Regeneration in recalcitrant-seeded species and risks from climate change

Pritchard, Hugh W.; Sershen,; Tsan, F. Y.; Wen, Bin; Jaganathan, Ganesh K.; Calvi, Geângelo Petene; Pence, Valerie C.; Mattana, Efisio; Ferraz, Isolde Dorothea Kossmann; Seal, Charlotte E.

doi:10.1016/b978-0-12-823731-1.00014-7

Cited by 14 publications

(14 citation statements)

References 129 publications

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“…For instance, tropical trees show a positive correlation between T b and Ψ b that is probably due to a high frequency of rainfall in tropical areas. However, the ongoing variability in rainfall frequency and intensity due to climate change may affect tropical trees through the germination phase of the life cycle (Pritchard et al ., 2022).…”

Section: Discussionmentioning

confidence: 99%

The seed germination spectrum of 528 plant species: a global meta-regression in relation to temperature and water potential

Maleki

Soltani

Seal

et al. 2022

Preprint

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The germination niche of plant species depends primarily on the responsiveness of seeds to temperature and water potential. However, to appreciate future climate risks to natural regeneration through germination, a global level synthesis across species is needed. We performed a meta-regression of primary data from 377 studies on 528 species, including trees, grasses, crops and wild species, to determine patterns and co-correlants in the cardinal values that define germination niche of species. A negative correlation was found between thermal time and base temperature, and positive correlations between other cardinal temperatures and base temperature. Mean values of thermal time indicate that annual crops germinate more rapidly compared to wild species, potentially as a consequence of domestication, and tropical tree seeds the slowest. Dryland species (Cactaceae and Agavaceae) have the widest upper thermal and lower moisture niche, indicative of an ability to grow under harsh conditions, while forages have the narrowest thermal and moisture niche, suggesting higher sensitivity to frost or drought. We propose a new conceptual framework for understanding germination niche as shaped by thermal and moisture traits. Our database represents a unique source of information to further determine the vegetation boundaries of wild or cultivated species, including within simulation studies on plant species adaptations under changing land-use and climate.

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Section: Discussionmentioning

confidence: 99%

The seed germination spectrum of 528 plant species: a global meta-regression in relation to temperature and water potential

Maleki

Soltani

Seal

et al. 2022

Preprint

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“…Nevertheless, numerous means of predicting the binary separation of orthodox vs. recalcitrant seeds have been proposed in the last 30 years (see [ 111 ]). Such models are based mainly on trait preferences and frequency estimates for recalcitrant seeds: higher preponderance in the wet tropics and amongst trees and in certain families, larger seed mass, thinner seed coats, less likely to have dormancy, seed/fruit dispersal coinciding (more likely) with peak rainfall, preferring to form seedling banks rather than soil seed banks [ 112 ]. The most instructive models for recalcitrant behaviour have relied on ecological correlates, such as: (i) heavier seeded species in Araucariaceae [ 107 ]; (ii) multiple criteria keys for certain families (e.g., Meliaceae), using seed weight, moisture content at the time of seed shedding, seed shape and general habitat information [ 113 ]; and habitat assessment, with low frequency (≤10%) in the drylands vs c. 50% for tropical moist evergreen forests [ 18 ].…”

Section: Prediction Of Seed Storage Behaviourmentioning

confidence: 99%

“…An association has also been made between recalcitrance and relatively quick germination [ 81 ], facilitated by less resource allocation to protective seed coats (small seed coat ratio). However, tree seed threshold modelling for germination reveals that recalcitrant tree seeds can have longer thermal times than orthodox tree seeds [ 112 ]. Nonetheless, the seed coat ratio:seed mass (SCR:SM) probability model for desiccation sensitivity [ 17 ] has proven to be valuable in seed storage behaviour studies on species of the wet forests of Australia [ 114 ], China [ 19 ], Brazil [ 115 ] and the Caribbean [ 116 ].…”

Section: Prediction Of Seed Storage Behaviourmentioning

confidence: 99%

Seed Longevity—The Evolution of Knowledge and a Conceptual Framework

Jayanthi

Walters

Pritchard

et al. 2023

Plants

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The lifespan or longevity of a seed is the time period over which it can remain viable. Seed longevity is a complex trait and varies greatly between species and even seed lots of the same species. Our scientific understanding of seed longevity has advanced from anecdotal ‘Thumb Rules,’ to empirically based models, biophysical explanations for why those models sometimes work or fail, and to the profound realisation that seeds are the model of the underexplored realm of biology when water is so limited that the cytoplasm solidifies. The environmental variables of moisture and temperature are essential factors that define survival or death, as well as the timescale to measure lifespan. There is an increasing understanding of how these factors induce cytoplasmic solidification and affect glassy properties. Cytoplasmic solidification slows down, but does not stop, the chemical reactions involved in ageing. Continued degradation of proteins, lipids and nucleic acids damage cell constituents and reduce the seed’s metabolic capacity, eventually impairing the ability to germinate. This review captures the evolution of knowledge on seed longevity over the past five decades in relation to seed ageing mechanisms, technology development, including tools to predict seed storage behaviour and non-invasive techniques for seed longevity assessment. It is concluded that seed storage biology is a complex science covering seed physiology, biophysics, biochemistry and multi-omic technologies, and simultaneous knowledge advancement in these areas is necessary to improve seed storage efficacy for crops and wild species biodiversity conservation.

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“…While these examples confirm the value of such predictive models, they also highlight the importance of generating new data on seed desiccation sensitivity, particularly for populations and species from tropical and sub-tropical regions (see De Jr Lima et al , 2014 ; Lan et al , 2014 ; Sánchez et al , 2018 ; Chau et al , 2019 ; Waiboonya et al , 2019 ; Mattana et al , 2020 ; Ititiaty et al , 2020 ; Athugala et al , 2021 ; Sommerville et al , 2021 ), through screening approaches such as the ‘100-seed test’. These kinds of studies are especially needed for biodiversity hotspots in Mesoamerica, West Africa, Madagascar, Sundaland and Indo-Burma ( Pritchard et al , 2022 ). The resulting data not only can support plant conservation and development programmes in those regions, but also improve the performance of available and future predictive models, as also previously highlighted by Wyse and Dickie (2017 , 2018 ).…”

Section: Case Example 1: Predicting Seed Desiccation Sensitivitymentioning

confidence: 99%

Low availability of functional seed trait data from the tropics could negatively affect global macroecological studies, predictive models and plant conservation

et al. 2022

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Background Plant seeds have many traits that influence ecological functions, ex situ conservation, restoration success and their sustainable use. Several seed traits are already known to vary significantly between tropical and temperate regions. Here we present three additional traits for which existing data indicate differences between geographical zones. We discuss evidence for geographical bias in availability of data for these traits, as well as negative consequences of this bias. Scope We reviewed the literature on seed desiccation sensitivity studies that compare predictive models to experimental data and show how a lack of data on populations and species from tropical regions could reduce the predictive power of global models. In addition, we compiled existing data on relative embryo size and post-dispersal embryo growth and found that relative embryo size was significantly larger, and embryo growth limited, in tropical species. The available data showed strong biases towards non-tropical species and certain families, indicating that these need to be corrected to perform truly global analyses. Furthermore, we argue that the low number of seed germination studies on tropical high-mountain species makes it difficult to compare across geographical regions and predict the effects of climate change in these highly specialized tropical ecosystems. In particular, we show that seed traits of geographically restricted páramo species are studied less than those more widely distributed, with most publications unavailable in English or in the peer-reviewed literature. Conclusions The low availability of functional seed trait data from populations and species in the tropics can have negative consequences for macroecological studies, predictive models and their application in plant conservation. We propose that global analyses of seed traits with evidence for geographical variation prioritise generation of new data from tropical regions as well as multi-lingual searches of both grey- and peer-reviewed literature in order to fill geographical and taxonomical gaps.

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Regeneration in recalcitrant-seeded species and risks from climate change

Cited by 14 publications

References 129 publications

The seed germination spectrum of 528 plant species: a global meta-regression in relation to temperature and water potential

The seed germination spectrum of 528 plant species: a global meta-regression in relation to temperature and water potential

Seed Longevity—The Evolution of Knowledge and a Conceptual Framework

Low availability of functional seed trait data from the tropics could negatively affect global macroecological studies, predictive models and plant conservation

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