δ13C as a tool for iron and phosphorus deficiency prediction in crops

Many studies proposed the use of stable carbon isotope ratio (delta C-13) as a predictor of abiotic stresses in plants, considering only drought and nitrogen deficiency without further investigating the impact of other nutrient deficiencies, that is, phosphorus (P) and/or iron (Fe) deficiencies. To fill this knowledge gap, we assessed the delta C-13 of barley (Hordeum vulgare L.), cucumber (Cucumis sativus L.), maize (Zea mays L.), and tomato (Solanum lycopersicon L.) plants suffering from P, Fe, and combined P/Fe deficiencies during a two-week period using an isotope-ratio mass spectrometer. Simultaneously, plant physiological status was monitored with an infra-red gas analyzer. Results show clear contrasting time-, treatment-, species-, and tissue-specific variations. Furthermore, physiological parameters showed limited correlation with delta C-13 shifts, highlighting that the plants' delta C-13, does not depend solely on photosynthetic carbon isotope fractionation/discrimination (Delta). Hence, the use of delta C-13 as a predictor is highly discouraged due to its inability to detect and discern different nutrient stresses, especially when combined stresses are present.

Automated summary

Many studies have suggested using stable carbon isotope ratio (delta C-13) to predict abiotic stresses in plants, specifically drought and nitrogen deficiency. However, the impact of other nutrient deficiencies, such as phosphorus and/or iron deficiencies, has not been thoroughly examined. This study assessed the delta C-13 of four plant species suffering from different nutrient deficiencies and found contrasting variations in time, treatment, species, and tissue-specific responses. The results also showed limited correlation between physiological parameters and delta C-13 shifts, indicating that delta C-13 cannot solely be relied upon as a predictor for nutrient stresses, especially when combined stresses are present.