大豆雜交後裔各世代產量選拔效果及遺傳力之研究

Heritability Estimates and Effectiveness of Selection for Yield in Various Generations of Two Soybean Crosses

詹國連(Kuo-Lein Chan)

《中華農業研究》 25卷3期 (1976/09) Pp. 206-213

https://doi.org/10.29951/JARC.197609.0005

摘要

（一）本研究以兩個雜交組台之後代(F2、F3、F4)爲材料，在63、64年春、夏作實施目測單株粒重之選拔，藉以探知在早期選種下各世代單株粒重之遺傳力，以及選種之遺傳增進量，供作大豆雜種俊裔產量選拔之參考。
（二）兩個組台F1之平均粒重，均較高產親本高出45%及69%，較兩親之中間數高出89%及82%，呈甚高之雜種優勢；自F2起，平均粒重隨世代之增進而依序遞減（表2）。
（三）兩個雜交組合後代粒重的遺傳力，均以F2較高，各別爲25.5、28.5%;F4次之，各別爲24.8-24.6%；以F3最低，各爲3.6-7.6%。F3粒重之遺傳力值奇低，可能係該F3受春作（64年）旺盛生長環境作用之影響，過大之環境變方，隱蔽其真正遺傳力之故。
（四）兩個雜交組合後代(F2、F3、F4)單株粒重之預期值與實得值概不相符台，前者遠較後者爲小，顯示本研究所選得的粒重平均，非來自原來相同之族羣，亦即本研究在早期世代施行的單株粒重目測選種，並無效果。

並列摘要

Two soybean crosses, P1 200492 (P1)×Shih-Shih (P2), and Tainung No. 4 (P3)×Flambeau (P4) were grown 200 and 41 plants in the F2 generation in Summer crop 1974 and 32 and 26 lines in the F3 and 48 and 36 lines in the F4 generation in Spring and Summer crops 1975, respectively. The study reported herein was conducted to estimate the heritabilities and predicted gains for the two segregating populations under visual selection for seed yield on single plant performance of each progeny studied. The predict gain was then compared with the actual mean performance differential between the progeny of the selected parent and the population mean, and the close agreements between the predict and actual gains was reffered to as the effectiveness of visual seed yield selections. The results are summarized as follows:
1. The F3 hybrids gave an average of 45% and 69% heterosis for seed yield per plant over their respective high parent, and of 89% and 82% higher than their mid-parent value in the two crosses evaluated. The average seed weight per plant, however, decreased definitely from F2 generation downward to F5 generation in both crosses.
2. 1-Ieritabilities for seed yield per plant estimated varied greatly between F2 and F3 generations in both crosses, and F2 generation gave the highest heritability estimates (25.5% and 28.5%) while the F3 generation had the lowest with 3.6% and 7.6%. Heritability estimated from F4 generation were 24.8% and 24.6%, nearly close to the F2 generations. Since F3 generations were grown in spring season which provided the most favourable vegetation environment, the lowest heritability for F3 probably resulted in having larger environmental variance large enough to cover the express of its true heritability.
3. The disagreements were found between actual and predict gains for visual seed yield selection per plant, and the former were overall generations larger than the later in both crosses. This result showed that the sampled mean in F2, F3, and F4 generations were not from the same populations. It was concluded that there was no genetic progress to be expected from the visual selection for seed yield based on single plant performance in progeny studied.