Flush development in Tahitian lime

Abstract

The relationship between the cycle of flush development and temperature is not well described for Tahitian lime, or citrus species in general. We pruned trees over 16 months in the humid subtropics of northern New South Wales (NSW), and monitored post-pruning flush development over two cycles, in terms of flush commencement and flowering. We also recorded temperatures over this period. The time from pruning to the emergence of the first post-pruning flush was correlated with mean daily temperature, with emergence being slower at cooler temperatures. Emergence times ranged from 11 to 39 days. The time between the commencement of the first and second flushes was also correlated with mean daily temperature, with slower development of the first flush at cooler temperatures. The duration of the first flush varied from 41 to 128 days. There was more flowering on the first than the second flush (16% of shoots versus 3%). There was no flowering on flushes that commenced in the warmer months, from November to March. The temperature threshold for flowering appeared to be at a mean daily temperature of ~20°C. Regressions between flush development and temperature were used to estimate the effects of climate warming from 1963–1971 to 2003–2011, using long-term temperature records. The warming decreased bud emergence time by 1.6 days in winter and 1 day in summer; and reduced the time from the first to the second flush by 11.8 days in winter and 9.2 days in summer. The results for Tahitian lime were similar to those for other recurrent flushing trees.