Evaluation of experimental designs and spatial analyses in wheat breeding trials

Thirty-three wheat breeding trials were conducted from 1994 to 1996 in the Northern Grains Region (QLD and Northern NSW) of Australia to evaluate the influence of experimental designs and spatial analyses on the estimation of genotype effects for yield and their impact on selection decisions. The re lative efficiency of the alternative designs and analyses was best measured by the average standard error of difference between line means. Both more effective designs and spatial analyses significantly improved the efficienc y relative to the randomised complete block model, with the preferred model (which combined the design information and spatial trends) giving an avera ge relative efficiency of 138% over all 33 trials. When the Czekanowski sim ilarity coefficient was used, none of the studied models were in full agree ment with the randomised complete block model in the selection of the top l ines. The agreement was influenced by selection proportions. Hence, the use of these methodologies can impact on the selection decisions in plant bree ding.