Smaller trees could boast bigger outputs

The Queensland Department of Agriculture and Fisheries (QDAF) is leading the long-term multi-disciplinary Small Tree High Productivity Initiative which aims to achieve higher avocado, macadamia and mango yields from smaller trees.

The research is based on “high density” apple crops in temperate climates.

Over a 30 to 40 year period, apple growers have achieved yield increases from 10-15 to 60-100 tonnes per hectare.

Project leader Dr John Wilkie from QDAF said one of the goals of the research is to develop cropping systems that put a greater proportion of their productive effort into fruit, rather than stems and branches.

The project covers many aspects of crop growth and fruit production from tree architecture to crop vigour, optimising canopy light distribution and crop load.

The program has field work based at Queensland Department of Agriculture and Fisheries (DAF) field stations in Bundaberg and the Atherton Tableland.

The researchers hope the project will result in incremental productivity gains over a program time frame of up to 20 years.

The project is still in its early development stages with the first experimental crops of mangoes planted in 2013 and macadamias and avocados in 2014.

The project has the support of the Queensland and NSW State Governments, QAAFI, the University of Queensland and Horticulture Innovation Australia.

The long term nature of tree crop cycles means a major plank in the research relies on the development of sophisticated modelling by a team of specialists at the QAAFI Centre for Plant Science led by Associate Professor Jim Hanan.

While simulations are being developed to look at specific tree crops and their obvious physical differences, Associate Professor Hanan said the work would also pinpoint underlying similarities between species.

“Modelling will also let us integrate different parts of the overall productivity equation such as the interaction between canopy light environment, flowering and fruit set,” Associate Professor Hanan said.

Laboratory simulations will help in the design and targeting of field experiments to optimise research outcomes.

“This approach will help shorten the time to achieve really meaningful results by many years,” Associate Professor Hanan said.

QAAFI is also playing a collaborative role in genetic research with scientists from the University of Queensland’s School of Biological Sciences.

It is expected that a new understanding of genetic switches and crop physiology could result in productivity gains in the years ahead.

UQ researcher Rosanna Powell said there was a focus on tree architectural development, a variable trait important to crop production.

Her specialist field is the number of branches a tree produces with more branches generally leading to opportunity for more bud, flower and fruit production.

Ms Powell said an early focus of the research effort was on setting up data processing protocols and developing high speed analysis of plant tissue samples coming from the field.

The UQ team, led by Professor Christine Beveridge, also studies the role of plant hormones in crop development.

They recently discovered a novel plant hormone, strigolactone, which is important for nutrient uptake and also has a role in shoot architecture and root development.

The project is led by the Queensland Government and jointly supported by the Department of Agriculture and Fisheries, the University of Queensland and Horticulture Innovation Australia with the Across Industry levy and funds from the Australian Government.