Heterosis for Catechins and Caffeine in Kenyan Tea (Camellia sinensis) (L.) O. Kuntze).

Tea quality is manifested in its aroma, flavour and taste properties, which are generated by volatile and non-volatile compounds, mainly catechins and caffeine. Several studies have revealed positive significant relationships between (flavan-3-ols) catechins and caffeine in green leaf and black tea quality. Additionally, the health benefits of tea in management of cancer, arthritis, cardiovascular diseases, diabetes and obesity have been attributed to catechins and caffeine. Eight biochemical traits of tea were used to investigate mid-parent heterosis (MPH), better parent heterosis (BPH) and standard heterosis (SDH) in a 4x4 diallel mating design. Overall, genotype x environment interaction influenced heterosis. For example, mean GA, EGC, C, EC and TC contents were higher at Timbilil compared to Kangaita while mean Caffeine, EGCG and ECG were higher at Kangaita compared to Timbilil. The results also showed that, inbreds (EPK TN14- 3, AHP S15/10 and TRFK 6/8) had improved catechins content and could be used in recurrent selection to develop tea with high catechins content. Crosses, which showed high positive heterosis over the mid-parent, better parent and the standard variety, could be utilized to generate transgressive segregants in the later generations with high catechins and caffeine

Effects of Nitrogen Fertilizer Rates and Seasons on Polyphenols and Catechins of Non-aerated Green Tea Processed from Seedling Tea (Camellia sinensis)

Seasonal biochemical profiling was performed on non-aerated green tea processed from high nitrogenous fertilizer rates (0-800 kg N/ha/year) trial on seedling tea to determine the effects of fertilizer rates and seasons on total polyphenols, catechins and caffeine levels. Increasing fertilizer rates significantly, (p>0.05) increased total polyphenols and catechins levels up to 400 kg N/ha/ year rate. There was no increase in the polyphenolic compounds beyond this rate. Although some non-aerated green tea producing countries apply very high rates, of up to 800 kg N/ha/year, to improve quality, in Kenyan seedling tea, there were no green tea quality benefits from applying higher rates beyond 400 kg N/ha/year. Polyphenols levels ranged from 21.19-21.85% while catechins ranged catechin form 16.01-17.31% between 0-800 kg N/ha/year application rates. There were seasonal biochemical variations. Polyphenols levels ranged from 22.91-23.37% during October-December, 21.17-21.18% in January-March, 16.47-16.48% in April-June and 20.38- 20.52% in July–September. Catechins values were 17.32-16.05%, 17.66-17.23%, 14.91-15.73% and 17.39-17.59%, while caffeine values were 3.02-3.20%, 3.43-3.25%, 3.88-3.94%, and 2.70- 2.78% in the respective seasons. Total polyphenols were higher during the cold and wet (October- December) and hot and wet (April-June) seasons and low in cold and dry (July September) and hot and dry (January-March) seasons. Irrespective of the temperatures, wet months produced higher levels of the parameters evaluated.

Seasonal and Environment Variations of Yields and Yield Components of Tea (Camellia sinensis) Cultivars in Kenya

In Kenya, tea is grown in highlands east and west of the Rift Valley at altitudes ranging from 1300 m to 2700 m above mean sea level. These areas vary widely in seasonal and locational environmental factors leading to differences in responses in growth, productivity and quality of tea genotypes. Despite these differences, tea husbandry practices are uniform across tea growing regions in the country. Understanding modes of variations in tea growth parameters and yields to varying environments is crucial for optimization of husbandry practices for tea productivity improvements. Responses in clonal tea growth and yield parameters to season and locations of production effects and their contribution to yields were evaluated, using 20 cultivars in a genotype × environment trial conducted in three locations (Kipkebe, Timbilil and Kangaita). There were yield variations (pd”0.05) between clones, locations and seasons. Tea yield components responses to weather parameters varied with location and season. Shoot growth rates in Kangaita and shoot density in Timbilil linearly correlated (pd”0.05) with yields but varied with season. Yield components and weather parameters contribution to the yield also varied with location and seasons causing significant (pd”0.05) interactions effects. Drought reduced yields while rainfall distribution influenced seasonal yield distribution. Seasonal yield variations were due to shoot growth rate, and shoot dry weight changes but not shoot density. The variations were due to seasonal environmental factors that limited yields rather than factors that increased yields.

Yields and Nitrogenous Fertiliser Use Efficiency Responses of Clonal Tea (Camellia Sinensis) to Locations of Production

Tea husbandry practices in Kenya are uniform despite variations in responses to agronomic inputs with locations. Nitrogen availability is the most limiting tea/crop growth factor. However, tea yields vary with region of production even with the same cultivar, suggesting responses to nitrogen fertiliser and nitrogen utilisation may vary with locations. Nitrogen use efficiency (NUE) of clone TRFK 6/8 was investigated across three different locations/environments in western Kenya. Yields responded significantly (pd”0.05) to nitrogen fertiliser rates, but the responses varied with location of production. The responses to nitrogen rates were significantly lower (pd”0.05) in Timbilil than in Arroket and Changoi. This suggests that optimal nitrogenous fertiliser application rates should vary with locations. Nitrogen application rates between 75- 300Kg N did not cause significant variation in harvestable shoots nitrogen contents. However, there were large differences in the amounts of nitrogen removed with crop. The NUE of tea decreased as nitrogen fertiliser rates increased and was low in areas where yield responses were low. Such areas need low nitrogen fertiliser application rates to justify return on investment. Quantity of nitrogen removed with crop followed same pattern. On replacement basis, nitrogen removed with crop did not exceed the recommended rate of application (150 kg N/ha/year) at any location or nitrogen rate. Shoot nitrogen contents suggest that soil applied nitrogen may not be responsible for locational variations in yield realisation. Results demonstrate that fertiliser management practices, especially nitrogen rates need to be location specific.

Evaluation of Shubhodoya Mycorrhizal Bio-fertilizer for Enhancing Rooting of Nursery Tea Plants.

Bio-fertilizers have not been exploited in Kenya on tea production despite benefits demonstrated in many crops. The bio-fertilizers are organisms that enrich nutrient soil quality. Plants have beneficial relationships with such organisms. Shubhodoya mycorrhizal bio-fertilizer is a consortium of three different species of Glomus mycorrhizal fungus, produced in laboratory under sterile conditions. They are cultured and used for inoculating seed or soil or both under ideal conditions to increase availability of plant nutrients. A nursery experiment was conducted to evaluate the efficacy of Shubhodaya mycorrhizal bio-fertilizer (SMB) in enhancing growth of two tea clones, TRFK 306 and EPK TN14-3. Different rates of SMB (0.6g, 0.9g, and 1.2g), standard treatment (6g diammonium phosphate) and control (no fertilizer) were laid out in randomized complete block design. Sleeved seedlings with the soil were randomly sampled from the nursery for analysis of soil pH, assessment of growth parameters and mycorrhizal colonization were conducted. Root samples were used to determine dry weight and to conduct assays for VAM infection. The SMB did not have adverse effects on soil pH in the nursery. Plants subjected to the DAP treatment all died after weeks 27. Increasing application of SMB rates and frequency increased shoot growth. SMB at 1.2 g exhibited the lowest shoots dry weight while SMB at 0.6 and 0.9g had the highest. After 62 weeks from planting, there was an abrupt increase in shoot dry weight. Successful colonization of tea roots with inoculation of SMB was also observed. SMB colonized the tea roots an indication that it has potential for exploitation.

Influence of Nitrogen Fertilisation on Red Spider Mites (Oligonychus coffeae Nietner) and Overhead Volatile Organic Compounds in Tea (Camellia sinensis)

Nitrogen fertilisation influences tea yields, quality and pests infestation levels. Red spider mites reduce tea production in western Kenya during prolonged droughts. Nitrogen fertiliser use maybe an agronomic practice that may influence infestation levels by mites. Overhead volatile compounds (OVOCs) composition also influences infestations of tea by mites. Influence of nitrogenous fertiliser rates on red spider mite infestations and OVOCS levels was determined. Mites populations varied (pd>0.05) with nitrogenous fertiliser rates. High infestations were at 0 and 300 kg N/ha/year, and sharp decline between 150 and 225 kg N/ha/year. Green leaf volatiles increased while some aromatic and terpenoid compounds decreased with increasing nitrogenous fertiliser rates. Significant (pd>0.05) direct linear regressions between 1-penten-3-ol, 3-penten- 2-ol, E-2-hexenal, Z-3-hexenyl acetate and inverse relationship between 2-phenyl ethanol, ethyl benzene, -methyl styrene, longifolene and ß-cedrene and nitrogenous fertiliser rates were observed. Most aromatic and terpenoid compounds, which are repellents of mites, were highest between 150 and 225 kg N/ha/year where infestations by mites were lowest. The recommended fertiliser rates of 100 to 225 kg N/ha/year in Kenya also produce most repellents of mites, protecting tea plants against infestations. Use of recommended nitrogen rates can protect tea from infestations by mites.

Changes in the Composition of Elements in Non-Aerated Green Teas Processed from Seedling Tea (Camellia sinensis) Due to Variations in Nitrogenous Fertilizer Rates and Seasons.

Soil nutrients are lost to the plant with harvested crop in tea production with most ending up as minerals and contribute to human nutrition upon tea consumption. Production of non-aerated green tea in Kenya has been low. The changes in the mineral profiles of these teas due to nitrogenous fertilizer rates and seasons is not been documented. Several elements were profiled from non-aerated green teas processed from seedling tea grown under varying fertilizer rates of up to 800kg N/ha/year in different seasons. They included N, P, Ca, Mg, Mn, Zn, Cu and Fe which registered 3.32-3.79%, 0.22-0.29 %, 1.47-2.13%, 0.42-0.87%, 0.14-0.38%, 0.11-0.28%, 19.29-41.88ppm, 11.68-25.53ppm and 175.83-206.28ppm respectively with nitrogenous fertilizer rates. The elements were significantly (pd”0.05) higher during the wet and warm, and wet and cold seasons than in the warm and dry, and cold and dry seasons. For the seasons, N, P, K, Ca, Mg, Mn, Zn, Cu and Fe registered 3.19-4.22%, 0.16-0.35%, 0.51-2.10%, 0.42-0.92%, 0.12- 0.44%, 0.13-0.35%, 8.74-84.94ppm, 6.67-84.67ppm and 66.07-363.39ppm respectively. The values changed with rainfall distribution, although the response patterns differed between individual elements. Inceasing NPKS fertilzer rate caused a rise in N, P and K values especially, from October to June. However, there was a shift in the months of July to September between 400 and 800 kg N/ha/year, in the first year of study. During the second year, the observed shift in year one of the study was revesred. Consequently throughout the year the increments in nutrients corresponded to that of fertilzer rates. The results demonstrate that soil nutrients removed with crop vary with seasons and nitrogenous fertilizer rates. High rate of fertilizer contributed to more N, P and K and other micro-elements such as Mn.and Fe to the finished products. The results also demonstrate that in non-aerated green tea production, application of high rates of nitrogen is necessary to maintain plant nutritional requirements and fresh leaf quality.

Clonal Variations in the Response of Hard Physically Withered Leaf to Rehydration Following Long Chemical Wither Durations

Long chemical wither durations and hard physical wither reduce the quality of plain black tea, through reduction in total theaflavins production while encouraging thearubigins formation. Such quality reduction may vary with genetic makeup of the tea plant. However, rehydration reactivates activities of oxidative enzymes responsible for producing plain black tea quality parameters. Influence of rehydrating hard physically withered leaf that had undergone long chemical wither durations on two clonal plain black tea quality parameters were assessed. Rehydration restored the formation of plain tea quality parameters from hard physically withered leaf. However, quality deterioration due to long chemical wither duration could not be reversed by rehydration. The patterns of responses of the clones used were similar. Thus in the processing of plain black tea, efforts should be made to maintain chemical wither durations to below 30 hours. However, rehydration reverses reduced plain black tea quality parameters by hard physical withers to equivalent of chemical wither

Characterization of New Tea (Camellia sinensis L.) Hybrid Progenies Based on Morphological Traits

Hybridization is the main method of obtaining genetic variation and breeding of new cultivars. Two parents selected for their desired characteristics were crossed to create genetic variation. One hundred and eighteen putative hybrids were generated by crossing two diverse parents, TRI 2043 which is characterized with high pubescence density, pigmented leaves, tolerant to blister blight disease, and TRI 3055 a non-pigmented, stem canker tolerant cultivar. A reciprocal cross was also made. Total progeny was characterized for five morphological traits; anthocyanin pigmentation in petiole, leaf vestiture, average number of pubescence of leaf, immature leaf colour, and petiole colour. Average number of pubescence in abaxil of the second leaf varied from 5 to 149 with the mean of 62. Parental cultivar TRI 2043 recorded the highest average number of pubescence and TRI 3055 had the lowest. Among the progenies, 93 individuals contained anthocyanin pigmentation in petiole, which was the characteristic feature of TRI 2043. Population was subjected to genetic analysis and the resultant dendrogram clearly categorized the progenies into four clusters. Significant variation was found among the individuals in the progeny. Forty individuals showed close resemblance with the parent TRI 2043 and 21 individuals grouped with cultivar TRI 3055. Rest of the individuals shared both parental morphological characteristics.

Dissipation rates of some selected pesticides from the soil of tea agroecosystem in Assam, India

An experiment was carried out in Rosekandy Tea Estate, Barak Valley, Assam to investigate the persistence of some selected pesticides (i.e Endosulfan, Fipronil, Paraquat and 2,4-D) on the soil. These pesticides were applied in the soil as per the application rate, where one year old tea plants were growing and the residue were analysed for a period of 50 days. Their degradation kinetics in soil was also studied and described. Soil samples were collected with the help of soil corer. The samples were brought to the laboratory, air dried in room temperature and extracted for analysis with high performance liquid chromatography (HPLC). Among the pesticides 2,4-D was highly persistent with half life of 57.75 days followed by Endosulfan which lost 42.64% of its initial concentration by the last sampling period (i.e 50 days) after the spraying. Fipronil and paraquat lost 65% and 70.32% of initial residue in soil making them the least persistent amongst these pesticides in the studied soil. Considering the impact of pesticide residues on human health, the less persistent pesticides may be used in tea plantations to minimize the potential negative impact of pesticides in the environment. The cost benefit ratios of the use of the pesticides should be also worked out.