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.

Salicylic acid (SA) was sprayed on “Seddik” mango transplants at concentrations of 0, 0.5, 1, and 1.5 mM. Then, the mango transplants were subjected to 72 h of chilling stress at 4 ± 1 °C, followed by a six-day recovery under greenhouse conditions. Untreated transplants exposed to chilling stress represented the positive control, while those not exposed were the negative control. SA-pretreated mango transplants were compared to the positive and negative controls, evaluating physiological and biochemical changes. The SA concentration of 1.5 mM L−1 was the most efficient in mitigating chilling injury (CI) in mango transplants by maintaining the integrity of the leaves’ cell membrane and minimizing electrolyte leakage (EL), specifically after six days of recovery. SA increased photosynthetic pigment content, total sugar content, and 2, 2-diphenyl-1-picrylhydrazyl (DPPH) radical scavenging activity and decreased proline and total phenolic content in the “Seddik” mango transplants’ leaves. After exposure to chilling stress, the antioxidant enzymes’ internal activities in SA-pretreated chilled mango transplants improved, especially on the sixth day of recovery, compared to the negative control; the transplants nearly attained normal growth levels. Thus, SA can protect plants against the adverse effects of chilling stress.

Interstock is commonly used in deciduous fruit trees as a sustainable strategy to reduce the vigor of the scion associated with the high quality of fruits. In this study, we tested the effect of Paulsen 1103 (Vitis berlandieri x Vitis rupestris) as interstock on the grafting success, growth, and the physiological and chemical parameters of Flame seedless (Vitis vinifera) grapevine grafted onto Freedom (Vitis champinii x 1613C) and Paulsen 1103 rootstocks. This study was conducted over two seasons (2019 and 2020). The results indicated that direct grafting on the Paulsen 1103 rootstock recorded the highest grafting success percentage. Moreover, the grafting success percentage increased significantly when Paulsen 1103 was used as interstock between Flame seedless and Freedom rootstock (FI/P/Fr) compared to the grafting success without Paulsen 1103 interstock (FI/Fr). Also, using Paulsen 1103 as interstock between Flame seedless scion and Freedom rootstock (FI/P/Fr) significantly reduced the morphological parameters (shoot length, leaf area and the dry weight of shoots and roots) and physiological parameters of leaf (relative water content, transpiration rate, and stomatal conductance) but significantly increased the leaf chemical content (peroxidase activity, total phenols, total proline, and total soluble sugar content) compared to values of the parameters measured in Flame seedless grafted onto Freedom rootstock (FI/Fr). Peroxidase activity could be used for predicting the degree of compatibility in grapevine grafts. This study suggested that the effect of Paulsen 1103 interstock on the vegetative growth of scion is correlated with its effect on chemical content and physiological responses of the scion.

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