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A Study on Pollination Biology of Paeonia suffruticosa subsp. spontanea (Paeoniaceae)

1 LUO Yi-Bo2 PEI Yan-Long1 PAN Kai-Yu1 HONG De-Yuan
1 (Laboratory of Systematic and Evolutionary Botany,Institute of Botany,the Chinese Academy of Sciences,Beijing 100093)
2 (Crop Institute, the Chinese Academy of Agricultural Sciences, Baishiqiao Road, Beijing 100081)

This compilation is the extract in english of the original article published on the web . Follow the link right above for the entire paper in chinese. The most of the paper is in chinese.

Abstract

Field observation on pollination in three populations of Paeonia suffruticosa subsp. spontanea in southern Shanxi Province showed that five species of bees in two families and four species of beetles were engaged in pollination. Examination on bodies of these insects under SEM, and seed set produced by controlled insect-pollination indicated that the bees, especially the species in the genus Andrena were main pollinators and the beetles except those of small size were only fluctuating vectors. Flowers of this taxon are scented and nonectariferous. Flowers attracted bees and beetles mainly by pollen. A study on seed-set in the three populations revealed considerable variation within and among populations. The plants were no apomict and autogamy, but geitonogamy sometimes could produce mature seeds (x=2.86 seeds per carpel). In the population with less flowers (less than 40 flowers), natural seed-set (x=3.88) was close to the seed-set produced by hand cross-pollination (x=3.21), but in the population with more flowers(near 100 flowers) natural seed-set (x=2.48) was lower than that by hand cross-pollination (x=3.21). The seed-set was low for both natural and artificial cross-pollination with only about one forth of ovules developing into seeds.

Key words

Paeoniaceae; Paeonia suffruticosa subsp. spontanea; Flowering; Pollination biology; Breeding system; Bees; Beetles


 

Fig.1 The distribution of Paeonia suffruticosa subsp. spontanea

Table 1 Species of bees collected in the flowers of Paeonia suffruticosa. subsp. spontanea (April, 1994)

Andrenidae

Andrena mikado Strand et Yasumatsu female

A. stellaria Hirashima female and male

Andrena sp. female

Halictidae

Lasioglossum simplicior Cockerell female

Lasioglossum sp.



 

Fig.2 The distribution of insect visiting frequency every hour in one day
Black collum in the Yongji population;

white collum in the Jishan population.

Table 2 The seed set of different treatments in two populations of Paeonia suffruticosa subsp. spontanea in S. Shanxi

Treatments

Popula-
tion

No. of
stem

No. of
flowers

No. of
follicles

No. of
seeds

No. of
flowers
with seeds

No. of
follicles
with seeds

No. of
seeds per
follicle

Seed set** (% of ovules foming mature seeds)

Isolation
after emasculation

a*
b

2
3

2
4

10
16

0
0

0
0

0
0

0
0

0
0

Isolation
without emasculation

a
b

2
15

3
17

15
85

0
0

0
0

0
0

0
0

0
0

Artificial
geitonogamy

a
b

3
9

5
17

15
82

20
0

3
0

7
0

1.33
0

12.59
0

Artificial
xenogamy

a
b

3
17

4
17

20
84

37
27

2
2

8
9

1.85
0.32

17.47
3.03

Artificial
cross-pollina-
tion between
populations

a
b

3
19

3
19

15
95

45
266

3
16

14
71

3.00
2.86

28.32
27.01

Natural pollination

a
b

12
24

12
29

60
142

159
114

10
14

41
46

2.65
0.80

25.02
7.60

* a: Yongji population. b: Jishan population.
* In Yongji
population the number of follicles with seeds and number of seeds per follicle were low,because the seed-collecting time was a little over.
** The mean number of ovules per follicle was 10.59,n=320.

Vectors

No of indiiduals

No of flowers

No of flowers with seeds

No of follides with seeds

No of seeds

No of seeds per follicle

Beetles

5

5

0

0

0

0

Bees

2

2

1

5

6

1.20

Natural
pollination

4

4

4

19

35

1.84

Table 3 Effect of different pollination vectors on seed out-put in the Jishan population


 

Plate 1 1,8. From Yongji population

1.Dorsal and ventral views of Hylovalgus bioculatus, showing a few pollen grains on its body; 8. Bees collecting pollen in withered androecia, showing many pollen grains on the stigmatic surface; 2,3,4,6,7,9. From Jishan population

2. Ventral view of Cetonia magnifica, showing many pollen grains on the body;

3. Cetonia magnifica in androecia;

 


 

4. Cetonia magnifica in gynoecia;

6. Some anthers above the gynoecia;

7. Cetonia magnifica in withered androecia;

9. Showing many pollen grains on the body of the bee after this bee visiting the flower;

5. Cetonia magnifica and bees in the same flower in Jishan population.


 

 


 

Plate 111. under SEM

1. Pollen of Exochorda giraldii x1 800

2. Pollen of Paeonia suffruticosa subsp. spontanea x1 200

3. Pollen of Exochorda giraldii and Paeonia suffruticosa subsp. spontanea on surface of Hylovalgus bioculatus in Yongji populationx 480;

4. A few pollen grains on the curve of one leg of Hylovalgus bioculatus in Yongji population x60;

5. No pollen grains on the surface of the leg of Hylovalgus bioculatus in Yongji population x24;

6. Small beetle in Yongji population x24;

7. An enlarged portion of Fig.6, showing a few pollen grains on the body x120;

8. A portion of the leg of a bee in Yongji population, showing a large amount pollen grains x120;

9. An enlarged portion of Fig.8, showing pollen grains of Paeonia suffruticosa subsp. spontanea1 x200;

10. The head of a Cetonia magnifica from Jishan population,showing many pollen grains x60;

11. An enlarged portion of Fig.10,showing pollen grains of Exochorda giraldii x900; 12,13.under LM

12. Pollen grains of Exochora giraldii x192;

13. Pollen grains of Paeonia suffruticosa subsp. spontanea x128.

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