The effect of rootstocks on mango tree vigour, scion architecture, yield, percentage of flowering terminals in young unpruned trees

Abstract

In Australia, commercial tree size management in mango orchards involves annual machine hedging and heavy hand pruning. In tropical growing regions, heavy pruning often stimulates strong vegetative regrowth that is less likely to flower due to insufficient terminal growth-unit dormancy required for flowering. A few mango rootstocks have been shown to reduce scion vigour and maintain regular, high yields; however, there is a lack of rigorous field-testing of these and other rootstocks under Australian scions growing in Queensland. Apart from some scion vigour control, the effects of mango rootstocks on scion architecture have not been studied in Australia and reports in the international literature are scarce. In this study, 90 genetically diverse rootstocks have been evaluated for their ability to reduce vigour in two Australian mango scion varieties from the National Mango Breeding Program (NMBP); ‘NMBP-1243’ and ‘NMBP-4069’. Tree height, canopy volume and shape, rootstock and scion trunk cross-sectional area were measured in young trees 30 months after planting to evaluate tree growth and vigour. Branch angle, length and diameter, number of growth units, number of leaves, and leaf size were also measured to characterize scion architecture. Ten rootstocks were identified as reducing vigour while maintaining the percentage of flowering terminals per canopy volume. Four rootstocks were also found to influence scion architecture by altering secondary branch angles to be closer to horizontal, potentially making them more suited to single-leader training used in high-density orchards systems. Canopy architecture parameters measured in this study suggest that rootstocks may be a useful technique for reducing tree vigour and altering the architecture of mango scion canopies to make them more suited to intensive orchard systems. © 2022 International Society for Horticultural Science. All rights reserved.