Effects of Different Fertilizer Rates on Total Polyphenols and Catechins of Selected Clones of Green Tea (Camellia sinensis L. [O] Kuntze)
World Journal of Applied Chemistry
Volume 5, Issue 2, June 2020, Pages: 13-19
Received: Jun. 4, 2020;
Accepted: Jun. 18, 2020;
Published: Jun. 28, 2020
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Evans Kenanda Okemwa, Department of Research and Extension, Kisii University, Kisii, Kenya
Koskei Kipkoech Silvanuss, Department of Chemistry, School of Pure and Applied Sciences, Kisii University, Kisii, Kenya
Application of inorganic NPK (nitrogen: phosphorus: potassium) fertilizers on tea (Camellia sinensis) has been common among small-scale tea farmers to increase production. However, the cost of fertilizers has been increasing and reducing their net returns. Fertilizers applications also affect the quality of the crop which is mainly dictated by the total polyphenols and catechins; these metabolites are responsible for its anti-oxidant activity, taste and aroma. The focus of this work was on the effect of varying NPK fertilizer application rate on the levels of total polyphenols and catechins of green tea made from three tea cultivars and development of an optimum NPK fertilizer application rate. Samples of three varieties, AHP S15/10, TRFK 6/8 (Tea Research Foundation of Kenya), and BBK 35, were collected from Mettarora, Arroket and Monire tea estates within Sotik highlands. Randomized complete block design sampling was used and sampling was done 6-8 weeks after application of the treatment. The fertilizer used was inorganic plain NPK fertilizer and NPK fertilizer supplemented with Molybdenum. The experimental treatments consisted of six treatments made up NPK 25:5:5; at 0, 75, 150, 225, 300, and 375 kg N/ha/year. The collected samples were processed as non-aerated green CTC (Cut, Tear and Curl) teas at the miniature processing factory unit at Kenya Agricultural and Livestock Research Organisation - Tea Research Institute (KALRO-TRI) at Kericho County. Processed tea samples were milled and chemical analysis done to quantify the levels of biochemicals in the samples. Data obtained were subjected to Analysis of Variance (ANOVA) and mean separation was done using the least significant difference test at p ≤0.05. TRFK 6/8 was found to have the highest mean percentage total polyphenols of 25.90 followed by BBK 35 with a mean percentage total polyphenols of 25.75. AHP S15/10 recorded the least mean percentage total polyphenols of 23.70. A similar trend was observed in the mean percentages of catechins with TRFK 6/8, BBK 35 and AHP S 15/10 recording 20.7%, 18.87% 18.46% respectively. Hence, use of optimum NPK fertilizer application rate specific to each clone supplemented with Molybdenum boosts the levels of polyphenols and catechins in green tea.
Evans Kenanda Okemwa,
Koskei Kipkoech Silvanuss,
Effects of Different Fertilizer Rates on Total Polyphenols and Catechins of Selected Clones of Green Tea (Camellia sinensis L. [O] Kuntze), World Journal of Applied Chemistry.
Vol. 5, No. 2,
2020, pp. 13-19.
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