OPTIMAL REPLICATION IN SELECTION EXPERIMENTS

The efficiency and selection gain of yield trial experiments is affect ed by experimental design. A larger number of genotypes, G, increases the chances of including markedly superior genotypes, and a larger num ber of replications, R, reduces errors and thereby increases the chanc es of correctly identifying truly superior material. But assuming that cost rises approximately as the number of plots GR, containing resear ch cost imposes a tradeoff between G and R. This paper gives tables sp ecifying the number of replications that optimizes selection of genoty pes with the highest true yields. It also quantifies the impact of sub optimal choices. Even with an optimal level of replication, the value of a selection experiment rises logarithmically with the number of plo ts and hence the cost. Since benefits from more data follow this sever e law of diminishing returns, statistical strategies for decreasing er rors and improving selections are quite important.