| Abstrakt: |
Seventeen nodulating (nod) plant introduction (PI) soybean lines [Glycine max(L.) Merr.] were crossed ‘Clark’ and ‘Harosoy’ cultivars to give nod ✕ nod crosses and to corresponding nonnodulating (nonnod) near isogenic derivatives of Clark and Harosoy to give nonnod ✕ nod crosses. The protein proportions in seeds from nonnod (rj1rj1) F2plants were 2 to 5% lower and the oil proportions 1 to 3% higher than those in seeds from nod (Rj1—) sibs. The proportions of protein and oil in Rj1Rj1F2plants from nod ✕ nod crosses were similar to those of Rj1— plants from corresponding nonnod ✕ nod crosses. Correlation coefficients between percent prorein and oil, protein and residual (0.95 × total seed wt less protein and oil), and oil and residual averaged −0.65, −0.43, and −0.41, respectively, over all F2genotypes. Apparently the absence of nodules did not affect the relationships between seed components. Frequency distributions for seed protein percentages in nod and nonnod F2plants overlapped with some rj1rj1individuals being higher in protein than some of their Rj1— sibs. Phenotypic variances for percent protein among rj1rj1F2plants averaged 1.6 times as much as those among Rj1— sibs. However estimated genetic variances averaged only 1.2 times as much. Broad sense heritability estimates were higher or lower for difference in protein percent in Rj1— than in rj1rj1F2classes depending upon how estimates of environmental variance were made. However heritability estimates based on regression of F3progeny means on F2plant phenotypes were 0.09 and 0.31 for the Rj1— and rj1rj1classes, respectively. It is suggested that in some crosses nitrogen fixation (in nod plants) may act as a “buffer” obscuring the segregation of genes for utilization of combined nitrogen. |
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