|dc.description.abstract||Background: There are a number of unresolved issues in the design of experiments in greenhouses. They include
whether statistical designs should be used and, if so, which designs should be used. Also, are there
thigmomorphogenic or other effects arising from the movement of plants on conveyor belts within a greenhouse?
A two-phase, single-line wheat experiment involving four tactics was conducted in a conventional greenhouse and
a fully-automated phenotyping greenhouse (Smarthouse) to investigate these issues.
Results and discussion: Analyses of our experiment show that there was a small east–west trend in total area of
the plants in the Smarthouse. Analyses of the data from three multiline experiments reveal a large north–south
trend. In the single-line experiment, there was no evidence of differences between trios of lanes, nor of movement
effects. Swapping plant positions during the trial was found to decrease the east–west trend, but at the cost of
increased error variance. The movement of plants in a north–south direction, through a shaded area for an equal
amount of time, nullified the north–south trend. An investigation of alternative experimental designs for equallyreplicated
experiments revealed that generally designs with smaller blocks performed best, but that (nearly) trendfree
designs can be effective when blocks are larger.
Conclusions: To account for variation in microclimate in a greenhouse, using statistical design and analysis is
better than rearranging the position of plants during the experiment. For the relocation of plants to be successful
requires that plants spend an equal amount of time in each microclimate, preferably during comparable growth
stages. Even then, there is no evidence that this will be any more precise than statistical design and analysis of the
experiment, and the risk is that it will not be successful at all. As for statistical design and analysis, it is best to use
either (i) smaller blocks, (ii) (nearly) trend-free arrangement of treatments with a linear trend term included in the
analysis, or, as a last resort, (iii) blocks of several complete rows with trend terms in the analysis. Also, we
recommend that the greenhouse arrangement parallel that in the Smarthouse, but with randomization where
|dc.subject||Automated phenotyping, Conveyor system, Greenhouse experiments, Greenhouse experimental design, Microclimate variation, Plant relocation, Statistical analysis, Thigmomorphogensis||en_US