Month of harvest and yield components of tea tree. I. Biomass

Abstract

The effect of month of harvest on the biomass production of coppice growth from tea tree plants (Melaleuca alternifolia) grown under plantation conditions and harvested annually was assessed in a field experiment on the north coast of New South Wales. Tea tree oil is obtained from leaves, and the yield of leaf is determined by the total plant yield, the proportion of twig in total yield, and the proportion of leaf in twig. Harvesting between July and October gave a significant increase in total plant yield over other months. This advantage appeared to come from synchronising the most efficient stage of growth (4-6 months after harvest) with the best growing conditions. Under the same environment conditions, the relative efficiencies of regrowth were 46, 100, and 71 during months 1-3, 4-6, and 7-12, respectively. District observations suggested that there would be little growth at mean monthly temperatures <16OC, and the data analysis showed a reduction in growth when the soil dried to <69% of the total available water capacity. The proportion of twig in total yield was affected by the total plant weight, and the proportion of leaf in twig responded to the air temperature. However, variation in both proportions had a relatively minor effect on leaf yield, and changes in total plant yield accounted for more than 90% of the variation in leaf yield.