Modulating the persistence and bioactivity of allelochemicals in the rhizosphere: salicylic acid, a case of study

ABSTRACT

The activity of allelochemicals in agroecosystems is highly dependent on their soil persistence. The aim of this work was to establish a link between the soil persistence of salicylic acid (SA) and its bioactivity, to better understand the mechanisms of allelochemical-mediated soil-plant interactions. Incubation and bioassay experiments were conducted for this purpose. The addition of HgCl₂ and decreasing temperature to 4 °C increased the persistence of SA in soil. Since these treatments greatly decreased the soil respiration, they probably slowed the SA dissipation by reducing the soil microbial activity. To a lesser extent, soil humidity and soil pH also influenced the SA dissipation rate. Exogenous olive-mill organic waste (ALP) increased the soil respiration, but interestingly, delayed the degradation of SA, presumably because ALP acted as an alternative source of C for soil microorganisms. The phytotoxicity of SA towards Eruca vesicaria in soil increased by the addition of ALP. Applied to soil at 0.5%, ALP reduced the SA dose for 50% Eruca vesicaria aerial biomass inhibition to 40%. Our results show how certain agronomic practices, such as the application of agri-industrial biosolids, could be used to modulate the persistence of allelochemicals in the rhizosphere and control their biological functions in soils.

Graphical Abstract

KEYWORDS:

• Agri-industrial wastes
• biodegradation
• biopesticides
• herbicides
• rhizosphere processes

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This work was supported by the Spanish Ministry of Economy, Industry and Competitiveness (MINEICO grants AGL2014-51897-R and AGL2017-82141-R), with FEDER-FSE funds. B.G. grateful acknowledges MINEICO for her Juan de la Cierva-Incorporación postdoctoral contract (IJCI-2015-23309).