Study On Mutation Effect And Inheritance Model Of Agronomic Traits Of Waxy Maize Mutagenized By Space Radiation

Combining ability, which is an important index for maize breeding material, as well as characteristic of genetic expression in main agronomic characters, can provide theoretical foundation for selecting the agronomic characters. In this thesis, Fourteen waxy maize inbred lines, which included eight females(S147 together with its mutation lines M562,M563,M564,M566,M567,M568,M569 )and six males(S181 together with its mutation lines M571,M573,M574,M575,M576), were crossed in a North Carolina designâ…¡(NCâ…¡). Effects of GCA (general combining ability) and SCA (special combining ability) were analyzed and mutation effect on agronomic characters of waxy maize inbred lines S147 and S181 were discussed. And then, the method of least significant difference (LSD) was used to compare difference of combining ability between mutated inbred lines and its CK. What's more, The six generations (P1, P2, F1, B₁, B₂ and F₂) from cross M578(P2)×S147(P1) were also used in this study. The genetic models of plant height, ear height, tassel length, tassel branch number, and ear diameter were established using series of mixed inheritance models of quantitative traits of major genes plus polygene. Finally, the major genetic effect, polygene effect and inheritance parameters were studied on the basis of such models. And the results indicated that:â‘ Space radiation can led to changes on main agronomic characters and combining ability of offspring lines. Responses to space mutation between waxy maize inbred lines S181and S147 were very significant difference.â‘¡Analysis showed that the GCA variance of plant height, ear height and ear length in male parents were notable. By means of LSD analysis, the differences of GCA effects of plant height between S181 and its five mutation lines was not reach significant level. The differences of GCA effects of ear height of M573and M574 were reach significant level. As for ear length , four mutation lines had notable difference compared to S181, there into, M571,M573,M574 had positive GCA effect. So long ear hybrids could probably be screened from crosses combined by those.Similarly, Analysis showed that the GCA variance of emergence-teaseling, emergence-silking, emergence-maturity, teaseling- silking, plant height, ear height , ear length , bald top length of ear, ear row, number of kernel per row, grain weight per ear, 100-grain weight, ratio of kernel dry weight per ear in female parents were prominence. By using LSD method, nine characters were discovered notable difference between S147 and its mutated line M562, As for M563, M564, M566, M567, M568 and M569; eight, six, six, seven, ten, eleven characters were detected respectively. Furthermore, the positive GCA effects for grain weight per ear in maize mutation lines M564 and M569 indicated that high yield hybrids can be obtained by using them as parents.Results also revealed significant or highly significant differences in SCA variance for emergence-teaseling, emergence-silking, emergence-maturity, weight per ear, and grain weight per ear among male and female parents.â‘¢The optimum genetic model of plant height was E-1,the inheritance were controlled by two pairs additive-dominance-epitasis major gene plus additive-dominance polygene. The optimum genetic model of tassel length was D-2,the inheritance was controlled by one pair additive major gene plus additive-dominance polygene. The optimum genetic models of ear height, tassel branch number and ear diameter were C-0, the inheritance were controlled by additive-dominance-epitasis polygene.â‘£The major genetic heritability of plant height in B₁, B₂ and F₂ were12.07%,39.88% and48.38% respectively,and the polygenetic heritability in B₁,B₂ and F₂ were 50.64%,0.00%and 15.24% respectively. The major genetic heritability of tassel length in B₁, B₂ and F₂ were0.20%,1.80% and21.40% respectively,and the polygenetic heritability in B₁,B₂ and F₂ were 43.20%,21.20%and 0.00% respectively; The polygenetic heritability of ear height in B₁, B₂ and F₂ were 31.97 %, 34.69% and19.80% respectively. The polygenetic heritability of tassel branch number in B₁, B₂ and F₂ were 25.02%, 3.08% and3.63% respectively. The polygenetic heritability of ear diameter in B₁, B₂ and F₂ were 35.48%, 44.47% and42.19% respectively.⑤At last, some problems which included maize materials for space radiation, parents used for genetic models analysis, heritability of agronomic characters, analysis means of major gene plus polygene inheritance model were discussed, and utilization mutation lines were also mentioned.