Inigo Auzmendi

Understanding fruit tree growth and yield through plant modelling (PhD project)

In collaboration with a multi-disciplinary team, we have developed a plant physiology model to simulate macadamia trees growing in an orchard with different management practices such as planting density, tree shape and size. Building on this macadamia model, new models for macadamia, mango and/or avocado will be developed. The PhD student will acquire a strong background in plant modelling techniques, as well as areas of plant physiology and horticultural management, to explore how modelling can be used to better understand and improve orchard productivity. Established field trials at Bundaberg and Mareeba will provide experimental material for initial analysis of tree architecture and determining the growth relationships to include in the modelling of the trees.

The physiology and modelling to be studied will relate to one of the following key research areas:

• orchard light environment and its manipulation by planting density, tree shape and size,
• tree architecture and its interaction with light environment and crop load,
• the effect of factors such as carbon allocation on fruit set and yield.

A working knowledge of plant modelling (functional-structural plant models or crop models), plant physiology and/or horticulture would be of benefit to someone working on this project.

Simulating fruit tree development and growth (Honours project)

Functional-structural plant models simulate organ development and growth in complex plant canopies. They are employed to improve our understanding of physiological mechanisms and interactions between management practices, environmental factors, plant carbon balance and growth.

This project will use avocado, macadamia or mango data already collected from field trials and/or previous literature to simulate development and growth with different training systems, planting densities and cultivars, and interpret the results of field trials, as well as to generate new hypothesis and experiments.

The project focuses on one of four areas: tree architecture, light interception, vegetative vigour and crop load. Our final aim is to improve management practices, e.g. training, pruning, fruit thinning, limb bending, planting density and tree size that will allow better yields in fruit and nut trees.

The student will gain experience in online tools for remote collaboration, computer simulation and computational modelling using L-systems, as well as in plant physiology.

Using virtual plants to simulate photosynthesis in horticultural plants (Research program)

Plants assimilate the carbon required for maintenance and growth through photosynthesis. Estimating photosynthesis is not straightforward in horticultural plants with a complex canopy structure like avocado, macadamia and mango, because individual leaves within the canopy present different photosynthetic characteristics. Therefore, different approaches to simulate photosynthesis could result into different estimates of carbon assimilation. This project will involve the use of virtual plants to simulate photosynthesis of individual leaves and whole canopy with specific management practices like mechanical hedging or topping, different planting density and tree shape. The results of these simulations will be used to evaluate several biochemical and physiological photosynthesis models under various management conditions. The final goal is to determine on each case the most adequate photosynthesis model, and propose new approaches if necessary.

Scholars may gain skills in online tools for remote collaboration, simulation software, understanding photosynthesis, data analysis, fruit tree management, and computer simulations using virtual plants. Scholars with previous knowledge in programing can learn to develop their own photosynthesis models. Students may be asked to produce a report or oral presentation at the end of their project.

Modelling fruit tree architecture and physiology (Research program)

Mathematical modelling of plant architecture can offer insights into the underlying biology, with the eventual outcome of increased yields in Queensland agriculture. In complex plant canopies like fruit and nut trees, simulation of plant architecture at the scale of internodes, leaves and fruit can help to understand aspects of organ growth and development. These models can subsequently be used to study interactions between management practices, environmental factors, plant carbon balance and growth. This project will use data already collected in avocado, macadamia or mango for modelling an aspect of orchard management of interest to the student, such as different training systems, planting densities and cultivars.

Scholars may gain skills in tools for remote collaboration, L-systems, computational modelling and simulations, as well as plant physiology. Students may be asked to produce a report or oral presentation at the end of their project.