| Safflower, Carthamus tinctorius L., is a member of the Asteraceae family, and an annual herbaceous plant that can grow1～2years. There are25species in this genus, China has only one species that is safflower. Safflower, a multipurpose crop, can be used in medicine, carthamin, silage, and feed and so on. To improve the efficient utilization of safflower in China and support the research of Sichuan Province on safflower breeding, the experiments were conducted on the pollination of safflower accessions which source different. The assay determines the effect of flora phenology, morphologies, color, scent and other floral traits on the frequencies of pollinator and seed set. The main results were described as follows:1. In the paper, the phenology and floral traits of25C. tinctorius accessions were investigated, and the frequency of visitors were also recorded in different weather (9accessions). The population flowering period lasted from late April to early June, with the peak flowering in May. The flowering span of the single flower, head and individual was about3～5,10,14～41d, respectively. The time is about3d from first flowering date to flowering peak date. The floral traits including herkogamy and pollen secondary presentation are distinctive in safflower, which indicated the special mechanism of pollination to safflower. The sequences of herkogamy and pollen secondary presentation displaying are different among accessions. Only two accessions were affected by weather (sunny and cloudy day) on the number of visiting insects. There are few insects visiting safflower in raining day. The number of insects visiting safflower is impacted by accessions in sunny day. The pollen vigor of C. tinctorius was above50%in the first day of flowering. After around5d, the vigor decreased below50%. The stigma receptivity was highest in the first day of flowering, safflower is a protandry plant. Thus, using the pollen opening no more than5d pollinated to the stigma in the first day of anthesis.2. According to the anthesis of25accessions,9accessions were selected to investigate the relationships among the floral morphologies, breeding system and pollination insects in Ya’an, Sichuan province, China. No significant differences in seed setting rate were observed among the accessions following unbagged treatment, but significant differences in seed setting rate were observed among the accessions following bagged treatment. Breeding experiments indicated that both reproductive systems (selfing and outcrossing) coexisted in each tested C. tinctorius accession. It exhibited reproductive assurance through automatic self-pollination, which might be an important factor in enhancing the amount of seeds. Among17species of visitors, the main effective pollinators were Apis cerana Fabricius, Apis mellifera Linnaeus and Eristalis tenax Linnaeus. All floral morphology traits (corolla length, corolla diameter, pistil length, anther length, stigma length, and stigma-anther separation) showed significant variations among the accessions. However, only corolla diameter showed a significant negative correlation with the frequency of pollinator visits and a positive correlation with seed set following unbagged treatment. There was a negative correlation between stigma-anther separation and seed set. and although this was not significant (r=-0.6239), it could be argued that if a pistil developed that was too long, seed set would decline under natural conditions. Corolla length was significant positively correlated with stamen and anther length, and corolla diameter was significant negatively correlated with pistil length. Stigma length was also significant positively correlated with stamen length. These findings indicate that corolla diameter could significantly affect seed set in C. tinctorius under the conditions in Ya’an, China, and corolla diameter affects seed set by the combined effect of multiple traits.3. Five accessions were selected to test the response of visitors to color (red, orange and yellow), color change (from the first day to the fifth day of anthesis) of flowers based on the anthesis and pollination and floral morphologies traits. The frequencies of pollinators are affected significantly by floral color and color change. Yellow group was distinctly preferred by the visitors, followed by orange group. The frequencies of pollinators display parabola forms with anthesis. The accession with deeper color reaching the peak of pollinators is faster. The peaks of frequency of pollinators were3-4d,2-3d and2d of anthesis, for yellow, orange and red group, respectively. The analyses of light absorbance of safflower petal show that absorption spectra were significant different. The high UV-visible light absorbance of petal in yellow group indicated it were likely to relate to the differences of the frequency of pollinators among color groups. However, the seed set were not significant different among different color groups, which inferred that the seed set of safflower do not depend on the floral color polymorphism.4. Using the five accessions above mentioned to determine the relationship among secondary pollen presentation (SPP), frequencies of pollinators and seed set, the results show that the seed set of SPP treatment (22.61%～39.74%) is higher than that of NSPP treatment (17.42%～38.17%) per accession. It indicated that SPP can improve indirectly the seed set of safflower. SPP could affect little to the frequency of pollinators in orange group, but great to increase the frequency of pollinator in red group and decrease that of yellow group. But seed set was not significantly related to frequency of pollinators, significant negative to anthesis and number of head. SPP treatment (with SPP), there was significant negatively correlation between secondary size and seed set. Under NSPP treatment (without SPP), the frequency of pollinators was significant positively correlated with the number of secondary pollen, and negatively with the number of pollen in anther. These implied that SPP could influence the frequency of pollinator by secondary pollen size and number, which impact seed set further.5. In our study, the flower essential oils of5safflower accessions above mentioned were investigated to study the relationship among scent and color and pollinator visiting at five flowering stages. The results show that the compositions and contents of essential oil are different among accessions and flowering stages. After the analyses to the main11components which were always detected from25samples, the main components of essential oil for all accessions were P-Allyltoluene and1-Acetoxytetralin. The change trends of PI198294and PI401479are similar in the main components contents, while PI470942is similar with Anbai accession. Only red group has some components with high molecular weight in its essential oil. For the ratio of P-Allyltoluene to1-Acetoxytetralin, only Anbai show change from>1to<1, but the ratios are still lower than1in other four accessions. There is no significant correlation between frequency of pollinators to PI198294and Anbai and content of11major components in essential oil. The frequency of pollinators to PI470942and PI401479has significant negative and positive correlation with component caryophyllene oxide and1-benzylcyclopropanecarboxylic acid, respectively. Red accession PI401480shows significant negative and positive correlation with component4,4-dimethyl-tetracyclo [6.3.2.0(2,5).0(1,8)] tridecan-9-ol and fluorene, respectively. However, the components which showed significant correlation with frequency of pollinator were low in the content (no more than3%). These results indicate that the content of essential oil component is not relative significantly with color and perhaps played some roles in the frequency of pollinators to red group.In conclusion, the seed set of C. tinctorius was not correlated with the frequency of pollinators, but correlated with corolla diameter, head number and head anthesis. And the seed set and outcorssing set were could be enhanced by biology pollination. The color, SPP, scent, morphologies of safflower were all influence the frequency of pollinators. Besides, these traits were interactive. Thus, for different accession, different factors played different roles in attracting insectors and setting seed. In red accession (PI401480), scent worked more than other traits in frequency of pollinators, while color were the main factor in yellow group and orange group impacted the pollinator mainly by floral morphologies. |
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