Specific root respiration of three plant species as influenced by storage time and conditions

Zana A Lak,Hans Sandén,Boris Rewald,Mathias Mayer

doi:10.1007/s11104-020-04619-9

Zana A Lak, Hans Sandén + Show 2 more

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https://doi.org/10.1007/s11104-020-04619-9

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Abstract

AimsSpecific root respiration (RRS) is a key root trait, determining i.e. nutrient foraging and uptake efficiencies. However, a considerable uncertainty exists regarding the effects of storage time and conditions on RRS measurements.MethodsFine root CO2 efflux rates of three plant types (tree seedling Carpinus betulus, legume Pisum sativum, grass Lolium perenne) were measured as depending on storage time (30–1440 min post-rinsing) and conditions (i.e. attached to plant, warm and cold water storage, and storage under dry conditions).ResultsShort-term storage conditions (30 min) had a significant effect on measured RRS rates, in specific, RRS rates of all three species were significantly lower under dry storage. Irrespective of plant species or temperature, storage of excised roots in water did not affect RRS for 300 min,. RRS measurements remained stable for 1 day if roots were stored cold.ConclusionsOur results have important implications on measurement routines of RRS—a generally understudied root trait. Henceforth it seems reasonable to collect roots in the field and transport them, hydrated but even uncooled, to the laboratory for subsequent measurements for at least 300 min post-rinsing.

Highlights

Root respiration (RR) is a major component of the terrestrial carbon cycle, contributing 10–90% to total soil respiration (Bond-Lamberty et al 2004; Hanson et al 2000)
Specific root respiration (RRS) is defined as the amount of CO2 released or O2 absorbed per unit root during a given time; RRS originates from three physiological processes: ion mobilization and uptake, growth and defence, and cell maintenance (Van der Werf et al 1994)
Storage conditions had a significant effect on the measured RRS rates, i.e. RRS rates were in all three species significantly lower after D-storage when compared to other storage conditions (Table 2)

Summary

Introduction

Root respiration (RR) is a major component of the terrestrial carbon cycle, contributing 10–90% to total soil respiration (Bond-Lamberty et al 2004; Hanson et al 2000). Respiration of root-associated microbes such as mycorrhizal fungi can contribute to measured RRS rates (Bulgarelli et al 2012; Nielsen et al 1998), the specific carbon or O2 costs per unit root indicate carbon- or O2-use efficiencies, respectively. Specific root respiration varies largely among plants and are generally considered greater in fast-growing species (Poorter et al 1990; Rewald et al 2014). Regarding the composition of the soil solution, acquisition and assimilation of ammonium is often less carbon costly than that of nitrate (Bloom et al 1992; Rewald et al 2016) and concentrations of other nutrients and heavy metals alter RRS rates depending on concentrations (e.g. Otgonsuren et al 2016). Related to the amount of carbon assimilates available, RRS was found to vary or not over the course of a day (e.g. Trolldenier and von Rheinbaben 1981; Widén and Majdi 2001)

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