Yield response of tea clone 6/8 to growing environments, nitrogenous fertiliser application and plucking intervals in East Africa.

Abstract

In East Africa, tea growing areas fall in several agro-ecological regions, differing widely in elevation and climatic factors. Despite the differences, agronomic inputs are uniform throughout the region. Clone TRFK 6/8 is dominant in the region. Recommended nitrogenous fertiliser rates vary between 100 and 250 kg N ha/year. Agronomic recommendations adapted from Kenya are used without re-testing in other tea growing areas. The uniform agronomic recommendations may be inappropriate in some regions. Trials were initiated to establish optimal nitrogen fertilizer application rates and plucking intervals to optimise yields in Lake Victoria Basin using clone TRFK 6/8. Trials were set up at three sites in Kenya; two in Rwanda and three in Tanzania. At each site, a 5×3 factorial experiment was laid out in a randomized complete block design, replicated thrice. Yields for 2008, 2009, and 2010 are reported. There were significant (P≤0.05) yield responses to sites. Mulindi and Maruku produced the lowest yields, while Changoi and Arroket in the first year, Changoi, Arroket, Timbilil and Katoke in the second year and, Changoi and Arroket in the third year, produced the highest yields. In 2008, application of 150 kg N ha/year gave higher yields than the control. In 2009, highest mean yield was obtained by applying 225 kg N ha/year. For the mean experimental period, 150 kg N ha/year yielded higher than the lower N-rates. The extent and rate of yield responses varied at the same rate of fertiliser application for all sites. In 2009 and 2010 short plucking intervals produced highest yields. The pattern of responses changed with sites causing significant interactions effects. Optimal harvesting intervals for clone TRFK 6/8 in the Lake Victoria region are region specific.