Kinnow mandarin production in arid regions is constrained by water-deficit and micronutrient imbalances, particularly iron (Fe) and zinc (Zn). This study evaluated the effects of Fe and Zn deficiency (Fe- and Zn-) and toxicity (Fe + and Zn+) under water-deficit conditions. Eight treatments, including individual and combined Fe/Zn deficiencies and toxicities along with control were assessed under pot conditions. Results revealed that water-deficit combined with Fe and Zn deficiency significantly reduced plant growth, biomass, leaf area, relative water content and chlorophyll concentrations. These effects were more severe under combined deficiencies compared to their individual deficiencies. In contrast, Fe and Zn toxicity enhanced vegetative traits such as leaf area and sprout length but induced abnormal morphogenesis, such as enlarged thorns and water sprouts. Root traits also showed sensitivity to nutrient treatments. Root length and root-shoot ratio increased under Zn toxicity, while specific root length was more severely affected by micronutrients deficiency. Leaf analysis exhibited treatment specific variations, indicating disrupted uptake. Nitrogen and potassium decreased under Fe-Zn deficiency, while phosphorus increased under Zn deficiency but decreased under Zn toxicity. The findings of the study revealed that Fe and Zn status influenced plant performance and nutrient balance under water-deficit conditions, highlighting the importance of balanced micronutrients management in citrus cultivation.
Góra et al. (Wed,) studied this question.