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 Title: Evaluation of Seed-Filling Period as an Indirect Selection Trait for Higher Yield and Its Relationship With Nitrogen Parameters in Soybean Author(s): Auyeung, Man Ting Department / Program: Agronomy Discipline: Agronomy Degree Granting Institution: University of Illinois at Urbana-Champaign Degree: Ph.D. Genre: Dissertation Subject(s): Agriculture, Agronomy Abstract: Previous reports have shown that seed-filling period (SFP) and seed yield are positively related in soybean (Glycine max (L.) Merr.). Indirect selection for yield using SFP is effective if heritability of SFP is higher than that for yield, and genetic correlation between SFP and yield is high. Relative selection efficiency of gain (p) was computed to determine the merit of using SFP in indirect selection for yield. Soybean population 1 and 2 were derived from cross PI 398.881 x PI 398.763 and PI 416.750 x PI 407.721, respectively. Determinate soybean lines in population 1 had a high heritability for SFP $({\rm h}\sp2$ = 0.84), and a high genetic correlation between SFP and yield (r = 0.92). However, the low number of lines (13) used prevent making a general conclusion for SFP as an indirect selection trait. Indeterminate soybean lines in population 2 had a low heritability for SFP $({\rm h}\sp2$ = 0.37) and SFP showed no relationship with yield. The low p value for SFP in indeterminate lines suggested that SFP would not be an effective indirect selection trait for yield. In population 2, neither heritability for SFP nor genetic correlation between SFP and yield was computed because genotypic variance for SFP and covariance for SFP and yield were negative. Phenotypic variance for SFP in population 2 was small.Two other experiments were conducted to determine the relationship between SFP and nitrogen parameters. Ten soybean lines were selected from each of the two ${\rm F}\sb5$ populations. Five lines were considered as having a long SFP and the other five lines having a short SFP. Seed-filling period showed no association with N concentration or N content in the vegetative tissue at the beginning of seed fill or at physiological maturity. Nitrogen content in the vegetative tissue was determined by its dry weight. Nitrogen form fixation was closely related with N content in the seed, but showed no association with SFP. The N concentration of vegetative tissue at physiological maturity was higher than that in the non-nodulated line (L63-1899) which suggested that N concentration might not have been low enough to affect physiological activities or SFP. Issue Date: 1987 Type: Text Description: 47 p.Thesis (Ph.D.)--University of Illinois at Urbana-Champaign, 1987. URI: http://hdl.handle.net/2142/71633 Other Identifier(s): (UMI)AAI8721578 Date Available in IDEALS: 2014-12-16 Date Deposited: 1987
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