Effects of location of production, nitrogenous fertilizer rates and plucking intervals on tea clone TRFK 6/8 tea in East Africa: I. yields

Abstract

The tea growing areas in East Africa fall in agro-ecological regions, differing in elevation and climatic factors but favourable growing conditions. Despite of these differences in elevation and climate, agronomic recommendations are uniform. Clone TRFK 6/8 is the most widely cultivated tea cultivar in East Africa, while nitrogen fertilizer and harvesting are the most expensive agronomic inputs in tea production. Trials were initiated to establish the optimal nitrogen fertilizer rates and plucking intervals to optimise yields within East Africa using clone TRFK 6/8. Experiments were set up at three sites in Kenya; two sites in Rwanda and three sites in Tanzania. At each site the plot was demarcated and the experimental trials were analysed by the 5 by 3 factorial split design for all the 8 locations with nitrogen rates as main treatment and plucking frequencies as sub treatment and the result yield from 2008 to 2010 was analysed. There were significant (P less than 0.05) yield difference due to sites, suggesting clone TRFK 6/8 is not adapting equally at the different sites. Although 225 and 300 kg N ha-1 year-1 fertiliser rates yielded higher than 150 kg N ha-1 year-1 rate, there was no yield difference between the two N-rates. During the whole experimental period, 150 to 225 kg N/ha/year produced yields considered optimal. The extend and rate of yield response to nitrogen fertilizer varied with location of production. Yields variations to plucking intervals were insignificant. For the whole experimental period, short plucking intervals (7 days) produced highest yields. However, differences in the pattern of response changed with sites leading to significant interactions effects.