二条オオムギにおける千粒重のダイアレル遺伝分析

The inheritance of 1,000-grain weight of two-rowed barley varieties was examined using a reciprocal F1 cross and a half F2 diallel cross among eight parents. The F1 generation was examined in five different ripening conditions i.e., (Ⅰ) control, (Ⅱ) leaf cut, in which all leaves were cut at the heading time, (Ⅲ) Spikelet thinned, in which a quarter of the spikelets were thinned at the heading time, (Ⅳ) dry, in which the plants were grown in a vinyl-film house without irrigation, and (Ⅴ) wet, in which the plants were mist-irrigated every two house in the daytime after the heading to the harvest. The experiment was repeated twice. The F2 populations were grown in the ordinary condition. The average 1,000-grain weight was largest in the dry plot followed by spikelet thinned, control, leaf cut, and wet plots. The 1,000-grain weight was predominantly controlled by the additive genes. The dominance effect was also significant. The large grain weight was controlled by the overdominant genes. Epistasis among the genes controlling the 1,000-grain weight was significant, but the maternal effect was absent. In the F1 diallel, heritability was 0.3~0.6 and 0.2~0.5 in a broad and a narrow sense, respectively. In the F2 diallel, it was 0.9 and 0.6 in a broad and a narrow sense, respectively. In each of the 28 F2 populations, the broad sense heritability was estimated as 0.3~0.8.

二条オオムギ8品種間の正逆ダイアレルF1および片面ダイアレルF2を供試して1,000粒重の遺伝分析を行った。1,000粒重は主として相加的な量的遺伝子に支配され、超優性およびエピスタシスが存在し、大粒の方向が優性で、F1ダイアレルにおける広義の遺伝率は一般に0.5～0.6、狭義の遺伝率は0.3～0.5、母性効果はないことなどが明らかにされた。F2ダイアレルにおける遺伝率は広義0.9、狭義0.6、28のF2集団における広義の遺伝率は0.3～0.8であった。