Resumo

SAHAGUN-CASTELLANOS, J. Inbreeding coefficient of combined sampling for regeneration of plant genetic resources. Rev. Chapingo Ser.Hortic [online]. 2010, vol.16, n.2, pp.133-138. ISSN 2007-4034.

For the regeneration of plant genetic resources of monoecious species certain artificial crosses produce desirable effective population sizes but the cost is high. To avoid the cost of these crosses, random mating of the sample can be used. The sample can be taken completely at random, as in the ideal population (IP), or randomly taken at each of two stages (IPTS): first n families and then m individuals of each selected family. Further, since the concept of efective population size as a measure of the effectiveness of the sampling and reproduction strategies to regenerate populations is not always well known as the concept of inbreeding coefficient is, it was derived for IPTS as a measure of the efficiency of the IPTS method of regeneration. This derivation was based on the calculation of the contribution of each of six sources (selfings and crosses) of the inbreeding coefficient already active in the second regeneration cycle (F2e). The calculations were made based on a probabilistic approach applied to the concept of identity by descent. It was found that with IPTS, E decreases as m is closer to 1 and its minimum value occurs when m = 1, and only when m = 1 and n > 1 is smaller than IP's. This implies that, for regeneration purposes, for a sample of size x, a random individual from each of x random families should be included in the sample.

Palavras-chave : Physalis ixocarpa Brot.; half-sib families; identity by descent; selfing; intrafamiliar crosses.

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