Abstract:

Aims: Floral color (visual) and scents (olfactory) are pivotal signals in plant‒pollinator interaction, serving the purpose of in attracting specific pollinators and ensuring successful pollination. Punica granatum, a commonly cultivated fruit plant exhibiting andromonoecy (i.e. hermaphrodite flower size bigger than that in male flowers), features red flowers and is primarily pollinated by bees in plantation settings. However, the effects of variations in color and scents across distinct floral on pollinator attraction and the subsequent reproductive success of P. granatum has received limited research attention.

Methods: In this study, we examined an investigation to assess the effects of visual signals (color, size), as well as olfactory signals (volatile compounds, relative content) along with rewards, on pollinator visitation, fruit set, and seed set. Four distinct treatments (natural, removal of petal, stamen-petal, and stamen) were analyzed, using P. granatum flowers in Kashi City, South Xinjiang.

Results: The main pollinators observed for P. granatum in Kashi City were Apis mellifera(honey bees) and Syrphidae sp. (a type of wasp).Our results yielded significant findings indicating that yellow stamens possess key visual and olfactory signal characteristics that are more effective in attracting pollinators compared to red petals. Notably, the removing of the petals led to in a significantly higher visiting frequency (P< 0.05) and duration time (P< 0.05) of the main pollinator, A. mellifera, when compared to the other three treatments (natural flowers and flowers removing stamen-petals and stamens). Furthermore, we observed a significantly higher fruit set in flowers with the removal of petals (82.33% ± 4.45%) in comparison to flowers with stamen-petal removal (66.31% ± 3.02%), natural flowers (50.88% ± 0.88%), and flowers with stamen removal (43.60% ± 2.04%).

Conclusion: These results from the study suggest that yellow stamens play a crucial role in attracting insect pollinators, whereas red petals may a negatively impact on pollination success in P. granatum. Consequently, the contrasting colors exhibited by different floral structures likely facilitate the attraction of diverse range of pollinators in this important fruit plant, ultimately promoting reproductive success.

Key words: Punica granatum, floral color, pollination success, fruit set, stamen