Effect of Rootstock and Scion on Nutrient Uptake of Two Pomegranate Cultivars Rabab-e-Neyriz and Khafr-e-Jahrom

IntroductionPomegranate (Punica granatum L.) from the family Punicaceae, is an important and exportable fruit crop in Iran. At present, Iran is the leading producer of this fruit followed by India, Turkey and Spain. As the main area under pomegranate cultivation in Iran are located in arid and semi-arid adjacent to desert regions. Low irrigation water quality, lime induced Fe chlorosis, soil salinity, nutrient imbalance and soil-borne diseases are the most limiting factors in this areas. Currently about 760 genotypes and cultivars of pomegranate have been identified, collected and growth in Pomegranate Research Institute in Yazd province, central Iran. In rich collection, it is likely that some genotypes are tolerant to adverse environmental conditions but neglected due to their low quality fruits. These genotypes could be evaluated and used as potential rootstocks. ‘Rabab-e-Neyriz’ is one of the most important pomegranate cultivar that is planted in parts of western south of Iran to gather ‘Khafr-e-Jahroom’ cultivar. Fruits in ‘Rabab-e-Neyriz’ cultivar are big with dark red color arils. In the last decades, there has been a tremendous towards using grafted/budded plants in fruit orchards. Moreover, the available reports indicate that rootstock could affect the tolerance of scion to soil borne diseases, lime-induced Fe-deficiency chlorosis and salinity stress that they can control with grafting on tolerance rootstocks. There are inadequate formations on the effects of rootstock on scion of pomegranate. The aim of the study was effects of three rootstocks; ‘Gorj-e-Dadashi’, ‘Gorj-e-Shahvar’ and ‘Post Ghermaz-e-Aliaghai’ on nutrient concentration of two pomegranate cultivars; ‘Rabab-e-Neyriz’ and ‘Khafr-e-Jahroom’; as scion.Material and MethodsIn order to investigate the interaction of rootstock and scion on nutrient uptake in two pomegranate cultivars ‘Rabab-e-Neyriz’and ‘Khafr-e-Jahroom’, research was performed in the form of a factorial experiment in complete randomized blocks design with scion factors at two levels (‘Rabab-e-Neyriz’and ‘Khafr-e-Jahroom’) and the rootstock on four levels (‘Post Ghermaz-e-Aliaghai’, ‘Gorj-e-Dadashi’, ‘Gorj-e-Shahvar’and without graft) with five repetitions. Omega grafting method was used to production grafting plants. One year grafting plants were planted on farm with 2.0 m apart within rows and 4.0 m apart between rows. Non grafting cuttings of scions that rooted same time with rootstocks were planted in farm as control. In the first summer leaf samples were collected to determine macro and micro elements. Results and DiscussionThe results showed that the interaction of rootstock and scion is effective on the uptake of elements. The concentration of elements in the scion varied depending on the type of graft combination. The highest levels of phosphorus, potassium, and calcium of leaves were observed in the grafting plants of ‘Rabab-e-Neyriz’ scion on ‘Gorj-e-Dadashi’ rootstock, ‘Khafr-e-Jahroom’ scion on ‘Gorj-e-Dadashi’ rootstock, and ‘Rabab-e-Neyriz’ scion on ‘Gorj-e-Shahvar’ rootstock, respectively. Also, the highest amounts of iron (75 mg/g dry weight), manganese (65 mg/g dry weight), and copper (25 mg/g dry weight) were obtained from the grafting plants of ‘Rabab-e-Neyriz’ scion on ‘Gorj-e-Dadashi’ rootstock, ‘Khafr-e-Jahroom’ scion on ‘Gorj-e-Dadashi’ rootstock and, in both scions on ‘Gorj-e-Shahvar’ rootstock compared to non-grafted plants.  ConclusionThe results of this research have shown that the amount of nutrients in the leaves of grafted pomegranate cultivars is not only influenced by the rootstock, but also by the genetics of the scion. The concentration of mineral elements in the scion is mainly related to the characteristics of the root system of rootstock, including the lateral and vertical expansion of the root, which increases the absorption of water and minerals. Due to the weaker root system, the ‘Post Ghermaz-e-Aliaghai’ has a lower concentration of mineral elements in the cultivars grafted on this rootstock. According to the results of the present study, the reason for the higher nutritional elements in plants grafted with the rootstocks of ‘Gorj-e-Dadashi’ and ‘Gorj-e-Shahvar’ can be attributed to the greater growth power of these roots  and their extensive root system. He attributed that wider research is recommended in this field.