Breeding System and Hybridization Affinity of Rhododendron irroratum

doi:10.7525/j.issn.1673-5102.2024.03.006

Abstract

Abstract:

To protect germplasm resources and provide technical support for native garden species， the breeding system and hybrid affinity of wild Rhododendron irroratum were studied. The experiments included flowering biological characteristics， the characteristics of breeding system and the cross pollination with fine horticultural varieties of Rhododendron. The process of pollen germination and pollen tube growth were observed by fluorescence microscope， and the fruiting and seed setting were calculated. The results showed that （1） the flowering time of R. irroratum dewdrop was from late April to late May， and pollen viability and stigma receptivity decreased gradually with the extension of flowering time. （2）Hybridization index（OCI） was 3， P/O value was 343.47. （3）The main pollinator was Apis cerana. The breeding system was facultative outbred， self-compatible， requiring pollinators. （4）No apomixis was found in artificial pollination， which could automatically self-pollinate. The fruit setting rates of different strains cross-pollination， strains cross-pollination and self-pollination were 46.96%， 45.03% and 37.16% respectively. The average fruit setting rate of artificial pollination was basically consistent with that of natural pollination. （5）The hybrid incompatibility was observed in the parent for artificial cross pollination. Fluorescence microscopy revealed callose embolism in the pollen tube of the mother， which prevented the tube from extending to the ovary. Through observation， it is found that the difficulty of cross compatibility lies in pollen tube growth process.

Key words: Rhododendron irroratum, breeding system, hybridization affinity, fluorescence microscopy

CLC Number:

S685.21

Wenyan XIONG, Yawen WU, Tian BAI, Weijia XIE, Yan DONG, Jingli ZHANG. Breeding System and Hybridization Affinity of Rhododendron irroratum[J]. Bulletin of Botanical Research, 2024, 44(3): 370-379.

Figures/Tables 8

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统计指标 Statistical index	花冠直径 Corolla diameter/mm	花瓣轴长度 Flower tube/mm	花筒轴长度 Petal length/mm	裂片长度 Lobation length/mm	花柱轴长度 Style length/mm
最小值Minimum	33.50	28.50	13.00	11.50	18.00
最大值Maximum	58.00	44.50	26.00	22.50	33.50
平均值Average	45.11	37.27	19.21	18.07	26.12
标准差S_D	6.74	4.88	3.62	2.95	3.48
变异系数C_v	0.15	0.13	0.19	0.16	0.13
统计指标 Statistical index	柱头长度 Stigma length/mm	柱头直径 Stigma diameter/mm	花萼长度 Calyx length/mm	花萼宽度 Calyx wide/mm	子房长度 Ovary length/mm
最小值Minimum	1.00	1.50	2.00	1.50	5.50
最大值Maximum	2.50	3.50	5.00	4.00	8.50
平均值Average	1.35	2.56	3.56	2.77	7.18
标准差S_D	0.33	0.65	0.77	0.66	1.08
变异系数C_v	0.25	0.25	0.22	0.24	0.15
统计指标 Statistical index	子房宽度 Ovary wide/mm	花丝轴长度 Filaments length/mm	花药长度 Anther length/mm	雄蕊数量 Anther number	子房室数量 Ovary room number
最小值Minimum	2.50	17.00	2.00	9.00	8.00
最大值Maximum	6.50	37.00	4.50	10.00	10.00
平均值Average	3.80	26.23	3.10	9.62	8.87
标准差S_D	0.83	5.14	0.59	0.50	0.86
变异系数C_v	0.22	0.19	0.19	0.05	0.09

单花开花时间 Flowering time/d	柱头可授性 Stigma receptivity
1	+
2	++
3	++
4	+
5	+
6	+/-
7	+/-
8	+/-
9	-

处理 Treatment	坐果率 Fruit setting rate/%	结实率 Seed setting rate/%
自然授粉Natural pollination	23.75	19.95
去雄不套袋No bagged and emasculation	22.43	18.75
不去雄套袋Bagged，no emasculation	12.20	11.20
去雄套网袋Netting and emasculation	0.92	0
去雄套袋Bagged and emasculation	0	0
去柱头不套袋No bagged and no stigma	0	0
异株异花授粉Different strains cross-pollination	46.96	35.85
同株异花授粉Strains cross-pollination	45.03	40.00
同株同花授粉Self-pollinated	37.16	31.20

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