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Abstract Detail

Physiology & Ecophysiology

Wang, Xiaoyin [1], Yang, Mei [2], Downing, Jason [3], Liu, Hong [4], Manage Goodale, Uromi [5].

Temperature effects on the asymbiotic germination of two Paphiopelilum species.

Paphiopedilum, commonly known as the "lady's slipper orchid" is a fascinating genus of orchids, which are threatened due to over exploitation, habitat loss and climate change. Here we studied the asymbiotic seed germination of P. dianthum and P. hirrsutissimum under two temperature treatments, 23 and 27 C. These two temperatures represent mean temperatures in July at high and low elevational distributions for these species in southern China. Seeds were wild collected from the Yachang Orchid National Nature Reserve (YONNR) at a site representing the high elevation distribution limit and germination experiments were conducted on specialized orchid seed sowing media (p723 from PhytoTechnology) at Guangxi University in Nanning, China. Temperature had a significant effect on early stages of germination with higher probability of germination at 23 C compared to 27 C in both species. P. hirrsutissimum had a greater imbibition response compared to P. dianthum at 27 C. After 30 days from seed sowing, embryo enlargement and swelling of the testa into an ellipsoid shape was observed in both species. None of the P. hirrsutissimum seeds that germinated showed advanced protocorm development at 27 C and both species halted germination process after appearance of protomeristem at 23 C. One seed of P. dianthum at the 27 C treatment progressed into a seedling after germinating seeds were shifted to full spectrum light conditions, which induced chloroplast formation at 236 days from seed sowing. Given the low success rate we observed using asymbiotic germination techniques, we explored the symbiotic germination of both species by using four fungal strains isolated from fungal pelotons within root cells. Our results so far indicate that for both Paphiopedilum species standard asymbiotic methods were not effective for protocorm development, and identifying potential fungal strains necessary for seedling development is critical for the long term security of these threatened species. Surveying and the preservation of orchids and their symbiotic fungi are vital for developing sound conservation strategies and ex situ propagation for these economically valuable species. Better propagation methods will also benefit commercial manufacturing of plants for medicinal and horticultural purposes. Based on the results of the asymbiotic germination trials, we conclude that P. hirrsutissimum requires a fungal partner for germination and seedling development while very low germination success can be observed for P. dianthum in the absence of germination promoting fungi.

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1 - Guangxi University, Forestry College, 100, Daxuedonglu, Nanning, GX, 530004, China
2 - Guangxi Yachang Orchid National Nature Reserve Administration, Scientific Research Section, 46, Jinanlu, Nanning, GX, 530011, China
3 - Fairchild Tropical Botanic Garden, 10901,Old Cutler Rd, Miami, Florida, 33156, USA
4 - Florida International University, Department of Earth and Environment, 11200 SW 8th Street, Miami, Florida, 33199, USA
5 - Guangxi University, Guangxi Key Laboratory of Forest Ecology and Conservation, Forestry College, 100, Daxuedonglu, Nanning, GX, 530004, China

Seed Germination

Presentation Type: Oral Paper
Session: 39, Ecophysiology
Location: 114/Mayo Civic Center
Date: Wednesday, July 25th, 2018
Time: 9:00 AM
Number: 39005
Abstract ID:366
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize,Physiological Section Best Paper Presentation

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