at a very early phase of its life cycle. The practical field application of these strategies requires further research but could lead to effective Striga control components that can be used in Integrated Striga Management.
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pre attachment Striga hermonthica resistance of new rice for africa nerica cultivars based on low strigolactone production
New Phytologist, 2011Co-Authors: Muhammad Jamil, Jonne Rodenburg, Tatsiana Charnikhova, Harro J BouwmeesterAbstract:Summary •Striga hermonthica (Striga) is an obligate hemiparasitic weed, causing severe yield losses in cereals, including rice, throughout sub-Saharan Africa. Striga germination depends on strigolactones (germination stimulants) exuded by the host roots. The interspecific New Rice for Africa (NERICA) cultivars offer a potentially interesting gene pool for a screen for low germination-inducing rice cultivars. •Exudates were collected from all NERICA cultivars and their parents (Oryza sativa and Oryza glaberrima) for the analysis of strigolactones. In vitro and in situ Striga germination, attachment and emergence rates were recorded for each cultivar. •NERICA 1 and CG14 produced significantly less strigolactones and showed less Striga infection than the other cultivars. NERICAs 7, 8, 11 and 14 produced the largest amounts of strigolactones and showed the most severe Striga infection. Across all the cultivars and parents, there was a positive relationship between the amount of strigolactones in the exudate and Striga germination, attachment and emergence rates. •This study shows that there is genetic variation in Striga pre-attachment resistance in NERICA rice. Cultivars combining this pre-attachment resistance with post-attachment resistance (already identified) can provide a key component for durable integrated management of this noxious weed in cereal production systems in sub-Saharan Africa.
R. O. Akinwale - One of the best experts on this subject based on the ideXlab platform.
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Efficiency of secondary traits in selecting for improved grain yield in extra‐early maize under Striga‐infested and Striga‐free environments
Plant Breeding, 2014Co-Authors: Baffour Badu-apraku, R. O. Akinwale, Muhydeen OyekunleAbstract:A base index involving Striga damage, number of emerged Striga plants and ears per plant is used for selecting for maize (Zea mays L.) grain yield under Striga infestation. There are contradictory reports on the reliability of number of emerged Striga plants for selecting for Striga resistance. The objective of this study was to confirm reliability of the secondary traits for selecting for improved grain yield under Striga infestation. Ten Striga-resistant extra-early cultivars were evaluated for 3 years under artificial Striga-infested and Striga-free environments in Nigeria. Analysis of variance combined across years and locations showed significant mean squares for genotype, year, location and their interactions for most traits. Sequential path analysis identified ear aspect as the only trait with significant direct effect on yield under artificial Striga infestation, while GGE biplot confirmed ear aspect, ears per plant and Striga damage as the most reliable traits. Ear aspect should be included in the base index for selecting for improved grain yield of extra-early maize under Striga infestation, while the number of emerged Striga plants should be excluded.
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Heterotic grouping of tropical early-maturing maize inbred lines based on combining ability in Striga-infested and Striga-free environments and the use of SSR markers for genotyping
Field Crops Research, 2014Co-Authors: R. O. Akinwale, Baffour Badu-apraku, M. A. B. Fakorede, I. Vroh-biAbstract:a b s t r a c t Identification of heterotic groups among inbreds is crucial to the success of a maize (Zea mays L.) hybrid breeding program. The objectives of this study were to determine the combining ability of 28 early maturing inbreds, classify them into heterotic groups, identify suitable testers under Striga-infested and Striga free environments and to assess the efficiency of three heterotic grouping methods. Three hun- dred and seventy-eight hybrids derived from diallel crosses of 28 early inbreds along with two checks were evaluated in Striga-infested and Striga-free environments for 2 years at two locations in Nigeria. Twenty-seven of the 28 inbreds were genotyped with 46 polymorphic simple sequence repeats (SSR) markers previously mapped on the 10 maize chromosomes. Analysis of variance revealed highly signif- icant (P < 0.01) general combining ability (GCA) and specific combining ability (SCA) mean squares for most traits under test conditions. Based on the SCA effects and heterotic group's specific and general combining ability (HSGCA) for grain yield, four and five heterotic groups were identified under Striga- infested and Striga-free environments, respectively. Two inbreds could not be classified into any of the four groups under Striga-infestation. The SSR markers revealed a wide genetic variability among the inbred lines as the genetic distance ranged between 0.21 and 0.68. Four heterotic groups were identified based on genetic distance (GD) derived from the SSR analysis. Correlation analyses showed that grouping using GD was more consistent with grouping based on SCA under Striga-free than under Striga-infested environments. The HSGCA method was the most effective in classifying early maturing maize inbreds under Striga-infested and Striga free environments. A total of 4 and 8 inbred testers were identified under Striga-infested and Striga-free environments, respectively. These inbred testers are invaluable resources for tropical maize breeding programs.
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genetic diversity assessment of extra early maturing yellow maize inbreds and hybrid performance in Striga infested and Striga free environments
The Journal of Agricultural Science, 2013Co-Authors: I C Akaogu, B Baduapraku, Victor O Adetimirin, I Vrohbi, M Oyekunle, R. O. AkinwaleAbstract:Maize ( Zea mays L.), a major staple food crop in West and Central Africa (WCA), is adapted to all agro-ecologies in the sub-region. Its production in the sub-region is greatly constrained by infestation of Striga hermonthica (Del.) Benth. The performance and stability of the extra-early maturing hybrids, which are particularly adapted to areas with short growing seasons, were assessed under Striga -infested and Striga -free conditions. A total of 120 extra-early hybrids and an open-pollinated variety (OPV) 2008 Syn EE-Y DT STR used as a control were evaluated at two locations each under Striga -infested (Mokwa and Abuja) and Striga- free (Ikenne and Mokwa) conditions in 2010/11. The Striga -resistant hybrids were characterized by higher grain yield, shorter anthesis–silking interval (ASI), better ear aspect, higher numbers of ears per plant (EPP), lower Striga damage rating, and lower number of emerged Striga plants at 8 and 10 weeks after planting (WAP) compared with the susceptible inbreds. Under Striga infestation, mean grain yield ranged from 0·71 to 3·18 t/ha and 1·19 to 3·94 t/ha under Striga -free conditions. The highest yielding hybrid, TZEEI 83×TZEEI 79, out-yielded the OPV control by 157% under Striga infestation. The hybrids TZEEI 83×TZEEI 79 and TZEEI 67×TZEEI 63 were the highest yielding under both Striga -infested and Striga -free conditions. The genotype main effect plus genotype×environment interaction (GGE) biplot analysis identified TZEEI 88×TZEEI 79 and TZEEI 81×TZEEI 95 as the ideal hybrids across research environments. Twenty-three pairs of simple sequence repeat (SSR) markers were used to assess the genetic diversity among the inbred lines. The correlations between the SSR-based genetic distance (GD) estimates of parental lines and the means observed in F 1 hybrid under Striga infestation and optimum growing conditions were not significant for grain yield and other traits except ASI under optimum conditions. Grain yield of inbreds was not significantly correlated with that of F 1 hybrids. However, a significant correlation existed between F 1 hybrid grain yield and heterosis under Striga infestation ( r =0·72, P Striga endemic areas in WCA.
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EVALUATION OF Striga-RESISTANT EARLY MAIZE HYBRIDS AND TEST LOCATIONS UNDER Striga-INFESTED AND Striga-FREE ENVIRONMENTS
African Crop Science Journal, 2013Co-Authors: R. O. Akinwale, B. Badu-apraku, M. A. B. FakoredeAbstract:Emergence of several seed companies in the West Africa sub-region during the last decade has necessitated intensified efforts towards hybrid development and extensive testing. The objectives of the present study were to evaluate selected Striga-resistant maize (Zea mays L.) hybrids for grain yield and stability of performance based on multiple traits. Thirty Striga-resistant single–cross maize hybrids plus two checks were evaluated under artificial Striga infestation and Striga-free conditions at 2 locations in Nigeria in 2008 and 2009. The two test locations possessed high discriminating ability. More promising genotypes were identified under Striga infestation based on multiple traits than based on yield per se, suggesting that grain yield alone is not a precise predictor of Striga resistance. Based on both biplot analyses, TZEI12 x TZEI25 was identified as the most outstanding in performance under both research conditions. Furthermore, TZEI11 x TZEI127 and TZEI80 x TZEI2B were identified as the most outstanding under Striga-infested conditions and TZEI60 x TZEI87 under Striga-free conditions by the two biplot methods. The hybrids with outstanding performance should undergo extensive multilocational testing and promotion for adoption for commercial production. Key Words : GGE biplot, multiple traits, Zea mays
D.e Hess - One of the best experts on this subject based on the ideXlab platform.
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Integrated control of Striga hermonthica (Del.) Benth. in Burkina Faso through host plant resistance, biocontrol and fertilizers
International Journal of Biological and Chemical Sciences, 2012Co-Authors: D. Yonli, D.e Hess, T A Van Mourik, H. Traoré, P. Sérémé, P SankaraAbstract:A two-year field study investigated integrated management of Striga hermonthica on sorghum through host crop resistance, biocontrol ( Fusarium oxysporum isolate 34-FO), and fertilizer application. The experiment was conducted in a field with natural Striga infestation at Kouare Research Station in Fada N’Gourma, Burkina Faso. Treatments combining sorghum resistance with Fusarium inoculum and N-fertilizer or manure significantly reduced emerged Striga plant number, plant vigour and dry biomass of Striga and the area under the Striga number progress curve (ASNPC) in 2002, as compared to the control. Integrated Striga Management (ISM) plots fertilized with urea, urea plus growth medium or urea plus manure associated with Fusarium inoculum resulted in improved sorghum grain yield of at least 15% in 2001 and of at least 97% in 2002. Economic analysis showed that the combination of sorghum resistance with fungal inoculum or urea at 200 kg ha -1 allowed for a significant financial profit in sorghum production. The results suggest that to reduce Striga infestation below economic threshold, ISM treatments should be consistently applied for several years without expecting very high returns. Keywords : Striga hermonthica, integrated control, Fusarium inoculum, Sorghum resistance, fertilization, Burkina Faso
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Pathogenicity of Fusarium isolates to Striga hermonthica in Burkina Faso.
Pakistan journal of biological sciences : PJBS, 2010Co-Authors: D. Yonli, D.e Hess, H. Traoré, P. Sérémé, P SankaraAbstract:Striga hermonthica (Del.) Benth. is an important constraint to cereal crop production in Burkina Faso, of which sorghum (Sorghum bicolor L. Moench) is the most important component. Native Fusarium species to use as bio-control agents to S. hermonthica has been investigated. Fifty one Fusarium isolates obtained from diseased plants of S. hermonthica were evaluated for their pathogenicity against Striga under controlled environmental conditions. Of 51 Fusarium isolates, 14 were pathogenic to S. hermonthica but their virulence differed. These 14 isolates were evaluated for their effects on Striga seed germination in the laboratory and their ability to kill emerged Striga plants growing in greenhouse pots. Spores of Fusarium sp. isolates 150a-M, 125b-Za, 6-Fa, Fusarium equiseti isolates 5-Kou, 31-Kom, 32-Or, 13-Ba and Fusarium oxysporum isolate 34-Fo reduced Striga germination by 78 to 96% compared to the untreated control. The study showed that at the rate of 33 mg mL(-1), metabolites of Fusarium sp. isolates 125b-Za, 6-Fa, F. equiseti 5-Kou and F. oxysporum 34-Fo prevented Striga seed germination. In addition to these four isolates, Fusarium sp. isolates 141b-O, 150a-M and F. equiseti isolate 32-Or were effective at 67 mg mL(-1). Percentage of Striga mortality ranged from 17-37% between 14 and 28 days after inoculation with spores of F. oxysporum 34-Fo and F. equiseti 5-Kou. Striga dry biomass was reduced by 84 and 78% for the respective isolates compared to the untreated control with Striga. Sorghum yield was improved by 84 and 99% with Fusarium sp. 6-Fa and F. oxysporum 34-Fo, respectively, compared to the control without Striga. The use of Fusarium spores and metabolites against Striga offers different possibilities of bio-herbicides formulation that can be combined with other controls methods in the integrated Striga management. Further studies will be carried out under field conditions to assess the efficacy and safety of these Fusarium isolates to environment and humans and evaluate low cost strategies for transfer to subsistence farmers.
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Effect of growth medium, Striga seed burial distance and depth on efficacy of Fusarium isolates to control Striga hermonthica in Burkina Faso
Weed Research, 2006Co-Authors: D. Yonli, D.e Hess, H. Traoré, P Sankara, P. SéréméAbstract:Summary Striga hermonthica is a destructive parasite of cereal crops in the semi-arid tropical zone. Two greenhouse experiments were conducted at Kamboinse, Burkina Faso, to investigate the effect of inoculum substrate and location of Striga seeds on the ability of 14 indigenous Fusarium isolates to control the parasite. In Expt 1, Fusarium isolates reduced emerged Striga number, Striga vigour and dry biomass. As a result, sorghum dry biomass and grain yield were enhanced. Inoculum substrate did not influence the ability of Fusarium isolates to control Striga. In Expt 2, Fusarium isolates, substrate and their interaction significantly influenced germination of Striga seeds at both 35 and 50 days after sowing. Isolates grown on compost were more effective at reducing germination of Striga seeds than those grown on chopped sorghum straw. The per cent germination of seeds 50 days after sowing, buried at 5 cm depth, was significantly lower than that of seeds buried at 10 cm. At 10 cm depth, Fusarium isolates still reduced Striga seed germination with respect to the control; horizontal planting distance, 5 or 10 cm from sorghum hills, had no effect.
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How can field selection for Striga resistance and tolerance in sorghum be improved
Field Crops Research, 2005Co-Authors: Jonne Rodenburg, Lammert Bastiaans, Eva Weltzien, D.e HessAbstract:Breeding for high yielding Sorghum bicolor varieties with effective resistance and tolerance against the hemi-parasitic weed Striga hermonthica requires suitable selection measures for both characteristics. The objective of this research was to constitute a set of practical selection measures that contain independent, reliable and discriminative criteria for resistance and tolerance. Ten sorghum genotypes were grown in the field with and without Striga infestation in a split-plot design in 3 successive years (2001–2003) using different Striga infestation levels (low, high and intermediate). Resistance against Striga in the below-ground stages was determined separately in an agar-gel assay and a pot trial. The addition of Striga-free control plots facilitated the calculation of the relative yield loss, which represents the result of resistance and tolerance combined. Correlation analysis indirectly demonstrated that both resistance and tolerance are important yield determining traits under Striga infestation. Tolerance was relatively more important under low Striga infestation levels, whereas resistance was relatively more important at high infestation levels. With respect to resistance, both the area under the Striga number progress curve (ASNPC) and maximum above-ground Striga number (NSmax) turned out to be discriminative and consistent selection measures. Both measures also corresponded well with the expression of resistance during below-ground stages of the parasite. It proved more difficult to arrive at a satisfactory measure for tolerance. Inclusion of Striga-free plots is an essential step for the determination of tolerance, but in itself not sufficient. It provides a basis for the determination of the relative yield loss, which then needs to be corrected for differences in infection level resulting from genotypic differences in resistance. A linear correction for infection level disregards the density dependency of the relative yield loss function. It is expected that clarification of the relation between Striga infection level and yield loss, provides a solid basis for the development of unambiguous tolerance measures in the field. This will enable the breeder to select for resistance and tolerance separately, which is likely to result in the optimum combination of both defence mechanisms.
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effect of growth medium and method of application of fusarium oxysporum on infestation of sorghum by Striga hermonthica in burkina faso
Biocontrol Science and Technology, 2004Co-Authors: D. Yonli, D.e Hess, H. Traoré, A A Abbasher, I J BoussimAbstract:A 2-year (1997–1998) study was conducted at Kouare, Burkina Faso, to investigate effect of growth medium and application method of Fusarium oxysporum isolate 4-3-B to control Striga hermonthica. In 1997, growth medium and isolate 4-3-B delayed Striga emergence by 9 days. Isolate 4-3-B reduced emerged Striga number by 33% compared to treatments without Fusarium. In 1998, Striga emergence was delayed by 13 days by growth medium and Fusarium. The fungus reduced the number of emerged Striga by 27% and, as a result, sorghum straw and grain yields were significantly improved by 10 and 38%, respectively.
Harro J Bouwmeester - One of the best experts on this subject based on the ideXlab platform.
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Striga hermonthica parasitism in maize in response to n and p fertilisers
Field Crops Research, 2012Co-Authors: Muhammad Jamil, Fred Kanampiu, Tatsiana Charnikhova, H. Karaya, Harro J BouwmeesterAbstract:Parasitism by the parasitic weed, Striga hermonthica (Striga), constitutes a major biological constraint to maize production in sub-Sahara Africa. Nutrient deficiency is known to aggravate Striga infestation and in a number of plant species it was recently shown that this may be due to increased secretion of Striga germination stimulants into the soil. The present study was designed to observe the connection between soil fertility, secretion of germination stimulants and Striga infection in maize under greenhouse and field conditions. The experiments were conducted during two successive cropping seasons (2008 and 2009). The greenhouse study showed that maize secretes a number of so far unidentified strigolactones that induce Striga seed germination and the amount of these strigolactones increases upon N and P deficiency. The increased secretion of germination stimulants under N and P deficiency resulted in increased Striga infection in pot experiments. The on-station and on-farm field trials in Western Kenya also showed reduction in Striga infestation with the application of mineral nutrients but the results were less consistent than in the greenhouse. Increasing levels of N showed a fair reduction of Striga in the field especially during the first year, whereas P application did not have much effect in contrast to the greenhouse study where both N and P clearly reduced Striga infection. The likely explanation for this discrepancy is that availability of mineral nutrients under field conditions is less predictable than under greenhouse conditions, due to a number of factors such as soil texture and structure, pH, salinity, drought, leaching and runoff. Hence, further studies are needed on the importance of these factors before a fertiliser application strategy can be formulated to improve control of Striga in maize in the field.
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pre attachment Striga hermonthica resistance of new rice for africa nerica cultivars based on low strigolactone production
New Phytologist, 2011Co-Authors: Muhammad Jamil, Jonne Rodenburg, Tatsiana Charnikhova, Harro J BouwmeesterAbstract:Summary •Striga hermonthica (Striga) is an obligate hemiparasitic weed, causing severe yield losses in cereals, including rice, throughout sub-Saharan Africa. Striga germination depends on strigolactones (germination stimulants) exuded by the host roots. The interspecific New Rice for Africa (NERICA) cultivars offer a potentially interesting gene pool for a screen for low germination-inducing rice cultivars. •Exudates were collected from all NERICA cultivars and their parents (Oryza sativa and Oryza glaberrima) for the analysis of strigolactones. In vitro and in situ Striga germination, attachment and emergence rates were recorded for each cultivar. •NERICA 1 and CG14 produced significantly less strigolactones and showed less Striga infection than the other cultivars. NERICAs 7, 8, 11 and 14 produced the largest amounts of strigolactones and showed the most severe Striga infection. Across all the cultivars and parents, there was a positive relationship between the amount of strigolactones in the exudate and Striga germination, attachment and emergence rates. •This study shows that there is genetic variation in Striga pre-attachment resistance in NERICA rice. Cultivars combining this pre-attachment resistance with post-attachment resistance (already identified) can provide a key component for durable integrated management of this noxious weed in cereal production systems in sub-Saharan Africa.
Baffour Badu-apraku - One of the best experts on this subject based on the ideXlab platform.
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Gains in Genetic Enhancement of Early Maturing Maize Hybrids Developed during Three Breeding Periods under Striga-Infested and Striga-Free Environments
Agronomy, 2020Co-Authors: Baffour Badu-apraku, G.b. Adu, Abdoul-madjidou Yacoubou, Johnson Toyinbo, Samuel AdewaleAbstract:Striga hermonthica is a major maize production constraint in West and Central Africa (WCA). Fifty-four early maturing maize hybrids of three breeding periods: 2008–2011, 2012–2013, 2014–2015, were evaluated under Striga-infested and non-infested environments in WCA. The study aimed at assessing genetic improvement in grain yield of the hybrids, identifying traits associated with yield gain during the breeding periods, and grain yield and stability of the hybrids in Striga infested and non-infested environments. Annual increase in grain yield of 101 kg ha−1 (4.82 %) and 61 kg ha−1 (1.24%) were recorded in Striga-infested and non-infested environments, respectively. The gains in grain yield from period 1 to period 3 under Striga-infested environments were associated with reduced anthesis-silking interval, reduced Striga damage, number of emerged Striga plants, improved ear aspect, and increased ears per plant. Ear aspect, ears per plant, and Striga damage at 8 and 10 weeks after planting (WAP) were significantly correlated with yield in Striga-infested environments, whereas ears per plant and plant and ear aspects had significant correlations with yield in non-infested environments. Hybrids TZdEI 352 × TZEI 355, TZdEI 378 × TZdEI 173, and TZdEI 173 × TZdEI 352 were outstanding in grain yield and stability in Striga-infested environments, whereas TZEI 326 × TZdEI 352, TZEI 495 × ENT 13, and TZdEI 268 × TZdEI 131 were superior in non-stress environments. These hybrids should be further tested extensively and commercialized. Significant genetic gains have been made in breeding for resistance to Striga hermonthica in early maturing maize hybrids.
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Breeding for Striga Resistance
Advances in Genetic Enhancement of Early and Extra-Early Maize for Sub-Saharan Africa, 2017Co-Authors: Baffour Badu-apraku, M. A. B. FakoredeAbstract:Striga hermonthica(L.) Kuntze, a parasitic weed, is endemic in a large part of the Guinea savanna of West and Central Africa (WCA). Strigaplants do much damage underground before the parasitic plants appear on top of the soil around the maize plant. The weed, which could cause 100% yield loss in the maize crop, has defied all control efforts at the national level of WCA countries thereby forcing farmers to abandon their farmlands. Teaming up with the national research scientists, IITA initiated a massive control effort on Striga. Screening and breeding were done for tolerance, the ability of the host to perform well regardless of the number of Striga plants parasitic on the host plant, as well as resistance, the ability of the host plant to reduce the number of Striga plants surviving on it. An efficacious manual infestation method was established and has been in use since its discovery. Genetics of tolerance/resistance was investigated, along with combining ability of inbred lines in hybrid seed production. Early and extra-early maize populations have been subjected to recurrent selection under Striga infestation, and the response to selection along with correlated responses in other nonselected traits has been evaluated under Striga-infested and Striga-free conditions. Early and extra-early Striga-tolerant/Striga-resistant populations, inbred lines, and hybrids are now available to farmers in the Striga endemic areas of sub-Saharan Africa (SSA). The materials also have value addition of good performance in non-Striga environments.
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Efficiency of secondary traits in selecting for improved grain yield in extra‐early maize under Striga‐infested and Striga‐free environments
Plant Breeding, 2014Co-Authors: Baffour Badu-apraku, R. O. Akinwale, Muhydeen OyekunleAbstract:A base index involving Striga damage, number of emerged Striga plants and ears per plant is used for selecting for maize (Zea mays L.) grain yield under Striga infestation. There are contradictory reports on the reliability of number of emerged Striga plants for selecting for Striga resistance. The objective of this study was to confirm reliability of the secondary traits for selecting for improved grain yield under Striga infestation. Ten Striga-resistant extra-early cultivars were evaluated for 3 years under artificial Striga-infested and Striga-free environments in Nigeria. Analysis of variance combined across years and locations showed significant mean squares for genotype, year, location and their interactions for most traits. Sequential path analysis identified ear aspect as the only trait with significant direct effect on yield under artificial Striga infestation, while GGE biplot confirmed ear aspect, ears per plant and Striga damage as the most reliable traits. Ear aspect should be included in the base index for selecting for improved grain yield of extra-early maize under Striga infestation, while the number of emerged Striga plants should be excluded.
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Heterotic grouping of tropical early-maturing maize inbred lines based on combining ability in Striga-infested and Striga-free environments and the use of SSR markers for genotyping
Field Crops Research, 2014Co-Authors: R. O. Akinwale, Baffour Badu-apraku, M. A. B. Fakorede, I. Vroh-biAbstract:a b s t r a c t Identification of heterotic groups among inbreds is crucial to the success of a maize (Zea mays L.) hybrid breeding program. The objectives of this study were to determine the combining ability of 28 early maturing inbreds, classify them into heterotic groups, identify suitable testers under Striga-infested and Striga free environments and to assess the efficiency of three heterotic grouping methods. Three hun- dred and seventy-eight hybrids derived from diallel crosses of 28 early inbreds along with two checks were evaluated in Striga-infested and Striga-free environments for 2 years at two locations in Nigeria. Twenty-seven of the 28 inbreds were genotyped with 46 polymorphic simple sequence repeats (SSR) markers previously mapped on the 10 maize chromosomes. Analysis of variance revealed highly signif- icant (P < 0.01) general combining ability (GCA) and specific combining ability (SCA) mean squares for most traits under test conditions. Based on the SCA effects and heterotic group's specific and general combining ability (HSGCA) for grain yield, four and five heterotic groups were identified under Striga- infested and Striga-free environments, respectively. Two inbreds could not be classified into any of the four groups under Striga-infestation. The SSR markers revealed a wide genetic variability among the inbred lines as the genetic distance ranged between 0.21 and 0.68. Four heterotic groups were identified based on genetic distance (GD) derived from the SSR analysis. Correlation analyses showed that grouping using GD was more consistent with grouping based on SCA under Striga-free than under Striga-infested environments. The HSGCA method was the most effective in classifying early maturing maize inbreds under Striga-infested and Striga free environments. A total of 4 and 8 inbred testers were identified under Striga-infested and Striga-free environments, respectively. These inbred testers are invaluable resources for tropical maize breeding programs.
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Genetic gains from selection for high grain yield and Striga resistance in early maturing maize cultivars of three breeding periods under Striga-infested and Striga-free environments
Field Crops Research, 2013Co-Authors: Baffour Badu-apraku, C. G. Yallou, M OyekunleAbstract:Abstract Maize is the most important staple cereal crop in sub-Saharan Africa (SSA) and has great potential to rectify the food insecurity in the sub-region. A study was conducted at four locations two each in Nigeria and Benin in 2010 and 2011 to determine the rate of genetic improvement in the grain yield of 50 maize cultivars developed during three breeding periods, 1988–2000 (period 1), 2001–2006 (period 2) and 2007–2010 (period 2) under Striga -infested and Striga -free conditions. Under Striga infestation, mean grain yield ranged from 2537 kg ha −1 for the period 1 cultivars to 3122 kg ha −1 for period 3 cultivars with a corresponding annual genetic gain of 1.93%. When Striga -free, grain yield ranged from 3646 kg ha −1 for the period 1 cultivars to 4227 kg ha −1 for the period 2 cultivars with an annual genetic gain of 1.0%. The average annual rate of increase in grain yield was 41 kg ha −1 when Striga -infested and 34 kg ha −1 when Striga -free. The annual genetic gain in grain yield was 0.86% for period 1 cultivars, 2.07% for period 2 cultivars, and 2.11% for period 3 cultivars under Striga infestation. The increase in grain yield under Striga infestation was associated with significant decrease in Striga damage and the number of emerged Striga plants at 8 and 10 weeks after planting (WAP), an improvement in ear aspect, lodging resistance, plant height, and increase in the number of ears per plant (EPP) from the period 1 to the period 3 cultivars. For the emerged Striga plants, the annual genetic gains of −0.63% for 8 WAP and −0.57% for 10 WAP were obtained from the period 1 to the period 2 cultivars. The increase in genetic gains was 0.70% for EPP and −0.65% for ear aspect. The increase in grain yield from period 1 to period 3 cultivars when Striga -free was associated with increased days to anthesis, increased plant and ear heights, improvement in ear aspect, and husk cover and increased EPP. Cultivars 28, 14, 29, and 26 were the most outstanding across Striga -infested environments. Substantial progress has been made in breeding for high yielding, Striga resistant/tolerant cultivars during the past three decades.
