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In order to explain the main reasons for the low natural seed-set ratio of Plumbago auriculata, which can contribute to the large-scale production of P. auriculata and also help to get rid of the situation that the seeds over-rely on the import from abroad at the same time. We attempted to measured the dynamic changes of the pollen viability by the method of TTC and the stigma receptivity and the method of Benzidine-H2O2 in two ways, which respectively focused more on the pollination biology and the breeding system. And we also estimated the type of the breeding system pollen-ovule ratio(P/O), and verified the out-crossing index(OCI)by the pollination experiments. The results of the experiment were as follows:(1)About P. auriculata, the maturity time of the L-type female organs and the S-type male organs,and also that of the L-type female organs and the L-type male organs overlaped a lot,there was no obvious difference in the maturity time between the female and the male organs. On the other hand,the maturity time of the S-type female organs and the L-type male organs,and also that of the S-type female organs and the S-type male organs overlaped a little,but the continuous blossoming pattern of P. auriculata reduced reproductive isolation caused by the different maturity time of the male and the female sexual organs.(2)The P/O of L-type was 502±52.30,the P/O of S-type 482.7±87.91,both the out-crossing index of the L-type and that of the S-type are 4. The result of the manual-controlled pollination experiments suggested that the breeding system of P. auriculata was obligate outcrossing and it had the feature of the heteromorphic incompatibility. To sum up,the reasons for the low natural seed-set ratio of P. auriculata were the combination of both internal and external factors. Among these factors,the short same maturity time of the male and the female sexual organs was not the main reason,while the strong self-incompatibility of P. auriculata itself might be the key internal factor to lead to the low natural seed-set ratio. Due to the breeding system of the obligate outcrossing,it was quite necessary for P. auriculata to had the pollination medium to lead to the successful pollination. However,the introduction environment and the original environment were distinctly different,in addition,the mode of the scattered blooming led to the cross-pollinator,which might be the key external factor of low success rate of outcrossing. In a conclusion,the improvement of the natural seed-set ratio of P. auriculata should mainly focus on overcoming the incompatibility of P. auriculata itself,and also properly bringing in some insects as the safe medium. This would provide the theoretical guidance and the application foundation for the expansion of this kind of species resource and also the acceleration of the promotion and the application. [ABSTRACT FROM AUTHOR]

The role of distyly in the heteromorphic selfing incompatibility is a controversial question In order to dicusse this question, we chose Plumbago auriculata as material, observed it floral morphs, regulated the height of styles,polinate these style,and analyzed the fruit set. The results were as folows: (1) Significant differences were found in floral tube width,floral tube length,pistil height,stamen height,stigma length,anther width,stamen (L) and style (S) height There was no significant difference in corola width,petal length, calyx length, ovary diameter, an ther length,stamen (S) and style (L) height (S) and style (L); (2) Suitable IAA,NAA and GA could regulate the length of style; (3) There was no significant difference in fruit set of blank control and regulated style. There was typical dimorphism in the floral morphs of P. auriculata It was evolutionary adaptation strategy for reciprocal herkogamy in P. auriculata. The spatial distribution of sex-organ had absolutely no afect on incompatibility through the effective spread of legal polen,incompatibility of abnormal shape flower could be seen more clearly on physiological mechanism. [ABSTRACT FROM AUTHOR]