Efficiency of check-plot designs in unreplicated field trials

Area of Science:

• Agricultural Science
• Plant Breeding
• Biometrical Genetics

Background:

• Check-plot designs are commonly used in plant breeding trials.
• These designs can have lower selection intensity compared to unreplicated non-check-plot designs when the number of selected lines (s) and total plots (N) are constant.

Purpose of the Study:

• To determine the conditions under which check-plot designs can be more efficient than non-check-plot designs.
• To identify the factors influencing the efficiency of check-plot designs in plant breeding.

Main Methods:

• Theoretical analysis comparing selection intensity and error variance between check-plot and non-check-plot designs.
• Derivation of conditions for check-plot design efficiency based on plot error variance, genetic variance, check-plot frequency, and selection fraction.

Main Results:

• Check-plot designs require substantial reduction in plot error variance and increase in heritability to compensate for reduced selection intensity.
• The necessary reduction in error variance is dependent on check-plot frequency (fc), selection fraction (k = s/N), and the ratio of error variance to genetic variance (w0 = σ0(2)/σg(2)).
• Lower w0 and higher fc and k necessitate a greater reduction in plot error variance for check-plot designs to be efficient.

Conclusions:

• Check-plot designs are not always more efficient; their efficiency hinges on effectively controlling plot error variance.
• A specific condition is derived to identify scenarios where check-plot designs may never achieve superior efficiency compared to non-check-plot designs.