Imbalanced Ca/Mg and Ni excess effects on the growth, nutrient uptake, photosynthesis and antioxidant response of Punica granatum (cv. Granada) plants

Imbalanced Ca/Mg and excess Ni (due to serpentine stress) are limiting factors for plant productivity. The purpose of this study was to investigate if growth, nutrient uptake, PSII activity, photosynthesis and antioxidant activity of pomegranate (Punica granatum L., cv. Granada) plants were affected by serpentine stress. Pomegranate plants were grown in soil substrates from parent material marl (control), serpentine and serpentinized peridotite. Plant height, leaf, stem, root and total plant dry weight, as well as foliar N, P, K, Ca, Zn, Cu, chlorophyll content, fluorescence parameters, photosynthetic rate, and internal water use efficiency (WUEi) were significantly lower for the plants grown in the serpentinized peridotite soil. In contrast, higher ferric reducing antioxidant power (FRAP), total phenolics and total flavonoid content (TFC) levels were found in the serpentinized peridotite soil. The insignificant differences between the marl and serpentine soils in plant growth, PSII activity, photosynthesis and nutrient uptake indicated that P. granatum could tolerate a mild (not with extremely high Ni) serpentine stress. However, P. granatum could not tolerate stress showing excess Mg and imbalanced Ca/Mg, as found for the serpentinized soil of our study.