Have you ever had some house plants become more and yellow and start looking sad?

Whilst leaf yellowing can be caused by many problems, one of them might be nutrient deficiency. Some of the most common fertilisers contain nitrogen, phosphorus and potassium (NPK) but there are many other essential and non-essential elements which plants need.

An essential mineral element is manganese (Mn) which is important for photosynthesis and respiration. However, in extreme quantities, Mn can cause phytotoxicity especially in acidic soils or whilst the plant is waterlogged (i.e. roots are in standing water). Another non-essential metalloid element is silicon (Si), which is the second most abundant element in the earth’s crust and is important for plant growth and development.

In the previous decades, the role of Si addition for tolerating environmental stresses has been gaining a lot of interest as it can lead to plant cell wall thickening. Testing if Si can help some crops to withstand Mn toxicity can be done in greenhouse experiments using different doses of the elements and looking at how the plants grow. Whilst these observations lead to perhaps overoptimistic conclusions, a new technique of using micro-X-ray fluorescence (µ-XRF) enables scientists to visualise where and how much of these elements are taken up by the plant.

van der Ent and colleagues (2020) at the University of Queensland used a synchrotron-based (i.e. the electromagnetic radiation emitted when charged particles are accelerated radially) µ-XRF to visualise Si distribution on soybean and sunflower plants experiencing Mn toxicity. You can watch Dr Antony van der Ent talking about his research on hyperaccumulation by plants to avoid toxicity on Gardening Australia.