Shoot population densities, stages of development (that is, the number of leaves per shoot) and shoot mass were recorded on an irrigation × fertilizer experiment at the Ngwazi Tea Research Unit in Southern Tanzania from 1986 to 1990. Over this period the mean basal shoot population density increased from about 310 to 560 m−2, with peaks of over 850 m−2 in high-input plots. Large fertilizer application rates increased both the total number of shoots per unit area and the proportion that were actively growing. By contrast, the main effect of water stress was to delay the peak shoot population density from the warm-dry season until the early rains without affecting the annual mean. Overall, between 20 and 60% of the harvested shoots were dormant, depending on season and fertilizer application rate. Of the active shoots harvested, about two thirds had two leaves and a terminal bud whilst the remainder were split almost equally between shoots with one or three leaves. The fresh mass of individual shoots was linearly related to the number of leaves, with the slope of the line (0.16–0.35 g leaf−1) largely dependent on the season and irrigation treatment. The dry matter content of shoots varied in the range 19–30%, and was primarily determined by the season. The dry matter content was also affected by the treatments and was decreased by irrigation in the dry season and by fertilizer in the wet season. Alternative models for predicting annual yields (based on the components of yield) and seasonal yield variations (based on dry matter production and partitioning) are discussed.
Densidad de poblacióon tamaño y masa de los brotes de té