Mass selection in maize composites by means of selection indices

摘要: General considerations A selection index may be applied to based either upon the performance of single plants or progenies. In latter case however, should only result in a modest gain efficiency, when is compared single-trait for desired character. Index relatively efficient method it individual plants. Individual selection, as we call this type presented study initial stage population improvement programme. general used cross-pollinating crops. combines advantages mass with these from selection. The are most obvious during Mass takes one generation per cycle. large number generations can grown short period time. When under not yet at linkage equilibrium successive will give high frequency recombinants implying progressive breaking up blocks. With possible, even limited facilities, include thereby preventing any premature loss genetic variability. There several arguments application makes an optimal use information available phenotype. possible select simultaneous traits. on traits which observed before flowering seed parent but also pollen parent, doubling response Furthermore, conditions differing normal environment crop. This means that choose such maximize single-plant heritability and then off-season Selection indices maize were calculated using estimates parameters obtained parent-offspring relationship sib analysis. relationship. Using estimated directly multiple regression value offspring characters parents, independent quantitative interpretation data. experimental procedure kept rather simple. It obtain realized by growing environment, while measured cropping environment. Results was studied hundred twenty-one open-pollinated Samaru Composite 2 thirty-six Colombian Composite. Recorded each plant twelve different mean yield its progeny. These records construct yield. test 2, vice versa. could improved between thirty-five seventy-one percent through index. An including about four superior 'estimated' index, weighing factors represented according some rule thumb. For populations study, composites recent origin, shown favourably methods progeny means. analysis carried out forty-four half-sib progenies Most lost sudden outbreak disease, caused Helminthosporium maydis race T, so had results progenies, resistant disease. estimate heritabilities phenotypic correlations resistance stem- rootlodging thirty found character leaf angle correlated yield, indicates Mokwa, despite low level crop, light already limiting factor production. stalk crushing strength dry weight 5-cm section highly stemlodging. correlation stemlodging rind thickness stalk. root pulling roots both rootlodging, two stemlodging, constructed rootlodging. three objectives included first all weight, secondly section, thirdly angle. aimed attractive alternative Out there flowering. were: days shooting, total leaves length width eight. improving As might practise trait area, measuring area product