| Abstrakt: |
A 3‐yr study was conducted to determine the response in seed yield from a tandem selection scheme in which the first step was to select desirable lines from each of two single‐cross populations of soybean [Glycine max(L.) Mew.] for morphological and developmental traits, by using independent culling. The second step was to select for greater plant N content at the R5 developmental stage. The genetic material was 213 F6‐derived indeterminate lines from three maturity groups (79 lines early, 93 medium, and 41 late) from a single‐cross population (IX139) and 102 lines from three different stem‐termination types (28 determinate lines, 40 semideterminate, and 34 indeterminate) from different cross (IX149). Yield increase from the first part of the selection scheme was 2.2% in the early, 1.8% in the medium, and 5.5% in the late maturity groups of IX139, with a mean of 3.2%. Selection for morphological and developmental traits decreased seed yield by 4.4% in the determinate group of IX149 and increased the seed yield in the semideterminate and indeterminate groups of IX149 by 1.0 and 4.7%, respectively. In the second portion of the tandem selection scheme, selection for greater plant N content at R5 decreased seed yield by an average of 0.06% across the maturity groups of IX139 and increased the yield by an average of 1.1% across the three stem‐termination types of IX149. The average yield increase across the groups, locations, and years was 0.5%. In assessing the overall response to tandem selection in all groups within IX139 and IX149, most groups responded positively, but the determinates decreased in seed yield by 3.8%. Plant N content at the R5 stage, because of its poor association with seed yield and the inconsistent seed‐yield response to selection, did not seem to play a significant role in determining the final yield of F6‐derived lines of soybean. |
Plný text