ISHS Acta Horticulturae 637: XXVI International Horticultural Congress: Advances in Vegetable Breeding
ESTIMATION OF VARIANCE COMPONENTS WITH LIMITED SEED PRODUCTION |
| Author: | J. Sahagún-Castellanos |
| Keywords: | Plant breeding, additive variance, dominance variance, mating designs, inbreeding depression |
| Abstract:
For those crop species in which a seed increase is required for evaluation of the crosses among individuals from a random sample taken to estimate the variance components of the sampled population, the selfing of the crosses has been suggested. Although this procedure assures the necessary amount of seed for the evaluation to yield the required information to assess the breeding potential of the population under study, it might be expensive and laborious. In addition, the theory for panmictic populations with multiple alleles has not been developed. This study was designed to derive a cheap and simple estimation method of genetic variance components of populations under these circumstances. From a sample of m males and h females the mh possible crosses were considered (each male was crossed with each female). From the h crosses of each male, the seed was composited to evaluate m half-sib families. S1 seed from the selfing of each family was considered as well. The common parent of each half-sib family was also selfed. Thus, 3m families were considered for field evaluation. On the basis of the experimental information from this evaluation, estimators were derived for the variance of the additive and dominance effects and for the dominance deviations effects of the genotypes with identical-by-descent alleles. Estimators were also derived for the covariance between the additive and the dominant effects, the mean inbreeding depression of the population, and for the square of this mean. The described procedure makes possible the estimation of six parameters, and requires less resources than North Carolina Designs I and II. | |
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