Due to high demand for tea beverages, Camellia sinensis is grown under diverse climatic condition... more Due to high demand for tea beverages, Camellia sinensis is grown under diverse climatic conditions. The demand has led to development of high yielding clones which require high nutrients amounts usually lost through continuous cropping, leaching and surface runoff due to which it is very important to replenish these nutrients through the application of fertilizers. Tissue analysis is the reliable way to predict nutritional status leading to time migitation through supplementation of nutrients through fertilizer. To guide fertilizer requirements in East Africa, first mature leaf type analysis is done and the same analysis was adopted for clonal tea. It is not known, the standard set for the seedling tea are relevant for clonal tea and how the levels are influenced by nitrogen fertilizer rates or plucking intervals in different locations. This study assessed effects of location of production, nitrogen rates and plucking intervals on mature leaf nutrients of clone TRFK 6/8, the most wi...
Mau Forest in the upper reaches of the Mara River basin has recently undergone increased forest d... more Mau Forest in the upper reaches of the Mara River basin has recently undergone increased forest destruction followed by human settlement and agricultural activities. These anthropogenic activities may be contributing nutrients and heavy metals, ultimately polluting the river water and eventually Lake Victoria water hence damaging these aquatic ecosystems. This study sought to establish the effect of anthropogenic activities and season on the water quality of the Amala and Nyangores tributaries of the River Mara in Kenya. Pristine springs in the Mau Forest were used as reference sites. Water samples were analyzed for pH, temperature, conductivity, nutrients, selected heavy metals, and selenium. The mean range of the parameters measured from sites along the tributaries was pH 5.44–7.48 and that for conductivity was 20–99 μS/cm while the mean range of nutrient levels (μg/L) was 80–443 (NO3−−N), 21.7–82.7 (NH4+–N), 11.9–65.0 (soluble reactive phosphorous), and 51–490 (total phosphorous). The mean range for heavy metals and selenium (in μg/L) from sites along the tributaries were 6.56–37.6 (Cu), 0.26–4.97 (Cd), 13.9–213 (Zn), 0.35–3.14 (Cr), 0.19–5.53 (Mn), 1.90–9.62 (Pb), and 0.21–4.50 (Se). The results indicated a significant difference (p ≤ 0.05) between the reference sites and the different sampling sites, indicating that anthropogenic activities were impacting the quality of water in the two tributaries. Although most of the parameters were within the WHO (2004), USEPA (2014) and NEMA (2006) acceptable limits for surface waters, they were above the permissible levels for domestic use. Moreover, the levels of nutrients, heavy metals, and selenium were significantly higher in the wet season than in the dry season, further indicating that anthropogenic activities are causing a disturbance in the aquatic system. Therefore, further anthropogenic activities should be checked and limited so as to conserve the ecosystem.
Abstract Tea beverages, from tender shoots of Camellia sinensis L., are the most widely consumed ... more Abstract Tea beverages, from tender shoots of Camellia sinensis L., are the most widely consumed fluids after water. The young tender shoots of the plant are harvested using various plucking methods. Incorrect plucking leads to yield and quality declines. It is therefore necessary that this process is optimised. Extensive research showed changes in the chemical composition, quality and yields of black tea due to plucking standards. Black tea quality deteriorates as the leaves become older and the rate of decline varies with crop varieties. A plucking standard of two leaves and a bud is recommended in most tea growing countries. However, due to rising harvesting costs, many tea producers are resorting to various mechanical harvesters. Mechanical harvesters or shears produce lower quality black tea compared to hand plucking. But this evens out after the plants are subjected to continuous/ long term mechanical harvesting. There is decline in quality with long plucking intervals even wh...
Sugarcane farming has been identified as the single most cultivated cash crop in Lake Victoria ba... more Sugarcane farming has been identified as the single most cultivated cash crop in Lake Victoria basin. Use of high agronomic inputs is employed in these regions for better yields. Most rivers feeding Lake Victoria from these catchments have been reported to accumulate total heavy metals downstream above background concentrations. The source of these heavy metals to the rivers is not known. This study, therefore, aimed at determining levels of pH, Cd, Cu, Zn, Pb and Cr in River Kuywa surface water and sediments before and after traversing sugarcane farms within Lake Victoria basin as well as in farm soils, canals runoff water and sediments within the sugarcane farms to assess if agronomic input in sugarcane farming influenced their levels. The results indicated significant differences at p ≤ 0.05 in the heavy metal levels of River Kuywa before the farms and after the farms. Canals water and sediments levels were significantly higher than river water levels suggesting them to be the ma...
7a-Acetylugandensolide together with thirteen known drimane-type sesquiterpenes have been isolate... more 7a-Acetylugandensolide together with thirteen known drimane-type sesquiterpenes have been isolated from Warbugia ugandensis bark extracts. Their structures were established by spectroscopic and physical methods as well as comparison with data available in the literature. The in vitro antimicrobial activities of the extracts and isolates were investigated against fungi and bacteria which infect sweet potato. Ethyl acetate extract exhibited the highest (P � 0.05) antifungal and antibacterial activities compared to nhexane and methanol extracts. Rhizopus stolonifer was more susceptible to ethyl acetate extract (inhibition zone = 24.5 mm) than Blitox which was used as a positive control. The minimum inhibitory concentration (MIC) for the isolates ranged between 12.5 and 200 mg/ml with the lowest MIC value of 12.5 mg/ml being observed with polygodial against Fusarium solani; warburganal against Aspergillus niger and F. solani; and mukaadial against A. niger
Page 1. Effects of Genotype, Environment and Management on Yields and Quality of Black Tea P. Oki... more Page 1. Effects of Genotype, Environment and Management on Yields and Quality of Black Tea P. Okinda Owuor, David M. Kamau, Samson M. Kamunya, Solomon W. Msomba, Marie A. Uwimana, Amos W. Okal, and Bowa O. Kwach ...
... These studies demonstrated that the composition of the volatile flavour compounds in black te... more ... These studies demonstrated that the composition of the volatile flavour compounds in black tea ( [Wicremasinghe et al., 1973] , [Yamanishi et al., 1968a] and [Yamanishi et al., 1968b] ), black tea aroma ( [Aisaka et al., 1978] and [Owuor and Obanda, 1996] ) and black tea plain ...
Due to high demand for tea beverages, Camellia sinensis is grown under diverse climatic condition... more Due to high demand for tea beverages, Camellia sinensis is grown under diverse climatic conditions. The demand has led to development of high yielding clones which require high nutrients amounts usually lost through continuous cropping, leaching and surface runoff due to which it is very important to replenish these nutrients through the application of fertilizers. Tissue analysis is the reliable way to predict nutritional status leading to time migitation through supplementation of nutrients through fertilizer. To guide fertilizer requirements in East Africa, first mature leaf type analysis is done and the same analysis was adopted for clonal tea. It is not known, the standard set for the seedling tea are relevant for clonal tea and how the levels are influenced by nitrogen fertilizer rates or plucking intervals in different locations. This study assessed effects of location of production, nitrogen rates and plucking intervals on mature leaf nutrients of clone TRFK 6/8, the most wi...
Mau Forest in the upper reaches of the Mara River basin has recently undergone increased forest d... more Mau Forest in the upper reaches of the Mara River basin has recently undergone increased forest destruction followed by human settlement and agricultural activities. These anthropogenic activities may be contributing nutrients and heavy metals, ultimately polluting the river water and eventually Lake Victoria water hence damaging these aquatic ecosystems. This study sought to establish the effect of anthropogenic activities and season on the water quality of the Amala and Nyangores tributaries of the River Mara in Kenya. Pristine springs in the Mau Forest were used as reference sites. Water samples were analyzed for pH, temperature, conductivity, nutrients, selected heavy metals, and selenium. The mean range of the parameters measured from sites along the tributaries was pH 5.44–7.48 and that for conductivity was 20–99 μS/cm while the mean range of nutrient levels (μg/L) was 80–443 (NO3−−N), 21.7–82.7 (NH4+–N), 11.9–65.0 (soluble reactive phosphorous), and 51–490 (total phosphorous). The mean range for heavy metals and selenium (in μg/L) from sites along the tributaries were 6.56–37.6 (Cu), 0.26–4.97 (Cd), 13.9–213 (Zn), 0.35–3.14 (Cr), 0.19–5.53 (Mn), 1.90–9.62 (Pb), and 0.21–4.50 (Se). The results indicated a significant difference (p ≤ 0.05) between the reference sites and the different sampling sites, indicating that anthropogenic activities were impacting the quality of water in the two tributaries. Although most of the parameters were within the WHO (2004), USEPA (2014) and NEMA (2006) acceptable limits for surface waters, they were above the permissible levels for domestic use. Moreover, the levels of nutrients, heavy metals, and selenium were significantly higher in the wet season than in the dry season, further indicating that anthropogenic activities are causing a disturbance in the aquatic system. Therefore, further anthropogenic activities should be checked and limited so as to conserve the ecosystem.
Abstract Tea beverages, from tender shoots of Camellia sinensis L., are the most widely consumed ... more Abstract Tea beverages, from tender shoots of Camellia sinensis L., are the most widely consumed fluids after water. The young tender shoots of the plant are harvested using various plucking methods. Incorrect plucking leads to yield and quality declines. It is therefore necessary that this process is optimised. Extensive research showed changes in the chemical composition, quality and yields of black tea due to plucking standards. Black tea quality deteriorates as the leaves become older and the rate of decline varies with crop varieties. A plucking standard of two leaves and a bud is recommended in most tea growing countries. However, due to rising harvesting costs, many tea producers are resorting to various mechanical harvesters. Mechanical harvesters or shears produce lower quality black tea compared to hand plucking. But this evens out after the plants are subjected to continuous/ long term mechanical harvesting. There is decline in quality with long plucking intervals even wh...
Sugarcane farming has been identified as the single most cultivated cash crop in Lake Victoria ba... more Sugarcane farming has been identified as the single most cultivated cash crop in Lake Victoria basin. Use of high agronomic inputs is employed in these regions for better yields. Most rivers feeding Lake Victoria from these catchments have been reported to accumulate total heavy metals downstream above background concentrations. The source of these heavy metals to the rivers is not known. This study, therefore, aimed at determining levels of pH, Cd, Cu, Zn, Pb and Cr in River Kuywa surface water and sediments before and after traversing sugarcane farms within Lake Victoria basin as well as in farm soils, canals runoff water and sediments within the sugarcane farms to assess if agronomic input in sugarcane farming influenced their levels. The results indicated significant differences at p ≤ 0.05 in the heavy metal levels of River Kuywa before the farms and after the farms. Canals water and sediments levels were significantly higher than river water levels suggesting them to be the ma...
7a-Acetylugandensolide together with thirteen known drimane-type sesquiterpenes have been isolate... more 7a-Acetylugandensolide together with thirteen known drimane-type sesquiterpenes have been isolated from Warbugia ugandensis bark extracts. Their structures were established by spectroscopic and physical methods as well as comparison with data available in the literature. The in vitro antimicrobial activities of the extracts and isolates were investigated against fungi and bacteria which infect sweet potato. Ethyl acetate extract exhibited the highest (P � 0.05) antifungal and antibacterial activities compared to nhexane and methanol extracts. Rhizopus stolonifer was more susceptible to ethyl acetate extract (inhibition zone = 24.5 mm) than Blitox which was used as a positive control. The minimum inhibitory concentration (MIC) for the isolates ranged between 12.5 and 200 mg/ml with the lowest MIC value of 12.5 mg/ml being observed with polygodial against Fusarium solani; warburganal against Aspergillus niger and F. solani; and mukaadial against A. niger
Page 1. Effects of Genotype, Environment and Management on Yields and Quality of Black Tea P. Oki... more Page 1. Effects of Genotype, Environment and Management on Yields and Quality of Black Tea P. Okinda Owuor, David M. Kamau, Samson M. Kamunya, Solomon W. Msomba, Marie A. Uwimana, Amos W. Okal, and Bowa O. Kwach ...
... These studies demonstrated that the composition of the volatile flavour compounds in black te... more ... These studies demonstrated that the composition of the volatile flavour compounds in black tea ( [Wicremasinghe et al., 1973] , [Yamanishi et al., 1968a] and [Yamanishi et al., 1968b] ), black tea aroma ( [Aisaka et al., 1978] and [Owuor and Obanda, 1996] ) and black tea plain ...
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