Long-term trunk strangulation reduces photosynthesis, sap flow and growth, but improves flowering and plant water status of mango trees

摘要

Bark girdling and strangulation techniques have been used to induce early and intense flowering in tropical and subtropical fruit tree species, including mango [Mangifera indica L.J. We investigated the effects of trunk strangulation with an adjustable metal band over 8 months in 4-year-old mango trees in northern Australia. Results included significantly reduced vegetative growth and the promotion of early and intense flowering. The plant water status of the trees was not adversely affected, as shown by measurements of predawn and midday leaf water potentials, daily branch shrinkage and whole-tree hydraulic conductance. However, leaf gas exchange (net photoassimilation (PN), stomatal conductance and transpiration) and xylem sap flow were significantly reduced. The maximum recorded Pn in strangulated trees following the wet season was 2.38 umol m2 s1, while the value for control trees was 10.54 umol m2 s1. These results showed for the first time at the whole-tree level that the reduction in PN of strangulated mango trees was due to strong stomatal limitation but not degraded water status. These findings have implications in terms of understanding the follow-on effects of strangulation, a flower promotion treatment, on tree photosynthesis and the capability for future productivity.