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Browsing by Author "Gweyi-Onyango, Joseph P."

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Agricultural Extension Approaches Influencing Uptake of Improved Sorghum Technologies in Embu County, Kenya
(Horizon Research Publishing, 2016) Chimoita, E. L.; Onyango, Cecillia M.; Kimenju, John W.; Gweyi-Onyango, Joseph P.
Agricultural extension and technology transfer services play a vital role in disseminating research knowledge, skills and income generating strategies among the farming communities in Kenya. However, there exists a kind of disconnect between the amount of information and technologies developed in research centres and what is implemented by the farmers. The study evaluated the access and use of extension approaches in promoting uptake of improved sorghum technologies. The study systematically selected 129 farmers from four villages. Data on farmers’ gender, age, household leadership, occupation and agricultural extension approaches were collected. The study revealed that 83% of the respondents were female out of which, 67% were engaged in improved sorghum production technologies. Besides, 56% young women (20 to 49 years) had embraced the growing of improved sorghum varieties Gadam and Sila 1. Further, mobile phones and radio services were the main means of access to the improved sorghum technologies. In addition, there was a strong positive correlation (r=0.122, P=0.01) between extension approaches and uptake of the sorghum technologies. Besides government agricultural extension agents, visits to progressive farmers and/or research sites and use of demonstration plots contributed to 68% and influenced uptake of improved sorghum technologies. It was concluded that gender, family position and age of the farmer contribute to the uptake of improved sorghum technologies. Moreover, mobile phones and radio technologies play an important role in access of sorghum technologies.
Agromorphological Performance and Character Association of Finger Millet under Varying Phosphorus Regimes
(Macrothink Institute, 2017) Wekha, Wafula Nelson; Korir, Nicholas K.; Siambi, Moses; Ojulong, Henry F.; Gweyi-Onyango, Joseph P.
Cadmium Uptake and Distribution to Edible Organs in African Indigenous Vegetables
(Tropentag, 2015) Onyuka, Enos; Husen, Wilhelm van; Nambafu, Godfrey N.; Bessler, Holger; Andika, Darius O.; Gweyi-Onyango, Joseph P.; Mwonga, Samuel; Ulrichs, Christian; Engels, Christof
Cadmium (Cd) is toxic to humans. The most important source for dietary intake is consumption of plant products, whereby Cd concentrations in leafy vegetables are particularly high. In periurban areas, soils are often contaminated with Cd. Thus, recommendations to increase vegetable consumption should consider species-specific uptake and allocation to edible plant organs. Cadmium uptake and distribution within plant was compared in various species to derive recommendations for vegetable production on contaminated soils. Four African indigenous vegetable species (African Nightshade Solanum scabrum, amaranth Amaranthus cruentus, cowpea Vigna unguiculata, spider plant Cleome gynandra), and a standard species commonly grown in Asia (Pak Choi Brassica rapa chinensis) were grown in nutrient solution at three Cd-concentrations: 0.1 (low), 1.0 (moderate) and 2.5 μM Cd (high contamination). Biomass and mineral nutrient concentrations were measured in roots, leaves, stems and lateral branches. Growth was little affected by Cd supply with the exception of amaranth and cowpea. In these species, growth of shoot organs was substantially reduced at moderate and high supply. Growth depression was associated with low leaf iron concentrations indicating Cd-induced iron deficiency. In all species Cd concentrations were higher in roots than in shoot organs, which is in accordance with xylem loading being an important barrier for Cd distribution within plants. At moderate and high supply, Cd concentrations in shoot organs strongly differed among species. Concentrations were particularly low in cowpea, and high in amaranth and African Nightshade. Low Cd concentrations in shoot organs of cowpea were associated with low apparent uptake and translocation rates of Cd from roots to shoots. At all rates of Cd supply, Cd density in edible organs was significantly influenced by species. Cadmium density was particularly low in cowpea and Pak Choi. Based on a vegetable dish of 250 g fresh mass, best choice of species reduced Cd intake by 0.1 mg at low supply (amaranth versus African Nightshade), 0.7 mg at moderate (cowpea versus African Nightshade) and 1.7 mg at high Cd supply (cowpea versus
Differential Biomass Accumulation among African Leafy Vegetables as Affected by Wastewater Irrigation in Kitui County, Kenya
(International Journal of Plant & Soil Science, 2019) Wambua, Judy Mwende; Ngene, Shadrack; Korir, Nicholas K.; Ntinyari, Winnie; Gweyi-Onyango, Joseph P.
Water scarcity of fresh water in Sub-Saharan has led to utilization of the wastewater in home gardening and also in commercial production of vegetables. Wastewater is associated with various substances including nutrients and heavy metals hence it is pertinent to evaluate its effects on growth and yield of vegetables. An experiment was conducted to evaluate the effect of waste water released from the municipal council on the biomass accumulation in African leafy vegetables. Field experiments were carried out in two seasons and one greenhouse experiment. The field trial was laid out in a Randomized Complete Block Design (RCBD) and in the greenhouse the treatments were arranged in Complete Randomized Design (RCD) replicated three times. Four leafy vegetables were the treatments replicated three times. The vegetables were irrigated with waste water. Plant samples were collected at 6 WAP and 12 WAP, partitioned and dried in an oven and later weighed using electronic weighing balance. The findings revealed differences in biomass accumulation into various organs. Black nightshade depicted the highest leaf dry matter in the greenhouse at both 6 weeks after plant (WAP) and 12 WAP (24.62 g and 81.12 g respectively). Cowpea showed the highest increment (7 folds) in leaf weight between 6 to 12 WAP as compared to was paltry 3.6 folds. The highest stem dry weight was obtained in the amaranth species at 6 WAP and 12 WAP both in the greenhouse; recording 32.59 g and 90.12 g respectively. A similar trend was noted in root dry weight and root: shoot ratio. Cowpea had the least biomass accumulation potential across all the parameters in both seasons and in the greenhouse. The increased biomass growth is an indication sufficient availability of nutrient that promoted vibrant plant growth and also less toxicity from the heavy metals. Therefore, waste water can be put into use to enhance improved productivity of African leafy vegetables.
Differential Impact of Nitrogen Forms on Selected Phytochemicals and Oxalate Contents in Three Vegetable Amaranth Varieties in Kenya
(Valahia University Press, 2017) Munene, Rozy; Changamu, E. O.; Korir, Nicholas; Gweyi-Onyango, Joseph P.
Amaranthus are a great source of phytochemicals important for nutritive and remedial benefits. However they are also great accumulators of anti-nutrients such as oxalates. Nitrogen (N), a vital plant nutrient is a strong determinant of plant nutritive value. The study therefore investigated the total flavonoids content (TFC) and phenolic content (TPC) accumulation, antioxidant activity and oxalates content in relation to different N forms in three vegetable amaranth varieties. Three N forms were used; ammonium, nitrate, ammonium/nitrate mixture {ammonium and ammonium nitrate were stabilized with Piadin® as nitrification inhibitor} and control on three amaranth varieties were AB5, AB6 and AB7 in randomized complete block design replicated three times. Sole ammonium and the control enhanced accumulation of both TFC and TPC, compared to the nitrate and ammonium nitrate mixture. Under ammonium treatment, TFC increased by 13.8% in AB5, 17.4% in AB6 and 14.7% in AB7 while TPC increased by about 19.5% in AB5, 23% in AB6 and 20% in AB7 in greenhouse. Similar trends were observed from the field experiment. Likewise, NH4+ - N form had higher antioxidant DPPH scavenging activity indicated by high inhibiting capacity and lower IC50 value (concentration which scavenged 50% of the DPPH radicals). Compared to control, nitrate elevated oxalate accumulation unlike ammonium treatment which on contrary inhibited oxalate buildup. It was therefore concluded that TFC, TPC and antioxidant capacity increased with N deficiency and ammonium-N provision while oxalate content was enhanced under nitrate treatment in leafy amaranth. This is relevant for nutritive wellbeing in human beings.
Effect of Phosphate Levels on Soil Rhizosphere Nutrient Balances and Finger Millet Yield
(SCIENCEDOMAIN International, 2016) Wafula, Wekha N.; Korir, Nicholas K.; Ojulong, Henry F.; Gweyi-Onyango, Joseph P.
Effects of genotype and agro-ecological conditions on storability of soybean [Glycine max (L.) Merr.] seed
(Society for Tropical Plant Research, 2017) Chirchir, Grace J.; Mwangi, Maina; Nyamongo, Desterio O.; Gweyi-Onyango, Joseph P.
Soybean seed storability in the tropics is especially important due to rapid deterioration that varies with the environment, genotype and management practices. The objective of this study was to investigate soybean seed quality during storage as influenced by genotype and agroecological conditions in Meru South Sub-County, Kenya. Seeds of two commonly grown soybean genotypes- Gazelle and TGx 1740-2F (SB19) harvested in February 2013 were used to investigate seed storability. Seed samples (2.5 kg) were stored in gunny bags in a completely randomized design with three replications, giving a total of 6 experimental units per site. The storage treatments were set on farm under ambient conditions in two contrasting agro-ecologies: Upper Midlands II (altitude- 1529 m above sea level; temp.- 18.2–20.6 ºC) at Kirege and Lower Midlands IV (altitude- 1129 m above sea level; temp.- 21.0–23.5 ºC) at Igambatuntu. Changes in seed quality were monitored at 0, 123 and 246 days of storage by subjecting them to germination, electrical conductivity and accelerated aging tests. Data were analyzed using SAS 2009. Results revealed that smaller-seeded soybean genotype TGX 1740-2F was a better storer seed than larger seeded Gazelle as shown by a higher vigor at end 246 days (8 months) of storage. In addition, seed storage environmental conditions significantly influenced the degree of seed deterioration. Soybean seed stored at cooler Upper Midlands II had greater vigor than that stored at the warmer Lower Midlands IV agro-ecology. This study concludes that soybean seed deteriorates in storage and that genotype by environment interaction plays an important role in expression of seed storability. It is recommended that soybean be stored in the cooler higher agro-ecologies of the tropics for improved storability.
Finger millet (Eleusine coracana L.) grain yield and yield components as influenced by phosphorus application and variety in Western Kenya
(Society for Tropical Plant Research, 2016) Wafula, Wekha N.; Nicholas, Korir K.; Henry, Ojulong F.; Siambi, Moses; Gweyi-Onyango, Joseph P.
Finger millet is one of the potential cereal crops that can contribute to the efforts of realization of food security in the Sub-Saharan Africa. However, scientific information available with regards to improving soil phosphorus supply and identification of P efficient varieties for the crops potential yield is limited. In order to investigate the effects of P levels on yield components and grain yield On-station field experiments were conducted in two sites of western Kenya during the long and short rain seasons of 2015. The experiment was laid out in a Randomized Complete Block Design in factorial arrangement with four levels of P (0, 12.5, 25 and 37.5 kg P2O5 ha-1 and three finger millet varieties (U-15, P-224 and a local check-Ikhulule) and the treatments replicated three times. The increase of phosphorus levels significantly (P≤0.05) increased the grain yield over the control up to 25 kg P2O5 ha-1 during the long rain seasons and 25 kg P2O5 ha-1 during the short rain seasons in both sites. Interactions at P≤0.05 were revealed on the grain yield where improved variety P-224 at 25 kg P2O5 ha-1 produced the highest grain yield of 4.74 t.ha-1 in Alupe and 4.77 t.ha-1 in Kakamega and the consistent results suggest that the combination is highly recommended. Therefore the use of judicious and proper rates of P fertilizers can markedly increase the grain yield of finger millet in western Kenya
Finger Millet (Eleusine coracana) Fodder Yield Potential and Nutritive Value under Different Levels of Phosphorus in Rainfed Conditions
(SCIENCEDOMAIN International, 2017) Wafula, Wekha N.; Siambi, Moses; Ojulong, Henry; Korir, Nicholas; Gweyi-Onyango, Joseph P.
Scarcity of fodder is the major limiting factor for increasing livestock production in Kenya. With rising energy costs and declining water levels in the semi-arid tropics and sub-tropics, crops that use less water like finger millet could become an alternate fodder crop. The fodder potential of three finger millet varieties (U-15, P-224 and a local check) were evaluated under four P fertilizer levels (0, 12.5, 25 and 37.5 kg ha-1 P2O5) at three sites in Kenya for two cropping seasons. The trials were laid in randomized complete block design in factorial arrangement and replicated three times. A maximum of 28,189 kg ha-1 fresh stover yield was realized in the 25 kg ha-1 P2O5 treatment and consequently 11,616 kg ha-1 dry stover yield. The 25 kg ha-1 rate elicited the highest fresh stover yield at Kakamega and Alupe for both seasons while at Kiboko a linear increase was observed on the stover yield with increasing rates where the highest rate had more than 15% yield compared to the control. The varieties also showed significant differences in all the sites with the local variety, Ikhulule, showing the highest fresh and dry stover yield at Kakamega and Alupe peaking at 28,852 and 12,826 kg ha-1 fresh and dry stover yields respectively. Interactions between variety and phosphorus rates were revealed on the crude protein content of the finger millet stover. At Kiboko, the highest crude protein (11.0%) on varieties P-224 and U-15 was exhibited at the highest rate while on the local variety, Ekalakala, the highest protein (10.9%) was realized at the 25 kg ha-1 P2O5. At Kakamega and Alupe, the highest protein was observed on the local variety, Ikhulule at 12.5 kg ha-1 P2O5 rate with variety P-224 and U-15 showing the highest at the 25 and 37.5 kg ha-1 P2O5 respectively. Therefore, finger millet can provide a unique opportunity to improve the availability of fodder to smallholder livestock farmers.
Flowering and maturation periods of Finger Millet as influenced by phosphorus and variety in different agro-ecologies in Kenya
(Elixir Publishers, 2016) Wafula, Wekha N.; Korir, Nicholas K.; Ojulong, Henry F.; Gweyi-Onyango, Joseph P.
Phosphorus is important for finger millet production in many tropical African soils with low phosphorus fertility. Knowledge of redirection of this limited resource for reproduction is fundamental in realization of potential yields. The effect of four phosphorus levels (0, 12.5, 25.0 and 37.5 kg ha-1 P2O5) and three varieties (U-15, P-224 and a local check) on the days to flowering and maturity of finger millet were evaluated in three agro-ecologies in Kenya during the raining seasons of 2014-2015. Phosphorus application significantly (P<0.05) increased early flowering and physiological maturity in Kakamega and Busia. The varieties elicited significantly different days to 50% flowering and maturation periods in all the study sites. The days to flowering and maturity were found to be lowly but negatively correlated with the grain yield of finger millet in all the sites.
Influence of Mulching Materials on the Growth and Yield Components of Green Pepper at Busia County in Kenya
(SCIENCEDOMAIN International, 2016) Edgar, Ocharo N.; Gweyi-Onyango, Joseph P.; Korir, Nicholas K.
Aims: Green pepper (Capsicum annuum) also named the bell pepper or sweet pepper is one of the most important and remunerative vegetable crops in the world. Due to the increased pressure on land, climate change and increased demand for the crop, there is need for better agronomical practices that will ensure enough food production. Place and Duration of Study: In Kenya, little attention has been given to the use of organic and inorganic mulch materials to increase productivity of horticultural crops and therefore this study was conducted in Alupe, Busia-Kenya, during the long and short rains season of 2015 to assess the efficacy of black plastic, transparent plastic and straw mulch on growth and yield of green pepper. Methodology: The treatments were black polythene mulch, transparent polythene mulch, straw mulch and bare soil as the control. Results: The straw mulch elicited significantly vigorous growth of seedlings compared to the other treatments but had the lowest number of leaves unlike transparent mulch which had the most with 58. The widest stem circumference was observed on mulched plots as well as the plant height where the control recorded the lowest height. The black polythene mulch gave significantly (P=.05) heavier fruits of 924.5 g/plant during the long rain and 681.1 g/plant in the short rain season. Unmulched plots of either variety had the lowest mass recorded for fruit in both seasons. The transparent mulch showed significantly (P=.05) more seeds per fruit (196), longest fruit length (8.5 cm) and greatest fruit diameter (9.2 cm). Based on the experimental results the black polythene mulches had greatest effects on the growth, and yield of sweet pepper and showed superior performance among the plastic mulches in the study area and therefore is recommended.
Integration of mulching and row spacing on weed management in Green Pepper varieties
(Society for Tropical Plant Research, 2017) Ocharo, Edgar N.; Korir, Nicholas K.; Gweyi-Onyango, Joseph P.
A field experiment was conducted at the Kenya Agricultural and Livestock Research Organization, Alupe Research Farm, Busia County for two cropping seasons during the year 2015 to determine the impact of row spacing and mulching materials on weed management of two green pepper varieties. The two varieties California Wonder and Yolo Wonder were sown in a randomized complete block design in factorial arrangements, comprising three-row spacing treatments and four mulching materials then replicated thrice. The row spacing were; 30, 40 and 50 cm whereas the mulching materials were; black plastic mulch, transparent plastic mulch, straw mulch and bare soil which was the control. Data collected was subjected to SAS statistical software for analysis and means separated using LSD at P≤0.05. Significant differences (p≤0.05) were observed between the treatment combination of mulch and row spacing in the fresh and dry weed biomass, weed species density per m2 and the weed growth vigor. The highest fresh weed biomass (5008 g.m-2) was elicited by the control mulch treatment at the widest row spacing during the long rains season while the lowest (188 g.m-2) was observed in the black plastic mulch at the narrow row spacing of 30 cm. The weed species density was highest (7) in the control at 40 cm row spacing with the lowest elicited in the black plastic mulch at the 40 cm row spacing (1.7) during the short rain seasons. The weed growth vigor was highest in all the control mulch treatments at 30 cm row spacing while the lowest vigor was in the black plastic mulch which was closely followed by the transparent mulch at the various row spacings. The competitiveness of sweet pepper with weeds can be significantly enhanced by using black plastic as mulch under narrow row spacing with an optimum of 30 cm.
Iron Concentrations in Roots and Edible Organs of African Indigenous Vegetable Species
(Tropentag, 2015) Eckhardt, Ulrich; Beer, Julius; Bessler, Holger; Nambafu, Godfrey N.; Onyuka, Enos; Mwonga, Samuel; Andika, Darius O.; Gweyi-Onyango, Joseph P.; Engels, Christof
Iron (Fe) deficiency is among the 10 leading human health risks causing “hidden hunger” in sub- Saharan Africa. Iron concentrations and bioavailability are often higher in leafy vegetables than in staple crops like maize and sorghum. Therefore, increasing food diversity through vegetable production and consumption is an option to mitigate Fe deficiency. The aim was to quantify Fe uptake and distribution between roots, stems and leaves in selected African indigenous vegetable (AIV) species, and to compare species responses to different rates of Fe supply. Plants of five leafy AIV species (African night shade Solanum scabrum, amaranth Amaranthus cruentus, cowpea Vigna unguiculata, spider plant Cleome gynandra, Ethiopian kale Brassica carinata) and a standard species commonly grown in Kenya (kale Brassica oleracea acephala group) were grown in nutrient solution at three rates of Fe supply (sub-optimal to induce Fe deficiency responses, optimal for growth, supra-optimal to test if Fe density in edible organs can be enhanced by additional Fe fertiliser application). Leaf chlorophyll content (SPAD-meter) and pH of the nutrient solution were measured at regular intervals to quantify shoot and root responses to Fe deficiency. At harvest, biomass and mineral nutrient concentrations were measured separately for roots, stems and leaves. The species markedly differed in their early root responses to Fe deficiency. Whereas in amaranth, proton extrusion from roots was significantly increased at low Fe supply compared to medium and high Fe supply, in spider plant and kale proton extrusion was not influenced by Fe supply. Fe concentrations in the plant dry mass strongly varied among plant organs and decreased in the order roots >> leaves > stems. In all organs, Fe concentrations were significantly affected by species. Concentrations in shoots varied from 17 (Ethiopian kale) to 39 mg Fe kg−1 dry mass (amaranth) at low Fe supply, and from 42 (Ethiopian kale) to 127 mg Fe kg−1 dry mass (cowpea) at high supply respectively Responses of Fe density in edible plant organs indicate that the potential for increasing the nutritional value of leafy vegetables by Fe fertilisation (biofortification) is largest in cowpea and spider plant.
Maize response to Tithonia diversifolia and rock phosphate application under two maize cropping systems in Kenya
(F.a.C.T Ltd, 2014) Ahmat, Filbert L.; Mugwe, Jayne; Kimani, Stephen K.; Gweyi-Onyango, Joseph P.
Objective: The experiment was conducted with the aim of investigating maize response to Tithonia diversifolia and Minjingu Rock phosphate (MPR) applied under maize-bean intercrop as compared to the traditional maize monocrop to improve maize grain yields. Methodology: The experiment was conducted in pots in a greenhouse for the duration of 8 weeks.. The trial was laid out in a split plot arrangement with three replicates. The main plots comprised of sole maize crop and maize-bean intercrop whereas the sub plots included the control (no input), Tithonia biomass applied alone, MPR also applied alone, TSP again applied alone and Tithonia biomass co-applied with MPR. Soil samplings were done at 4 and 8 weeks after planting and assessed for .P availability and soil labile P. Data was also taken on maize dry matter yield at 8 weeks. ANOVA was done using SAS (version 9.2) and means separated at 5% probability level using DMRT. Results: Maize-bean intercrop was effective in increasing PR solubilisation, P availability and shoot dry matter production. At the same level of P input from MPR, P availability under maize-bean intercrop increased above the ones under sole maize by 154.8% and 91.4% in the first and second samplings, respectively. The increase is thought to have been partly due to the effect of the rhizosphere acidification by bean (Phaseolus vulgaris) during the process of biologically nitrogen fixation. Implications: This farmers-practices matching and also environmentally-friendly low input approach enables farmers to boost production, cut down the cost of production and consequently increase the profit margin.
A Mechanism to Discover Hidden Markets and to Improve Information Flow Towards Food Producers: A Case of Kiambu District, Kenya
(Tropentag, 2012) Nyaga, Elizabeth Kabura; Muriithi, Anthony Gikandi; Gweyi-Onyango, Joseph P.
Food insecurity in many regions in Kenya is mainly attributed to changes in rainfall patterns, lack of markets to sell agricultural produce from regions with surplus and poor infrastructure to distribute to regions facing deficits. Small scale farmers are in desperate need of markets to sell their produce at a good price. They require information on credit and input markets. This paper discusses the methodologies to improve farmers’ access to these markets and enhance access to relevant information that they may find useful in making decisions. The study argues that providing a platform for farmers to interact and transact business directly with buyers, sellers, researchers and other relevant stakeholders in agribusiness would provide market for the farmers. This interaction may facilitate exchange and dissemination of update information on changes in the markets and, changes in consumer needs and taste. Many studies have shown that networking among individual or groups either in social or professional networks may help in development of the members. This paper argues that providing farmers and agricultural extension agents with access to current information and communication technologies (ICT) could be instrumental in finding new markets for the farmers and in dissemination of relevant information. By facilitating the agricultural extension agents to have access to internet, mobile phone and rural radio, hidden markets can be discovered and new information and technology can reach the farmers before they become obsolete. Many businesses have grown through advertising their products online. A national website managed by extension agents can help farmers advertise their produce so that anyone willing to buy can contact the farmer directly. Agricultural based businesses can also advertise their products in the website. Consumers can use the website to buy fresh produce directly from the farmers. Although internet is not available to most households in Kenya, agricultural extension agents can post information of buyers and sellers in village boards and in the market place. This paper discusses how ICT can be implemental in finding new markets and reducing food insecurity in Kenya
Nutrient fluxes from soil to market in African indigenous vegetable production systems
(Tropentag, 2017) Nambafu, Godfrey N.; Adam, A.; Onyuka, E.A.; Bessler, H.; Andika, D.O.; Mwonga, S.; Gweyi-Onyango, Joseph P.; Engels, C.
Phosphorus Influence on Plant Tissue Nitrogen Contents and Yield Attributes of Finger Millet Varieties in Semi-arid Region of Kenya
(SCIENCEDOMAIN International, 2016) Wafula, Wekha N.; Korir, Nicholas K.; Ojulong, Henry F.; Siambi, Moses; Gweyi-Onyango, Joseph P.
Plant Residue-Derived Organic Carbon Input into Soil in African Indigenous Vegetable Production Systems
(Tropentag, 2016) Onyuka, Enos; Nambafu, Godfrey; Bessler, Holger; Adam, Anna; Andika, Darius O.; Gweyi-Onyango, Joseph P.; Mwonga, Samuel; Engels, Christof
Food production in sub Saharan Africa is constrained by low soil fertility, whereby soil organic matter (SOM) is key factor regulating many soil functions that determine the yielding ability of soils. SOM content is influenced by the mass and quality of organic carbon input into soil. In smallholder farming systems manure and composts are scarce, and only small fractions are allocated to soil amendment due to alternative use as feed and fuel. Therefore, organic matter input into soil is often restricted to plant residues remaining in the field. In this study, we quantified the effects of species and harvesting method on the mass and quality of plant-derived carbon input into soil with the aim to improve soil fertility management in African indigenous vegetable (AIV) production systems. Five AIV species (amaranthus - Amaranthus cruentus, cowpea - Vigna unguiculata, African kale - Brassica carinata, African nightshade - Solanum scabrum, spider plant - Cleome gynandra) and common kale (Brassica oleracea acephala) were grown in a field experiment. Plants were harvested by two different methods, which are both commonly used in Kenya: Plants were either pulled out with some coarse roots adhering to the stems or cut about 5 cm above the soil surface. Leaf litter, above-ground plant residues and below-ground residues (coarse root, fine roots in 0–0.3m and 0.3– 0.6m soil depth) were quantified and analysed for C content. The humification efficiency of plant residues was determined in incubation studies under controlled conditions. Input of plant residue-derived organic carbon into the soil significantly differed among species with minimum of 0.3 kg C m−2 for cowpea and maximum of 0.8 kg C m−2 for amaranthus. In all species, input with leaf litter was negligible, while the contribution of fine roots to C input varied between about 40% in spider plant and 80% in cowpea. Pulling out instead of cutting plants reduced carbon input by 14% in cowpea and nearly 60% in African kale and spider plant. It is concluded that in AIV production systems with low availability of organic fertilisers species selection and harvesting method are important determinants for soil C dynamics and fertility.
Plant Row Spacing Effect on Growth and Yield of Green Pepper (Capsicum annuum L.) in Western Kenya
(SCIENCEDOMAIN International, 2017) Edgar, Ocharo N.; Gweyi-Onyango, Joseph P.; Korir, Nicholas K.
Green pepper production based on the package of recommendations developed has not given the desired growth and yield performances in the world and specifically Kenya. Information is required with which to evolve the agronomic practices that will be adopted to maximize yield in green pepper production. Great attention should be paid when selecting the most appropriate spacing where there are very few reports and limited information regarding plant spacing in cultivation of the crop under the agro-climatic conditions of Kenya. Therefore, a field study was carried out at the Alupe Research Station, Busia County, to evaluate the growth and yield responses of green pepper under three row plant spacings namely: 50x40 cm, 40x40 cm and 30x40 cm during the long and short rainy seasons of 2015. The experiment was set up in a randomized complete block design with three replicates. The treatment effects were measured on plant growth for 12 weeks and ripe fruit yield parameters which were later cleaned statistically analyzed. The plant spacing had significant variation in almost all the growth and yield components except the fruit length. In both seasons, the number of branches per plant, stem girth and number of fruits per plant were found to be significantly increased with the increasing of plant spacing but the plant height, number of leaves per plant, fruit breadth and yield per plant were found to be significantly increased with the decreasing plant spacing. The highest yield per plant of 555.1 g and 551.8 g were realized during the short and long rainy seasons respectively in the 40 by 40 cm spacing treatment. Considering the yield of fruits per plant, the 40 by 40 cm plant spacing appeared to be the most recommendable for the cultivation of green pepper.
Soybean farm-saved seed viability and vigor as Influenced by agroecological conditions of Meru South Sub-county, Kenya
(F.a.C.T Ltd, 2016-05) Chirchir, Grace J.; Mwangi, Maina; Nyamongo, Desterio O.; Gweyi-Onyango, Joseph P.
Objective: The experiment was conducted with the aim of assessing the soybean farm-saved-seed viability and vigor as influenced by agro-ecological conditions of Meru South Sub-County, Kenya. Methodology and results: Within one month of harvest, soybean farm-saved-seed was randomly sampled from 30 households in February 2013 from areas representative of agro-ecological zones Upper Midlands II (Ann. Mean temp. (18.2-20.60C); Upper midlands III (19.2-20.60C; Lower Midlands III (20.9-22.90C) and Lower Midlands IV (21-240C). Standard germination, electrical conductivity and moisture content tests were done according to ISTA rules (2007). Analysis of Variance was done using SAS (9.2) and means separated using LSD. Results revealed that seed moisture was lowest in the warmer LM4 (6.3%) than in the cooler LM3 (8%); UM3(8.4% and UM2(10%). In addition, soybean seed from the cooler agro-ecologies (UM2 (94%), UM3 (86.6%) and LM3 (99.5%) had significantly higher germination than seed from the lower warmer LM4 (57%). Similarly, seed vigor was highest in the cooler UM2 (41.7 C/cm/g), UM3 (45.8C/cm/g), LM3 (31.6C/cm/g) as shown by reduced seed leachates; indicative of better integrity of seed membranes than seed from the warmer LM4 (79.1C/cm/g). In addition, there was a strong negative correlation between electrical conductivity and germination, showing a faster deterioration due to leakage of electrolytes. Conclusions and applications of findings: The soybean farm saved-seed germination and vigor were significantly influenced by agro-ecological conditions. Considering that seed moisture, content in the lower warmer agroecologies was significantly lower than those from higher cooler agroecologies the observed seed deterioration was attributable to the higher temperatures characteristic of lower altitudes agro-ecologies. Therefore, since the farm saved seed viability and vigor was better retained in the cooler higher agroecological zones (UM2, UM3 and LM3) of Meru South Sub-County, farmers should source better quality soybean seed from these areas. The results validate the need for ecological zoning of suitable areas for the production of high quality soybean seed in Kenya.

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