Poster Presentation Science Protecting Plant Health 2017

Taking full advantage of nematode resistance testing for wheat cultivars over multiple experiments (#138)

Maria Valeria Paccapelo 1 , Alison Kelly 1 , Jason G Sheedy 2 , John P Thompson 2
  1. Department of Agriculture and Fisheries, Toowoomba, Queensland, Australia
  2. Centre for Crop Health, University of Southern Queensland, Toowoomba, Queensland, Australia

Root-lesion nematodes (Pratylenchus thornei and P. neglectus) are microscopic eel-worms that feed on plant roots and can reduce the yield of intolerant wheat cultivars by more than 50% and cost the Australian industry approximately 123 M/yr. A plant is said to be resistant if it has the ability to inhibit nematode multiplication in its roots. In the period from 1996 to 2015, the resistance or susceptibility of more than 900 wheat cultivars was evaluated in glasshouse experiments. The results of these experiments were used to provide comparative ratings of cultivar performance to industry. In total, 22 pot experiments for P. thornei and 18 for P. neglectus were conducted, where resistance was determined by counting the final number of nematodes in the roots and soil of each pot after 16 weeks growth. The objective of this study was to combine multi-experiment data for resistance testing to deliver improved predictions of cultivar performance relative to separate analyses of individual experiments. The statistical analysis implemented a factor analytic mixed model approach, which was found to provide accurate predictions of the cultivar effects as well as a parsimonious and informative model for the cultivar by experiment interaction. The information obtained from this analysis gave insight into the consistency of cultivar resistance across experiments for each nematode species. It resulted in both an overall measure of nematode-resistance by species, as well as a measure of stability to environmental change, allowing for the selection of stable check cultivars with resistant or susceptible performance. Further research will be focused on measuring the improvement of the accuracy under this model as well as determining the minimum number of years of testing required for reliable cultivar rankings.