Effect of flower orientation variation on pollinator foraging behavior and pollination efficiency in Prunus mume f. purpurea

doi:10.17520/biods.2025221

Abstract

Abstract:

Aims: Flower orientation is shaped by both biotic and abiotic factors, reflecting their adaptation to the environment. Such variation may influence floral traits and pollinator visitation, ultimately affecting plant reproductive success. However, the effect of within-individual variation in flower orientation on pollinator visitation and pollination efficiency remains understudied in woody plants. Prunus mume f. purpurea is a woody species with important ornamental and economic value. It exhibits three different flower orientations (upward, horizontal, and downward) within a single plant. It is an ideal model for exploring the effects of flower orientation on pollinator visitation and pollination efficiency.

Methods: We investigated the proportion of flowers with different orientations and quantified the floral traits, floral longevity, pollen viability, stigma receptivity, and the pollination characteristics.

Results: Our results showed that proportion of downward flowers (53.2% ± 1.8%) was significantly higher than that of horizontal (29.7% ± 1.7%) and upward (17.1% ± 1.3%) flowers (P < 0.001). Differences in floral traits were observed among the three flower orientations. Specifically, downward flowers exhibited greater male reproductive resource investment than horizontal and upward flowers (P < 0.001), including longer stamens, a higher number of stamens, and greater pollen production. Downward flowers also exhibited significantly longer floral longevity, as well as higher stigma receptivity and pollen viability compared to horizontal and upward flowers. Apis cerana was identified as the primary pollinator of P. mume f. purpurea. Apis cerana visited downward flowers significantly more frequently, spent significantly more time per visit, and transferred significantly more pollen grains per visit than it did with upward flowers.

Conclusion: Our findings demonstrate that the differentiation in floral traits of different orientations in P. mume f. purpurea influences pollinator visitation behavior. Therefore, our study suggests that the proportion of downward flowers in P. mume f. purpurea may enhance reproductive success as an adaptive strategy.

Key words: flower orientation, Prunus mume f. purpurea, floral traits, pollination efficiency

Xiangxiang Ge, Yujie Xu, Ju Tang. Effect of flower orientation variation on pollinator foraging behavior and pollination efficiency in Prunus mume f. purpurea[J]. Biodiv Sci, 2025, 33(9): 25221.

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URL: https://www.biodiversity-science.net/EN/10.17520/biods.2025221

https://www.biodiversity-science.net/EN/Y2025/V33/I9/25221

Figures/Tables 5

References 48

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花部性状 Floral traits	样本量 N	朝上型 Upward	水平型 Horizontal	朝下型 Downward	Wald χ²	df	P
花萼长 Calyx length (mm)	30	4.86 ± 0.09^a	4.49 ± 0.09^b	4.51 ± 0.09^b	10.069	2	0.007
花萼宽 Calyx width (mm)	30	3.91 ± 0.07^a	3.52 ± 0.06^b	3.42 ± 0.07^b	31.355	2	< 0.001
花冠直径 Corolla diameter (mm)	30	24.81 ± 0.30^a	24.12 ± 0.28^a	24.89 ± 0.30^a	4.131	2	0.127
花瓣长 Petal length (mm)	30	10.24 ± 0.09^a	9.91 ± 0.17^ab	9.64 ± 0.16^b	8.821	2	0.012
花瓣宽 Petal width (mm)	30	10.20 ± 0.09^a	9.54 ± 0.15^b	9.30 ± 0.17^b	21.932	2	< 0.001
雄蕊长 Stamen length (mm)	30	8.81 ± 0.10^b	8.82 ± 0.20^b	9.51 ± 0.14^a	13.576	2	0.001
花药长 Anther length (mm)	30	0.51 ± 0.10^a	0.50 ± 0.01^a	0.38 ± 0.03^b	36.420	2	< 0.001
雄蕊数目 Number of stamens	30	50.27 ± 0.44^b	47.47 ± 0.66^c	57.57 ± 0.57^a	166.383	2	< 0.001
雌蕊长 Pistil length (mm)	30	10.26 ± 0.19^a	9.79 ± 0.32^a	10.71 ± 0.21^a	5.745	2	0.057
花粉数 Number of pollen grains	25	26,216.0 ± 921.3^b	29,944.0 ± 872.7^a	32,080.0 ± 903.3^a	21.524	2	< 0.001
花粉体积 Pollen volume (μm³)	40	12,930.03 ± 355.76^a	13,166.58 ± 476.43^a	13,819.83 ± 388.69^a	2.525	2	0.283
胚珠数 Number of ovules	20	2.1 ± 0.1^a	2.0 ± 0.1^a	2.0 ± 0.1^a	1.307	2	0.520
单花寿命 Flower longevity (d)	17	5.47 ± 0.40^c	6.76 ± 0.49^b	8.41 ± 0.48^a	20.689	2	< 0.001

花部性状 Floral traits	样本量 N	朝上型 Upward	水平型 Horizontal	朝下型 Downward	Wald χ²	df	P
花萼长 Calyx length (mm)	30	4.86 ± 0.09^a	4.49 ± 0.09^b	4.51 ± 0.09^b	10.069	2	0.007
花萼宽 Calyx width (mm)	30	3.91 ± 0.07^a	3.52 ± 0.06^b	3.42 ± 0.07^b	31.355	2	< 0.001
花冠直径 Corolla diameter (mm)	30	24.81 ± 0.30^a	24.12 ± 0.28^a	24.89 ± 0.30^a	4.131	2	0.127
花瓣长 Petal length (mm)	30	10.24 ± 0.09^a	9.91 ± 0.17^ab	9.64 ± 0.16^b	8.821	2	0.012
花瓣宽 Petal width (mm)	30	10.20 ± 0.09^a	9.54 ± 0.15^b	9.30 ± 0.17^b	21.932	2	< 0.001
雄蕊长 Stamen length (mm)	30	8.81 ± 0.10^b	8.82 ± 0.20^b	9.51 ± 0.14^a	13.576	2	0.001
花药长 Anther length (mm)	30	0.51 ± 0.10^a	0.50 ± 0.01^a	0.38 ± 0.03^b	36.420	2	< 0.001
雄蕊数目 Number of stamens	30	50.27 ± 0.44^b	47.47 ± 0.66^c	57.57 ± 0.57^a	166.383	2	< 0.001
雌蕊长 Pistil length (mm)	30	10.26 ± 0.19^a	9.79 ± 0.32^a	10.71 ± 0.21^a	5.745	2	0.057
花粉数 Number of pollen grains	25	26,216.0 ± 921.3^b	29,944.0 ± 872.7^a	32,080.0 ± 903.3^a	21.524	2	< 0.001
花粉体积 Pollen volume (μm³)	40	12,930.03 ± 355.76^a	13,166.58 ± 476.43^a	13,819.83 ± 388.69^a	2.525	2	0.283
胚珠数 Number of ovules	20	2.1 ± 0.1^a	2.0 ± 0.1^a	2.0 ± 0.1^a	1.307	2	0.520
单花寿命 Flower longevity (d)	17	5.47 ± 0.40^c	6.76 ± 0.49^b	8.41 ± 0.48^a	20.689	2	< 0.001

时期 Flowering stages	花形态变化 Changes in flower morphology	开花动态(开放的天数) (d) Flowering dynamics (number of days) (d)
时期 Flowering stages	花形态变化 Changes in flower morphology	朝上型 Upward	水平型 Horizontal	朝下型 Downward
花苞期 Bud stage (I)	花被片紧包, 柱头伸出不明显, 花药呈黄色。 The perianth segments are tightly wrapped, the stigma does not protrude prominently, and the anthers are yellow.	0	0	0
始花期 Earlier flowering stage (II)	花被片包裹, 花冠口微微张开, 花柱逐渐伸长且已明显可见, 雄蕊开始平展。 The perianth segments are wrapped, the corolla is slightly open, the style gradually elongates so that it is clearly visible, and the stamens begin to stretch flat.	2-3	2-3	2-4
盛花期 Blooming stage (III)	花被片松动展开, 花柱伸长至最长, 柱头具有黏性; 雄蕊逐渐平展, 花药开裂并外张, 散粉后逐渐内收。 The perianth segments loosen and unfold, the style elongates to its maximum length, and the stigma becomes sticky. The stamens gradually stretch flat, the anthers crack open outward, and they gradually adduct after pollen dispersal.	3-4	3-5	4-6
末花期 Late flowering stage (IV)	花瓣部分掉落, 花色变浅, 雄蕊开裂散粉后卷曲并包围花柱, 柱头开始褐化。 Part of the petals fall off, and the flower color becomes lighter. Following cracking and pollen dispersal, the stamens curl up and surround the style, and the stigma begins to brown.	4-5	5-6	7-8
枯萎期 Withering stage (V)	花瓣呈褐色枯萎, 雌蕊直立外伸, 柱头褐变。 The petals turn brown and wither. The pistil remains erect and elongates, while the stigma undergoes browning.	5-6	6-7	8-9

时期 Flowering stages	花形态变化 Changes in flower morphology	开花动态(开放的天数) (d) Flowering dynamics (number of days) (d)
时期 Flowering stages	花形态变化 Changes in flower morphology	朝上型 Upward	水平型 Horizontal	朝下型 Downward
花苞期 Bud stage (I)	花被片紧包, 柱头伸出不明显, 花药呈黄色。 The perianth segments are tightly wrapped, the stigma does not protrude prominently, and the anthers are yellow.	0	0	0
始花期 Earlier flowering stage (II)	花被片包裹, 花冠口微微张开, 花柱逐渐伸长且已明显可见, 雄蕊开始平展。 The perianth segments are wrapped, the corolla is slightly open, the style gradually elongates so that it is clearly visible, and the stamens begin to stretch flat.	2-3	2-3	2-4
盛花期 Blooming stage (III)	花被片松动展开, 花柱伸长至最长, 柱头具有黏性; 雄蕊逐渐平展, 花药开裂并外张, 散粉后逐渐内收。 The perianth segments loosen and unfold, the style elongates to its maximum length, and the stigma becomes sticky. The stamens gradually stretch flat, the anthers crack open outward, and they gradually adduct after pollen dispersal.	3-4	3-5	4-6
末花期 Late flowering stage (IV)	花瓣部分掉落, 花色变浅, 雄蕊开裂散粉后卷曲并包围花柱, 柱头开始褐化。 Part of the petals fall off, and the flower color becomes lighter. Following cracking and pollen dispersal, the stamens curl up and surround the style, and the stigma begins to brown.	4-5	5-6	7-8
枯萎期 Withering stage (V)	花瓣呈褐色枯萎, 雌蕊直立外伸, 柱头褐变。 The petals turn brown and wither. The pistil remains erect and elongates, while the stigma undergoes browning.	5-6	6-7	8-9