Interest of hemp for phytomanagement of heavy metal contaminated agricultural soil : putative impact of silicon in relation to fibre production
(2021)
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- Abstract
- Cannabis sativa L. is a promising species for non-food production on moderate heavy metal (HM)-contaminated farmland soils and considered as a potential crop for cleaning the soil from HM because of its high biomass production, its long root system and its capacity to absorb and accumulate HM. However, until now, “soil remediation” is usually considered independently of “soil production”, and there is an obvious lack of information regarding the possibility to conciliate phytomanagement and obtaining valuable marketable products. The global aim of the present thesis is to contribute to fil this gap, with specific attention to hemp fibres, the most economically valuable part of the plant. Using two different growing systems (nutrient solution or contaminated agricultural soil), we investigated the contaminant concentration and distribution in hemp raw material, hemp HM tolerance, and the impact of HM on fibre production and quality, considering for the first time industrial standards. We showed that C. sativa is suited for fibre production associated with HM management due to its extraction potential. However, this strategy should be limited to soils with a moderate content of HM, considering that high HM bioavailability negatively impacted plant growth and development. The management of moderately HM-contaminated soils with hemp can contribute to reduce the dispersion of HM in the environment through its high biomass yield and its important root system. Besides, HM impacted fibre elongation and thickening, but not their mechanical properties, and were mainly accumulated in trichomes rather than in fibres. Fibres could thus be used in special products like insulating material and cements, with a specific attention to the stability of these material regarding the erosion of the final product. To devise agricultural strategies aimed at improving crop yield, the effect of silicon (Si) on plants’ stress resistance was also considered. Overall, we demonstrated that the addition of Si had numerous physiological impacts on the plant behavior occurring rapidly after HM stress application and before any modification in terms of growth. The main beneficial effects involved HM sequestration, improved oxidative response, and stimulation of energy metabolism. Si thus has the potential of enabling the plant to react adaptively against HM stress responses and promotes tolerance. Si also accumulated in bast fibres and influenced the timing of fibre elongation and transition from elongation to thickening. Si application can thus have an impact on fibres’ final properties after harvest.
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Luyckx, M. (2021). Interest of hemp for phytomanagement of heavy metal contaminated agricultural soil : putative impact of silicon in relation to fibre production. https://hdl.handle.net/2078.5/110760