Response to family selection based on replicated trials

Abstract

The theory of expected response to selection between families is extended to allow for the effects of field replication and its interactions with number of plants per plot.

Efficiency of Indirect Selection for Dry Matter Yield Based on Fresh Matter Yield in Perennial Ryegrass Sward Plots

“…The benefit of increasing replication or i on the efficiency of indirect selection followed a curvilinear pattern (Fig. 1) similar to that observed by England (1977) The benefit:cost ratio was significantly greater based on increasing i rather than that based on increasing the number of replicates. For example, doubling the number of plots to increase the number of replicates from two to four increased the efficiency of indirect selection from a mean 0.88 to 0.94.…”

The effect of varying the number of drills per plot and the amount of replication on the efficiency of potato yield trials

“…It therefore follows that the theoritically optimal design would be single plant plots with a high degree of replication. This, however, ignores the possible agricultural or biological differences that are introduced by growing single plants as opposed to plots which contain more than one plant (as noted by ENGLAND, 1977). For instance, if single plants are grown they have to be spaced sufficiently to allow tubers produced in each plot to be harvested separately, which is of course, a wider spacing than would be used in normal agricultural practice and could affect tuber number, size, etc (ALLEN, 1978).…”

Maximizing Efficiency of Recurrent Phenotypic Selection for Neutral Detergent Fiber Concentration in Smooth Bromegrass

“…Selection differentials generally increased as more harvests were included in the selection criterion, by 3.1 ± 0.5 and 2.7 ± 0.5 g kg −1 harvest −1 for one‐block and two‐block selection criteria, respectively (Table 2). This was a result of more accurate genotype rankings because of averaging over multiple repeated measurements of the phenotype (Aung et al, 1994). On average, spatial replication (mean NDF over two blocks vs. NDF value for one block) increased the selection differential by 3.4 ± 0.5 g kg −1 block −1 , indicating that the effects of spatial and temporal replication were similar and interchangeable.…”

“…In addition, taking measurements on several harvests throughout the year leads to more precise measurements as well as an increased likelihood of selecting truly superior plants (Aung et al, 1994). Five repeated measurements provides an 83% chance of selecting at least three of the five most extreme genotypes, a 52% chance of selecting at least four of the five most extreme genotypes, and a near certainty that the most extreme genotype will be identified (Aung et al, 1994). Utilizing repeated measures of body condition score improved the ability to predict fertility in dairy cattle by 28 to 53% compared with single‐measure analysis (Banos et al, 2004).…”

“…Replication of selection units in space and/or time provides a mechanism to improve the precision of measurements. Heritability can be increased by clonal propagation of selection units (England, 1977). There is always some advantage in replicating selection units if it can be accomplished without reducing selection intensity, especially when the trait of interest has low heritability (England, 1977).…”