The Experts below are selected from a list of 306 Experts worldwide ranked by ideXlab platform
James M Bokosi - One of the best experts on this subject based on the ideXlab platform.
-
role of variety and fertilizer practices on cowpeas vigna unguiculata yield and field incidence of the parasitic weed Alectra vogelii benth in central malawi
The Journal of Agricultural Science, 2020Co-Authors: V H Kabambe, James M BokosiAbstract:Grain legumes are an important component of the food systems in Malawi. The parasitic legume witchweed species Alectra vogelii (Benth) is among the problem pests with serious infestations in groundnuts (Arachis hypogea), soybeans (Glycine max), cowpeas (Vigna unguiculata) and other legumes. A study was conducted in 2013/14 and ‘14/15 seasons to evaluate the effects of three cowpea varieties (IT82E-16, Sudan 1 and Alectra-resistant Mkanakaufi) and fertilizer practices (no fertilizer applied, 5 t ha-1 cattle manure and 100 kg ha-1 of inorganic 23:21:0+4S on cowpea grain yield, yield components and Alectra emergence at three sites in central Malawi. Cowpea grain yields ranged 400-2400 kg ha-1. There were significant (P < 0.05) variety effects on yield in 4 of 6 site-years, with variety IT82-16 consistently giving the highest yields (range 1200-2400 kg ha-1). There were significant variety effects on A. vogelii emergence with Mkanakaufiti having no Alectra throughout. Application of cattle manure strongly suppressed A. vogelii in 6 site-years all at 60 days after planting, while inorganic fertilizer suppressed Alectra in 3 of the 6 site-years. Cattle significantly but marginally (about 250 kg ha-1) increased yield in 2 of the 6 site-years. The results show potential to suppress A. vogelii with cattle manure application. However, further studies are required to understand the causes of the limited yield response under manure or fertilizer application to make the practices attractive to farmers. More variety improvement studies to produce a range of varieties with better local adaptability and response to fertility amendments are recommended.
-
release of cowpea line it99k 494 6 for yield and resistance to the parasitic weed Alectra vogelii benth in malawi
African Journal of Plant Science, 2014Co-Authors: V H Kabambe, James M Bokosi, E D L Mazuma, E KaziraAbstract:Field trials were conducted between 2008/09 and 2009/10 seasons to evaluate four new cowpea lines, selected in preliminary studies, for yield, adaptation and resistance to the parasitic weed Alectra vogelii in Malawi. The design was randomised complete block design with 4 replicates at research stations and 5 at on-farm sites. For on-farm, villages were the sites and each farmer hosted one replicate. The trial sites were Lisasadzi, Mngwangwa, Bunda College, Chitedze Research Station, Rivirivi and Mpokwa in 2008/09 season and in 2009/10 the sites at Chitedze and Mpokwa were replaced by Mkwinda and Chitala Research Station. Four promising cowpea lines, IT98K-503-1, IT97K-825-15, IT99K-7-21-2-2-1 and IT99K-494-6, all originally from IITA and selected for resistance to parasitic weed Alectra vogelii in screen house studies, were compared with released varieties Sudan 1, IT82E-16 and a farmers local entry. The following parameters were evaluated: cowpea grain yield, plants/m2, seeds/pod, seed weight (g/100 seeds), days to mid-flower, days to maturity, disease scores (scale 1 [clean] – 9 [most severe]) and A. vogelii emergence (plants/m2). The line IT99K-494-6 was found to have comparable or better agronomic traits as compared to control varieties and was eventually released in Malawi in January 2011. The line which is medium maturing has brown grain texture with yield potential of 1-2.0 t/ha. Such a resistant variety is important in A. vogelii hot spots to reduce build up in soil seed bank and a viable option for farmers to rotate with cowpeas in order to manage other pests such as Striga asiatica, an important parasitic weed, or improve soil fertility through the nitrogen fixation of cowpeas. Key words: Legumes, witchweeds, parasitic weeds, cowpea, Alectra vogelii, Vigna unguiculata.
V H Kabambe - One of the best experts on this subject based on the ideXlab platform.
-
role of variety and fertilizer practices on cowpeas vigna unguiculata yield and field incidence of the parasitic weed Alectra vogelii benth in central malawi
The Journal of Agricultural Science, 2020Co-Authors: V H Kabambe, James M BokosiAbstract:Grain legumes are an important component of the food systems in Malawi. The parasitic legume witchweed species Alectra vogelii (Benth) is among the problem pests with serious infestations in groundnuts (Arachis hypogea), soybeans (Glycine max), cowpeas (Vigna unguiculata) and other legumes. A study was conducted in 2013/14 and ‘14/15 seasons to evaluate the effects of three cowpea varieties (IT82E-16, Sudan 1 and Alectra-resistant Mkanakaufi) and fertilizer practices (no fertilizer applied, 5 t ha-1 cattle manure and 100 kg ha-1 of inorganic 23:21:0+4S on cowpea grain yield, yield components and Alectra emergence at three sites in central Malawi. Cowpea grain yields ranged 400-2400 kg ha-1. There were significant (P < 0.05) variety effects on yield in 4 of 6 site-years, with variety IT82-16 consistently giving the highest yields (range 1200-2400 kg ha-1). There were significant variety effects on A. vogelii emergence with Mkanakaufiti having no Alectra throughout. Application of cattle manure strongly suppressed A. vogelii in 6 site-years all at 60 days after planting, while inorganic fertilizer suppressed Alectra in 3 of the 6 site-years. Cattle significantly but marginally (about 250 kg ha-1) increased yield in 2 of the 6 site-years. The results show potential to suppress A. vogelii with cattle manure application. However, further studies are required to understand the causes of the limited yield response under manure or fertilizer application to make the practices attractive to farmers. More variety improvement studies to produce a range of varieties with better local adaptability and response to fertility amendments are recommended.
-
screening of Alectra vogelii ecotypes on legume and non legume crop species in malawi
The South African Journal of Plant and Soil, 2019Co-Authors: C K Phiri, V H Kabambe, J Bokosi, P MumbaAbstract:The parasitic angiosperm Alectra vogelii Benth. is a growing problem in Malawi, particularly with the current emphasis on legume crops. Therefore, a screen-house study was conducted to determine th...
-
screening for resistance mechanisms in cowpea genotypes on Alectra vogelii
American Journal of Plant Sciences, 2018Co-Authors: C K Phiri, V H Kabambe, J Bokosi, P MumbaAbstract:Parasitic angiosperm Alectra vogelii Benth is a growing problem in Malawi, particularly with current emphasis on legumes. Therefore, two studies were set in order to understand the possible mechanisms of resistance in cowpea genotypes on their reaction to the parasitic weed. In the first experiment, Mkanakaufiti, IT99K-7-21-2-2XIT82E-16, Sudan 1 and IT82E-16 were grown in Alectra infested and non-infested pots. The experiment (2*4 factorial treatment combination) was arranged in an RCBD and replicated eight times. The second experiment, involved Petri-dish techniques where 4 genotype roots were assessed on their ability to stimulate the germination of A. vogelii as a proxy for germination stimulant production. The experiment was arranged in an RCBD and replicated five times. In the first experiment, data was collected on; the number of days to first Alectra emergence, Alectra shoot counts at 6, 8, 10, and 12 weeks after planting (WAP), Alectra attachment at 5 and 12 WAP, Alectra biomass at 12 WAP, cowpea biomass parameters at 5 and 12 WAP, yield and yield components per pot. While in the second experiment, number of germinated Alectra seeds per Petri dishes was recorded. The results indicated that IT82E-16 (33.25 days) and Sudan 1 (34.25 days) were earlier infested whilst late on IT99K-7-21-2-2XIT82E-16 (38 days) which correlated to the number of Alectra attachments. There were significant differences (p = 0.05) in weekly Alectra counts between cowpea varieties from 6 up to 10 WAP. Mkanakaufiti and IT99K-7-21-2-2XIT82E-16 were observed with no and few Alectra shoots infestation respectively which was an indicator of resistance mechanism in the study. Number of pods, grain weight (g) and harvest index per pot were significantly affected by inoculation protocol with lower yield on infested cowpea genotypes. The same trend was observed on cowpea varieties where Mkanakaufiti (21.9 g/pot) shown higher yield followed by IT82E-16 (12.5 g/pot) which is susceptible but with tolerance ability to the parasitic weed. The study has shown that resistance mechanisms can be categorized as no or few Alectra shoots, death of Alectra shoots and late infestation. In the Petri dishes, only 3 WAP grown Mkanakaufiti root media failed to induce the germination of Alectra seeds while the opposite occurred on IT82E-16, Sudan 1 and IT99K-7-21-2-2XIT82E-16. On the contrary, 4 WAP grown root media of the four genotypes stimulated Alectra germination which shed more light on the seed behaviour in the soil. This is worth exploring as more could be known to what causes termination of Alectra shoots on Mkanakaufiti. Still, intensifying resistant genotypes should be a goal in order to reduce Alectra seed banks in the soil, thereby, increasing cowpea yield.
-
release of cowpea line it99k 494 6 for yield and resistance to the parasitic weed Alectra vogelii benth in malawi
African Journal of Plant Science, 2014Co-Authors: V H Kabambe, James M Bokosi, E D L Mazuma, E KaziraAbstract:Field trials were conducted between 2008/09 and 2009/10 seasons to evaluate four new cowpea lines, selected in preliminary studies, for yield, adaptation and resistance to the parasitic weed Alectra vogelii in Malawi. The design was randomised complete block design with 4 replicates at research stations and 5 at on-farm sites. For on-farm, villages were the sites and each farmer hosted one replicate. The trial sites were Lisasadzi, Mngwangwa, Bunda College, Chitedze Research Station, Rivirivi and Mpokwa in 2008/09 season and in 2009/10 the sites at Chitedze and Mpokwa were replaced by Mkwinda and Chitala Research Station. Four promising cowpea lines, IT98K-503-1, IT97K-825-15, IT99K-7-21-2-2-1 and IT99K-494-6, all originally from IITA and selected for resistance to parasitic weed Alectra vogelii in screen house studies, were compared with released varieties Sudan 1, IT82E-16 and a farmers local entry. The following parameters were evaluated: cowpea grain yield, plants/m2, seeds/pod, seed weight (g/100 seeds), days to mid-flower, days to maturity, disease scores (scale 1 [clean] – 9 [most severe]) and A. vogelii emergence (plants/m2). The line IT99K-494-6 was found to have comparable or better agronomic traits as compared to control varieties and was eventually released in Malawi in January 2011. The line which is medium maturing has brown grain texture with yield potential of 1-2.0 t/ha. Such a resistant variety is important in A. vogelii hot spots to reduce build up in soil seed bank and a viable option for farmers to rotate with cowpeas in order to manage other pests such as Striga asiatica, an important parasitic weed, or improve soil fertility through the nitrogen fixation of cowpeas. Key words: Legumes, witchweeds, parasitic weeds, cowpea, Alectra vogelii, Vigna unguiculata.
-
screening legumes for integrated management of witchweeds Alectra vogelii and striga asiatica in malawi
African Journal of Agricultural Research, 2008Co-Authors: V H Kabambe, L Katunga, T KapewaAbstract:In Malawi the parasitic weeds (witchweeds) for cereals and legumes exist simultaneously. The predominant species for cereals is Striga asiatica, while for legumes it is Alectra vogelii, which causes damage in groundnuts (Arachis hypogea L.), cowpeas (Vigna unguiculata) and soybeans (Glycine max.). Growing legumes is a control measure for S. asiatica in cereal crops. Studies were initiated in 2000/2001 at Chitedze Research Station to screen amongst several entries of groundnuts, pigeon peas (Cajanus cajan), sunhemp (Crotalaria spp.), soybeans, velvet beans (Mucuna spp) for resistance to A. vogelii. In 2002/2003 a similar experiment was repeated, utilizing the promising entries. In 2003/2004 a screen house pot study was conducted at Bunda College to evaluate soybean lines with and without A. vogelii infection. Results from the 2000/2001 screening study indicated that amongst the crops soybean are the most susceptible to Alectra. Within soybeans, Bossier, Ocepara-4 and 501/6/12 were the least susceptible, with < 1.0 plant m -2 , compared to 5.0 plants m -2 with 427/5/7. All pigeon peas and green manure entries had no Alectra emerging on them. Similar results were obtained when the study was repeated with a few entries in 2002/2003. In a screen house study of 2003/2004, soybean varieties Bossier and Ocepara-4 had the least Alectra on them (<0.33 plants pot -1 ), while other entries such as
E I Aigbokhan - One of the best experts on this subject based on the ideXlab platform.
-
potential of imazaquin seed treatment for control of striga gesnerioides and Alectra vogelii in cowpea vigna unguiculata
Plant Disease, 1994Co-Authors: D K Berner, A E Awad, E I AigbokhanAbstract:The herbicide imazaquin was tested for efficacy in Striga gesnerioides and Alectra vogelii control when applied as a cowpea (Vigna unguiculata) seed treatment. Four sets of experiments were conducted in the laboratory and screenhouse. Two cowpea cultivars, three geographical isolates of S. gesnerioides from two hosts, and two geographical isolates of A. vogelii from two hosts were used. Preliminary experiments indicated cowpea seed treatments of 5-min duration in aqueous solutions of the ammonium salt of imazaquin, ranging from 1.8 to 7.2 mg a.i./ml, fit our test criteria of 50% germination and observable radicle growth inhibition. Treated cowpea seeds were dried and planted in soil-filled pots infested with 3,000 germinable S. gesnerioides or A. vogelii seeds
E G Njoku - One of the best experts on this subject based on the ideXlab platform.
-
application of quikscat backscatter to smap validation planning freeze thaw state over Alectra sites in alaska from 2000 to 2007
IEEE Transactions on Geoscience and Remote Sensing, 2012Co-Authors: Andreas Colliander, Kyle C Mcdonald, Reiner Zimmermann, R Schroeder, John S Kimball, E G NjokuAbstract:The mapping of the predominant freeze/thaw state of the landscape is one of the main objectives of the National Aeronautics and Space Administration's proposed Soil Moisture Active Passive (SMAP) mission. This study applies Alaska Ecological Transect (Alectra) biophysical network temperature measurements and satellite radar scatterometer data from the Quick Scatterometer (QuikSCAT) to evaluate some of the validation issues regarding the planned SMAP freeze/thaw measurements. Although the QuikSCAT data are acquired at Ku-band frequency, rather than at the L-band frequency of the proposed SMAP instrument, QuikSCAT data do provide a high temporal fidelity over the Alectra sites, similar to SMAP. The results of this study show that multiple temperature measurements representative of individual landscape components (soil, snow cover, vegetation, and atmosphere) covering different types of terrain within the satellite field of view are important for understanding the freeze/thaw process and the aggregate radar backscatter response to that process. The backscatter temporal dynamics and relative contribution of the freeze/thaw state of these landscape elements to radar signal vary with land cover, seasonal weather, and climate conditions.
-
quikscat backscatter sensitivity to landscape freeze thaw state over Alectra sites in alaska from 2000 to 2007 application to smap validation planning
International Geoscience and Remote Sensing Symposium, 2010Co-Authors: Andreas Colliander, Kyle C Mcdonald, Reiner Zimmermann, Thomas Linke, R Schroeder, John S Kimball, E G NjokuAbstract:The mapping of freeze/thaw state of the landscape is one of the main objectives of NASA's upcoming SMAP (Soil Moisture Active and Passive) mission. This study applies Alectra (Alaska Ecological Transect) biophysical network and QuikSCAT scatterometer data to evaluate some of the validation issues regarding the SMAP freeze/thaw measurements. Although the QuikSCAT data is at Ku-band frequency, rather than the L-band of the SMAP instrument, the data is utilized due to its uniquely high temporal resolution over the Alectra sites. The results show that multiple temperature measurements representative of individual landscape (soil, snow cover, vegetation and atmosphere) elements and spatial heterogeneity within the satellite field-of-view are important for understanding the radar backscatter process and aggregate freeze/thaw signal. The backscatter temporal dynamics and relative contribution of these landscape elements to the freeze-thaw signal varies with land cover type, seasonal weather and climate conditions.
Zakaria Dieni - One of the best experts on this subject based on the ideXlab platform.
-
inheritance and allelic relationships of Alectra vogelii benth resistance genes in cowpea genotypes b301 and kvx414 22 2
The Journal of Agricultural Science, 2021Co-Authors: Zakaria Dieni, Benoit Joseph Batieno, Felicien Serge W M Zida, Abdou Kader CongoAbstract:Alectra vogelii Benth. is the second most important parasitic weed in cowpea [Vigna unguiculata (L.) Walp.] production in Burkina Faso. Several resistant varieties to this weed have been identified in the country among which are B301 and KVx414-22-2. The inheritance and allelic relationships of the resistance genes in the two varieties have not been studied with A. vogelii strains in Burkina Faso. The objective of this study was to determine the inheritance and allelic relationship of the resistance genes in B301 and KVx414-22-2. To determine the inheritance of the genes for resistance, the resistant varieties (B301 and KVx414-22-2) were each crossed to a susceptible variety IT82D-849 to generate F1 and F2 populations. For the allelic relationship study the two resistant genotypes were crossed among themselves to generate F1 and F2 offspring. The parents and their F1 and F2 progenies were screened in artificially infested pots with Alectra seed in a screen house at Kamboinse Research Station in Burkina Faso. Resistance/susceptibility of genotypes was assessed by recording the number of emerged Alectra shoots. The data were subjected to the Chi-Square goodness-of-fit test for one, two and three genes segregation ratios. The results revealed that two independent dominant genes confer resistance in the variety B301 and a single dominant gene confers resistance in variety KVx414-22-2. The single dominant gene in KVx414-22-2 is non-allelic to the two genes in B301. The two resistance genes in variety B301 have already been named Rav1 and Rav2 whilst Rav3 is the name of the resistance gene in variety IT81D-994. Therefore, we propose the symbol Rav4 as the name for the resistance gene in variety KVx414-22-2.
-
diallel analysis of cowpea vigna unguiculata l walp for seed size and resistance to Alectra vogelii benth
International Journal of Biological and Chemical Sciences, 2019Co-Authors: Zakaria Dieni, Benoit Joseph T Batieno, Antoine Barro, Felicien Marie Serge Zida, Daniel DzidzienyoAbstract:Cowpea production is hampered by several abiotic and biotic constraints. Parasitic weed Alectra vogelii is a formidable biotic constraint in cowpea production. This study was implemented to determine gene actions involved in cowpea seed size and its resistance to Alectra in order to determine the appropriate breeding approach to develop resistant cowpea varieties to Alectra vogelii . For this purpose, a half diallel of 9 parents was developed at Kamboinse in 2016. The F1 and their parents were screened in screen house with Alectra vogelii seed collected from Alectra infested field in Koupela in centre east Burkina Faso. Data were collected on dates to cowpea flowering, cowpea hundred seeds weight and the severity of Alectra 70 days after planting and analysed with Diall 98 software. Both additive and non-additive gene actions were operative for the investigated characters. Additive gene effects were more important, resulting in high narrow sense heritability, inferring that breeding progress can be achieved through backcross or single seed descent method. Keywords : additive, Burkina Faso, dominance, general combining ability, gene action, heritability.
-
identification of sources of resistance to Alectra vogelii in cowpea vigna unguiculata l walp germplasm from burkina faso
Euphytica, 2018Co-Authors: Zakaria Dieni, Daniel Dzidzienyo, Pangirayi Tongoona, Isaac Asante, Kwadwo OforiAbstract:In Burkina Faso, cowpea serves as both a food and cash crop generating significant income for stakeholders. However, cowpea production is seriously hampered by several constraints among which is the parasitic weed Alectra vogelii. There is therefore an urgent need to identify Alectra-resistant genotypes, possessing farmers’ desired traits, in cowpea germplasm in Burkina Faso. Cowpea genotypes were screened under artificial (screen house) and natural (field) A. vogelii infestation for their reaction to the weed. For the screen house experiment the data were collected on parameters such as days to cowpea flowering and maturity, days to Alectra shoots emergence, the severity of Alectra attack. Cowpea grain yield, Alectra shoots count and severity were scored from the field experiment. These data were subjected to analysis of variances in SAS 9.4. Correlation analysis was also run to determine the association between Alectra infestation parameters and cowpea yield. Twenty Genotypes including KVx414-22-2, KVx165-14-1, Komcalle, IT99K-573-2-1, IT98K-205-8, IT86D10-10, IT93K-693-2 and B301 were identified to be resistant to A. vogelii. Variety Komcalle, IT99K-573-2-1 and IT98K-205-8 are improved and farmers’ adopted varieties. Therefore, these varieties can be recommended for Alectra-infested areas. The other genotypes showing resistance are potential donor parents for resistance to A. vogelii.