ALTITUDE, TEMPERATURE AND SHOOT PRODUCTION OF TEA IN THE KENYAN HIGHLANDS

Shoot production was examined for two clones at four sites in western Kenya, differing by up to 300 m in altitude and from 16.4 to 18.1-degrees-C in mean air temperature. The duration of the shoot growth cycle increased with altitude, and the rate of shoot extension decreased, mainly because of the temperature differences. Outside a dry season, linear regressions of both extension rate and 1/duration on temperature were significant for Clone S.15/10, and gave apparent base temperatures around 7.5-degrees-C, but were not significant for Clone TN. 14/3 which responded only slightly to temperature. The dry weight per shoot was stable and the growing point frequency did not change systematically with altitude. Analysis that excluded the effects of drought indicated that the yield of Clone S.15/10 decreased from 740 g M-2 at the lowest site by about 10% per degree fall in temperature, whereas the yield of TN.14/3 did not change systematically with altitude.