To determine the sample size of each bulks (Tol vs Sus) from a segregating population screened for quantitative traits using bulked segregant analysis (BSA), there are a few factors that need to be taken into consideration.

Firstly, it is important to ensure that each bulk is representative of the phenotype being screened for. Therefore, the selection of individuals for each bulk should be based on the phenotype of interest. For example, in the case of abiotic stress tolerance, individuals with extreme phenotypes for the stress tolerance trait should be selected for each bulk.

Secondly, the sample size of each bulk will depend on the level of genetic variation in the population and the desired power of the analysis. Generally, a larger sample size will provide greater power to detect significant differences between the bulks. However, the sample size should also be balanced between the bulks to ensure equal representation of the two genotypes being compared.

A commonly used approach for determining sample size in BSA is to perform a power analysis. This involves estimating the effect size of the genetic variant responsible for the trait of interest, as well as the expected allele frequency and genetic diversity in the population. Based on these estimates, the power analysis can provide an estimate of the minimum sample size required to detect significant differences between the bulks.

These video playlists might be helpful to you:

https://www.youtube.com/playlist?list=PLzBiAPKi8vOPbE7Db9mKwloe34E8rXXEU

https://www.youtube.com/playlist?list=PLzBiAPKi8vONSqjcweFWHMRy13y3484bE

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Hi Nikolay, many thanks for your input. I highly appreciate your time and effort.