Developments in the use of chlorophyll a fluorescence to diagnose phosphorus deficiency in plants

Keywords: phosphorus, nutrient deficiency, chlorophyll ? fluorescence, diagnosis, OJIP, photosynthesis.

Phosphorus (P) is a finite natural resource and an essential plant macronutrient with a major impact on crop productivity and global food security. Phosphorus deficiency is not easily diagnosed whether by analysis of soil or plant tissue, and excessive P application is often the practical solution to ensure optimal crop yield. This paper demonstrates that time-resolved chlorophyll ? fluorescence is a unique tool to monitor bioactive P in plants, and that the approach can be used to detect latent P deficiency.

When plants suffer from P deficiency, the shape of the time-dependent fluorescence transients is altered distinctively, as the so-called I-step gradually straightens and eventually disappears. This effect is shown to be fully reversible, as P resupply leads to a rapid restoration of the I-step. Among the essential plant nutrients, the effect of P deficiency is rather specific and sufficiently sensitive to enable rapid in situ determination of latent P deficiency across different plant species, thereby providing a unique tool for the timely remediation of P deficiency in agriculture.