大豆种间杂种早代回交和高代选择性回交性状改良效果的研究

THE IMPROVEMENT OF DELETERIOUS TRAITS BY MEANS OF BACKCROSS IN EARLIER GENERATION (F_1) AND LATTER GENERATION (F_3) FROM G. max×G. soja HYBRID

分别运用早代(F_1)连续回交和高代(F_3)选择性回交两种交配方式,探讨了改良大豆种间杂种野生性状及最大限度遴选优良基因型的有效途径。结果表明,高代有选择地回交可以有效地保持野生大豆的高蛋白特性;同时,对提高百粒重和扩大黄色种皮类型入选率也有明显效果。早代随机回交使高蛋白、高亚油酸和丰产基因型频率大幅度下降。从育成超高蛋白(>45％)品种考虑(长期计划),野生种质渗入率不应低于0.25;而从育成普通高蛋白(<45％)品种考虑(短期计划),渗入率可以降到0.125以下。在大豆种间杂种后代,种皮色遗传较复杂,出现IIrrttW_1W_1gg基因型的机率非常低。不同种皮色的BC_0F_2单株分离产生含黄色种皮类型的能力为:黄褐(单株)>黄黑>褐绿>黑绿>黑>褐。野生大豆炸荚性的遗传比较简单,但不符合3:1分离模式,通过二次回交炸荚卒降至25％以下。本研究选择指数结果指出,在早代回交和高代回交后代,用对蛋白质含量有较强相关选择进度的生育期、茎粗和主茎节数,间接选择高蛋白基因型,将产生良好的效果。

Interspecific crosses and backcrosses of soybeans were conducted to evaluate genetic parameters in backcross populations with different rate of wild germplasm introgression, to explore various means of discarding wild deleterious traits. The purpose of the attempt was to promote the utilization of wild germplasm in soybean breeding.The results showed that backcross to F3 hybrid strains maintained the characteristic of high protein content from wild soybean greatly, and it was also beneficial for increasing 100-seed weight and percentage of plants with yellow seed coat. Conversely, the succesive backcross started from F1 would quickiy reduce the rate of genotypes with high protein, high methionine and high linoleic acid content. For the purpose of transfering high protein trait from wild soybean to cultivated soybean, backcross population should contain approximately 25% wild germplasm. In F2 generation of G, max×G, soja cross, inheritance of seed coat color appeared to be much complicated with low rate of yellow seed coat genotypes (IIrrttW1W1gg), but more lines containing yellow seed coat could easily be derived from populations if F2 plants with yellow-brown seed coat were selected for further backcrossing. It was proved that shattering from G, soja was controled only by two or three genes, and the ratio of shattering could be reduced to 25% percentage after two backcross generations. In addition, the result showed that high protein genetypes would be indirectly obtained using selection of maturity and node no. in main stem.