| Maize Breeding has mainly focused on heterosis, the superioriy about the Corn Hybridscomes from parental inbred lines, high combining ability inbred lines is the basis for theutilization of heterosis.Through long period of practice, Maize Breeding workers have commonunderstanding that combining ability is the core element in the inbred lines and hybrid breeding.It is the primary factor in the heterosis, but the key indicators in the selection of parents.According to the design of4×8incomplete diallel crossing in Pingliang Maize Breedingstation,32crossing combinations were conducted to analyze general and special combiningability and their corresponding genetic parameters of8plant-type characters in12maize inbreds.The12parents and32crosses were evaluated for ASI and the other15agronomic characters.Analysis of combining ability, genetic parameter and genetic correlation were made respectivly.The main results were as followed:1. Study on the general combining ability of plant-type characters and ear-kernal charactersshowed that integrated characters of9046, F83, huang201,598, Mo17and chang7-2performedbetter. Erect plant type and high yield crosses could probably be screened from crosses combinedby these inbred line and we should take full advantage of them.2. According to analysis the special combining ability of32hybridized combinations,F83×9046,340×B73, ZX09-1002×B73, F83×B73, ZX09-1002×478,598×478,340×ye107,zong31×9046were better combinations in most traits.3. The estimation for the genetic parameters of plant-type characters showed: plantheight,ear height,tassel main axis length and leaf angle are majorly controlled by the effects ofadditive gene, which should be chose in the early generation. ASI, stem diameter, tassel branchnumber and leaf area are controlled by the non-additive gene effects, which should not be chosein the early generation. Ear length, ear diameter, rows per ear, kernel per row,100-kernal weightand rate of grain yield were mainly controlled by additive gene effect; ear barren tip and kernelweight per ear are controlled by the non-additive gene effects. Furthermore, The broad-senseheritability and narrow sense heritability of ear diameter, rows per ear, kernel per row,100-kernal weight, rate of grain yield were higer than50%. And this showed these characterswere mainly influenced by genetic factors, which should be chose in the early generation, thenarrow sense heritability of ear length, ear barren tip and kernel weight per ear were less than50%, And this showed these characters were more influenced by environment, which should notbe chose in the early generation.4. Genetic correlation analysis of main quantitative characters indicated that the erect plant type had negative correlated with leaf area and tassel branch number;kernel weight per ear hadnegative correlated with kernel per row and rate of grain yield,and significantly positivelycorrelated with100-kernal weight, rows per ear and ear diameter.100-kernal weight wassignificantly correlated to ear diameter,and negatively correlated with kernel per row; kernel perrow and Ear length appeared in a obvious positive correlation; rows per ear had positiverelevance with ear diameter.5. Comprehensive analysis of inbred line F83and ZX09-1002showed: The inbred line F83played a central role in shorting ASI, reducing plant height, ear height, leaf angle, when it wasused as the parent. In addition, ear diameter, rows per ear, rate of grain yield and kernel weightper ear of inbred F83showed excellent GCA, indicating that big ear hybrids can be obtained byusing it as a parent, so it was the best germplasm. ZX09-1002has big ear and high yieldpotential, but longer Ear barren tip. Therefore, further improvement inbred line ZX09-1002willbe necessary. |
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