Abstract Detail

Ecophysiology

Chen, Huayang [1], Geekiyanage, Nalaka [2], Wen, Bin [3], Cao, Kun-Fang [4], Manage Goodale, Uromi [5].

Regeneration responses to water and temperature stress drive recruitment success in hemiepiphytic fig species.

Mechanisms for surviving water and temperature stress in epiphytes are essential adaptations for successful regeneration in forest canopies. Hemiepiphytes start their life cycle as epiphytes, eventually establishing aerial root connections to  the ground. This strategy allows for greater light capture, while benefitting from minimized risk of fire, flooding and  damage by terrestrial herbivores, but exposes the vulnerable seedling stage to heat and drought stress. However,  the response to temperature and water stress during early regeneration in hemiepiphytes is not known. In this study,  we tested the effect of temperature (15/5, 25/15 and 35/25 â—¦C; day/night diurnal variation) and water availability, as  substrate moisture (0.00, −0.20 and −0.35 MPa) and water vapor (18.5-99.5% relative humidity), on seed germination,  seedling emergence and survival in six hemiepiphytic and nine non-hemiepiphytic Ficus species. Under high-temperature  conditions (35/25 â—¦C), hemiepiphytes had higher gemination and seedling survival, achieved peak germination slower  and extended germination. Greater water stress (−0.35 MPa) in the growth substrate resulted in higher germination of  non-hemiepiphytes; hemiepiphytes, in contrast, took a shorter time to complete germination, but had higher seedling  emergence and survival. Hemiepiphytes germinated at 99.5% relative humidity more readily compared with nonhemiepiphytes.  These findings provide the first comprehensive evidence that hemiepiphytic Ficus species are better  adapted to drier and warmer conditions during the critical transition from seed to seedling. Through greater flexibility in  achieving peak germination and duration of regeneration activity, hemiepiphytes modulate their recruitment process to  be more resilient under abiotic stressors. This may allow them to be more successful in regenerating in forest canopies  under ambient conditions that are transient. These results support previous work showing greater drought tolerance  of hemiepiphytic Ficus species in larger size classes and extend this finding to show that physiological adaptations for  drought and heat tolerance start from the early seedling emergence stage.

Related Links:
http://doi.org/10.1093/treephys/tpaa165

1 - Institute Of Botany, The Chinese Academy Of Sciences, State Key Laboratory Of Vegetation And Environmental Change, No.20 Nanxincun, Xiangshan, Beijing, 100093, P.R. China, Beijing, 11, 100093, China
2 - Rajarata University of Sri Lanka, Department of Plant Sciences, Faculty of Agriculture,, Anuradhapura 50000, Sri Lanka
3 - Xishuangbanna Tropical Botanical Garden, Chinese Academy of Sciences, Center for Integrative Conservation, Menglun, Mengla 666303, Yunnan, China
4 - Guangxi University, State Key Laboratory of Conservation and Utilization of Subtropical Agro-bioresources, College of Forestry, Daxuedonglu 100, Nanning, Guangxi 530004, China
5 - Guangxi University, Plant Ecophysiology And Evolution Group, State Key Laboratory Of Conservation And Utilization Of Subtropical Agro-bioresources, College Of Forestry,, Daxuedonglu 100, Nanning, 530005, China

Keywords:
aridity
drought resilience
growth habit
heat stress
recruitment limitation
water potential.

Presentation Type: Oral Paper
Session: ECOPH2, Ecophysiology II
Location: /
Date: Tuesday, July 20th, 2021
Time: 11:15 AM(EDT)
Number: ECOPH2006
Abstract ID:92
Candidate for Awards:Physiological Section Best Paper Presentation