DELAYED SELFING IN AN ALPINE SPECIES GENTIANOPSIS BARBATA

doi:10.17521/cjpe.2007.0014

Abstract

Abstract:

Aims Gentianopsis barbata displays showy flowers and conspicuous nectaries and has stigma and anthers at different positions (herkogamy) until the fifth day after flower opening. All of these floral syndromes were assumed to favor outcrossing.

Methods We studied pollination biology of this species at Haibei Station on the Qinghai-Tibetan Plateau for three years to test this assumption.

Important findings Contrary to expectation, reproduction in the studied population was mainly through self-pollination. Pollinator visitation was rare, and bagged flowers with anthers set abundant seeds. Both stigma receptivity and pollen viability extended beyond five days. Although stigma receptivity based on seed number decreased after the fourth flowering day, contact of anthers and stigma during floral development resulted in delayed selfing in this species. This delayed selfing retained the floral syndromes and mechanisms for outcrossing, avoided competition between selfing and outcrossing and insured reproduction of G. barbata despite lack of pollinators in arid habitats of the Qinghai-Tibetan Plateau.

Key words: herkogamy, delayed selfing, reproductive assurance, Gentianopsis barbata, Qinghai-Tibetan Plateau

DUAN Yuan-Wen, HE Ya-Ping, ZHANG Ting-Feng, LIU Jian-Quan. DELAYED SELFING IN AN ALPINE SPECIES GENTIANOPSIS BARBATA[J]. Chin J Plant Ecol, 2007, 31(1): 110-117.

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URL: https://www.plant-ecology.com/EN/10.17521/cjpe.2007.0014

https://www.plant-ecology.com/EN/Y2007/V31/I1/110

Figures/Tables 7

Table 1 Floral syndrome of Gentianopsis barbata in 2002

	平均值 Mean	标准误 SE	范围 Range	样本量 Sample size
萼片 Sepal (mm)	23.5	0.6	20.1~33.5	25
花冠筒 Corolla tube (mm)	33.6^a	0.5	28.5~38.9	25
花冠檐直径 Diameter of corolla brim (mm)	25.3	0.7	19.8~32.3	25
花冠口径Diameter of corolla mouth (mm)	3.0	0.1	2.5~3.5	25
花粉、胚珠比例 Pollen/ovule ratio	40.9	5.4	10.8~100.2	20

Fig.1 A. The stigma was bifurcate but anthers did not shed pollen and were situated below stigma in bud stage B. Anthers were shedding pollen but situated below stigma when a flower just opened C. Anthers were shedding pollen and touched stigma on the fifth day after opening D. Anthers terminated shedding pollen and were situated above stigma when corolla brims closed

Table 2 Floral duration of Gentianopsis barbata in 2003

	平均值 Mean	标准误 SE	范围 Range
散粉持续期 Duration of pollen shedding	4.7^a	0.1	4.3~5.4
花持续期 Duration of flower opening	4.7^a	0.1	4.3~5.4

Fig.2 Change of distance from stigma and anthers after flower opening

Table 3 No. of mature seeds/fruits from different treatment of Gentianopsis barbata

	2002	2003
	成熟种子数(平均值±标准误) No. of mature seeds/fruits (Mean±SE)	成熟种子数(平均值±标准误) No. of mature seeds/fruits (Mean±SE)
对照 Control	754.2±36.1^a	797.0±31.2^a
不去雄隔离昆虫 Isolation without emasculation	857.8±37.4^a	650.6±26.7^b
去雄不隔离昆虫 Emasculation without isolation	53.1±16.3^b	84.0±20.2^c
去雄隔离昆虫 Isolation after emasculation	30.0±8.6^b	36.4±11.6^c

Fig.3 No. of mature seeds/fruits pollinated after flower opening Values with different letters indicated the difference are significant at the 0.01 level

Fig.4 Pollen germination rate after flower opening Values with different letters indicated the difference are significant at the 0.01 level

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