Abstract Detail

Ecophysiology

Mocko, Kerri [1], Jones, Cynthia S. [2].

Functional traits and drought physiology of geophyte seedlings represent more than one “functional group”.

Geophytes have high species diversity throughout Mediterranean regions worldwide but are often overlooked in assessments of global patterns in functional traits and when included, are considered as one functional group. Geophyte diversity in South Africa is exceptional in the winter rainfall region where more than 2000 geophyte species comprise 20-40% of species diversity in an already hyper-diverse region. Functional traits and physiology of geophytes are often assumed to be similar to those of desert annuals because in both groups, vegetative growth coincides with water availability and moderate temperatures, although reliance on tuber storage of water and carbohydrates is unique to the life history of geophytes. The seedling stage is especially vulnerable but also crucially important: seedlings depend on what little above- or below-ground biomass they have accumulated to survive the hot, dry summers in Mediterranean regions. We investigated whether seedlings of species that vary in morphology (e.g. tuber size, leaf size) also show varying responses to drought. We ask: Do geophytes employ a common physiological strategy despite morphological variation? Can seedling functional traits be used to predict physiological responses to drought? Seed from four morphologically diverse Pelargonium species, all from the monophyletic section Hoarea, were germinated and grown under common greenhouse conditions. Seven-week-old seedlings underwent a drought until all species showed full stomatal closure. We measured predawn water potentials, rates of photosynthesis and stomatal conductance, rates of leaf production and senescence, leaf area, LMA and whole plant biomass. Plants were re-watered, and we measured functional and structural traits after three weeks recovery. We detected a range of traits and strategies across species: those investing in early tuber growth have high LMA and close stomata with declining water availability. In contrast, species with small tubers and low LMA keep stomata open and turnover leaves more rapidly. Clearly species survival depends on seedling responses to drought, yet even among species with a common life history strategy, multiple functional strategies exist.

1 - University Of Connecticut, Ecology And Evolutionary Biology, U-3043, 75 N. Eagleville Rd, Storrs, CT, 06269, USA
2 - University of Connecticut, Ecology and Evolutionary Biology, 75 N. Eagleville Rd, U-3043, Storrs, CT, 06269, USA

Keywords:
South Africa
Pelargonium
functional leaf traits
geophyte
seedlings
photosynthesis
stomatal conductance
experimental drought.

Presentation Type: Oral Paper
Session: 3, Ecophysiology
Location: 104/Savannah International Trade and Convention Center
Date: Monday, August 1st, 2016
Time: 9:00 AM
Number: 3005
Abstract ID:341
Candidate for Awards:Physiological Section Physiological Section Li-COR Prize