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Using interstock with a potential genetic base is considered more recent and sustainable strategy for mitigating the water deficit. This investigation was carried out on transplant of Flame seedless (Vitis vinifera) grapevine grafted onto two rootstocks namely; Freedom (Vitis champinii x 1613C) and 1103Paulsen (vitis berlandieri x Vitis rupestris) with or without 1103Paulsen as interstock to determine its performance under deficit irrigation condition (50% of field capacity). The results indicated that Paulsen as rootstock or as interstock significantly increased the growth vigor of Flame seedless scion as well as the leaf content of total proline, phenols and sugars. Paulsen rootstock has decreased stomatal conductance, leaf transpiration rate and increased diffusion resistance under 50% deficit irrigation compared with grafting on Freedom rootstock. Moreover, Paulsen as interstock for Flame seedless grafted onto Freedom rootstock significantly increased relative water content accompanied by an increase in thickness of leaf anatomical characters such as midvein, lamina, palisade, xylem and phloem tissue under deficit irrigation compared with grafts without Paulsen interstock. This study suggests that using Paulsen as interstock, can be an adaptation strategy for water stress through controlling in some morphological, chemical physiological and anatomical responses of scion.

The grafting of grapevines has become essential to overcome biotic and abiotic stresses because permits access to the benefits of the agronomical characteristics of different rootstocks. Stimulating the rapid formation of the grafting union is the key to grafting success. This investigation studied the effect of removing growth inhibitors through soaking in water for 24 hours versus adding growth stimulate through fast dipping in 250 mg/L benzyladenine (BA) for 30 seconds of graft wood before grafting on the grafting success of ‘Flame Seedless’ and ‘Early Sweet’ scions (Vitis vinifera) grafted onto ‘Freedom’ rootstock (Vitis champinii x 1613C). Water soaking came first and followed by treatment of 250 mg/L BA, which significantly improved the grafting success of both cultivars. Grafting success was positively associated with increasing callus formation at the grafting zone, which was accompanied with the highest total indols content, the lowest total phenols content, and peroxidase activity above and below the grafting zone. However, water soaking significantly increased total indols and decreased the total phenols content of the ungrafted cuttings. In this study, it was suggested that the application of water soaking to grafted cuttings prior to grafting is an environmentally friendly and alternative practice for synthetic growth regulators to improve grafted cuttings success.

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