Populations of arable weed species show intra-specific variability in germination base temperature but not in early growth rate.

Shahid Farooq,Jana Bürger,Nathalie Colbach,Andrey V Malyshev

doi:10.1371/journal.pone.0240538

Abstract

Key plant traits affecting growth performance can differ among and within species, influencing competitive plant community dynamics. We determined the intra-specific variability of germination base temperature among 13 arable weed species and the seedlings' early post-emergence relative growth rate among 21 species in climate chamber and green house experiments. Intra-specific variability was quantified with two seed populations (originating from contrasting climate in Germany & France) for the germination base temperature of 6 species and for the early growth rate of 16 species. Inter-specific variability for both traits was always higher than intra-specific variability. Within a given species, we found that germination base temperatures were higher in seeds stemming from colder climate populations. Seedling relative growth rates did not differ between seed populations. Models simulating weed growth should reflect these differences in germination traits among populations, especially when they are used for weed community assembly studies in a local to regional extent.

Highlights

Over the last decades, there has been an increase in trait-based analyses and modelling, both in ecology in general [1] and in weed ecology in particular [2, 3] followed by a debate on the importance and implications of intra-specific trait variability
Base temperatures varied between -0.2 ̊C (Apera spica-venti) and 11.9 ̊C (Setaria viridis)
We found a positive relationship between germination base temperature and early relative growth rate in the studied species (Fig 4)

Summary

Introduction

There has been an increase in trait-based analyses and modelling, both in ecology in general [1] and in weed ecology in particular [2, 3] followed by a debate on the importance and implications of intra-specific trait variability. The assumption of many trait-based approaches was that intra-specific variability is negligible compared to the inter-specific (between-species) variability, and that species can be characterised by mean trait values [4] This has since been challenged by a number of studies [5, 6]. The mechanisms that cause intra-specific variability as a species’ response to its environmental conditions include adaptation via genetic changes and phenotypic plasticity [8]. Such mechanisms are expressed in a range of functional plant and seed traits [4, 9]. Functional traits have been defined as measurable features which interact with ecological factors through

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