| Abstrakt: |
Three hierarchal populations in the F6generation were used to estimate the importance of additive, additive‐by‐additive, and dominance genetic variances for heading date in three winter wheat (Triticum aestivumL. em. Thell) populations. The populations were progenies from three single crosses between the cultivars ‘Aobakomugi’, ‘Doublecrop’, and the Purdue Univ. line, P6879. Under Indiana conditions, Aobakomugi heads about 5 and 14 days earlier than Doublecrop and P6879, respectively. Two random F3plants were grown from each of 291 random F2plants from the three crosses. Two random F4plants were grown from each of the F3plants. Twenty random F5plants from each of the 1164 F4plants were grown in a row 1 m long. F6seed from plants within each row was bulked to give rise to the 1164 F6lines. F6lines, the three parents, and two cultivars, ‘Monon’ and ‘Beau,’' were grown in a randomized complete block design in experiments at Lafayette and Sullivan. Ind. in 1980 and analyzed as a nested effects model. Additive variance was significant for heading date in the cross Aobakomugi/Doublecrop; additive and dominance variances were significant in the cross Aobakomugi/P6879; and additive × additive effects were significant in the cross Doublecrop/P6879. A duplicate dominant genetic system is proposed to account for part of the genetic variance in populations from crosses with P6879. The appropriateness of early and advanced generation selection for heading date is briefly discussed. |
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