GTranslate

Research Papers

Variation of East African sorghums based on biochemical characteristics

Variation of East African sorghums based on biochemical characteristics

A total of 30 sorghum varieties from East Africa were analysed for their biochemical characteristics. The objective was to ascertain the extent of the genetic diversity underlying their biochemical and physiological characteristics that included starch (%), amylose (%), amylopectin (%), proteins (%), tannins (mg/100 ml), yield (Kg/ha) and height (cm). The principal component analysis (PCA) showed that the first two contributed to the 69.66% of the variability among the sorghum varieties. Cluster analysis of these parameters resulted into four distinct groups with a genetic distance ranging from 0.74 - 6.42. The open pollinated and the hybrids showed the greatest genetic distances while the hybrids exhibited relatively low genetic distances. The biochemical content is a useful tool for measuring the genetic divergence among sorghum varieties to identify possible donors for future sorghum quality enhancement/breeding.

Larvicidal Activity of Selected Aloe Species Against Aedes aegypti (Diptera: Culiciade) Judith K. Chore,1 Meshack Obonyo,1,2 Francis N.Wachira,1 and Paul O. Mireji3

Larvicidal Activity of Selected Aloe Species Against Aedes aegypti (Diptera: Culiciade) Judith K. Chore,1 Meshack Obonyo,1,2 Francis N.Wachira,1 and Paul O. Mireji3

Management of mosquito vectors by current classes of mosquitocides is relatively ineffective and necessitates prospecting for novel insecticides with different modes of action. Larvicidal activities of 15 crude extracts from three geographically isolated Aloe ngongensis (Christian), Aloe turkanensis (Christian), and Aloe fibrosa (Lavranos & L.E.Newton) (Xanthorrhoeaceae) species (five each) were evaluated against Aedes aegypti (Linnaeus in Hasselquist) (Diptera: Culiciade L.) yellow fever mosquito. Freshly collected leaves were separately shade-dried to constant weight at room temperature (2562C) and powdered. Each powder was macerated in solvents of increasing polarity (hexane, chloroform, ethyl acetate, acetone, and methanol) for 72 h and subsequently filtered. Third-instar larvae (n¼25) of the mosquito were exposed to the extracts at different concentrations for 24 h to establish dose response relationships. All the fractions of A. ngongensis were active below 1 mg/ml except A. fibrosa and A. turkanensis. The highest activity (LC50) mg/ml was obtained with extracts of A. fibrosa hexane (0.05 [0.04–0.06]), followed by A. ngongensis hexane (0.11 [0.08–0.15]) and A. turkanensis ethyl acetate (0.11[0.09–0.12]). The activities are apparently Aloe species specific and extraction solvent dependent. These findings suggest that extracts from selected Aloe species have mosquitocidal principles that can be exploited in development of new insecticides.

Polyphenolic composition and antioxidant activity of Kenyan Tea cultivars Karori S.M, Wachira F.N, Ngure R.M and Mireji P.O

Polyphenolic composition and antioxidant activity of Kenyan Tea cultivars Karori S.M, Wachira F.N, Ngure R.M and Mireji P.O

Polyphenolic fractions in tea are potent bioactive molecules. In this study, the polyphenolic composition of 25 different types of Kenyan tea cultivars was determined using the HPLC and the Folins Ciocalteus spectrophotometric methods. Total Polyphenols, Total Catechins, individual catechins and Antioxidant Activity were significantly (P<0.05) different among tea varieties, with green tea had the highest levels of Total Polyphenols ranging from (19.70-26.12%), TC (8.51%-17.60%), individual catechins, and AA (86.65-94.50%). In vitro bioassay carried out using 2, 2’-diphenyl picrylhydrazyl radical showed epigallocatechin gallate was the most potent catechin and the most potent in antioxidant activity (r=0.968***). Epigallocatechin (r=0.659***, p<0.001), Epicatechigallate (r=0.454*, p<0.001) and Epicatechin (EC) (r=0.780***, p<0.001) showed significant (p<0.05) antioxidant activity. Black tea contained high levels of Theaflavins and Thearubigins (2.072% to 17.12%), respectively) which accounted for its antioxidant activity (r=0.803*** and r=0.859***, respectively). Gallic acid also showed significant (r=0.530*) contribution to the antioxidant activity in black tea. Data obtained from this study reveals that different Kenyan tea cultivars have different polyphenolic composition which imparts on their unique biochemical qualities. Green and white tea products are rich in catechins, black tea products are rich in TFs and TRs while purple teas are rich in anthocyanins.

Polyphenolic composition and antioxidant activity of Kenyan Tea cultivars Karori S.M, Wachira F.N, Ngure R.M and Mireji P.O

Polyphenolic composition and antioxidant activity of Kenyan Tea cultivars Karori S.M, Wachira F.N, Ngure R.M and Mireji P.O

The antimutagenic effects of the aqueous tea extracts from Kenyan black, green and purple cultivars were evaluated by the Ames test using Salmonella typhimurium tester strains TA 1538. Results obtained showed that tea had no toxicity or mutagenic activity at a concentration of 20% (w/v) unlike the mutagen sodium azide. However, using the formulae, percentage inhibition = [1-T/M] ×100 where T is number of revertants per plate in presence of mutagen and test sample and M is number of revertants per plate in positive control, tea extracts had a significant (P<0.05) antimutagenic activity where the percent inhibition was 65% for green tea, 38% for purple tea and 19.17% for black tea. This was attributed to the radical scavenging activity of polyphenols. There is need therefore to carry out further research to help understand the precise mechanism of action especially for black and purple teas, and to explore other beneficial effects that these polyphenols may have, before they can be adopted for therapeutic use.

Tea that penetrates the brain, maize that ignores drought and more....

Tea that penetrates the brain, maize that ignores drought and more....

Using mice to prove the ability of Kenyan purple tea to cross into the brain and boost its capacity; using desert plant Xerophytaviscosa and a model plant species Arabidopsis thaliana to transfer drought tolerance into local maize varieties; and using feeding fish with locally formulated feeds to increase production. These are exciting discoveries, aren’t they? Well, during the Second ASARECA General Assembly and Scientific Conference in Bujumbura, Burundi (December 9 – 13, 2013), researchers from the 11 ASARECA countries, presented research results with many such exciting breakthroughs. Some of the soul lifting discoveries and trials are presented in the African Crop Science Journal (Volume 22, September 4, 2014). The papers are derived from research for development projects that were supported by ASARECA over the last five years (2008-2013). The papers describe the process of generation and deployment of cost effective technologies, innovations and management practices, besides providing examples of regional policy and farmer empowerment initiatives. They were presented to ASARECA’s stakeholders drawn from its 11 member countries: Burundi, DR Congo, Ethiopia, Eritrea, Kenya, Madagascar, Rwanda, Sudan, South Sudan, Tanzania and Uganda at the General Assembly in Burundi.

Effects of Foliar Fertilizer Application on Quality of Tea (Camellia sinensis) Grown in the Kenyan Highlands

Effects of Foliar Fertilizer Application on Quality of Tea (Camellia sinensis) Grown in the Kenyan Highlands

Effects of Foliar Fertilizer Application on Quality of Tea (Camellia sinensis) Grown in the Kenyan Highlands

Participatory selection and characterization of quality protein maize (QPM) varieties in Savanna agro-ecological region of DR-Congo

Participatory selection and characterization of quality protein maize (QPM) varieties in Savanna agro-ecological region of DR-Congo

Participatory selection and characterization of quality protein maize (QPM) varieties in Savanna agro-ecological region of DR-Co

Body:

Maize (Zea mays L.) is a major cereal crop for human nutrition in the Democratic Republic of Congo (DR- Congo). Prevailing normal maize is deficient in two essential amino acids, lysine and tryptophan. Participatory variety selection was applied to select diversified quality protein maize (QPM) varieties that possess farmers’ preferred plant and grain traits. The varieties were planted with and without chemical fertilization. Selection was based primarily on agronomic traits such as time to maturity, plant and ear aspect, disease and insect resistance, yield and yield components as well as flour quality. There were significant differences among QPM varieties for several agronomic traits. The use of participatory approach in agricultural research allowed selection of one QPM, (QPMSRSYNTH), and one normal improved maize (AK9331-DMR-ESR-Y) for their yield advantage over currently released normal maize varieties in more than one criterion. The adoption of these newly introduced varieties is expected to be high since they were selected based on farmer’s preference. 

Key words: Quality protein maize, participatory varietal selection, DR-Congo.

Mbuya etal; 
 Journal of Plant Breeding and Crop Science Vol. 2(11), pp. 325-332, December 2010

Quantitation of the Total Catechin Content in Oils Extracted from Seeds of Selected Tea (Camellia sinensis (L) O. Kuntze, Theaceae) Clones by RP-HPLC

Quantitation of the Total Catechin Content in Oils Extracted from Seeds of Selected Tea (Camellia sinensis (L) O. Kuntze, Theaceae) Clones by RP-HPLC

Catechins (flavan-3-ols) are polyphenolic plant secondary metabolites that have been strongly associated with a wide variety of beneficial health effects in vitro, in vivo and clinically. This study reports findings on the content of catechins in tea seed oil (TSO) extracted by Soxhlet extraction from seeds of different clones of Kenyan tea. Extraction of catechins from the crude oils was achieved by sequential liquid-liquid extraction (LLE) using methanol and quantified by reverse phase High Performance Liquid Chromatography (RP-HPLC). Results obtained revealed that all the crude test oils contained catechins, with oils extracted from clones TRFK K-Purple and GW-Ejulu having the highest total catechin content of 9.8 ± 0.25 and 9.0 ± 0.83 (×10−3% flavonoids) respectively. Statistically significant differences (p < 0.05) were evident in the total catechin contents of crude oils extracted from tea seeds with those extracted from corn, sunflower and soybean seeds. Moreover, clonal variations were evident, as the total catechin contents of oils extracted from clones TRFK K-Purple and GW-Ejulu were statistically different (p < 0.05) from those extracted from clones
TRFK 301/3, TRFK 301/4, TRFK 301/5, TRFK 306, TRFK 91/1 and TRFCA SFS 150. Thus, the current findings strongly suggest that oils from seeds of Kenyan tea cultivars can be a potential source of potent natural antioxidants.

Strategies for rehabilitation of banana fields infested with Xanthomonas campestris pv. musacrearum

Xanthomonas campestris pv.musacrearum causes Banana wilt disease (BXW disease) which occurs at different epidemic phases in East and Central Africa (ECA). In the endemic areas, there are many banana fields with over 80% BXW disease incidence.

This study aimed at rehabilitating banana fields heavily infected with BXW disease in Uganda, Kenya and DR. Congo.

Farmer managed trials were established in BXW disease hotspots in western Kenya and DR. Congo, while in Uganda, similar trials were established at community level i.e. clusters of at least 200 heavily infected banana fields. The control options evaluated included single stem removal, suspension of pruning in affected fields, male bud removal and disinfection of tools with fire or Sodium hypochlorite.

Data was collected on the proportion of affected fields (BXW disease prevalence), BXW disease incidence and the number of banana bunches sold at 3-month intervals. BXW disease incidence was reduced by over 80% in 11 months in Kenya and DR. Congo, resulting in yield recovery by up to 70% within one year.

In Uganda, the proportion of farmers that effectively controlled BXW disease increased 5% to 60% within a year in some hotspots. Consequently banana sales recovered up to 30% in some hotspots. This study demonstrates that it is possible to effectively control BXW disease within 12 months in previously severely infected fields in various areas of ECA.

Nutritional Analysis of Quality Protein Maize Varieties Selected for Agronomic Characteristics in a Breeding Program

Nutritional Analysis of Quality Protein Maize Varieties Selected for Agronomic Characteristics in a Breeding Program

Nutritional characteristics of QPM genotypes that have been released are limited. A breeding program has been initiated in 2008 in DR-Congo using varieties selected from several agro-ecological regions. The objective of the present study was to establish a nutritional profile including amino acid and carotenoid content of selected QPM from the DR-Congo breeding program. Six Quality Protein Maize (QPM) and seven normal maize varieties were evaluated for agronomic characteristics and disease reaction. The grain amino acid and carotenoid concentrations were evaluated. The impact of QPM diet on chick’s weight was also determined. QPM Longe 5 produced the highest grain yield in several trials in famer’s fields. Lysine content of QPM-SR-SYNTH and QPM Longe 5 showed significant increase of 33 and 37%, respectively, over the other maize varieties. There was a 50% increase in tryptophan in QPM Longe 5 compared to normal maize varieties. More importantly, the two QPM varieties provide proteins with a better amino acid balance than the normal maize varieties. The level of the carotenoids analyzed was significantly higher in the maize MUS-1 variety with yellow endosperm compared to all the genotypes with white endosperm. The total carotenoid content in MUS-1 was over 250 fold compared to QPM and other maize varieties. The use of QPM in poultry resulted in a 50% increase in body weight compared to normal maize over a 9 week-period. A breeding program combining the benefits of QPM and the high level of carotenoid of yellow maize endosperm should produce superior QPM varieties for human and animal nutrition.

Mbuya K, Nkongo K, Kalonji M;
International Journal of Plant Breeding and Genetics 5 (4): 317- 327, 2011

Pages

Subscribe to Research Papers