Selection Of Dwarf Inbreed Lines And Study On Genetic Law Of Main Ornamental Traits Of Zinnia Elegans

Zinnia elegans is an annual plant,flowering in summer and autumn,meaning beautiful,having excellent ornamental traits and widely landscaping use.It’s dwarf plants can be used for potted flower and high height plants are fir for cut flower.Our research group have got more than 20 inbred lines by many years of breeding,which all of them were high and medium height,lacking for dwarf materials.Given on this basis,our experiment made further breeding dwarf inbred lines,and explored the correlation of inflorescence growth height and offspring.At the same time,to analyze the genetic law of main ornamental characteristics,this paper selected 5 inbred lines as parents,which were A1-GH,A3N,S5,J13 and J18,and prepared complete diallel cross and two pairs of reciprocal cross test,including 4 combinations of selfing and16 cross combinations,and then selfing and backcross was carried out by 8 F₁hybrids.The main results were as follows:1.Breeding of inbred lines（1）Using F₁hybrid named‘Dreamland’series to single plant self-pollination and build extreme selection population of F₂generation,obtained a stake and 4 color unstable dwarf inbred lines through 4 generations of breeding by combing the pedigree method with extreme selection method,which were pink,rose,red,deep pink and orange-yellow,named them A5F（whose plant height about 13.3 cm,flower diameter 5.7 cm,plant type compact）,A5M,A5H,A5DF and A5CH in turn,whose plant height all 15 cm around,plant type were dwarf and compact,belonging to medium flower type.（2）Using J8b as material to single plant self-pollination,a white dwarf inbreed line named J8D was got after 6 generations by the pedigree method.Whose characters were as follows:plant height 14.9 cm,flower diameter 6.0 cm,plant type compact.（3）Take advantage of the inflorescence height difference among S5 inbred lines to single flower head self-pollination.The result showed that all of the characters of flower head’s offspring haven’t any significant difference.2.The analysis of genetic law（1）The analysis of plant height heterosis of 16 cross combinations demonstrated that selecting the inbreed lines with short plant height as crossing parents,moreover,shorter inbreed lines as female,was likely to get shouter F₁hybrids.Analysis of combing ability and heritability showed that the non-additive genetic effect of plant height was grater than the additive genetic effect,the broad sense heritability was higher and the narrow sense heritability was lower,showing that plant height in heredity was greatly influenced by the environment and cannot be passed on to offspring steadily,however,its heterosis can be utilized in breeding.（2）The result of analysis of 20 F₁cross combinations,8 F₂generations and 30backcross combinations was:the heredity of Zinnia elegans flower color followed the genetic law of quantitative characters,which were controlled by multi-genes and a certain additive effect existed among those genes.In addition,it also had the genetic feature of qualitative characters,dominant and implicit relationship existed among allele.Rose was complete dominant inheritance for yellow,white and orange,and vermilion for scarlet,yellow,saffron orange and naples yellow for yellow and white were incomplete dominant inheritance respectively.（3）The heredity of Zinnia elegans petal type was controlled by a pair of alleles in nucleus,moreover,silk type for flat type and tube type was dominant inheritance and flat type for tube type was dominant inheritance.（4）The heredity of Zinnia elegans petal character was in conformity with the genetic law of quantitative characters,which were controlled by multi-genes,and the genetic ability of double was greater than single.（5）The heredity of Zinnia elegans leaf shape was controlled by a pair of alleles in nucleus,and the ovals leaves for the narrow lanceolate leaves showed the dominant inheritance.