In the 1980’s, Australian apple orchards produced between 10 and 15 tonnes per hectare. Today they produce between 60 and 100 tonnes per hectare, an increase of 600% over 30 years. Researchers from the Queensland Department of Agriculture and Fisheries (DAF), inspired by this success, have commenced a major project that will investigate how similar gains can be achieved in the Australian mango industry. The Small Tree High Productivity initiative has been underway since 2013 and is focused on improving the productivity of the mango, macadamia and avocado industries.
Ian Bally, leader of the Mareeba based mango research team, believes that this research will allow higher planting density of trees in orchards by developing a range of strategies for growers to manage tree size more effectively.
“This holds huge potential to increase the productivity of the Australian mango industry. If we can replicate the successes of the apple industry it will mean more profitable orchards and higher quality fruit,” he said.
“The project focuses on four key areas that currently underlie our understanding of productivity in mango orchards: vigour management, canopy architecture, canopy light relations and crop load,” Dr Bally said.
Vigour management with rootstocks
Reducing mango tree vegetative vigour and diverting energy into fruit production is critical for sustainable high yields. The project has begun to look for new rootstocks that will reduce vigour while still providing high yields of quality fruit in high density mango orchard systems. Thirty experimental rootstocks were grafted and field planted in late 2014 with another 60 to be planted over the next 18 months. The effects of the different rootstocks on scion vigour control are likely to become apparent when the trees begin regular cropping at two to three years old.
Canopy architecture and training
New ways of pruning and training mangoes to optimise light and manage vigour in high density orchards systems are a focus of this research. Responses of Keitt, Calypso and NMBP1243 to conventional, single leader or hedged canopy architectures grown at planting densities of 156, 440 and 1,250 trees per hectare will be monitored. Since planting, the trees have been pruned to establish the three canopy architecture styles and precise measurements of growth and architecture have been regularly made. This research will be used to determine which varieties are most suited to high density production.
Canopy light relations
Researchers are studying the relationships between light, canopy architecture, productivity and fruit quality. Understanding light relationships will help to determine the best plant spacing and canopy training options for high density mango orchards to maximise productivity and fruit quality.
Light interception has been measured and compared with tree age, canopy characteristics and yield on seven Kensington Pride orchards with a variety of planting configurations, ages and pruning systems in the Mareeba and Mutchilba districts. Early findings have found that on average, light interception reached a maximum of 68% in 25 year old Kensington Pride trees with a canopy volume of 13,300 cubic meters per hectare. Yields increased up to 50% light interception, after which the increase in yields slowed with maximum yields being reached at 68% light interception. Future work will study the distribution of light within the canopy and investigate how to optimise light interception in younger trees to reach maximum yields earlier in an orchard’s life.
The project team extend their thanks to growers who participated in this work and are looking for additional 10 to 25 year old orchards to measure in the Mareeba and Dimbulah district. If you are interested in co-operating, please contact DAF Mareeba on 07 4048 4600.
A multiyear study to investigate the effects of crop load on subsequent yield, canopy growth and flowering with the aim of managing crop load to reduce irregular and biennial bearing has begun. Flowers on Calypso trees were removed to give a range of flowering percentages. Early findings, based on one season of study, have shown that Calypso trees have a strong ability to compensate for poor flowering. The results show that the number of mangoes at harvest was similar between trees with 100% and 10% flowering, because the trees with a lower flowering percentage had more fruit per panicle. Average fruit weight remained consistent from full flowering to about 30% flowering, below which average fruit weights increase by approximately 15%. Factors such as tree nutrition, health and cultivar may cause trees to respond differently to reduction in percentages of flowering. A second year of observations is needed before any conclusions can be made about any effects on biennial bearing.
The following researchers are acknowledged for their contributions to this work: Dr Ian Bally, Dr Paula Ibell, John Wilkie, Jim Hanan, Ram Kolala, Cheryl Maddox, Anahita Mizani and Carole Wright.
The Small Tree High Productivity Initiative focuses on improved productivity of mango, macadamia and avocados and is an initiative of the Queensland Government. Major partners include the DAF, DAF’s research alliance with The University of Queensland (Queensland Alliance for Agriculture and Food Innovation), and the NSW Department of Primary Industries.
This project has been funded by Horticulture Innovation Australia Limited using the Across Horticulture levy with co-investment from Queensland DAF and funds from the Australian Government.
The full version of this article can be found on the AMIA website at: