Determination of the Minimum Number of Stool Bed Ortets Required to Capture a Desirable Genotype from Full-Sibling Family Crosses

Two important questions for clonal forestry are: (I) how many ortets must be established to ensure that one or more of the best genotypes in a family will be available for field tests and plantation establ ishment; and (2) how certain can one be that at least one top genotype wil l be present in a sample of n ortets . In this s tudy, we calculated the level of confidence (LOC) in having included one or more desirable, rootable genotypes in a random sample of n ortets from a full-sibling family. We also calculated the number of unique ortets required to achieve a given LOC in having included one or more desirable, rootable genotypes in a sample. In general , when the sample s ize is small , e i ther because the original number of or te t s was low or because of poor rootabi l i ty , the LOC is lower. When rootabi l i ty i s low or when only a smal l percentage of the possible genotypes is considered desirable , the original number of ortets required to achieve a given LOC is higher. Both LOC and sample size are highly influenced by the target number of desirable genotypes to be captured in a sample of ortets. South. J. Appl. For. 27(3):160-163.