Cecilia Moraa Onyango

The Physico-Chemical Characteristics and Some Nutritional Values of Vegetable Amaranth Sold in Nairobi-Kenya

Twenty one major supermarkets and ten independent green grocers in the city of Nairobi were surveyed for types of vegetable amaranths sold and their post harvest handling. The nutrient composition of the vegetables was also analyzed. In addition, information on three other traditional leafy vegetables (TLVs) namely, Cleome gynandra, Solanum nigrum, and Vigna unguiculata was obtained. All the vegetables were sold in bundles of average weight 0.45 kg. The edible fraction per bundle averaged 38.9%. Chemical analyses showed that vegetable amaranth had a moisture content of 85.5%, therefore a dry matter content of 14.5%. Expressed on dry matter basis, the mean total ash content was 19.2%, crude protein content 26.1% and the crude fiber content 14.7%. The mean ascorbic acid content was 627 mg/100 g, zinc content 5.5m g/100 g and iron content 18 mg/100 g. The men nitrate content was 732.5 mg/100 g, total oxalates 5830 mg/100 g and soluble oxalates 3650 mg/100 g, while the lead content averaged 1.03 mg/100 g. The study concludes that vegetable amaranth has potential as popular vegetable in the diets of Kenyans to significantly contribute to provision of micronutrients, particularly iron and zinc.

Current status on production and utilization of spider plant (Cleome gynandra L.) an underutilized leafy vegetable in Kenya

Spider plant exists as semi-cultivated indigenous leafy vegetable with ecological, social and cultural values in most home gardens in Kenya. It plays a significant role in the food and nutrition security of local communities. The tender leaves are usually consumed as a cooked vegetable while the roots, stem and whole leaves are used for medicinal purposes. The importance of spider plant has been discussed in the context of biodiversity conservation and food security because the vegetable is rich in micronutrients and phytochemicals associated with antioxidant, anti-malaria, and anti-microbial properties.

Effects of shoot tip and flower removal on growth and yield of spider plant (Cleome gynandra L.) in Kenya

Aims: Despite spider plant’s (Cleome gynandra L.) high nutritional value, it has received minimal research attention compared to exotic vegetables and other indigenous vegetables such as amaranth (Amaranthus spp.) and cowpeas (Vigna unguiculata). This has led to a lack of scientific production recommendations. This study contributes to developing best agronomic practices for spider plant by determining its response to shoot tip and flower removal that can lead to more profitable small-scale commercial production of the vegetable. Place and Duration of Study: Two field experiments were conducted at the Upper Kabete Field Station of the University of Nairobi, Kenya, during the long rains (February-May) and in the dry Original Research Article Wangolo et al.; AJEA, 8(6): 367-376, 2015; Article no.AJEA.2015.181 368 season (June-August) 2014. Methodology: A randomized completed block design with three replications was used. Commercial spider plant seeds were drilled in raised beds with cow manure as nutrient input (50 kg N ha -1 ). Plants were thinned to 30 x 20 cm, 30 x 15 cm and 20 x 15 cm spacings at six weeks after planting. Shoot tips were removed once when plants were 10-15 cm tall, and flowers were removed at bud formation throughout the experiment. Results: Flower removal produced significantly (P=.05) greater plant height, leaf yield, and fresh and dry shoot weight than both shoot tip removal and the control. Flower removal plants reached a height of 66 cm, compared to 48 and 49 cm for shoot tip removal and the control, respectively. For total leaf yield, flower removal produced 12.3 t ha, which was significantly greater than both shoot tip removal (8.4 t ha -1 ) and the control (6.5 t ha -1 ). Fresh shoot weight was 22.1, 15.2 and 14.4 t ha -1 for flower removal, shoot tip removal and the control, respectively. Conclusion: Flower removal during production of spider plant should be practiced in order to increase growth and leaf yield.

Influence of organic and mineral fertilization on germination, leaf nitrogen, nitrate accumulation and yield of vegetable amaranth

The influence of manure and diammonium phosphate (DAP) mineral fertilizer on germination, leaf nitrogen content, nitrate accumulation and yield of vegetable amaranth (Amaranthus hypochondriacus) was investigated. Field trials were set up at the University of Nairobi Field Station at the Upper Kabete Campus during the long rains of March–May in 2007 and 2008. Trials were laid out as complete randomized block design with four fertilization treatments: 20, 40, and 60 kg nitrogen (N) ha−1 supplied by DAP (18:46:0), 40 kg N ha−1 supplied by cattle manure and an unfertilized control variant. The vegetables were harvested at three maturity stages at 6, 7, and 8 weeks after planting. Results indicated that there were significant differences between treatments in germination percentage, leaf nitrogen content, nitrate accumulation and vegetable yield. Plants that received manure had a higher germination percentage than those that received the same amount of N supplied by the chemical fertilizer DAP. The yields generally increased from week 6 to week 8. The highest yield was recorded in plots receiving 40 kg N ha−1 from DAP at eight weeks after planting. Plots that were supplied with manure recorded the lowest yield when compared to the fertilizer treated plots at all rates. Leaf nitrogen content increased with increasing rate of N but only when N was supplied by DAP fertilizer. The leaf nitrogen content decreased with increasing age of the plants. The leaf nitrate content increased with increase in DAP application rate. Results indicate that manure application produced quality vegetables in terms of low nitrate levels, but leaf nitrogen and vegetable yields were low. DAP application effected higher yields, but the vegetables had high though acceptable nitrate levels.

Analysis of the Molecular Diversity of Kenyan Sorghum Germplasm Using Microsatellites

The aim of this study was to estimate the extent of the genetic diversity present in sorghum germplasm grown in Kenya using simple sequence repeat markers. A total of 139 accessions were genotyped using 11 microsatellite markers or simple sequence repeats (SSRs) and the genetic diversity was estimated. The markers showed a wide range of differences in quality index from 0.005 to 0.39. The average Polymorphic Information Content value observed was 0.6241 indicating a high level of diversity. The gene diversity index ranged between 0.2419 and 0.9313 with a mean of 0.6627 per locus. A total of 105 alleles were observed with an average of 10.4 alleles per locus. The average heterozygosity level per locus was low at 0.1717. The variability within accessions among the populations was 74.85% and within individual accessions was 18.67%. The results showed that genetic diversity within Kenyan sorghum germplasm accessions is higher than that between the different populations. It is implied that such genetic diversity can be exploited as such or in hybridization programs to improve sorghum varieties currently grown by subsistence farmers in Kenya.

Influence of Selected Ecological Farming Practices on Soil Moisture Retention and Yield of Sorghum (Sorghum bicolor (L.) Moench) and Cassava (Manihot esculanta Crantz) in Semi-Arid Yatta Sub-County, Kenya

In this study, the influence of ecological farming practices on soil moisture and yield of cassava (Manihot esculanta Crantz) and sorghum (Sorghum bicolor (L.) Moench) was investigated. The study was conducted in semi-arid Katangi and Ikombe divisions of Yatta sub-county between October 2010 and August 2012. A randomised complete block design with a split plot arrangement was used. Main plots were three cropping systems: (i) Intercropping; (Dolichos [Lablab purpureus]/Cassava, Dolichos/Sorghum, Pigeon pea [Cajanus cajan (L.) Millsp.]/Sorghum, Pigeon pea/Cassava); (ii) Rotation; Dolichos-Cassava, Dolichos-Sorghum, Pigeon pea-Cassava, Pigeon pea-Sorghum and (iii) Monocrop (pure cassava and sorghum). Split plots were organic inputs; farm yard manure (FYM), compost and absolute control. Sorghum/pigeon pea intercrop+FYM treatment had high moisture levels during short rain season (SRS) of 2010 at Katangi (5.21%), SRS of 2011 at Ikombe (5.19%) and long rain season (LRS) of 2011 at both sites (5.83%, 12.30%). Grain yields were highest under sorghum/dolichos intercrop+ FYM during LRS of 2011 at Katangi (1.36 t ha-1) and Ikombe (1.48 t ha-1), and SRS of 2010 at Katangi (1.39 t ha-1) only. Cassava/dolichos intercrop recorded high soil moisture levels in both sites under sorghum/dolichos intercrop during SRS of 2010 (6.48%, 8.35%), LRS of 2011 (7.63%, 8.77%) and LRS of 2012 (6.41%, 3.65%) for Katangi and Ikombe, respectively. Tuber yields were higher under cassava/pigeon intercrop in Katangi (18.63 t ha-1) and Ikombe (28.73 t ha-1) during SRS of 2010 and LRS of 2011, and SRS of 2011 and LRS of 2012 at Katangi (20.86 t ha-1). Intercropping sorghum with dolichos and cassava with pigeon pea + FYM would be a viable strategy to boost crop yields in smallholder farming systems of Yatta sub-county.

Assessment of soil nutrient balances in organic based cassava (Manihot esculenta Crantz) and sorghum (Sorghum bicolor (L.) Moench) cropping systems of Yatta Subcounty, Kenya.

Long-term food production in developing countries is under threat due to soil nutrient mining resulting from unsustainable production practices. In this study, the sustainability of various cropping systems and organic input combinations were assessed through monitoring nutrient flows and balances at crop production level. The study was conducted in Katangi and Ikombe divisions of Kitui sub-county between October 2010 and August 2012. A randomised complete block design with a split plot arrangement was used. The main plots were three cropping systems: (i) Intercropping (Dolichos [Lablab Original Research Article American Journal of Experimental Agriculture, 4(12): 1557-1578, 2014 1558 purpureus]/Cassava, Dolichos/Sorghum, Pigeon pea [Cajanus cajan (L.) Millsp.]/Sorghum, Pigeon pea/Cassava); (ii) Rotation (Dolichos-Cassava, DolichosSorghum, Pigeon pea-Cassava, Pigeon pea-Sorghum); (iii) Monocrop (pure cassava and sorghum). The split plots were; farm yard manure (FYM), compost and control. All crops had above ground biomass incorporated after harvest in the same plot they were harvested from. Nutrient flows; nitrogen (N), phosphorus (P) and potassium (K), were monitored for four seasons; short rain season (SRS) of 2010, long rain season (LRS) of 2011, SRS of 2011 and LRS of 2012 using NUTMON toolbox. There were no significant differences in nutrient balances between the four seasons except in sorghum based cropping systems where N and P balances were significantly lower in the second year. Losses across the seasons occurred mainly through harvested products in both sorghum and cassava cropping systems while addition mainly occurred through biological N fixation and incorporation of crop residue. Negative NPK balances were found in cassava than sorghum-based cropping systems regardless of legumes used in both sites. Dolichos rotation with sorghum and compost applied resulted in positive N balances. Dolichos-cassava rotation with compost also had reduced N losses compared to when pigeon pea was used. P losses were less negative under pigeon pea-sorghum and pigeon pea-cassava rotation with FYM applied. Pigeon pea rotation with sorghum and FYM applied resulted in reduced K losses while with cassava the same cropping system was superior but with application of compost. The choice of legume and organic input for use would depend on environment farmer operates in. In N, P and K limited environments; dolichos rotation with compost application, pigeon pea rotation plus FYM and, pigeon pea-sorghum rotation plus FYM and pigeon pea-cassava rotation with compost applied would, respectively, be recommended as farming practices.

Produce Quality and Safety

Within sustainable production, produce quality and safety are essential features. However, methods, requirements, conditions and even legislation for produce quality and safety in production in rural areas cannot always be directly transferred to production in urban areas and on rooftops. This chapter describes features of produce quality, produce safety and safety hazards in urban rooftop farming employing various technological solutions and serving various purposes in different climate zones. Sustainability is discussed in terms of product quality and safety, and requirements to resolve the principal issues are presented.

Microbial Performance of Food Safety Control and Assurance Activities in a Fresh Produce Processing Sector Measured Using a Microbial Assessment Scheme and Statistical Modeling

Current approaches such as inspections, audits, and end product testing cannot detect the distribution and dynamics of microbial contamination. Despite the implementation of current food safety management systems, foodborne outbreaks linked to fresh produce continue to be reported. A microbial assessment scheme and statistical modeling were used to systematically assess the microbial performance of core control and assurance activities in five Kenyan fresh produce processing and export companies. Generalized linear mixed models and correlated random-effects joint models for multivariate clustered data followed by empirical Bayes estimates enabled the analysis of the probability of contamination across critical sampling locations (CSLs) and factories as a random effect. Salmonella spp. and Listeria monocytogenes were not detected in the final products. However, none of the processors attained the maximum safety level for environmental samples. Escherichia coli was detected in five of the six CSLs, including the final product. Among the processing-environment samples, the hand or glove swabs of personnel revealed a higher level of predicted contamination with E. coli , and 80% of the factories were E. coli positive at this CSL. End products showed higher predicted probabilities of having the lowest level of food safety compared with raw materials. The final products were E. coli positive despite the raw materials being E. coli negative for 60% of the processors. There was a higher probability of contamination with coliforms in water at the inlet than in the final rinse water. Four (80%) of the five assessed processors had poor to unacceptable counts of Enterobacteriaceae on processing surfaces. Personnel-, equipment-, and product-related hygiene measures to improve the performance of preventive and intervention measures are recommended.

Influence of maturity at harvest, N fertiliser and postharvest storage on dry matter, ascorbic acid and β-carotene contents of vegetable amaranth (Amaranthus hypochondriacus)

Vegetable amaranth is a leafy vegetable traditionally grown in sub-Saharan Africa and Asia where it is the most consumed traditional vegetable. It is considered to have high nutritional quality, containing relatively large amounts of vitamins A and C. We have assessed the influence of the maturity of the vegetable and soil nutrition on the visual and nutritional quality of amaranth. We found that leaf ascorbic acid content is strongly influenced by both maturity and soil nutrition, with leaves of seven week old matured plants having the highest content. β-carotene increased with increasing amount of soil nitrogen and with increasing plant age. The loss of both visual and nutritional quality during storage was influenced more by maturity at harvest and the temperature of storage than the soil nutrition.