The risk-takers and -avoiders: Germination sensitivity to water stress in an arid zone with unpredictable rainfall

Corrine Duncan, Nick L. Schultz, Megan K. Good, Wolfgang Lewandrowski, Simon Cook

Research output: Contribution to journalArticle

Abstract

Water availability is a critical driver of population dynamics in arid zones, and plant recruitment is typically episodic in response to rainfall. Understanding species' germination thresholds is key for conservation and restoration initiatives. Thus, we investigated the role of water availability in the germination traits of keystone species in an arid ecosystem with stochastic rainfall. We measured seed germination responses of five arid species, along gradients of temperature and water potential under controlled laboratory conditions. We then identified the cardinal temperatures and base water potentials for seed germination, and applied the hydrotime model to assess germination responses to water stress. Optimum temperatures for germination ranged from 15 to 31 °C under saturated conditions (0 MPa), and three species had low minimum temperatures for germination (<3 °C). A small proportion of seeds of all species germinated under dry conditions (ψ ≤ -1 MPa), although base water potential for germination (ψb50) ranged from -0.61 to -0.79 MPa. Species adhered to one of two germination traits: (i) the risk-takers which require less moisture availability for germination, and which can germinate over a wider range of temperatures irrespective of water availability (Casuarina pauper and Maireana pyramidata), and (ii) the risk-avoiders which have greater moisture requirements, a preference for cold climate germination, and narrower temperature ranges for germination when water availability is low (Atriplex rhagodioides, Maireana sedifolia and Hakea leucoptera). High seed longevity under physiological stress in H. leucoptera, combined with a risk-avoiding strategy, allows bet-hedging. The hydrotime model predicted lower base water potentials for germination than observed by the data, further supporting our assertion that these species have particular adaptations to avoid germination during drought. This study provides insights into the complex physiological responses of seeds to environmental stress, and relates seed germination traits to community dynamics and restoration in arid zones.

Original languageEnglish
Article numberplz066
JournalAOB Plants
Volume11
Issue number6
DOIs
Publication statusPublished - 8 Nov 2019

Fingerprint

arid zones
water stress
germination
rain
water potential
Maireana
Leucoptera
seed germination
temperature
seeds
Hakea
Casuarina
Atriplex
keystone species
saturated conditions
water
cold zones
physiological response
temperature profiles
water temperature

Cite this

@article{c6a3cd5eaf3b4c0ea8dd007d509bf09e,
title = "The risk-takers and -avoiders: Germination sensitivity to water stress in an arid zone with unpredictable rainfall",
abstract = "Water availability is a critical driver of population dynamics in arid zones, and plant recruitment is typically episodic in response to rainfall. Understanding species' germination thresholds is key for conservation and restoration initiatives. Thus, we investigated the role of water availability in the germination traits of keystone species in an arid ecosystem with stochastic rainfall. We measured seed germination responses of five arid species, along gradients of temperature and water potential under controlled laboratory conditions. We then identified the cardinal temperatures and base water potentials for seed germination, and applied the hydrotime model to assess germination responses to water stress. Optimum temperatures for germination ranged from 15 to 31 °C under saturated conditions (0 MPa), and three species had low minimum temperatures for germination (<3 °C). A small proportion of seeds of all species germinated under dry conditions (ψ ≤ -1 MPa), although base water potential for germination (ψb50) ranged from -0.61 to -0.79 MPa. Species adhered to one of two germination traits: (i) the risk-takers which require less moisture availability for germination, and which can germinate over a wider range of temperatures irrespective of water availability (Casuarina pauper and Maireana pyramidata), and (ii) the risk-avoiders which have greater moisture requirements, a preference for cold climate germination, and narrower temperature ranges for germination when water availability is low (Atriplex rhagodioides, Maireana sedifolia and Hakea leucoptera). High seed longevity under physiological stress in H. leucoptera, combined with a risk-avoiding strategy, allows bet-hedging. The hydrotime model predicted lower base water potentials for germination than observed by the data, further supporting our assertion that these species have particular adaptations to avoid germination during drought. This study provides insights into the complex physiological responses of seeds to environmental stress, and relates seed germination traits to community dynamics and restoration in arid zones.",
keywords = "bet-hedging, cardinal temperatures, hydrotime, seed mass, seed physiology, t, water potential, ψ50",
author = "Corrine Duncan and Schultz, {Nick L.} and Good, {Megan K.} and Wolfgang Lewandrowski and Simon Cook",
year = "2019",
month = "11",
day = "8",
doi = "10.1093/aobpla/plz066",
language = "English",
volume = "11",
journal = "Annals of Botany Plants",
issn = "2041-2851",
publisher = "Oxford University Press",
number = "6",

}

The risk-takers and -avoiders : Germination sensitivity to water stress in an arid zone with unpredictable rainfall. / Duncan, Corrine; Schultz, Nick L.; Good, Megan K.; Lewandrowski, Wolfgang; Cook, Simon.

In: AOB Plants, Vol. 11, No. 6, plz066, 08.11.2019.

Research output: Contribution to journalArticle

TY - JOUR

T1 - The risk-takers and -avoiders

T2 - Germination sensitivity to water stress in an arid zone with unpredictable rainfall

AU - Duncan, Corrine

AU - Schultz, Nick L.

AU - Good, Megan K.

AU - Lewandrowski, Wolfgang

AU - Cook, Simon

PY - 2019/11/8

Y1 - 2019/11/8

N2 - Water availability is a critical driver of population dynamics in arid zones, and plant recruitment is typically episodic in response to rainfall. Understanding species' germination thresholds is key for conservation and restoration initiatives. Thus, we investigated the role of water availability in the germination traits of keystone species in an arid ecosystem with stochastic rainfall. We measured seed germination responses of five arid species, along gradients of temperature and water potential under controlled laboratory conditions. We then identified the cardinal temperatures and base water potentials for seed germination, and applied the hydrotime model to assess germination responses to water stress. Optimum temperatures for germination ranged from 15 to 31 °C under saturated conditions (0 MPa), and three species had low minimum temperatures for germination (<3 °C). A small proportion of seeds of all species germinated under dry conditions (ψ ≤ -1 MPa), although base water potential for germination (ψb50) ranged from -0.61 to -0.79 MPa. Species adhered to one of two germination traits: (i) the risk-takers which require less moisture availability for germination, and which can germinate over a wider range of temperatures irrespective of water availability (Casuarina pauper and Maireana pyramidata), and (ii) the risk-avoiders which have greater moisture requirements, a preference for cold climate germination, and narrower temperature ranges for germination when water availability is low (Atriplex rhagodioides, Maireana sedifolia and Hakea leucoptera). High seed longevity under physiological stress in H. leucoptera, combined with a risk-avoiding strategy, allows bet-hedging. The hydrotime model predicted lower base water potentials for germination than observed by the data, further supporting our assertion that these species have particular adaptations to avoid germination during drought. This study provides insights into the complex physiological responses of seeds to environmental stress, and relates seed germination traits to community dynamics and restoration in arid zones.

AB - Water availability is a critical driver of population dynamics in arid zones, and plant recruitment is typically episodic in response to rainfall. Understanding species' germination thresholds is key for conservation and restoration initiatives. Thus, we investigated the role of water availability in the germination traits of keystone species in an arid ecosystem with stochastic rainfall. We measured seed germination responses of five arid species, along gradients of temperature and water potential under controlled laboratory conditions. We then identified the cardinal temperatures and base water potentials for seed germination, and applied the hydrotime model to assess germination responses to water stress. Optimum temperatures for germination ranged from 15 to 31 °C under saturated conditions (0 MPa), and three species had low minimum temperatures for germination (<3 °C). A small proportion of seeds of all species germinated under dry conditions (ψ ≤ -1 MPa), although base water potential for germination (ψb50) ranged from -0.61 to -0.79 MPa. Species adhered to one of two germination traits: (i) the risk-takers which require less moisture availability for germination, and which can germinate over a wider range of temperatures irrespective of water availability (Casuarina pauper and Maireana pyramidata), and (ii) the risk-avoiders which have greater moisture requirements, a preference for cold climate germination, and narrower temperature ranges for germination when water availability is low (Atriplex rhagodioides, Maireana sedifolia and Hakea leucoptera). High seed longevity under physiological stress in H. leucoptera, combined with a risk-avoiding strategy, allows bet-hedging. The hydrotime model predicted lower base water potentials for germination than observed by the data, further supporting our assertion that these species have particular adaptations to avoid germination during drought. This study provides insights into the complex physiological responses of seeds to environmental stress, and relates seed germination traits to community dynamics and restoration in arid zones.

KW - bet-hedging

KW - cardinal temperatures

KW - hydrotime

KW - seed mass

KW - seed physiology

KW - t

KW - water potential

KW - ψ50

UR - http://www.scopus.com/inward/record.url?scp=85076533429&partnerID=8YFLogxK

U2 - 10.1093/aobpla/plz066

DO - 10.1093/aobpla/plz066

M3 - Article

VL - 11

JO - Annals of Botany Plants

JF - Annals of Botany Plants

SN - 2041-2851

IS - 6

M1 - plz066

ER -