سعید شفیعی

The soils citrus rootstocks grow in are mostly calcareous and iron defciency is a common problem for crops growing in calcareous soil. Therefore, the present study was conducted to investigate the efect of diferent citrus rootstocks and rhizosphere distance on chemical forms of iron in calcareous soil and the study of correlations between chemical forms of iron. To investigate the efect of rhizosphere (rhizosphere soil, 2, 4, 6 mm distance from rhizosphere and non-rhizosphere soils) and diferent citrus rootstocks (Poncera, Narenj, Backraii, Citrumelo, Raf lemon, Rangpur lime, Cleopatra, Valkameriana, Troyer citrange) on chemical forms of iron, a greenhouse experiment was conducted in a factorial and completely randomized design with three replications. The seed of the plants was cultivated and settled in the rhizobox for 5 months. Then in the collected samples, the chemical forms of iron (using a sequential extraction method) and absorbable iron were measured through DTPA method. The results showed that the exchangeable Fe, oxide bound Fe and organically bound Fe in the rhizosphere had a lower concentration of iron than the other parts, but carbonate bound Fe at a distance of 2 mm from the rhizosphere had the lowest concentration of iron compared to other distances. Also, In Narenj, Raf lemon and Troyer citrange rootstocks, the concentration of active iron in the roots was lower than that in the shoot, which indicates the high efciency of iron transfer from root to leaf in these rootstocks. The highest uptake of active iron in the shoot was in Raf lemon (21793 mg kg−1) and Narenj rootstocks (19690 mg kg −1), and the lowest uptake of active iron in the shoot was obtained from the rootstock of Backraii (74892 mg kg−1). In general, the results of this study showed that the concentration and uptake of iron in the plant were strongly dependent on the type of rootstock. The highest amount of active iron in the shoot was obtained in the Raf lemon and Narenj rootstocks, which indicates the high efciency of iron transfer from root to leaf in these rootstocks. Also, the study of the correlation between iron fractions in rhizosphere soil and the concentration and uptake of iron in the root and shoot showed that there is a positive relationship only between the oxide-bound Fe component and active iron of the shoot which this shows the direct relationship between these two traits.