蓝花丹结实率低的传粉生物学和繁育系统初探

为解释蓝花丹自然结实率低的原因,该研究从传粉生物学和繁育系统入手,采用TTC法与联苯胺-过氧化氢法分别测定花粉活力和柱头可授性的动态变化;用花粉-胚珠比(P/O比)、杂交指数(OCI)估算蓝花丹繁育系统类型并通过人工控制授粉试验验证。结果表明:(1)蓝花丹L型雌器官与S型雄器官、L型雄器官与L型雌器官成熟时间重叠区域较多,雌雄性器官在成熟时间上无显著差异;而S型雌器官与L型雄器官、S型雌器官与S型雄器官成熟时间重叠区域较少,但蓝花丹持续开花的模式缓解了雌雄性器官时间差异而引起的生殖隔离。(2)蓝花丹L型花P/O为502.00±52.30,S型花P/O为482.70±87.91,OCI为4,综合判断蓝花丹的繁育系统属于专性异交型且具有异型自交不亲和的特性。综上可初步解释蓝花丹自然结实率低的原因为内外因素共同作用的结果,其中雌雄性器官同熟时间短不是主要原因,而其本身较强的自交不亲和性可能是自然结实率低下的关键性内因。由于蓝花丹的专性异交繁育系统使其成功授粉需要传粉媒介,但因引种地与原产地环境存在显著差异,同时开花模式不集中导致的缺乏传粉者完成异花授粉或许是引起异交成功率降低的主要外因。因此,提高蓝花丹的结实率应从克服其自身自交不亲和性以及适当引入安全传媒昆虫入手。

Pollination biology and the breeding system of Plumbago auriculata low seed-set ratio

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.