| In order to understand the genetic law of grain weight impact on yield and to provide basis for selection of elite parents in hybrid breeding,six varieties with high 1 000-grain weight,SH4300,S5707,Heng 4568,D08-6,LS6109 and Huayu 116 and six varieties with low 1 000-grain weight,H083-366,Hanyou 0602-25,Tainong 8681,Linkang 6180,Tainong 2987,and DH155 were selected as parents. Thirty-six cross combinations were made according to NCⅡ genetic design,using the 6×6 incomplete diallel crosses. Seven characters were studied and combining ability and heritability analysis were conducted in parents and F1 generation including the plant height,spike length,tiller,spike number per plant,spike grain number,yield per plant and 1 000-grain weight. The results showed that D08-6 had the highest 1 000-grain weight general combining ability,but the general combining ability of other traits was not high,resulting in the lowest general combining ability of yield per plant. Therefore,it could only increase 1 000-grain weight alone as a parent. The 1 000-grain weigh general combining ability of the three parents: LS6109,Huayu 116 and S5707 was not the highest,but the general combining ability of yield per plant was the highest. The increased yield was obtained by increasing panicle length,tiller,spikelet number and grain number. The general combining ability of Tainong 8681 and DH155 was high,and the general combining ability of the yield per plant was the highest. Therefore LS6109,Huayu 116,S5707,Tainong 8681 and DH155 are the best parent materials in this test. The analysis of special combining ability showed that the combination with the highest special combining ability of yield per plant were LS6109/Tainong 2987,SH4300/Tainong 2987 and D08-6/Hanyou 0602-25. The highest specific combining ability of 1 000 grain weight was D08-6/Linkang 6180,LS6109/Tainong 2987 and D08-6/H083-366. Among them,the tillers and 1 000-grain weight in LS6109/Tainong 2987 had higher special combining ability. The special combining ability of SH4300/Tainong 2987 for 1 000-grain weight was high,and the special combining ability of D08-6/Hanyou 0602-25 for tillers and grains per spike was very high. In summary,combination LS6109/Tainong 2987,SH4300/Tainong 2987,D08-6/Hanyou 0602-25 performed well in this experiment. Heritability analysis showed that plant height,spike length and spikelet number had higher general heritability and narrow heritability(>65%).These traits were suitable to choose in the early generation. Although tiller,ear grain weight,and 1 000-grain weight were higher in general heritability,their narrow heritability was lower(<50%). These three traits were suitable for selection in higher generation. |
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