The classifications for a large number of wheat varieties used in APSIM by the Yield Prophet tool have been updated, improving the accuracy of outputs for Yield Prophet subscribers.

The updated maturity parameters and classifications are the result of field work carried out across Australia. The work, which was led by Dr Zvi Hochman (CSIRO), sought to back the paramertisation of wheat varieties used by APSIM.

According to Dr Hochman, many variety parameters (the value attributed to a function that effects resulting output) had previously been set without reference of data and often on the basis of breeder maturities or having a maturity similar to another variety (possibly also without reference data).

To remedy this situation Dr Hochman and his team observed the Zadok’s growth stages of 19 wheat varieties in replicated plot experiments at a total of 23 sites with three times of sowing  per year ranging from late April to late June.

This work resulted in updated phenology parameters for 12 reference varieties used by Yield Prophet (shown in bold and shaded in Table 1).  This parameterisation should prove beneficial in modelling the phenology of these varieties. 

However, the benefit is not limited to these 12 varieties. Other varieties in the APSIM wheat database have consistent photoperiod and vernalisation genes (haplotypes) to those parameterised by Dr Hochman. The Yield Prophet team has identified these varieties and put them into maturity groupings according to these genes.

This work has resulted in a number of changes to the maturity parametrisation of wheat varieties used by APSIM (Tables 1 and 2).

Table 1: Shared phenology parameters and updated maturity classifications for relevant APSIM cultivars

 * Please note that not all cultivars that share the same genes as the reference varieties are included. The excluded varieties have varying maturity, driven by other factors, and thus should not be assigned shared phenology parameters.

Table 2: Updated maturity classifications for relevant APSIM cultivars. These changes were suggested by Dr James Hunt (La Trobe University).

References

Hochman, Z., Horan, H. & Huth, N. (2015) Optimised phenology parameters for APSIM Wheat Unpublished CSIRO.