Among and within family selection and combined half-sib family selection in Panicum maximum Jacq.

Janaina Azevedo Martuscello,Dilermando Miranda Da Fonseca,Cosme Damião Cruz,Daniel De Noronha Figueiredo Vieira Da Cunha Cunha,Liana Jank

doi:10.1590/s1516-35982009001000003

Abstract

The objective of this study was to select superior genotypes in half-sib populations obtained from crosses between sexual plants and apomictic accessions. The experiment also proposed to compare among and within family and combined selection strategies. Ten plots of sexual plants were randomly distributed among 230 plots of apomictic accessions. After natural pollination, seeds of each sexual plant constituted a half-sib family. Thirty plants of each female progenitor were evaluated in a randomized block design experiment, with five plants per plot and five replications. Five evaluation harvests were made in the rainy seasons and two in the dry seasons of all plants. The production and quality characteristics were evaluated. The selection criteria used was: among and within family selection and combined selection with 50% selection in both. The selection criteria used (among and within family selection and combined selection), were efficient for use in P. maximum breeding, with medium to high gains for most characteristics evaluated. The highest genetic gains were obtained from combined selection. However, among and within family selection promoted high genetic gains and may be used in P. maximum breeding. The sexual progenitors identified as numbers 7, 1, 3 and 5 were promising and may be used in future crosses, as well as to increase the genetic variability in the P.maximum genebank.

Highlights

In the cultivation of productive pastures, it is important to consider genetic aspects besides the development of new management techniques, since the optimization of the use of a forage is the result of actions and interactions of the genotype with the environment
The objectives of this paper were to select superior genotypes and progenitors in P. maximum half-sib populations obtained from crosses between sexual and apomictic plants, and to compare among and within family and combined selection strategies
A higher value was attributed to among family selection for all characteristics except for dry matter yield (DMY) and LIG in stems. These results indicated, according to Negreiros (2006), that selection considering the information of individuals and families at only one stage, may be more efficient in terms of response percentile, than selection of families and individuals at two different stages

Summary

Introduction

In the cultivation of productive pastures, it is important to consider genetic aspects besides the development of new management techniques, since the optimization of the use of a forage is the result of actions and interactions of the genotype with the environment. The main breeding methods of most tropical forage grasses primarily include evaluation and mass selection of genotypes selected from the genetic variability of ecotypes collected in Africa (Hacker and Jank, 1998; Valle et al, 2001). This selection process has been used extensively, and with success, in the breeding of forages of relevant importance in the Brazilian beef production system such as Panicum maximum Jacq. New cultivars of forages with apomictic reproduction may be released in the market from the selection of the best genotypes from the germplasm, or by the generation of new variability from crossings, which, in this case, makes the identification of plants from sexual reproduction absolutely necessary

Objectives

Methods

Results

Conclusion