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Phytotoxic effects of (+/-)-catechin in vitro, in soil, and in the field.

- PLoS ONE (2008)

Bottom Line: Experimental application of (+/-)-catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations.Our results demonstrate that (+/-)-catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied at low concentrations in the field.However, there is substantial conditionality in the effects of the allelochemical.

View Article: PubMed Central - PubMed

Affiliation: Centre for Environmental Management of Degraded Ecosystems, University of Delhi, Delhi, India. inderjit@cemde.du.ac.in

ABSTRACT

Background: Exploring the residence time of allelochemicals released by plants into different soils, episodic exposure of plants to allelochemicals, and the effects of allelochemicals in the field has the potential to improve our understanding of interactions among plants.

Methodology/principal findings: We conducted experiments in India and the USA to understand the dynamics of soil concentrations and phytotoxicity of (+/-)-catechin, an allelopathic compound exuded from the roots of Centaurea maculosa, to other plants in vitro and in soil. Experiments with single and pulsed applications into soil were conducted in the field. Experimental application of (+/-)-catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations. Pulses replenished (+/-)-catechin levels in soils, but consistently at concentrations much lower than were applied, and even pulsed concentrations declined rapidly. Different natural soils varied substantially in the retention of (+/-)-catechin after application but consistent rapid decreases in concentrations over time suggested that applied experimental concentrations may overestimate concentrations necessary for phytotoxicity by over an order of magnitude. (+/-)-Catechin was not phytotoxic to Bambusa arundinacea in natural Indian soil in a single pulse, but soil concentrations at the time of planting seeds were either undetectable or very low. However, a single dose of (+/-)-catechin suppressed the growth of bamboo in sand, in soil mixed with organic matter, and Koeleria macrantha in soils from Montana and Romania, and in field applications at 40 microg l(-1). Multiple pulses of (+/-)-catechin were inhibitory at very low concentrations in Indian soil.

Conclusions/significance: Our results demonstrate that (+/-)-catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied at low concentrations in the field. However, there is substantial conditionality in the effects of the allelochemical.

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Related in: MedlinePlus

Measured soil concentrations of (±)-catechin applied at 500 µg g−1 to soils from western Montana (white bars) and eastern Romania (black bars) and measured over time after application.Error bars show 1 SE. ANOVA statistics are presented in the results.
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pone-0002536-g003: Measured soil concentrations of (±)-catechin applied at 500 µg g−1 to soils from western Montana (white bars) and eastern Romania (black bars) and measured over time after application.Error bars show 1 SE. ANOVA statistics are presented in the results.

Mentions: Soil concentrations measured immediately after application of (±)-catechin in the 5 soils from Montana and the 5 soils from Romania were highly variable, ranging from almost zero for one Montana soil to mean concentrations that were ≈200 µg g−1 higher than the calculated application rate of 500 µg g−1 (Fig. 3). After 1 day, the mean (±)-catechin concentration for all 10 soils was 126±34 µg g−1 soil and the concentration decreased to a range of 0–41±33 µg g−1 among the 10 soils 10 days after application. In an ANOVA, the effect of continent (fixed) was not significant (F = 2.298; df = 1,8; P = 0.204); the effect of site (nested, random) was not significant (F = 1.224; df = 8,4; P = 0.424), but the effect of time (fixed) after application was highly significant ((F = 10.535; df = 4,160); P<0.001). The high concentrations early in the time series indicate that our extraction protocol was effective for these soils, and the high degree of variation within sites, and the very high initial spike in one soil, was likely due to the variation in clay and silt fractions in soil and uneven dispersion of the applied (±)-catechin or differences in soil chemistry. The phosphoric acid extraction protocol used by Blair et al. [28], with which they reported the highest recovery of experimentally applied (±)-catechin, coupled with our HPLC detection protocol, extracted even less (±)-catechin in the two soils for which we compared the methods. Also, standards made using methods described by Blair et al. [28] also demonstrated a decrease in sensitivity for (±)-catechin (data not shown). For soils from Breazu, Romania, the methanol extraction recovered 17.0±10.0 (1 SE) µg g−1 10 days after application, whereas the phosphoric acid and methanol extraction recovered 4.3±2.9 µg g−1. For soils from Nelson Gulch, Montana 7.4±7.2 µg g−1 (±)-catechin was recovered using the methanol extraction but no (±)-catechin was recovered using the phosphoric acid and methanol extraction.


Phytotoxic effects of (+/-)-catechin in vitro, in soil, and in the field.

- PLoS ONE (2008)

Measured soil concentrations of (±)-catechin applied at 500 µg g−1 to soils from western Montana (white bars) and eastern Romania (black bars) and measured over time after application.Error bars show 1 SE. ANOVA statistics are presented in the results.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2481294&req=5

pone-0002536-g003: Measured soil concentrations of (±)-catechin applied at 500 µg g−1 to soils from western Montana (white bars) and eastern Romania (black bars) and measured over time after application.Error bars show 1 SE. ANOVA statistics are presented in the results.
Mentions: Soil concentrations measured immediately after application of (±)-catechin in the 5 soils from Montana and the 5 soils from Romania were highly variable, ranging from almost zero for one Montana soil to mean concentrations that were ≈200 µg g−1 higher than the calculated application rate of 500 µg g−1 (Fig. 3). After 1 day, the mean (±)-catechin concentration for all 10 soils was 126±34 µg g−1 soil and the concentration decreased to a range of 0–41±33 µg g−1 among the 10 soils 10 days after application. In an ANOVA, the effect of continent (fixed) was not significant (F = 2.298; df = 1,8; P = 0.204); the effect of site (nested, random) was not significant (F = 1.224; df = 8,4; P = 0.424), but the effect of time (fixed) after application was highly significant ((F = 10.535; df = 4,160); P<0.001). The high concentrations early in the time series indicate that our extraction protocol was effective for these soils, and the high degree of variation within sites, and the very high initial spike in one soil, was likely due to the variation in clay and silt fractions in soil and uneven dispersion of the applied (±)-catechin or differences in soil chemistry. The phosphoric acid extraction protocol used by Blair et al. [28], with which they reported the highest recovery of experimentally applied (±)-catechin, coupled with our HPLC detection protocol, extracted even less (±)-catechin in the two soils for which we compared the methods. Also, standards made using methods described by Blair et al. [28] also demonstrated a decrease in sensitivity for (±)-catechin (data not shown). For soils from Breazu, Romania, the methanol extraction recovered 17.0±10.0 (1 SE) µg g−1 10 days after application, whereas the phosphoric acid and methanol extraction recovered 4.3±2.9 µg g−1. For soils from Nelson Gulch, Montana 7.4±7.2 µg g−1 (±)-catechin was recovered using the methanol extraction but no (±)-catechin was recovered using the phosphoric acid and methanol extraction.

Bottom Line: Experimental application of (+/-)-catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations.Our results demonstrate that (+/-)-catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied at low concentrations in the field.However, there is substantial conditionality in the effects of the allelochemical.

View Article: PubMed Central - PubMed

Affiliation: Centre for Environmental Management of Degraded Ecosystems, University of Delhi, Delhi, India. inderjit@cemde.du.ac.in

ABSTRACT

Background: Exploring the residence time of allelochemicals released by plants into different soils, episodic exposure of plants to allelochemicals, and the effects of allelochemicals in the field has the potential to improve our understanding of interactions among plants.

Methodology/principal findings: We conducted experiments in India and the USA to understand the dynamics of soil concentrations and phytotoxicity of (+/-)-catechin, an allelopathic compound exuded from the roots of Centaurea maculosa, to other plants in vitro and in soil. Experiments with single and pulsed applications into soil were conducted in the field. Experimental application of (+/-)-catechin to soils always resulted in concentrations that were far lower than the amounts added but within the range of reported natural soil concentrations. Pulses replenished (+/-)-catechin levels in soils, but consistently at concentrations much lower than were applied, and even pulsed concentrations declined rapidly. Different natural soils varied substantially in the retention of (+/-)-catechin after application but consistent rapid decreases in concentrations over time suggested that applied experimental concentrations may overestimate concentrations necessary for phytotoxicity by over an order of magnitude. (+/-)-Catechin was not phytotoxic to Bambusa arundinacea in natural Indian soil in a single pulse, but soil concentrations at the time of planting seeds were either undetectable or very low. However, a single dose of (+/-)-catechin suppressed the growth of bamboo in sand, in soil mixed with organic matter, and Koeleria macrantha in soils from Montana and Romania, and in field applications at 40 microg l(-1). Multiple pulses of (+/-)-catechin were inhibitory at very low concentrations in Indian soil.

Conclusions/significance: Our results demonstrate that (+/-)-catechin is highly dynamic in natural soils, but is phytotoxic well below natural concentrations measured in some soils and applied at low concentrations in the field. However, there is substantial conditionality in the effects of the allelochemical.

Show MeSH
Related in: MedlinePlus