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Download or read book Evaluation of Ten Generations of Divergent Mass Selection for Ear Length in Iowa Long Ear Synthetic of Maize (Zea Mays L.). written by Hernan Cortez-Mendoza and published by . This book was released on 1977 with total page 248 pages. Available in PDF, EPUB and Kindle. Book excerpt: The purpose of this investigation was to study the direct and correlated responses to divergent mass selection for ear length in Iowa Long Ear Synthetic. Two phases were involved: (1) estimation of the genetic parameters in the base population to predict direct and correlated responses from selection; and (2) evaluation of direct and correlated responses in ear and other agronomic traits after ten generation of divergent mass selection. A biparental, or Design I, mating scheme was imposed on Iowa Long Ear Synthetic to develop 84 half-sib and 336 full-sib families which were evaluated at three locations in Iowa (Kanawha, Ames, and Ankeny) in 1966. From these types of relative, the pertinent estimates of genetic parameters to make predictions were obtained. Theresults from the combined analysis of Design I indicated that for yield, ear length, ear diameter, ear-row number, and 300-kernel weight, the additive genetic variance accounted for all or most of the total genetic variance, under the assumption of no epistasis. For silking date and ear height the estimates indicated that the greatest proportion of the total genetic variance was due to dominance effects. Since all estimates of dominance genetic variance for yield and its components were negative, it was suggested that either the assumptions necessary for the estimation of the genetic parameters were nos satisfied or sampling errors and geneotypes x environment interaction biased the estimated obtained. it was found that the most likely source of (...).