Jian (Frank) Liu

M.Ag.Sci. (2021)

Modelling approaches for lucerne growth and development under dryland conditions (PDF 7.4 MB)

Research Overview

Jian utilised lucerne data from dryland previous experiments to model lucerne growth and development under water stress environment using APSIM_Lucerne. The current lucerne model in the Agricultural production system simulator next generation (APSIMX) was not designed for simulating lucerne responses to dryland conditions. Hence, this study aimed to incorporate previous knowledge obtained from dryland experiments from Lincoln University into the APSIMX-Lucerne model. New equations were introduced to the model to constraint the growth and development processes including leaf area expansion rate, radiation use efficiency and phyllochron under water-limited conditions. However, of the two approaches evaluated to model DM prodution of water stressed lucerne both demonstrated that the demand-related parameters in the model were inadequate to impose the correct waster stress effects on lucerne. More specifically, the model failed to constrain above ground variables at water supply limited conditions while the model extracted inadequate water from soil at water demand limited conditions. Further work is needed and it was suggested that in-silico approaches, such as Bayesian inference or specialised root structure mechanistic models, might be required to assist the understanding in the full picture of lucerne growth and development under dryland conditions.

Jian is from China and is now working full time in the modelling team in Plant & Food Research located at the Lincoln campus. He was supervised by Prof Derrick Moot and supported by Dr Henry Chau from Lincoln University, Dr Hamish Brown and Dr Linley Jesson from Plant & Food Research.

The work was part of the Hill Country Futures programme (BLNZT1701) funded by Beef + Lamb New Zealand, MBIE, Seed Force New Zealand and PGG Wrightson Seeds.