| This research aims to discuss the cause of male sterile platycodon, the types of male sterile and the prospect of heterosis by testing the male sterile and fertile platycodons in respect of morphology, cytology and genetics.Also the purpose of this research is to prepare the theoretic ground for further study of male sterile platycodon and creating fine cross groups.The characteristic of cytological development period of microspore and corresponding shape, size of flower organ, the color of anther for platycodon grandiflorum were investigated. The results showed that there was high correlation between cytological development period of microspore and morphological characteristics of flower organ, therefore, cytological development period of microspore can be decided by size, color and shape of the flower organ. The research will be applied to guide suitable inoculation explant in the culture of anthers for P. grandiflorum.In this study, according to farming observation and paraffin section method, a comparative study on anther’s morphology and anatomy characters in platycodon grandiflorum was carried out between male sterile and male fertility varieties.The results showed that male fertility had no obvious differences from male sterile in morphology and anther’s length of flower, but after flowering, male fertility had full and lustrous anthers with pollen granule spilled out, male sterile had shiriveled and lacklustre anthers with empty pollen. Tapetum layer of male sterile was degenerated and disappeared before fertility, so as to the microspores degraded and developed abnormally at last.In order to research types of male sterile platycodon grandiform, a few methods are used in this study, i.e. to test male sterile asexualpropagation and the natural fertile germ plasma, to make up cross groups and to analyse the first generation of cross fertile segregation.It turns out that:F1 which comes from the stem between male sterility and natural fertility contains all types of sterile groups and fertile groups, also contains segregation groups between stertility and fertility and the segregation groups are the largest ones in terms of quantity, hence, according to the genetic features of nucleo sterility and nucleo-cytoplasmic sterility, the author believes JXB-1 is the fertile type of nucleo-cytoplasmic interaction. The male parents of all types of sterile groups which are in F1 are male sterile maintainer lines, the male parents of all types of fertile groups in F1 are male sterile storer lines and other male parents of groups are heterozygous of nucleo fertile gene.This research establishes the genetic mechanism for male sterile platycodon grandiform.To test male sterile platycodon grandiform X natural fertile F1,P1 and P2, to study the 8 agricultural properties of F1,P1 and P2, like the hight of stem and to analyse heterosis of platycodon, we can get the conclusions as shown below. Heterosises vary greatly from property to property. In tested 10 groups, the highest heterosis happened on the property of fresh weight root,as the percentage is 41.80%.The lowest heterosis happened on the property of long taproot,as the percentage is 18.05%.Heterosises vary greatly from group to group.In tested 10 groups, the group who has 8 highest properties is JXB-1×Jilinnongda,the average percentage is 49.40%, The lowest heterosis group is JXB-1 X Korean white flower and the heterosis is 13.6%. The difference between the highest and the lowest is 35.8%.The result of this research establishes possibilities for the uses of germ plasma of male sterile platycodon grandiform and the heterosis. |
