Combined effects of contrast between poor and rich patches and overall nitrate concentration on Arabidopsis thaliana root system structure

Abstract

Abstract. The law of correlative inhibition states that roots in a richer environment develop more intensively if other roots of the same plant are in a poorer environment. This probably occurs only when the cost of emitting these roots in the rich patch is compensated by the advantage of having more roots, i.e. in situations where the difference in concentration between rich and poor patches is strong or the overall nutrient amount in the environment is low. For the first time, we tested root system response to combined gradients of contrast between poor and rich patches and of overall NO 3 -concentration in agar gels. We set up a factorial in vitro experiment crossing contrast (null, weak, strong heterogeneity) with overall NO 3 -concentration (deficient, optimal, excessive). We observed an increase in ramification density with increasing heterogeneity in deficient situations; but a decrease with increasing heterogeneity in excessive situations. The interaction between overall NO 3 -concentration and heterogeneity had a significant effect on root ramification density and the distribution of root length in diameter classes. The overall nutrient status of the soil has to be considered to understand the effect of heterogeneity on plant development at the morphological as well as at the molecular level.Additional keywords: correlative inhibition law, heterogeneity, NO 3 -, root development and morphology, root length and ramification.

Contrasts between whole‐plant and local nutrient levels determine root growth and death inAilanthus altissima(Simaroubaceae)

“…Several researchers have noted that contrasts in resource levels are an important aspect of heterogeneity (Kotliar and Wiens, 1990; Lamb et al, 2004) and that the overall nutrient content of different contrasts can vary, confounding the influences of differences in soil nutrient levels on plant biomass growth (Lamb et al, 2004; Blouin and Puga‐Freitas, 2011). Lateral root proliferation and elongation of barley ( Hordeum vulgare cv.…”

“…The responses of a root to a resource patch may depend not only on the nutrient availability in the patch but also on the contrasts among the nutrient contents in other patches or overall (Friend et al, 1990; Wijesinghe and Hutchings, 1999; Blouin and Puga‐Freitas, 2011). Most studies examining root plasticity have focused on the responses to the level of resource in patches (Campbell and Grime, 1989; Einsmann et al, 1999; Wang et al, 2006), but little attention has been paid to the possible effects of contrasts among nutrient levels experienced by different roots of the plant (Kotliar and Wiens, 1990; Lamb et al, 2004).…”

“…The proportion of root biomass in enriched patches was significantly altered by the difference with other patches, and root to shoot ratios rose as the patch contrast increased, even though the overall resource level was unchanged. There was a significant effect of the contrast between poor and rich patches on the lateral root density and root elongation in Arabidopsis thaliana (Blouin and Puga‐Freitas, 2011). On the other hand, root mass, shoot mass, and C allocation to roots of Abutilon theophrasti did not respond to the degree of contrast in resource levels between rich patches and the background, but these contrasts may have been too weak to be detected by the plants (Lamb et al, 2004).…”

Root Foraging Precision: Do Experimental Conditions Matter?

“…Aside from the studied factors, the results of the root foraging precision experiments may be affected by the technical aspects of nutrient patch creation, particularly the level of the contrast between the patch and the background (Blouin and Puga-Freitas 2011;Weiser et al 2016). If the contrast between the patch and the background soil is too small, roots will not proliferate into the patch.…”

Editorial: Root systems for dry environments

“…It was developed to provide an efficient phenotyping screen for studying root architecture in lupins. Root system responses to poor and rich patches of nitrate is described by Blouin and Puga-Freitas (2011), who studied root systems in combined gradients of contrast between poor and rich patches and of overall nitrate concentration in the environment.…”